A Sodium Chromite Preparation Apparatus and Method Based on Mechanochemical Method

Abstract

This invention relates to the field of sodium ion electronics technology, specifically disclosing a sodium chromite preparation apparatus and method based on a mechanochemical method. The apparatus includes a base, on which a drive disk is rotatably mounted. A main ball mill jar is rotatably mounted in the center of the drive disk, and two symmetrically arranged auxiliary ball mill jars are rotatably mounted on the drive disk. This invention utilizes the synergistic effect of the main and auxiliary ball mill jars, and uses argon gas as a protective gas carrier to continuously flow, dynamically carrying the refined chromium oxide and sodium carbonate from the auxiliary ball mill jars into the main ball mill jar. This achieves a continuous process of raw material pretreatment and mechanochemical reaction, avoiding material accumulation, ensuring real-time contact of reactants, and improving the reaction rate. Furthermore, the product is sodium chromite powder produced by high-energy ball milling, eliminating the need for mechanical crushing and secondary ball milling, significantly shortening the production cycle and improving production efficiency.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a sodium chromite preparation apparatus and method based on a mechanochemical method. Background Technology

[0002] Sodium-ion batteries are rechargeable batteries that primarily function by the movement of sodium ions between the positive and negative electrodes, similar to the working principle of lithium-ion batteries. Layered oxide materials of sodium chromite possess a stable crystal structure and extremely high reversible capacity, making them considered ideal cathode materials for sodium-ion batteries. Furthermore, the application of layered sodium chromite as a cathode material in sodium-ion batteries enables them to exhibit high reversible capacity, high electrochemical activity, and excellent cycle stability.

[0003] Currently, sodium chromite is prepared by mixing, pressing, sintering, and grinding raw materials using sodium carbonate and chromium oxide to obtain sodium chromite powder. Additionally, patent number CN114180628A discloses a vacuum method for preparing sodium chromite, specifically: first, the raw materials are heated, dried, and mixed in a specific ratio; then, they are ball-milled, pressed into tablets, and finally calcined in a vacuum reactor to obtain sodium chromite.

[0004] The above method for preparing sodium chromite from sodium carbonate and chromium oxide has the following disadvantages: 1. It requires continuous high-temperature calcination, which consumes a lot of energy and increases costs; 2. The product becomes dense: the product after calcination is a flaky and dense block, which requires additional mechanical crushing and ball milling, increasing the complexity of the process and the production cycle of the sodium chromite powder, thus reducing production efficiency.

[0005] To address the above problems, this invention provides a sodium chromite preparation apparatus and method based on a mechanochemical method. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the existing defects and provide a sodium chromite preparation device and method based on mechanochemical method. Through the synergistic effect of the main ball mill and the auxiliary ball mill, and with argon gas as a protective gas continuously flowing as a carrier, the refined chromium oxide and sodium carbonate in the auxiliary ball mill are dynamically carried into the main ball mill, realizing a continuous process of raw material pretreatment and mechanochemical reaction, avoiding material accumulation, ensuring real-time contact of reactants, which is conducive to improving the reaction rate. It can also significantly shorten the interval time of multiple steps such as mixing, tableting, and calcination in traditional processes, reduce process complexity, and improve production efficiency, effectively solving the problems in the background technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a sodium chromite preparation apparatus based on a mechanochemical method, comprising a base, a drive disk rotatably disposed on the base, a main ball mill jar rotatably disposed in the center of the drive disk, and two symmetrically disposed auxiliary ball mill jars rotatably disposed on the drive disk, a main turntable rotatably disposed in the center of the lid of the main ball mill jar, and an auxiliary turntable rotatably disposed in the center of the lid of the auxiliary ball mill jar; The main turntable has a main shaft on its upper surface. The main shaft has evenly distributed feed holes in the middle of its side surface, and an annular hole at its lower end. The feed holes communicate with the inner cavity of the main ball mill jar through the annular hole. An annular sleeve is provided on the side of the main shaft corresponding to the feed holes. A feed pipe penetrating the secondary turntable is provided on the side of the annular sleeve, and a primary screen is provided at the feed inlet of the feed pipe. The upper side of the main shaft is provided with a vent pipe assembly that communicates with the inner cavity of the auxiliary ball mill jar. The main shaft is a hollow structure, and a hollow screw is threaded inside the main shaft. A secondary screen is installed at the bottom of the hollow screw via a connecting rod.

[0008] As a preferred embodiment of the present invention, the upper surface edge of the base is provided with a telescopic rod, and the top of the telescopic rod is provided with a fixing plate connected to the upper end of the side of the main shaft.

[0009] As a preferred embodiment of the present invention, the venting pipe assembly includes a distribution ring installed on the upper side of the main shaft. The distribution ring is a hollow structure, and an annular sealing plate is rotatably provided at the bottom of the distribution ring. An air outlet pipe is provided on the annular sealing plate. The air outlet of the air outlet pipe passes through the secondary turntable and extends into the inner cavity of the secondary ball mill jar. An air inlet pipe is provided on the side of the distribution ring.

[0010] As a preferred embodiment of the present invention, the drive disk has a belt groove on its peripheral side and a toothed ring on the inner side of the base, and the bottom of the auxiliary grinding jar has an auxiliary gear that meshes with the toothed ring.

[0011] As a preferred embodiment of the present invention, the bottom of the main grinding jar is provided with a main gear, and the bottom of the drive disk is provided with a transmission gear set, and the gear ring drives the main gear to rotate through the transmission gear set.

[0012] A method for preparing a sodium chromite preparation apparatus based on mechanochemical method, comprising the following steps: S1. Heat and dry chromium oxide powder and sodium carbonate powder separately, and put the dried chromium oxide powder and sodium carbonate powder into different auxiliary ball mill jars in proportion; S2. First, argon gas is introduced to purge the residual air in the auxiliary and main ball milling jars. Then, the external drive motor is controlled to work. The external drive motor controls the drive disc to rotate through the belt. The drive disc drives the main and auxiliary ball milling jars to rotate. Under the action of the gear ring and the auxiliary gear meshing, the auxiliary ball milling jar rotates on its own axis while revolving around the revolution, thereby ball milling chromium oxide powder and sodium carbonate powder. S3. Under the influence of argon gas, chromium oxide powder and sodium carbonate powder with particle sizes smaller than the primary sieve aperture enter the main ball mill jar through the feed pipe. Under the action of the gear ring, transmission gear set and main gear, the main ball mill jar rotates at high speed to generate high-energy ball milling. High-energy ball milling promotes atomic-level diffusion between chromium oxide particles and sodium carbonate particles, forming an amorphous interface layer and directly generating sodium chromite. At the same time, under the continuous introduction and discharge of argon gas, the by-product carbon dioxide is discharged through the hollow screw along with the argon gas, and the secondary sieve blocks the material in the main ball mill jar.

[0013] As a preferred embodiment of the present invention, in S1, the heating temperature of chromium oxide powder and sodium carbonate powder is 300-600℃, the heating time is 2-3h, and the molar ratio of chromium oxide powder and sodium carbonate powder is 1:1-1.2.

[0014] As a preferred embodiment of the present invention, both the main grinding jar and the auxiliary grinding jar use silicon carbide grinding balls; wherein, in the main grinding jar, the diameter of the large ball is 5-10 mm, the diameter of the small ball is 2-5 mm, and the mass ratio of the large ball to the small ball is 3-4:1; in the auxiliary grinding jar, the diameter of the large ball is 10-20 mm, the diameter of the small ball is 5-10 mm, and the mass ratio of the large ball to the small ball is 1-1.5:1.

[0015] As a preferred embodiment of the present invention, in S3, the primary screen uses a 150-200 mesh screen, and the secondary screen uses a 400-600 mesh screen.

[0016] As a preferred embodiment of the present invention, the main grinding jar rotates at a speed of 600-1000 rpm, the auxiliary grinding jar rotates at a speed of 250-400 rpm, and the auxiliary grinding jar revolves at a speed of 100-200 rpm.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. The sodium chromite preparation apparatus and method based on mechanochemical method of the present invention adopts the synergistic effect of main ball mill jar and auxiliary ball mill jar to realize the continuous process of raw material pretreatment and mechanochemical reaction, which can significantly shorten the interval time of multiple steps such as mixing, tableting and calcination in traditional process, thereby improving production efficiency.

[0018] 2. The sodium chromite preparation apparatus and method based on the mechanochemical method of the present invention uses argon gas as a protective gas as a carrier to continuously flow and dynamically carry the refined chromium oxide and sodium carbonate in the auxiliary ball mill jar into the main ball mill jar, avoiding material accumulation, ensuring real-time contact of reactants, and improving the reaction rate.

[0019] 3. The sodium chromite preparation apparatus and method based on the mechanochemical method of the present invention directly drive the solid reaction through high-energy ball milling, eliminating the need for high-temperature calcination in traditional processes and reducing energy consumption. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a bottom-view structural diagram of the present invention; Figure 3 This is a partial structural diagram of the present invention; Figure 4 for Figure 3 A schematic diagram of the structure viewed from below; Figure 5 This is a schematic diagram of the distribution ring structure in this invention.

[0021] In the diagram: 1. Base, 2. Telescopic rod, 21. Fixing plate, 3. Drive disc, 4. Main grinding jar, 41. Main turntable, 5. Secondary grinding jar, 51. Secondary turntable, 6. Main shaft, 61. Annular hole, 62. Feed hole, 63. Hollow screw, 64. Connecting rod, 65. Secondary screen, 7. Annular sleeve, 71. Feed pipe, 72. Primary screen, 8. Distribution ring, 81. Air inlet pipe, 82. Air outlet pipe. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1-5This invention provides a technical solution: a sodium chromite preparation device based on a mechanochemical method, comprising a base 1, a drive disk 3 rotatably mounted on the base 1, a main ball mill jar 4 rotatably mounted in the center of the drive disk 3, and two symmetrically arranged auxiliary ball mill jars 5 rotatably mounted on the drive disk 3. Through the cooperation of the main ball mill jar 4 and the auxiliary ball mill jars 5, during the ball milling process of the raw materials, the raw materials entering the main ball mill jar 4 can be directly subjected to high-energy ball milling, using mechanical energy to induce chemical reactions or induce changes in the material's microstructure, structure, and properties, thereby causing chromium oxide and sodium carbonate to react to form sodium chromite. A main turntable 41 is rotatably mounted in the center of the lid of the main ball mill jar 4, and an auxiliary turntable 51 is rotatably mounted in the center of the lid of the auxiliary ball mill jar 5. By directly driving the solid-state reaction through high-energy ball milling, the high-temperature calcination in traditional processes is eliminated, thus reducing energy consumption.

[0024] The upper surface of the main turntable 41 is provided with a main shaft 6. The middle of the side of the main shaft 6 is provided with evenly distributed feed holes 62. The lower end of the main shaft 6 is provided with an annular hole 61. The feed holes 62 are connected to the inner cavity of the main ball mill jar 4 through the annular hole 61. The side of the main shaft 6 corresponding to the feed holes 62 is provided with an annular sleeve 7. The side of the annular sleeve 7 is provided with a feed pipe 71 that penetrates the auxiliary turntable 51. The feed inlet of the feed pipe 71 is provided with a primary screen 72. The raw material after ball milling in the auxiliary ball mill jar 5 is filtered by the primary screen 72 and then enters the main ball mill jar 4 with argon gas for high-energy ball milling.

[0025] The upper side of the main shaft 6 is provided with a vent pipe assembly that communicates with the inner cavity of the auxiliary ball mill jar 5. The main shaft 6 is a hollow structure. A hollow screw 63 is threadedly connected inside the main shaft 6. A secondary screen 65 is installed at the bottom of the hollow screw 63 through a connecting rod 64. The secondary screen 65 is used to filter the material in the main ball mill jar 4 to prevent the material from being discharged.

[0026] Furthermore, the upper surface edge of the base 1 is provided with a telescopic rod 2, and the top of the telescopic rod 2 is provided with a fixing plate 21 connected to the upper side of the spindle 6, which serves to fix the spindle 6.

[0027] Furthermore, the ventilation pipe assembly includes a distribution ring 8 installed on the upper side of the main shaft 6. The distribution ring 8 is a hollow structure, and an annular sealing plate is rotatably provided at the bottom of the distribution ring 8. An air outlet pipe 82 is provided on the annular sealing plate. The air outlet of the air outlet pipe 82 passes through the secondary turntable 51 and extends into the inner cavity of the secondary ball mill jar 5. An air inlet pipe 81 is provided on the side of the distribution ring 8. The connection between the air outlet pipe 82 and the secondary ball mill jar 5 can be maintained by the rotating annular sealing plate.

[0028] Furthermore, the drive disk 3 has a belt groove on its peripheral side and a gear ring on the inner side of the base 1. The bottom of the auxiliary grinding jar 5 has a secondary gear that meshes with the gear ring. When the drive disk 3 rotates, it drives the auxiliary grinding jar 5 to rotate. Under the meshing action of the secondary gear and the gear ring, the auxiliary grinding jar 5 can rotate on its own, thereby improving the grinding effect.

[0029] Furthermore, a main gear is provided at the bottom of the main grinding jar 4, and a transmission gear set is provided at the bottom of the drive disk 3. The gear ring drives the main gear to rotate through the transmission gear set. The transmission gear set includes a first gear meshing with the gear ring, a second gear meshing with the first gear, a third gear set at the bottom of the second gear, and the third gear meshing with the main gear. The diameter of the third gear is larger than that of the second gear. The gear set speeds up the main gear, thereby increasing the rotational speed of the main grinding jar 4 to achieve high-energy ball milling.

[0030] A method for preparing a sodium chromite preparation apparatus based on mechanochemical method, comprising the following steps: S1. Heat and dry chromium oxide powder and sodium carbonate powder separately. The heating temperature of chromium oxide powder and sodium carbonate powder is 300-600℃ and the heating time is 2-3h. The dried chromium oxide powder and sodium carbonate powder are placed in different auxiliary ball mill jars 5 according to the molar ratio of chromium oxide powder and sodium carbonate powder of 1:1-1.2. S2. First, argon gas is introduced to remove the residual air in the auxiliary ball milling jar 5 and the main ball milling jar 4. Then, the external drive motor is controlled to work. The external drive motor controls the drive disk 3 to rotate through the belt. The drive disk 3 drives the main ball milling jar 4 and the auxiliary ball milling jar 5 to rotate. Under the action of the gear ring and the auxiliary gear meshing, the auxiliary ball milling jar 5 rotates on its own axis while revolving around the revolution, thereby ball milling chromium oxide powder and sodium carbonate powder. S3. Under the influence of argon gas, chromium oxide powder and sodium carbonate powder with a particle size smaller than the aperture of the primary sieve 72 enter the main ball mill jar 4 through the feed pipe 71. Under the action of the gear ring, transmission gear set and main gear, the main ball mill jar 4 rotates at high speed to generate high-energy ball milling. High-energy ball milling promotes atomic-level diffusion between chromium oxide particles and sodium carbonate particles, forming an amorphous interface layer and directly generating sodium chromite. At the same time, under the continuous introduction and discharge of argon gas, the by-product carbon dioxide is discharged through the hollow screw 63 along with the argon gas. The secondary sieve 65 blocks the material in the main ball mill jar 4.

[0031] In this invention, argon gas, which serves as a protective gas, is continuously flowing as a carrier to dynamically carry the refined chromium oxide and sodium carbonate from the auxiliary ball mill jar 5 into the main ball mill jar 4. This avoids material accumulation, ensures real-time contact of reactants, and is beneficial for improving the reaction rate.

[0032] Furthermore, both the main grinding jar 4 and the auxiliary grinding jar 5 use silicon carbide grinding balls; in the main grinding jar 4, the large balls have a diameter of 5-10 mm, the small balls have a diameter of 2-5 mm, and the mass ratio of large balls to small balls is 3-4:1; in the auxiliary grinding jar 5, the large balls have a diameter of 10-20 mm, the small balls have a diameter of 5-10 mm, and the mass ratio of large balls to small balls is 1-1.5:1.

[0033] Furthermore, in S3, the primary screen 72 uses a 150-200 mesh screen, and the secondary screen 65 uses a 400-600 mesh screen.

[0034] Furthermore, the main grinding jar 4 rotates at a speed of 600-1000 rpm, the auxiliary grinding jar rotates at a speed of 250-400 rpm, and the auxiliary grinding jar revolves at a speed of 100-200 rpm.

[0035] The principle of preparing sodium chromite using the mechanochemical method is as follows: First, the grinding balls collide and rub violently with the raw material powders (Cr2O3 and Na2CO3) under high-speed rotation, generating high energy input; the mechanical force causes the crystal structure of Cr2O3 and Na2CO3 to be distorted, generating a large number of grain boundaries, dislocations and surface defects; the atomic activity at the defects is significantly increased, providing activation sites for ion diffusion and chemical reactions; Then: During the ball milling process, the raw material powder is repeatedly broken down to the nanoscale (50-100 nm), increasing the specific surface area (up to 20-50 m²). 2 / g), Cr 3+ and Na + The contact probability is greatly increased, and the mechanically induced local high pressure (instantaneous pressure reaching several GPa) and instantaneous high temperature (local micro-region temperature can reach 500-1000℃) accelerate ion diffusion, driving the following reactions: Cr2O3+Na2CO3 →2NaCrO2+CO2↑; Mechanical force directly breaks the Cr-O and Na-O bonds, promoting the formation of new bonds (Cr-O-Na) and generating layered NaCrO2.

[0036] Mechatronics uses mechanical energy input instead of thermal energy, and the reaction can be completed at room temperature.

[0037] In addition, after the equipment has been running for 4-6 hours, the chromium oxide has completely reacted. At this time, the sodium chromite mixed with sodium carbonate powder is removed. The hollow screw 63 is rotated, and the hollow screw 63 drives the secondary screen 65 to move down through the connecting rod 64. The external negative pressure material extraction device is connected to the hollow screw 63. Argon gas carries the sodium chromite powder and sodium carbonate powder through the gap between the secondary screen 65 and the main shaft 6 and is discharged, and enters the storage chamber of the external negative pressure device. The mixture of sodium chromite powder and sodium carbonate powder is placed in oxygen-free water (boiled and cooled distilled water) and stirred. The high water solubility of sodium carbonate (35.7g / 100gH2O at 20℃) and the almost insoluble nature of sodium chromite are used for separation. The solid-liquid ratio is controlled at 1:8-1:10, the washing temperature is maintained at 50-60℃ (to enhance the dissolution kinetics of sodium carbonate), and centrifugal separation combined with vacuum filtration is used to obtain sodium chromite powder.

[0038] This invention achieves efficient, high-purity, and low-energy-consumption preparation of sodium chromite by designing a synergistic main ball mill jar 4 and a secondary ball mill jar 5, and by using a step-by-step ball milling, argon-carried, and mechanochemical-driven design. The synergistic effect of the main ball mill jar 4 and the secondary ball mill jar 5 enables a continuous process for raw material pretreatment and mechanochemical reaction, significantly shortening the intervals between multiple steps such as mixing, tableting, and calcination in traditional processes, reducing process complexity, and improving production efficiency.

[0039] This invention utilizes the synergistic effect of the main ball mill jar 4 and the auxiliary ball mill jar 5, with argon gas, acting as a protective gas, continuously flowing as a carrier to dynamically carry the refined chromium oxide and sodium carbonate from the auxiliary ball mill jar 5 into the main ball mill jar 4. This achieves a continuous process of raw material pretreatment and mechanochemical reaction, avoiding material accumulation, ensuring real-time contact of reactants, which is beneficial for improving the reaction rate. Furthermore, the product is sodium chromite powder produced by high-energy ball milling, eliminating the need for mechanical crushing and secondary ball milling, thus significantly shortening the production cycle and improving production efficiency.

[0040] All parts not disclosed in this invention are prior art, and their specific structures, materials, and working principles will not be described in detail. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sodium chromite preparation apparatus based on a mechanochemical method, comprising a base (1), characterized in that: A drive disk (3) is rotatably mounted on the base (1). A main grinding jar (4) is rotatably mounted in the middle of the drive disk (3), and two symmetrically arranged auxiliary grinding jars (5) are rotatably mounted on the drive disk (3). A main turntable (41) is rotatably mounted in the middle of the lid of the main grinding jar (4), and an auxiliary turntable (51) is rotatably mounted in the middle of the lid of the auxiliary grinding jar (5). A belt groove is provided on the circumferential side of the drive disk (3), and a toothed ring is provided on the inner side of the base (1). A secondary gear that meshes with the toothed ring is provided at the bottom of the auxiliary grinding jar (5). A main gear is provided at the bottom of the main grinding jar (4), and a transmission gear set is provided at the bottom of the drive disk (3). The toothed ring drives the main gear to rotate through the transmission gear set. The upper surface of the main turntable (41) is provided with a main shaft (6), and the middle of the side of the main shaft (6) is provided with a uniformly distributed feed hole (62). The lower end of the main shaft (6) is provided with an annular hole (61). The feed hole (62) is connected to the inner cavity of the main ball mill (4) through the annular hole (61). The side of the main shaft (6) corresponding to the feed hole (62) is provided with an annular sleeve (7). The side of the annular sleeve (7) is provided with a feed pipe (71) that penetrates the auxiliary turntable (51), and the feed inlet of the feed pipe (71) is provided with a primary screen (72). The raw material after ball milling in the auxiliary ball mill (5) is filtered by the primary screen (72) and then enters the main ball mill (4) for high-energy ball milling. The upper side of the main shaft (6) is provided with a venting pipe assembly that communicates with the inner cavity of the auxiliary ball mill jar (5). The venting pipe assembly includes a distribution ring (8) installed on the upper side of the main shaft (6). The distribution ring (8) is a hollow structure, and an annular sealing plate is rotatably provided at the bottom of the distribution ring (8). An air outlet pipe (82) is provided on the annular sealing plate. The air outlet of the air outlet pipe (82) passes through the auxiliary turntable (51) and extends to the inner cavity of the auxiliary ball mill jar (5). An air inlet pipe (81) is provided on the side of the distribution ring (8). The main shaft (6) is a hollow structure. A hollow screw (63) is threaded inside the main shaft (6). A secondary screen (65) is installed at the bottom of the hollow screw (63) through a connecting rod (64).

2. The sodium chromite preparation apparatus based on the mechanochemical method according to claim 1, characterized in that: The upper surface edge of the base (1) is provided with a telescopic rod (2), and the top of the telescopic rod (2) is provided with a fixing plate (21) connected to the upper side of the main shaft (6).

3. A method for preparing sodium chromite based on the mechanochemical method described in claim 1, characterized in that: The following steps: S1. Heat and dry chromium oxide powder and sodium carbonate powder separately, and put the dried chromium oxide powder and sodium carbonate powder into different auxiliary ball mill jars (5) in proportion; S2. First, argon gas is introduced to remove the residual air in the auxiliary ball milling jar (5) and the main ball milling jar (4). Then, the external drive motor is controlled to work. The external drive motor controls the drive disc (3) to rotate through the belt. The drive disc (3) drives the main ball milling jar (4) and the auxiliary ball milling jar (5) to rotate. Under the action of the gear ring and the auxiliary gear meshing, the auxiliary ball milling jar (5) rotates while revolving, thereby ball milling chromium oxide powder and sodium carbonate powder. S3. Under the carrying effect of argon gas, chromium oxide powder and sodium carbonate powder with a particle size smaller than the aperture of the primary sieve (72) enter the main ball mill jar (4) through the feed pipe (71). Under the action of the gear ring, transmission gear set and main gear, the main ball mill jar (4) rotates at high speed to generate high-energy ball milling. High-energy ball milling promotes atomic-level diffusion between chromium oxide particles and sodium carbonate particles, forming an amorphous interface layer and directly generating sodium chromite. At the same time, under the action of continuous argon gas inlet and outlet, the by-product carbon dioxide follows the argon gas and is discharged through the hollow screw (63). The secondary sieve (65) blocks the material in the main ball mill jar (4).

4. The preparation method of the sodium chromite preparation apparatus based on the mechanochemical method according to claim 3, characterized in that: In S1, the heating temperature of chromium oxide powder and sodium carbonate powder is 300-600℃, the heating time is 2-3h, and the molar ratio of chromium oxide powder and sodium carbonate powder is 1:1-1.

2.

5. The preparation method of the sodium chromite preparation apparatus based on the mechanochemical method according to claim 3, characterized in that: Both the main grinding jar (4) and the auxiliary grinding jar (5) use silicon carbide grinding balls; in the main grinding jar (4), the diameter of the large ball is 5-10 mm, the diameter of the small ball is 2-5 mm, and the mass ratio of the large ball to the small ball is 3-4:1; in the auxiliary grinding jar (5), the diameter of the large ball is 10-20 mm, the diameter of the small ball is 5-10 mm, and the mass ratio of the large ball to the small ball is 1-1.5:

1.

6. The preparation method of the sodium chromite preparation apparatus based on the mechanochemical method according to claim 3, characterized in that: In S3, the primary screen (72) uses a 150-200 mesh screen, and the secondary screen (65) uses a 400-600 mesh screen.

7. The preparation method of the sodium chromite preparation apparatus based on the mechanochemical method according to claim 3, characterized in that: The main grinding jar (4) has a rotational speed range of 600-1000 rpm, the auxiliary grinding jar has a rotational speed range of 250-400 rpm, and the auxiliary grinding jar has a revolution speed range of 100-200 rpm.

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