Continuous production rotary drying device for lithium hexafluorophosphate

Abstract

The invention relates to the technical field of electrolyte, and discloses a continuous production rotary drying device for lithium hexafluorophosphate, which comprises a furnace body, the left side of the furnace body is fixedly connected with a servo motor, the output end of the servo motor is fixedly connected with a material conveyor, and the left side of the outer wall of the furnace body is provided with a material inlet close to the edge. A nitrogen outlet is formed in the left side of the top of the outer wall of the furnace body, an electric stove wire is fixedly connected to the inner side of the furnace body, the middle of the right side of the furnace body communicates with a nitrogen pipeline, the other end of the nitrogen pipeline communicates with a nitrogen source, and a material outlet is formed in the bottom of the left side of the nitrogen pipeline. According to the lithium hexafluorophosphate drying device, lithium hexafluorophosphate is effectively prevented from being in contact with air to be deteriorated in the drying process by adopting a nitrogen protection device, meanwhile, the stability and consistency of the drying effect are guaranteed by adopting an electric furnace wire heating device, and the manufacturing and maintenance cost is lower than that of other heating modes.

Description

Technical Field

[0001] The invention relates to the technical field of electrolyte, in particular to a rotary drying device for continuous production of lithium hexafluorophosphate. Background Art

[0002] Lithium hexafluorophosphate is mainly used in lithium-ion batteries as a key component of the electrolyte. Lithium-ion batteries are currently the most widely used type of battery and are widely used in electric vehicles, portable electronic devices and energy storage devices. In lithium-ion batteries, the electrolyte plays the role of transmitting ions, allowing lithium ions to move between the positive and negative electrodes to achieve battery charging and discharging. In the existing lithium hexafluorophosphate production process, the material needs to be dried to evaporate hydrogen fluoride to obtain high-purity lithium hexafluorophosphate, and the rotary kiln is a relatively ideal drying equipment. As a key electrolyte salt in lithium-ion batteries, the rotary drying device can play an important role in the continuous production of lithium hexafluorophosphate. The rotary drying device can cooperate with the rotating cylinder to evenly heat and dry.

[0003] The rotary drying device can not only improve production efficiency and product quality in the continuous production of lithium hexafluorophosphate, but also meet the needs of large-scale production. It is one of the indispensable important equipment in the modern chemical industry. At the same time, lithium hexafluorophosphate is the core electrolyte of lithium-ion battery electrolyte, and its quality directly affects the performance of the battery. The traditional lithium hexafluorophosphate drying method has the problems of low efficiency, high energy consumption and unstable product quality. Therefore, the development of a new and efficient lithium hexafluorophosphate drying equipment has become an important research direction in this field. Summary of the invention

[0004] In order to make up for the above shortcomings, the present invention provides a rotary drying device for continuous production of lithium hexafluorophosphate, aiming to improve the problems existing in the drying technology in the prior art and improve the drying efficiency and quality of lithium hexafluorophosphate.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A rotary drying device for continuous production of lithium hexafluorophosphate, comprising a furnace body (1), a servo motor (12) fixedly connected to the left side of the furnace body (1), a material conveyor (8) fixedly connected to the output end of the servo motor (12), a material inlet (6) opened near the edge of the left side of the outer wall of the furnace body (1), a nitrogen outlet (5) opened on the left side of the top of the outer wall of the furnace body (1), an electric furnace wire (2) fixedly connected to the inside of the furnace body (1), a nitrogen pipeline (4) connected to the middle of the right side of the furnace body (1), the other end of the nitrogen pipeline (4) connected to a nitrogen source (3), and a material outlet (7) opened at the bottom of the left side of the nitrogen pipeline (4); In the material conveying part of the continuous production rotary drying device, the surface of the conveying mechanism including the servo motor and its output end connected is coated with anti-hydrofluoric acid corrosion.

[0006] Preferably, the right side of the outer wall of the nitrogen pipeline (4) is connected to a second end cap (15).

[0007] Preferably, a transmission mechanism is provided at the feed end of the furnace body (1), the transmission mechanism comprising a transmission motor (9) and a transmission gear (10), and the transmission motor (9) is connected to the transmission gear (10).

[0008] Preferably, the bottom of the transmission motor (9) is fixedly connected to a base (13), and the top of the base (13) is fixedly connected to a housing (16).

[0009] Preferably, the left side of the outer wall of the furnace body (1) is connected to a sealing head 1 (14).

[0010] Preferably, tugboat support rings (11) are fixedly connected to the bottoms of the left and right sides of the furnace body (1); and a second end cover (15) is connected to the right side of the outer wall of the furnace body (1).

[0011] Preferably, the preparation method of the hydrofluoric acid corrosion resistant coating is: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 120-140°C for 8-12 hours to obtain a pre-phosphating material; S2: Place the pre-phosphating treated material into the rotating disk of the ion implanter and inject titanium metal vapor with ion energy of 30-40keV at 100-120°C. Before vacuum arc ion implantation, control the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment to 1.0×10 -3 ~2.5×10 -3 Pa; during metal vapor vacuum arc ion implantation, the arc starting current is controlled to be 60-150A, the implantation voltage is 30-50KeV, and the deposition is carried out for about 10-25min to obtain a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

[0012] Preferably, the phosphating solution is prepared from the following raw materials in parts by weight: 15-30 parts of cis-propylene borate molybdenum complex, 3-6 parts of potassium hydroxide, 0.6-2.5 parts of 2-mercaptobenzimidazole zinc salt, 200-300 parts of methanol, stirring at 70-80 ° C for 100-150 minutes, distilling off methanol, adding 30-60 parts of calcium nitrate, 200-245 parts of phosphoric acid, mixing evenly to obtain the phosphating solution; Preferably, the preparation method of the cis-propylene borate molybdenum complex is: Weigh 20-41 parts of cis-propylene boric acid and 30-60 parts of molybdenum nitrate in a reaction kettle, then add 500-1000 parts of ethanol, react at 30-40°C for 40-100 minutes, then add 2-5 parts of sodium ethoxide, react at 60-70°C for 20-50 minutes, distill off the ethanol, and obtain a cis-propylene boric acid molybdenum complex.

[0013] Reaction mechanism The reaction mechanism of the process of titanium ion implantation after mixing the synergist containing molybdenum borate and imidazole zinc salt with calcium nitrate and phosphoric acid on the metal surface involves multiple steps. The first is the mercapto-propenyl addition reaction between cis-propenyl borate molybdenum complex and 2-mercaptobenzimidazole zinc salt. The key to this reaction is that molybdenum borate provides a stable platform, while zinc salt acts as a cross-linking agent to promote the addition between mercapto and propenyl, forming a more complex network structure. The next step is to evenly mix the synergist containing molybdenum borate and imidazole zinc salt with calcium nitrate and phosphoric acid to obtain a phosphating solution. This step involves the formation of metal phosphides. In this process, the surface of the metal (such as iron, zinc, etc.) reacts with the phosphate in the phosphating solution to form a dense phosphating film. This step is a key step to improve the corrosion resistance of the metal.

[0014] Through titanium ion implantation technology, titanium ions are forced to embed into the lattice of the metal surface, colliding and replacing with the atoms of the substrate to form a titanium-based layer. This layer not only improves the hardness of the surface, but also significantly improves the corrosion resistance, because titanium itself is a highly chemically inert material that can effectively block corrosive media such as hydrogen fluoride.

[0015] The present invention has the following beneficial effects: 1. In the present invention, by adopting a nitrogen protection device, lithium hexafluorophosphate is effectively prevented from deteriorating due to contact with air during the drying process, thereby improving product quality. At the same time, an electric furnace wire heating device is adopted, and the heating is uniform and the temperature is controllable, thereby ensuring the stability and consistency of the drying effect, and the manufacturing and maintenance costs are lower than those of other heating methods.

[0016] 2. In the present invention, the rotary furnace structure and the material conveying device are used to achieve continuous feeding, discharging and drying of lithium hexafluorophosphate, thereby improving production efficiency.

[0017] 3. Mercapto-propenyl addition reaction between cis-propenyl borate molybdenum complex and 2-mercaptobenzimidazole zinc salt. Molybdenum borate acts as a stable platform, and zinc salt acts as a cross-linking agent, promoting the addition between mercapto and propenyl, forming a more complex network structure. This structure can further enhance the corrosion resistance of the metal in the film formed on the metal surface. The products of the reaction are some compounds with excellent corrosion resistance, such as titanium-phosphorus compounds or alloy phases. The protective layer formed by these compounds on the metal surface can not only physically isolate the corrosive medium, but also prevent further erosion through chemical stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a front perspective view of a furnace body of a rotary drying device for continuous production of lithium hexafluorophosphate proposed by the present invention.

[0019] Legend: 1. Furnace body; 2. Electric furnace wire; 3. Nitrogen source; 4. Nitrogen pipeline; 5. Nitrogen outlet; 6. Material inlet; 7. Material outlet; 8. Material transmission; 9. Transmission motor; 10. Transmission gear; 11. Tugboat support ring; 12. Servo motor; 13. Base; 14. Head 1; 15. Head 2; 16. Shell. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1 Please refer to the attached Figure 1 , an embodiment provided by the present invention: a rotary drying device for continuous production of lithium hexafluorophosphate, comprising a furnace body 1, a servo motor 12 is fixedly connected to the left side of the furnace body 1, a material conveyor 8 is fixedly connected to the output end of the servo motor 12, a material inlet 6 is opened near the edge of the left side of the outer wall of the furnace body 1, a nitrogen outlet 5 is opened on the left side of the top of the outer wall of the furnace body 1, an electric furnace wire 2 is fixedly connected to the inner side of the furnace body 1, a nitrogen pipeline 4 is connected to the middle of the right side of the furnace body 1, the other end of the nitrogen pipeline 4 is connected to a nitrogen source 3, a material outlet 7 is opened at the bottom of the left side of the nitrogen pipeline 4, a head 2 15 is connected to the right side of the outer wall of the nitrogen pipeline 4, and a shell 16 is fixedly connected to the top of the base 13; Specifically, a servo motor 12 is located at a fixed position on the left side of the furnace body 1. The output end of the motor is connected to the material conveyor 8 through a fastening connection device to ensure that the material can enter and exit smoothly. A material inlet 6 is specially designed on the side wall of the furnace body 1 near the edge, so that the material can smoothly enter the furnace body 1. A nitrogen outlet 5 is provided on the left side of the top of the furnace body 1. This is to facilitate the introduction of nitrogen into the furnace body 1. On the inner side of the furnace body 1, an electric furnace wire 2 is installed. This is the main component for heating the furnace body 1 and can generate high temperature to heat the material. In the middle position of the right side of the furnace body 1, there is a channel connected to the nitrogen pipeline 4. This pipeline transports nitrogen from the nitrogen source 3 to provide the necessary protective atmosphere during the material heating process. On the lower left side of the nitrogen pipeline 4, a material outlet 7 is provided. When the material is heated, it can be smoothly taken out through this outlet.

[0022] Specifically, a transmission mechanism is provided at the feeding end of the furnace body 1 , and the transmission mechanism includes a transmission motor 9 and a transmission gear 10 , and the transmission motor 9 is connected to the transmission gear 10 .

[0023] Specifically, the bottom of the transmission motor 9 is fixedly connected with a base 13 .

[0024] Specifically, the left side of the outer wall of the furnace body 1 is connected to a head 14 .

[0025] Specifically, a tugboat support ring 11 is fixedly connected to the bottom of the furnace body 1 .

[0026] Specifically, the right side of the outer wall of the furnace body 1 is connected to a second end cover 15 .

[0027] Specifically, a transmission motor 9 is firmly connected to the bottom of the outer structure of the furnace body 1, and the transmission motor 9 cooperates with a transmission gear 10 to drive the furnace body to rotate. The bottom of the transmission motor 9 is tightly fixedly connected to a planar base 13. This design ensures the stability and load-bearing capacity of the entire furnace body 1; a head 14 and a head 2 15 are respectively provided at both ends of the inlet and outlet of the furnace body 1 to jointly ensure a sealed environment in the furnace; tugboat support rings 11 are respectively designed at the bottom of the left and right sides of the furnace body 1, and the function of the tugboat support rings 11 is to support the furnace body.

[0028] Working principle: the furnace body 1 is a rotary structure, and a plurality of electric furnace wire 2 heating elements are arranged inside. The nitrogen protection device includes a nitrogen source 3, a nitrogen pipeline 4 and a nitrogen outlet 5, so that the nitrogen pipeline 4 connects the nitrogen source 3 and the nitrogen outlet 5, and then the nitrogen is introduced into the furnace body 1. The material conveying device includes a material inlet 6, a material outlet 7 and a material conveyor 8. Then the material conveyor 8 brings the lithium hexafluorophosphate to be dried from the material inlet 6 into the furnace body 1 for drying, and continuously discharges it from the material outlet 7. Therefore, in actual operation, the heating temperature of the electric furnace wire 2 heating element and the nitrogen flow rate of the nitrogen protection device can be adjusted as needed to achieve the best drying effect.

[0029] Specifically, a hydrofluoric acid corrosion resistant coating is provided in the material conveying part of the continuous production rotary drying device, including the servo motor and the conveying mechanism connected to the output end thereof.

[0030] The preparation method of the hydrofluoric acid corrosion resistant coating is as follows: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 120°C for 8 hours to obtain a pre-phosphating material; S2: Place the pre-phosphating treated material into the rotating disk of the ion implanter and inject titanium metal vapor with ion energy of 30keV at 100°C. Before vacuum arc ion implantation, control the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment to 1.0×10 -3 Pa; during metal vapor vacuum arc ion implantation, the arc starting current was controlled to be 60A, the injection voltage was 30KeV, and the deposition was carried out for about 10 minutes to obtain a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

[0031] The phosphating solution is prepared from the following raw materials in parts by weight: 15kg cis-propylene borate molybdenum complex, 3kg potassium hydroxide, 0.6kg 2-mercaptobenzimidazole zinc salt CAS: 3030-80-6, 200kg methanol, stirred at 70 ° C for 100 minutes, distilled to remove methanol, added calcium nitrate 30kg, phosphoric acid 200kg, mixed evenly to obtain the phosphating solution; The preparation method of the cis-propylene borate molybdenum complex is: Weigh 20 kg of cis-propylene boric acid and 30 kg of molybdenum nitrate in a reactor, then add them to 500 kg of ethanol, react at 30° C. for 40 minutes, then add 2 kg of sodium ethoxide, react at 60° C. for 20 minutes, distill off the ethanol, and obtain a cis-propylene boric acid molybdenum complex.

[0032] Example 2 In this embodiment, except for the following technical solutions, other parts are the same as those in Embodiment 1: In the material conveying part of the continuous production rotary drying device, including the servo motor and the conveying mechanism connected to the output end thereof, a hydrofluoric acid corrosion resistant coating is provided.

[0033] The preparation method of the hydrofluoric acid corrosion resistant coating is as follows: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 130°C for 10 hours to obtain a pre-phosphating material; S2: Place the pre-phosphating treated material into the rotating disk of the ion implanter and inject titanium metal vapor with ion energy of 35keV at 110°C. Before vacuum arc ion implantation, control the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment to 2×10 -3 Pa; during metal vapor vacuum arc ion implantation, the arc starting current was controlled to be 105A, the injection voltage was 40KeV, and the deposition time was about 20min to obtain a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

[0034] The phosphating solution is prepared from the following raw materials in parts by weight: 22kg cis - propylene borate molybdenum complex, 4.5kg potassium hydroxide, 1.5kg2-mercaptobenzimidazole zinc salt, 250kg methanol, stirred at 75 ° C for 125 minutes, distilled to remove methanol, added calcium nitrate 45kg, phosphoric acid 225kg, mixed to obtain the phosphating solution; The preparation method of the cis-propylene borate molybdenum complex is: 30 kg of cis-propylene boric acid and 45 kg of molybdenum nitrate were weighed into a reactor, and then added to 750 kg of ethanol, reacted at 35° C. for 70 minutes, and then 3.5 kg of sodium ethoxide was added, reacted at 65° C. for 35 minutes, and the ethanol was distilled off to obtain a cis-propylene boric acid molybdenum complex.

[0035] Example 3 In this embodiment, except for the following technical solutions, other parts are the same as those in Embodiment 1: In the material conveying part of the continuous production rotary drying device, including the servo motor and the conveying mechanism connected to the output end thereof, a hydrofluoric acid corrosion resistant coating is provided.

[0036] The preparation method of the hydrofluoric acid corrosion resistant coating is as follows: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 140°C for 12 hours to obtain a pre-phosphating material; S2: The pre-phosphating treated material is placed in the rotating disk of the ion implanter, and titanium metal vapor with an ion energy of 40 keV is injected at 120°C. Before vacuum arc ion implantation, the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment is controlled to be 2.5×10 -3 Pa; during metal vapor vacuum arc ion implantation, the arc starting current was controlled to be 150A, the implantation voltage was 50KeV, and the deposition time was about 25min, thereby obtaining a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

[0037] The phosphating solution is prepared from the following raw materials in parts by weight: 30kg cis-propylene borate molybdenum complex, 6kg potassium hydroxide, 2.5kg 2-mercaptobenzimidazole zinc salt CAS: 3030-80-6, 300kg methanol, stirred at 80°C for 150 minutes, methanol was removed by distillation, 60kg calcium nitrate and 245kg phosphoric acid were added, and the mixture was uniformly mixed to obtain the phosphating solution; The preparation method of the cis-propylene borate molybdenum complex is: 41 kg of cis-propylene boric acid and 60 kg of molybdenum nitrate were weighed into a reactor, and then added to 1000 kg of ethanol, reacted at 40° C. for 100 minutes, and then 5 kg of sodium ethoxide was added, reacted at 70° C. for 50 minutes, and the ethanol was distilled off to obtain a cis-propylene boric acid molybdenum complex.

[0038] Comparative Example 1 In this embodiment, except for the following technical solutions, other parts are the same as those in Embodiment 1: In the material conveying part of the continuous production rotary drying device, including the servo motor and the conveying mechanism connected to the output end thereof, no anti-hydrofluoric acid corrosion coating is provided.

[0039] Comparative Example 2 In this embodiment, except for the following technical solutions, other parts are the same as those in Embodiment 1: In the material conveying part of the continuous production rotary drying device, including the servo motor and the conveying mechanism connected to the output end thereof, a hydrofluoric acid corrosion resistant coating is provided.

[0040] The preparation method of the hydrofluoric acid corrosion resistant coating is as follows: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 120°C for 8 hours to obtain a pre-phosphating material; S2: Place the pre-phosphating treated material into the rotating disk of the ion implanter and inject titanium metal vapor with ion energy of 30keV at 100°C. Before vacuum arc ion implantation, control the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment to 1.0×10 -3Pa; during metal vapor vacuum arc ion implantation, the arc starting current was controlled to be 60A, the injection voltage was 30KeV, and the deposition was carried out for about 10 minutes to obtain a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

[0041] The phosphating solution is prepared from the following raw materials in parts by weight: 15 kg of cis-propylene boric acid, 3 kg of potassium hydroxide, 0.6 kg of 2-mercaptobenzimidazole zinc salt CAS: 3030-80-6, and 200 kg of methanol are stirred at 70° C. for 100 minutes, the methanol is removed by distillation, and 30 kg of calcium nitrate and 200 kg of phosphoric acid are added and mixed uniformly to obtain the phosphating solution.

[0042] The full immersion corrosion test was carried out according to ASTM KG31-12A. The test temperature was 27℃, 35℃ and 40℃. The solution was 3.5% NaCl solution and 3.5% NaCl+0.25% NaCl solution. 2 S 2 O 8 The test time of the solution was 30 days, and a total of 6 batches were tested.

[0043] The results of the full immersion corrosion test are shown in the table: sample Corrosion rate kg / m2.h Local corrosion depth μm Example 1 0.0137 12 Example 2 0.0092 7 Example 3 0.0038 5 Comparative Example 1 0.5351 34 Comparative Example 2 0.1173 20 It can be seen from the table that in the mercapto-propenyl addition reaction between cis-propenyl borate molybdenum complex and 2-mercaptobenzimidazole zinc salt, molybdenum borate acts as a stable platform, while zinc salt acts as a cross-linking agent, promoting the addition between mercapto and propenyl, forming a more complex network structure. This structure can further enhance the corrosion resistance of the metal in the film formed on the metal surface.

[0044] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rotary drying device for continuous production of lithium hexafluorophosphate, comprising a furnace body (1), characterized in that: A servo motor (12) is fixedly connected to the left side of the furnace body (1), and a material conveyor (8) is fixedly connected to the output end of the servo motor (12). A material inlet (6) is provided on the left side of the outer wall of the furnace body (1) near the edge. A nitrogen outlet (5) is provided on the left side of the top of the outer wall of the furnace body (1). An electric furnace wire (2) is fixedly connected to the inner side of the furnace body (1). A nitrogen pipeline (4) is connected to the middle of the right side of the furnace body (1), and the other end of the nitrogen pipeline (4) is connected to a nitrogen source (3). A material outlet (7) is provided at the bottom of the left side of the nitrogen pipeline (4). In the material conveying part of the continuous production rotary drying device, the surface of the conveying mechanism including the servo motor and its output end connected is coated with anti-hydrofluoric acid corrosion.

2. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 1, characterized in that: The right side of the outer wall of the nitrogen pipeline (4) is connected to a second end cap (15).

3. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 1, characterized in that: The feed end of the furnace body (1) is provided with a transmission mechanism, the transmission mechanism comprising a transmission motor (9) and a transmission gear (10), and the transmission motor (9) is connected to the transmission gear (10).

4. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 3, characterized in that: The bottom of the transmission motor (9) is fixedly connected to a base (13), and the top of the base (13) is fixedly connected to a housing (16).

5. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 1, characterized in that: The left side of the outer wall of the furnace body (1) is connected to a sealing head 1 (14).

6. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 1, characterized in that: The bottoms of the left and right sides of the furnace body (1) are fixedly connected with tugboat support rings (11); the right side of the outer wall of the furnace body (1) is connected with a second end cover (15).

7. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 1, characterized in that: The preparation method of the hydrofluoric acid corrosion resistant coating is as follows: S1: The metal surface of the servo motor and the transmission mechanism connected to its output end is cleaned, immersed in the phosphating solution, and placed in an oven at 120-140°C for 8-12 hours to obtain a pre-phosphating material; S2: Place the pre-phosphating treated material into the rotating disk of the ion implanter and inject titanium metal vapor with ion energy of 30-40keV at 100-120°C. Before vacuum arc ion implantation, control the pressure of the vacuum chamber in the metal vapor vacuum arc ion implantation equipment to 1.0×10 -3 ~2.5×10 -3 Pa; during metal vapor vacuum arc ion implantation, the arc starting current is controlled to be 60-150A, the implantation voltage is 30-50KeV, and the deposition is carried out for about 10-25min to obtain a hydrofluoric acid corrosion-resistant coating with a dense structure and good corrosion resistance.

8. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 7, characterized in that: The phosphating solution is prepared from the following raw materials in parts by weight: 15-30 parts of cis-propylene borate molybdenum complex, 3-6 parts of potassium hydroxide, 0.6-2.5 parts of 2-mercaptobenzimidazole zinc salt, 200-300 parts of methanol, stirring at 70-80° C. for 100-150 minutes, distilling off the methanol, adding 30-60 parts of calcium nitrate and 200-245 parts of phosphoric acid, and mixing uniformly to obtain the phosphating solution.

9. A rotary drying device for continuous production of lithium hexafluorophosphate according to claim 8, characterized in that: The preparation method of the cis-propylene borate molybdenum complex is: Add 20-41 parts of cis-propylene boric acid and 30-60 parts of molybdenum nitrate into a reaction kettle, then add 500-1000 parts of ethanol, react at 30-40°C for 40-100 minutes, then add 2-5 parts of sodium ethoxide, react at 60-70°C for 20-50 minutes, distill off the ethanol, and obtain a cis-propylene boric acid molybdenum complex.

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