A continuous dynamic crystallization apparatus for lithium hexafluorophosphate

Abstract

The application relates to the lithium hexafluorophosphate preparation technical field, and particularly discloses a lithium hexafluorophosphate continuous dynamic crystallization equipment which comprises a first-stage crystallization kettle, a second-stage crystallization kettle, a third-stage crystallization kettle and more than one fourth-stage crystallization kettle, the first-stage crystallization kettle, the second-stage crystallization kettle, the third-stage crystallization kettle and the more than one fourth-stage crystallization kettle are arranged in a ladder shape at equal intervals, a material conveying pump is connected between adjacent crystallization kettles and after the fourth-stage crystallization kettle, and a stirring device is arranged in each crystallization kettle. Different crystallization stages are separated and carried out in different crystallization kettles, the crystallization kettles carrying out different crystallization stages are connected in a ladder shape, the crystallization process realizes continuous feeding and continuous discharging, the material flow between the crystallization kettles arranged in a ladder shape can be assisted by gravity to realize self-flow, so that stirring energy consumption is saved, and the multiple crystallization kettles arranged in a ladder shape can save the floor area.

Description

Technical Field

[0001] This utility model relates to the field of lithium hexafluorophosphate preparation technology, specifically to a continuous dynamic crystallization device for lithium hexafluorophosphate. Background Technology

[0002] There are several main methods for preparing lithium hexafluorophosphate: direct gas-solid reaction, solvent method, and ion exchange method. Among these, the hydrogen fluoride solvent method is the most researched, technologically mature, and widely used in industrial applications. The hydrogen fluoride solvent method uses hydrogen fluoride as the reaction medium. Lithium halide is dissolved in hydrogen fluoride, and then high-purity phosphorus pentafluoride is vaporized and passed into a solvent to react and generate lithium hexafluorophosphate crystals. After the reaction, the product is obtained through crystallization separation and drying.

[0003] There are two main methods for crystallizing lithium hexafluorophosphate: static crystallization and stirred crystallization. Stirred crystallization is an intermittent process, where the mother liquor of synthesized lithium hexafluorophosphate undergoes crystallization, grain growth, and ultimately, the desired grain size within the same crystallization vessel. Since the process from crystallization to grain growth involves several distinct stages, each stage requires different process parameters (such as temperature) to control the crystallization vessel. To improve the turnover efficiency of the crystallization vessel and further enhance the production efficiency of stirred crystallization of lithium hexafluorophosphate, Chinese Patent Publication No. CN218944402U discloses a lithium hexafluorophosphate crystallization system. This system includes a primary, secondary, tertiary, and quaternary crystallization vessel connected sequentially. By separating the different crystallization stages into different vessel stages, continuous feeding and discharging are achieved. However, because the multiple crystallization vessels in this system are arranged horizontally, maintaining material flow between them requires a stirring system, resulting in high energy consumption. Furthermore, the multiple horizontally arranged crystallization vessels occupy a large area. Utility Model Content

[0004] The purpose of this invention is to provide a continuous dynamic crystallization device for lithium hexafluorophosphate, so as to solve the problems of high stirring energy consumption and large footprint caused by the horizontal arrangement of multiple crystallization tanks in the existing crystallization system.

[0005] To address the above issues, the following technical solution is provided:

[0006] A continuous dynamic crystallization device for lithium hexafluorophosphate includes a primary crystallization vessel, a secondary crystallization vessel, a tertiary crystallization vessel, and one or more quaternary crystallization vessels. The primary crystallization vessel, the secondary crystallization vessel, the tertiary crystallization vessel, and the quaternary crystallization vessels are arranged in a stepped and equidistant manner. A feed pump is connected between adjacent crystallization vessels and after the quaternary crystallization vessel. Each crystallization vessel is equipped with a stirring device.

[0007] The basic principle and beneficial effects of the above technical solution are as follows: different crystallization stages are carried out in different crystallization vessels, and the crystallization vessels carrying out different crystallization stages are connected in a stepped manner to achieve continuous feeding and continuous discharge in the crystallization process. The flow of materials between different crystallization vessels arranged in a stepped manner can be assisted by gravity to facilitate the flow of materials by gravity, thereby saving stirring energy consumption. Furthermore, arranging multiple crystallization vessels in a stepped manner can save floor space.

[0008] Furthermore, the stirring device includes a stirring shaft vertically positioned in the center of the reactor. A motor is fixedly connected to the top of the stirring shaft, penetrating the top of the crystallization reactor. The motor controls the rotation speed of the stirring shaft at 30-180 rpm. A folding-blade stirring paddle is located at the upper part of the stirring shaft, and a propeller-type stirring paddle is located at the bottom. A fan-shaped rake is located at the bottom of the propeller-type stirring paddle. The diameters of the folding-blade and propeller-type stirring paddles are 0.3-1 m, the width of the folding-blade stirring paddle is 50-250 mm, the width of the propeller-type stirring paddle is 100-700 mm, the diameter of the fan-shaped rake is 100-500 mm, and the height of the fan-shaped rake is 150-800 mm. The area of ​​the propeller-type stirring paddle is larger than that of the folding-blade stirring paddle. The propeller-type stirring paddle at the bottom of the stirring shaft enhances the disturbance intensity at the bottom of the crystallization reactor, preventing crystals from settling. The fan-shaped rake rotates with the stirring shaft, effectively dispersing the material at the bottom of the crystallization reactor and preventing crystal deposition that could block the discharge pipe.

[0009] Furthermore, the upper end of the primary crystallizer is connected to a mother liquor supply pipeline, one end of which is connected to a lithium hexafluorophosphate mother liquor supply source. The mother liquor supply pipeline is equipped with a flow valve and a regulating valve, and the feed flow rate of the lithium hexafluorophosphate mother liquor is controlled at 0.5~5 m³ / h. The flow valve and regulating valve work together to achieve automatic control of the feed rate.

[0010] Furthermore, each crystallization vessel is equipped with a crystallization monitoring port on its bottom side, with the port opening positioned 200-800 mm above the bottom of the crystallization vessel head. The monitoring port uses an imager to monitor the crystal growth status in real time, analyzing particle size distribution and crystal morphology. The stirring speed of the stirring shaft is adjusted based on the material state monitored by the monitoring port, ensuring that the crystals do not sink excessively while maintaining uniform distribution, a favorable growth environment, and sufficient heat transfer.

[0011] Furthermore, each crystallizer is equipped with a side discharge pipe on one side of its upper part, with the height of the side discharge pipe from the bottom of the crystallizer head being 600~2000mm. Each crystallizer is also equipped with a bottom suction pipe on one side of its lower part, with the height of the bottom suction pipe from the bottom of the crystallizer head being 300~800mm. The end of the bottom suction pipe inside the crystallizer is beveled at 45°. The 45° beveled end facilitates material intake.

[0012] Furthermore, each of the secondary, tertiary, and quaternary crystallizers is equipped with an inner insert tube. This inner insert tube extends to the bottom of each crystallizer and is located on one side within the crystallizer. The top end of the inner insert tube connects to the outlet of the feed pump, and the bottom end of the inner insert tube is 150-500 mm above the bottom of the crystallizer head. The inner insert tube ensures that the material has a certain residence time within the crystallizer, creating a suitable growth environment and preventing material from flowing directly out of the crystallizer's overflow port.

[0013] Furthermore, the temperature of the primary crystallizer is controlled at 0~10℃, the temperature of the secondary crystallizer is controlled at -10~-5℃, the temperature of the tertiary crystallizer is controlled at -25~-20℃, and the temperature of the quaternary crystallizer is controlled at -35~-30℃. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the crystallization equipment of this utility model;

[0015] Figure 2 This is a schematic diagram of the structure of a primary crystallizer.

[0016] The reference numerals in the accompanying drawings of the instruction manual include: 1. Primary crystallizer; 2. Secondary crystallizer; 3. Tertiary crystallizer; 4. Quaternary crystallizer; 5. Feed pump; 6. Mother liquor supply pipeline; 7. Mother liquor supply source; 8. Flow valve; 9. Regulating valve; 10. Lower stage crystallization process device; 11. Stirring shaft; 12. Motor; 13. Folding blade stirring paddle; 14. Propeller stirring paddle; 15. Fan-shaped rake; 16. Crystallization monitoring port; 17. Side discharge pipe; 18. Bottom suction pipe; 19. Inner insertion pipe. Detailed Implementation

[0017] The following detailed description illustrates the specific implementation method:

[0018] The basic implementation examples are as follows: Figure 1-2 As shown:

[0019] A continuous dynamic crystallization device for lithium hexafluorophosphate includes a primary crystallizer 1, a secondary crystallizer 2, a tertiary crystallizer 3, and one or more quaternary crystallizers 4. The primary crystallizer 1, secondary crystallizer 2, tertiary crystallizer 3, and quaternary crystallizers 4 are arranged in a stepped, equidistant manner. Feed pumps 5 are connected between adjacent crystallizers and after the quaternary crystallizer 4. One feed pump 5 circulates internally, while the other feeds to the next crystallizer. The flow rate of the feed pump 5 is between 0.3 m³ and 8 m³, and the head is between 20 and 40 m. Each crystallizer is equipped with a stirring device. A mother liquor supply pipeline 6 is connected to the upper end of the primary crystallizer 1. One end of the mother liquor supply pipeline 6 is connected to a lithium hexafluorophosphate mother liquor supply source 7. The mother liquor supply pipeline 6 is equipped with a flow valve 8 and a regulating valve 9. The feed flow rate of the lithium hexafluorophosphate mother liquor is controlled at 5 m³ / h. The outlet of the feed pump 5 after the quaternary crystallizer 4 is connected to the downstream process device 10 of the crystallizing liquid. The stirring device includes a stirring shaft 11 vertically positioned in the center of the reactor. A motor 12 is fixedly connected to the top of the stirring shaft 11, penetrating the top of the crystallization reactor. The motor 12 controls the rotation speed of the stirring shaft between 30-180 rpm, and the motor speed can be adjusted according to the state of the material in the crystallization reactor. A folding-blade stirring paddle 13 is located at the upper part of the stirring shaft 11, and a propeller-type stirring paddle 14 is located at the bottom of the stirring shaft 11. A fan-shaped rake 15 is located at the bottom of the propeller-type stirring paddle 14. The diameters of the folding-blade stirring paddle 13 and the propeller-type stirring paddle 14 are both 0.5 mm. The width of the folding-blade stirring paddle 13 is 250 mm, the width of the propeller-type stirring paddle 14 is 500 mm, and the diameter and height of the fan-shaped rake 15 are both 200 mm. A crystallization monitoring port 16 is located on the side of the bottom of each crystallization reactor, with the port opening 400 mm above the bottom of the crystallization reactor head. Each crystallizer has a side discharge pipe 17 on one side of its upper part, which is 1000mm above the bottom of the crystallizer head. Each crystallizer has a bottom suction pipe 18 on one side of its lower part, which is 200mm above the bottom of the crystallizer head. The end of the bottom suction pipe 18 inside the crystallizer is beveled at 45°. The secondary crystallizer 2, tertiary crystallizer 3, and quaternary crystallizer 4 are all equipped with an inner insertion pipe 19. The inner insertion pipe 19 extends to the bottom of the secondary crystallizer 2, tertiary crystallizer 3, and quaternary crystallizer 4 and is located on one side inside the secondary crystallizer 2, tertiary crystallizer 3, and quaternary crystallizer 4. The top of the inner insertion pipe 19 is connected to the discharge port of the feed pump 5, and the bottom of the inner insertion pipe 19 is 200mm above the bottom of the crystallizer head. The temperature of the primary crystallizer 1 is controlled at 0~10℃, the temperature of the secondary crystallizer 2 is controlled at -10~-5℃, the temperature of the tertiary crystallizer 3 is controlled at -25~-20℃, and the temperature of the quaternary crystallizer 4 is controlled at -35~-30℃.

[0020] The specific implementation process is as follows:

[0021] Different crystallization stages are carried out in different crystallization vessels, and these vessels are connected in a stepped manner to achieve continuous feeding and discharging during the crystallization process. The flow of material between the different crystallization vessels arranged in a stepped manner can be assisted by gravity to facilitate the flow of material by gravity, thereby saving stirring energy consumption. Furthermore, arranging multiple crystallization vessels in a stepped manner can save floor space.

[0022] The above descriptions are merely embodiments of this utility model, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of this utility model, and these should also be considered within the scope of protection of this utility model. These modifications will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A continuous dynamic crystallization apparatus for lithium hexafluorophosphate, comprising a primary crystallization vessel, a secondary crystallization vessel, a tertiary crystallization vessel, and one or more quaternary crystallization vessels, characterized in that: The primary crystallizer, secondary crystallizer, tertiary crystallizer, and one or more quaternary crystallizers are arranged in a stepped, equidistant manner. A feed pump is connected between adjacent crystallizers and after the quaternary crystallizer. Each crystallizer is equipped with a stirring device.

2. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 1, characterized in that: The stirring device includes a stirring shaft vertically positioned in the center of the reactor. A motor is fixedly connected to the top of the stirring shaft, which passes through the top of the crystallization reactor. The motor controls the rotation speed of the stirring shaft at 30-180 rpm. A folding blade stirring paddle is provided at the upper part of the stirring shaft, and a propeller stirring paddle is provided at the bottom of the stirring shaft. A fan-shaped rake is provided at the bottom of the propeller stirring paddle. The diameter of the folding blade stirring paddle and the propeller stirring paddle is 0.3~1m, the width of the folding blade stirring paddle is 50~250mm, the width of the propeller stirring paddle is 100~700mm, the diameter of the fan-shaped rake is 100~500mm, and the height of the fan-shaped rake is 150~800mm.

3. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 2, characterized in that: The upper end of the primary crystallization reactor is connected to a mother liquor supply pipeline. One end of the mother liquor supply pipeline is connected to a lithium hexafluorophosphate mother liquor supply source. The mother liquor supply pipeline is equipped with a flow valve and a regulating valve, and the feed flow rate of lithium hexafluorophosphate mother liquor is controlled at 0.5~5m³ / h.

4. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 3, characterized in that: Each crystallizer is equipped with a crystallization monitoring port on the bottom side, and the height of the crystallization monitoring port from the bottom of the crystallizer head is 200~800mm.

5. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 4, characterized in that: Each crystallizer is provided with a side discharge pipe on one side of its upper part, the height of the side discharge pipe from the bottom of the crystallizer head is 600~2000mm, and a bottom suction pipe is provided on one side of its lower part, the height of the bottom suction pipe from the bottom of the crystallizer head is 300~800mm, and the end of the bottom suction pipe inside the crystallizer is obliquely cut at 45°.

6. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 5, characterized in that: The secondary, tertiary, and quaternary crystallizers are all equipped with internal insertion tubes. The internal insertion tubes extend to the bottom of the secondary, tertiary, and quaternary crystallizers and are located on one side inside the secondary, tertiary, and quaternary crystallizers. The top of the internal insertion tube is connected to the discharge port of the feed pump, and the bottom of the internal insertion tube is 150-500 mm above the bottom of the crystallizer head.

7. The lithium hexafluorophosphate continuous dynamic crystallization equipment according to claim 6, characterized in that: The temperature of the primary crystallizer is controlled at 0~10℃, the temperature of the secondary crystallizer is controlled at -10~-5℃, the temperature of the tertiary crystallizer is controlled at -25~-20℃, and the temperature of the quaternary crystallizer is controlled at -35~-30℃.

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