Drying system of lithium hexafluorophosphate

Abstract

The utility model provides a lithium hexafluorophosphate drying system which comprises a vibration drying machine and a vibration screening machine, the vibration drying machine is connected with the vibration screening machine, and materials sequentially pass through the vibration drying machine and the vibration screening machine. The vibrating screen classifier is connected with the vibrating dryer, the vibrating dryer is directly or indirectly connected with a negative pressure pipeline so as to extract gas impurities in materials, the vibrating screen classifier and / or the vibrating dryer are / is connected with a gas inlet pipeline, and the gas inlet pipeline is used for introducing inert gas so as to purge the gas impurities in the materials. According to the lithium hexafluorophosphate drying system, by combining two modes of negative pressure suction and gas purging, the drying efficiency of lithium hexafluorophosphate can be relatively improved, and the product quality of lithium hexafluorophosphate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium hexafluorophosphate drying process, and particularly relates to a lithium hexafluorophosphate drying system. BACKGROUND

[0002] Lithium hexafluorophosphate (LiPF6) is an inorganic compound, which is a white crystalline powder, easily soluble in water, soluble in low-concentration methanol, ethanol, acetone, carbonate and other organic solvents. Lithium hexafluorophosphate is mainly used as an electrolyte material for lithium ion batteries, which can be used to manufacture lithium ion power batteries, lithium ion energy storage batteries and other daily batteries, and is an important lithium ion battery electrolyte material that is difficult to replace at present.

[0003] There are mainly the following methods for preparing lithium hexafluorophosphate: gas-solid direct reaction method, solvent method and ion exchange method. Among them, the solvent method, also known as the wet synthesis method, is to dissolve lithium salt in anhydrous hydrogen fluoride acid to form a lithium fluoride-hydrogen fluoride solution (LiF-HF), and then pass high-purity phosphorus pentafluoride gas (PF5) to react to generate lithium hexafluorophosphate crystals. After crystallization separation, drying and other process steps, lithium hexafluorophosphate product is finally obtained.

[0004] At present, the widely used lithium hexafluorophosphate drying technology in the industry mainly adopts a rotary double-cone drying equipment. This method can effectively avoid the introduction of other impurities, and at the same time, the solid material particles have good fluidity in the double-cone equipment. However, this drying method also has some outstanding problems, for example, the feeding and discharging process of this type of drying equipment needs to be manually disassembled at the inlet and outlet of the equipment, which has a high operation risk. In the later stage of the drying process, only by means of vacuum pumping, a long time is needed to remove the remaining trace amount of hydrogen fluoride, so as to meet the requirements of the lithium hexafluorophosphate product in terms of pH and purity.

[0005] CN217613324U discloses a lithium hexafluorophosphate purification conical drying system, which comprises a drying machine main body composed of an upper cylindrical body and a lower conical body connected together. The outer side of the upper cylindrical body is provided with a first heating jacket, and the outer side of the lower conical body is also provided with a second heating jacket. A hollow screw stirring device is arranged in the upper cylindrical body and the lower conical body, and the hollow screw stirring device is driven to rotate through a hollow shaft. A straight section filter is fixed in the upper cylindrical body, and a segmented conical filter is fixed in the lower conical body, and the straight section filter and the segmented conical filter are connected together in series and communicate with each other.

[0006] The hollow screw stirring device of the lithium hexafluorophosphate purification conical drying system disclosed in the above-mentioned utility model will rub with lithium hexafluorophosphate material during stirring operation, which may introduce new impurity ions in the drying process. CONTENT OF THE UTILITY MODEL

[0007] The present application is made in view of the above-mentioned state of the art. The present application aims to provide a lithium hexafluorophosphate drying system, which uses a vibrating dryer and a vibrating sieve as the main drying equipment, and can improve the drying efficiency of lithium hexafluorophosphate and the product quality of lithium hexafluorophosphate by combining negative pressure suction and gas blowing.

[0008] The present application provides a lithium hexafluorophosphate drying system, which comprises a vibrating dryer and a vibrating sieve, the vibrating dryer is connected to the vibrating sieve, and the material passes through the vibrating dryer and the vibrating sieve in turn,

[0009] The vibrating dryer is directly or indirectly connected to a negative pressure pipeline to extract gas impurities in the material, and the vibrating sieve and / or the vibrating dryer is connected to a gas inlet pipeline for introducing inert gas to blow off the gas impurities in the material.

[0010] In at least one possible implementation, the lithium hexafluorophosphate drying system further comprises a filter connected to the vibrating dryer,

[0011] The filter is connected to a negative pressure pipeline, and the filter can filter and intercept solid materials to prevent the solid materials from entering the negative pressure pipeline; and / or the filter is connected to a gas outlet pipeline, and the filter can filter and intercept solid materials to prevent the solid materials from entering the gas outlet pipeline.

[0012] In at least one possible implementation, the vibrating sieve is connected to a product outlet pipeline above the sieve screen to discharge the material meeting the particle size requirement,

[0013] The vibrating sieve is connected to a small particle product outlet pipeline below the sieve screen to discharge the material not meeting the particle size requirement.

[0014] In at least one possible implementation, the vibrating dryer comprises a dryer jacket connected to a heat medium inlet pipeline to introduce heat medium into the dryer jacket,

[0015] The dryer jacket is connected to a heat medium outlet pipeline to discharge the heat medium from the dryer jacket.

[0016] In at least one possible implementation, the vibrating dryer is provided with a temperature sensor to display and / or feedback the temperature of the material in the vibrating dryer,

[0017] And / or, the vibrating sieve is provided with a pressure sensor to display and / or feedback the pressure in the vibrating sieve.

[0018] In at least one possible implementation, the drying system of lithium hexafluorophosphate further comprises a flexible connection,

[0019] The vibrating dryer is connected to at least one device or at least one pipeline through the flexible connection; and / or, the vibrating sieve is connected to at least one device or at least one pipeline through the flexible connection.

[0020] In at least one possible implementation, a switch valve and / or a regulating valve are arranged in the pipeline of the drying system.

[0021] In at least one possible implementation, the outlet of the gas inlet pipeline is arranged below the sieve screen, so that the inert gas is introduced into the vibrating sieve from below the sieve screen.

[0022] In at least one possible implementation, the small-particle product outlet pipeline is connected to a small-particle product tank, so that the small-particle material is collected for crystallization treatment.

[0023] In at least one possible implementation, the heat medium inlet pipeline is connected to the lower part of the dryer jacket, and the heat medium outlet pipeline is connected to the upper part of the dryer jacket.

[0024] The drying system of lithium hexafluorophosphate provided in the present application uses a vibrating dryer and a vibrating sieve as the main drying equipment, and can relatively improve the drying efficiency of lithium hexafluorophosphate and improve the product quality of lithium hexafluorophosphate by combining negative pressure suction and inert gas blowing. Specifically, negative pressure suction can be used as the first-stage impurity removal in the vibrating dryer, and inert gas can be introduced into the vibrating sieve and / or the vibrating dryer for secondary impurity removal. Negative pressure suction can quickly remove most of the gas impurities, and inert gas blowing can compensate for the poor removal effect of gas impurities in the later stage of negative pressure suction, i.e., using inert gas to carry out the gas impurities remaining in lithium hexafluorophosphate. In this way, after most of the gas impurities are removed by negative pressure suction, the next process can be entered without long-term negative pressure suction to ensure product quality, reducing the residence time in the vibrating dryer, improving the drying efficiency of lithium hexafluorophosphate, and ensuring the product quality of lithium hexafluorophosphate, meeting the purity and pH requirements of high-quality lithium hexafluorophosphate. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 FIG. 1 is a structural schematic diagram of a drying system of lithium hexafluorophosphate according to an embodiment of the present application.

[0026] REFERENCE SIGNS

[0027] 10 vibrating dryer

[0028] 11 dryer jacket

[0029] 20 filter

[0030] 30 vibrating sifter

[0031] 31 screen

[0032] 41 on-off valve

[0033] 42 regulating valve

[0034] 50 flexible connection

[0035] 61 temperature sensor

[0036] 62 pressure sensor

[0037] 71 feed line

[0038] 72 negative pressure line

[0039] 73 gas inlet line

[0040] 74 gas outlet line

[0041] 75 heat medium inlet line

[0042] 76 heat medium outlet line

[0043] 77 product outlet line

[0044] 78 small particle product outlet line DETAILED DESCRIPTION

[0045] Exemplary embodiments of the present application are described below with reference to the accompanying drawings. It is to be understood that the specific description is merely illustrative of how the application can be carried out, and is not intended to limit the scope of the application in any way.

[0046] Embodiments of the present application provide a drying system for lithium hexafluorophosphate (hereinafter, sometimes referred to simply as "drying system"), such as Figure 1 As shown, the drying system can include a vibrating dryer 10, a filter 20, and a vibrating sifter 30. Lithium hexafluorophosphate material can be sequentially passed through the vibrating dryer 10 and the vibrating sifter 30 to perform sufficient drying treatment on the lithium hexafluorophosphate material.

[0047] Specifically, the vibrating dryer 10 can be connected to a material feeding line 71 to feed the material to be dried into the vibrating dryer 10, and particularly, the material can be lithium hexafluorophosphate crystals to be dried. The vibrating dryer 10 can also be directly or indirectly connected to a negative pressure line 72, an inert gas feeding line 73 and an inert gas discharging line 74. The negative pressure line 72 can provide a negative pressure (vacuum) environment inside the vibrating dryer 10 to suck hydrogen fluoride, steam and other impurity gases in the material, so as to improve the drying effect of the material, and particularly, to remove hydrogen fluoride in the lithium hexafluorophosphate. The hydrogen fluoride sucked by the negative pressure line 72 can be further recycled. The inert gas feeding line 73 and the inert gas discharging line 74 can be used to feed or discharge inert gas into or out of the drying system, so as to blow hydrogen fluoride gas in the lithium hexafluorophosphate crystals. For example, the inert gas can be nitrogen, helium or argon, etc. Preferably, the inert gas can be nitrogen, which is easy to prepare and low in cost, and is suitable for industrial use.

[0048] Further, as shown in Figure 1 the vibrating dryer 10 can be connected to the filter 20, and the filter 20 can be connected to the negative pressure line 72 and the inert gas discharging line 74, that is, the vibrating dryer 10 can be connected to the negative pressure line 72 and the inert gas discharging line 74 through the filter 20. It can be understood that the negative pressure line 72 and the inert gas discharging line 74 can be connected to an external vacuum pump, an exhaust device, etc., and the filter 20 can filter and intercept the material particles when the negative pressure line 72 and the inert gas discharging line 74 are in operation, so as to prevent the material particles from entering the negative pressure line 72 and the inert gas discharging line 74.

[0049] Further, the vibrating dryer 10 can include a dryer jacket 11, and the dryer jacket 11 can be filled with a heat medium (heat exchange medium) to heat the material. It can be understood that in some processes, for example, when the vibrating dryer is maintained and repaired, the dryer jacket can be filled with a coolant such as cold water to quickly reduce the temperature of the vibrating dryer, so as to facilitate rapid repair. The dryer jacket 11 can be connected to a heat medium feeding line 75 and a heat medium discharging line 76 to feed the heat medium into the dryer jacket 11 and discharge the heat medium from the dryer jacket 11, so as to heat the vibrating dryer 10. The heat medium can be a heat exchange medium such as steam, water, pipeline gas, etc., and the specific type can be selected according to the actual working condition. Preferably, the heat medium feeding line 75 can be connected to the lower part (particularly, the bottom) of the dryer jacket 11, and the heat medium discharging line 76 can be connected to the upper part (particularly, the top) of the dryer jacket 11. It can be understood that the lower-in and upper-out arrangement is beneficial to fill the heat medium into the entire dryer jacket 11 to improve the heat exchange effect (particularly, when the heat medium is a liquid).

[0050] The vibratory dryer 10 may be equipped with a temperature sensor 61 for displaying and / or providing feedback on the material temperature inside the vibratory dryer 10. The opening of the regulating valve 42 on the heat inlet pipeline 75 can be adjusted based on the temperature data fed back by the temperature sensor 61. For example, the temperature probe of the temperature sensor 61 may extend into the interior of the vibratory dryer 10 through the dryer jacket 11.

[0051] like Figure 1 As shown, the vibrating dryer 10 can be connected to the vibrating screen 30, specifically, the bottom discharge port of the vibrating dryer 10 can be connected to the vibrating screen 30. The vibrating screen 30 has a screen 31 inside, which can screen materials according to particle size. That is, the screen 31 can retain materials that meet the particle size requirements above the screen 31, while smaller particles are screened below the screen 31. The top and bottom of the screen 31 of the vibrating screen 30 can be connected to a product outlet pipeline 77 and a small particle product outlet pipeline 78, respectively. The material that meets the particle size requirements above the screen 31 can be discharged through the product outlet pipeline 77, and the small particle material below the screen 31 can be discharged through the small particle product outlet pipeline 78. The small particle material can be collected and reused after discharge. For example, the small particle product outlet pipeline 78 can be connected to a small particle product tank, and the small particle material can be discharged into the small particle product tank for recrystallization, thereby saving materials and improving material utilization.

[0052] The vibration screening machine 30 can also be connected to the gas inlet pipeline 73, i.e. the gas inlet pipeline 73 can be indirectly connected to the vibration dryer 10 via the vibration screening machine 30. The gas inlet pipeline 73 can introduce nitrogen (or other inert gas) into the vibration screening machine 30 to purge the material particles, i.e. to purge the residual trace amount of hydrogen fluoride in the lithium hexafluorophosphate, especially the lithium hexafluorophosphate remaining above the screen 31. Preferably, the gas inlet pipeline 73 can be connected below the screen 31, so that the inert gas (nitrogen) is introduced from below the screen 31, i.e. the outlet of the gas inlet pipeline 73 can be arranged below the screen 31. It can be understood that the negative pressure suction provided in the vibration dryer 10 can be a primary impurity removal, and the inert gas purging provided in the vibration screening machine and / or the vibration dryer can be a secondary impurity removal. The negative pressure suction can quickly remove most of the gas impurities, and the inert gas purging can compensate for the poor effect of the negative pressure suction on the removal of gas impurities in the later stage, i.e. the inert gas is used to carry out the gas impurities remaining in the lithium hexafluorophosphate. In this way, after the negative pressure suction removes most of the gas impurities, the next step (which can be the inert gas purging in the vibration screening machine or the inert gas purging in the vibration dryer) can be entered without long-term negative pressure suction to ensure product quality, reducing the residence time in the vibration dryer, improving the drying efficiency of lithium hexafluorophosphate, and ensuring the product quality of lithium hexafluorophosphate to meet the purity and pH requirements of high-quality lithium hexafluorophosphate.

[0053] The vibration screening machine 30 can be provided with a pressure sensor 62 for displaying and / or feeding back the pressure in the vibration screening machine 30. The opening of the regulating valve 42 on the gas inlet pipeline 73 can be adjusted according to the pressure data fed back by the pressure sensor 62.

[0054] The dry system can be provided with on-off valves 41 and / or regulating valves 42 on each pipeline. For example, the feed pipeline 71, the negative pressure pipeline 72, the gas outlet pipeline 74, the product outlet pipeline 77 and the small particle product outlet pipeline 78 can be provided with on-off valves to control the opening and closing of the related pipelines. The gas inlet pipeline 73 and the heat medium inlet pipeline 75 can be provided with regulating valves 42 to adjust the flow and / or flow rate of the inert gas (nitrogen) and the heat medium.

[0055] Preferably, the vibration dryer 10 and the vibration sifter 30 can be connected to other devices, pipelines, etc. by soft connections 50 to compensate for the displacement and stress caused by the vibration of the vibration dryer 10 and the vibration sifter 30, and to reduce or eliminate the impact of vibration on the pipelines. Specifically, the vibration dryer 10 can be connected to one or more of the filter 20, the vibration sifter 30, the feed pipeline 71, the heat medium inlet pipeline 75, and the heat medium outlet pipeline 76 by the soft connections 50. The vibration sifter 30 can be connected to one or more of the gas inlet pipeline 73, the product outlet pipeline 77, and the small particle product outlet pipeline 78 by the soft connections 50. The soft connections 50 can be metal soft connections and rubber soft connections, etc., and the specific types thereof can be determined according to actual process needs.

[0056] It can be understood that the vibration dryer can rely on the vibration effect to dry the material, and does not need to be provided with a stirring device, so that metal ion impurities introduced by the frictional contact between the stirring device and the material can be avoided. The feeding and discharging process of the vibration dryer can be automatically operated without manual operation, and the automation level of the lithium hexafluorophosphate drying process can be improved.

[0057] The embodiments of the present application also provide a lithium hexafluorophosphate drying method (hereinafter, sometimes referred to as “drying method” for short), which can use the aforementioned lithium hexafluorophosphate drying system. The drying method can include the following steps:

[0058] The lithium hexafluorophosphate crystalline material produced by the upstream process is added into the vibration dryer 10 through the feed pipeline 71. After the feeding is completed, the on-off valve 41 of the feed pipeline 71 can be closed, and the vibration dryer 10 can be started.

[0059] The temperature in the dryer jacket 11 of the vibration dryer 10 is controlled by adjusting the opening degree of the adjusting valve 42 of the heat medium inlet pipeline 75, and then the drying temperature in the vibration dryer 10 is controlled. The temperature of the material in the vibration dryer 101 can be displayed and fed back by the temperature sensor 61.

[0060] The on-off valve 41 of the negative pressure pipeline 72 is opened, and hydrogen fluoride (gas) in the solid material of lithium hexafluorophosphate is removed by negative pressure through the filter 20. The filter 20 can intercept the material, so that the powder material cannot enter the negative pressure pipeline 72, and the removed hydrogen fluoride can be recycled and reused.

[0061] It can be understood that the negative pressure state can reduce the boiling point of liquid hydrogen fluoride, that is, the negative pressure state can promote the vaporization of hydrogen fluoride, and then promote the drying of the lithium hexafluorophosphate material.

[0062] After the material is preliminarily dried through the above steps, the on-off valve 41 of the negative pressure pipeline 72 and the adjusting valve 42 of the heat medium inlet pipeline 75 can be closed, and the material in the vibration dryer 10 is introduced into the vibration sifter 30 through the discharging pipeline at the bottom thereof.

[0063] The vibrating sieve 30 is started, and the material that meets the particle size requirement is retained on the upper layer of the screen 31, and a small amount of material with too small particle size that does not meet the requirement can pass through the screen 31. The regulating valve 42 of the gas inlet pipeline 73 is opened, and the nitrogen flow is controlled by controlling the regulating valve 42. The material on the upper layer of the screen 31 is purged with nitrogen for a certain period of time to bring out the trace amount of hydrogen fluoride remaining in the material. The pressure in the vibrating sieve 30 can be displayed and fed back by the pressure sensor 62.

[0064] After the material is dried to meet the process requirement, the regulating valve 42 of the gas inlet pipeline 73 and the on-off valve 41 of the gas outlet pipeline 74 can be closed, and the on-off valve of the product outlet pipeline 77 is opened, so that the dried lithium hexafluorophosphate enters the next process equipment or storage equipment, etc. A small amount of material with too small particle size that does not meet the requirement can be discharged through the small particle product outlet pipeline 78 for collection and re-crystallization treatment.

[0065] The following briefly describes some beneficial effects of the above-mentioned embodiments of the present application.

[0066] The drying system of lithium hexafluorophosphate provided by the embodiments of the present application uses a vibrating dryer and a vibrating sieve as the main drying equipment, and can relatively improve the drying efficiency of lithium hexafluorophosphate and the product quality of lithium hexafluorophosphate by combining negative pressure suction and gas purging. The equipment does not need manual operation when feeding and discharging, and can improve the automation level of the drying process. The vibrating dryer does not have a stirring device in contact with the material, and is not easy to introduce metal ion impurities. The metal screen of the vibrating sieve can screen out small particle materials, and the small particle materials can be collected and re-crystallized for treatment, thereby improving the utilization rate of the material.

[0067] It can be understood that, in the present application, when the number of components or members is not particularly limited, the number can be one or more, and the plurality herein refers to two or more. For the case where the number of components or members is specifically described as, for example, two, three, four, etc. in the drawings and / or the description, the specific number is generally exemplary and not limiting, and can be understood as a plurality, i.e. two or more, but this does not mean that the present application excludes the case of one.

[0068] It should be understood that the above-mentioned embodiments are only exemplary and are not used to limit the present application. Those skilled in the art can make various modifications and changes to the above-mentioned embodiments under the teaching of the present application without departing from the scope of the present application.

Claims

1. A drying system for lithium hexafluorophosphate, characterized in that, The drying system comprises a vibrating dryer and a vibrating sifter, the vibrating dryer is connected to the vibrating sifter, and materials pass through the vibrating dryer and the vibrating sifter in sequence, The vibrating dryer is directly or indirectly connected to a negative pressure pipeline to extract gas impurities in the materials, and the vibrating sifter and / or the vibrating dryer is connected to an inlet gas pipeline for introducing inert gas to purge gas impurities in the materials.

2. The drying system of lithium hexafluorophosphate according to claim 1, characterized in that, The drying system further comprises a filter connected to the vibrating dryer, The filter is connected to a negative pressure pipeline, and the filter can filter and intercept solid materials to prevent the solid materials from entering the negative pressure pipeline; and / or the filter is connected to an outlet gas pipeline, and the filter can filter and intercept solid materials to prevent the solid materials from entering the outlet gas pipeline.

3. The lithium hexafluorophosphate drying system according to claim 1, wherein An upper portion of the screen of the vibrating sifter is connected to a product outlet pipeline to discharge materials meeting the particle size requirements, A lower portion of the screen of the vibrating sifter is connected to a small particle product outlet pipeline to discharge materials not meeting the particle size requirements.

4. The drying system of lithium hexafluorophosphate according to claim 1, characterized in that, The vibrating dryer comprises a dryer jacket, the dryer jacket is connected to a heat medium inlet pipeline to introduce heat medium into the dryer jacket, The dryer jacket is connected to a heat medium outlet pipeline to discharge heat medium from the dryer jacket.

5. The lithium hexafluorophosphate drying system according to claim 1, wherein The vibrating dryer is provided with a temperature sensor to display and / or feedback the temperature of the materials in the vibrating dryer, And / or, the vibrating sifter is provided with a pressure sensor to display and / or feedback the pressure in the vibrating sifter.

6. The drying system of lithium hexafluorophosphate according to claim 1, characterized in that, The drying system further comprises a flexible connection, The vibrating dryer is connected to at least one device or at least one pipeline through the flexible connection; and / or the vibrating sifter is connected to at least one device or at least one pipeline through the flexible connection.

7. The drying system of lithium hexafluorophosphate according to any one of claims 1 to 6, characterized in that, The drying system is provided with an on-off valve and / or a regulating valve in the pipeline.

8. The drying system of lithium hexafluorophosphate according to claim 3, characterized in that, An outlet of the inlet gas pipeline is arranged below the screen, so that the inert gas is introduced into the vibrating sifter from below the screen.

9. The drying system of lithium hexafluorophosphate according to claim 3, characterized in that, The small particle product outlet pipeline is connected to a small particle product tank to collect small particle materials for crystallization treatment.

10. The drying system of lithium hexafluorophosphate according to claim 4, characterized in that, The heat medium inlet pipeline is connected to a lower portion of the dryer jacket, and the heat medium outlet pipeline is connected to an upper portion of the dryer jacket.

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