阅读说明：本技术 一种六氟磷酸锂的生产装置及方法 (Production device and method of lithium hexafluorophosphate ) 是由 不公告发明人 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种六氟磷酸锂的生产装置及方法,包括五氟化磷供料装置、氟化锂供料装置、六氟磷酸锂反应装置和六氟磷酸锂分离装置,所述六氟磷酸锂反应装置包括串联的预反应器和主反应器,所述预反应器出料口与主反应器进料口相连；所述五氟化磷供料装置连接至主反应装置进料口,所述主反应装置出料口连接六氟磷酸锂分离装置进口；所述氟化锂供料装置连接预反应器进料口,所述六氟磷酸锂分离装置出液口经循环泵连接至预反应器进料口。本发明在预反应器和主反应器中可以分别同时进行不同批次原料的预反应和主反应,使间歇反应进一步实现半连续化操作,大大提升了时间的利用率和反应效率。(The invention discloses a device and a method for producing lithium hexafluorophosphate, which comprise a phosphorus pentafluoride feeding device, a lithium fluoride feeding device, a lithium hexafluorophosphate reaction device and a lithium hexafluorophosphate separation device, wherein the lithium hexafluorophosphate reaction device comprises a pre-reactor and a main reactor which are connected in series, and a discharge hole of the pre-reactor is connected with a feed hole of the main reactor; the phosphorus pentafluoride feeding device is connected to a feeding hole of the main reaction device, and a discharging hole of the main reaction device is connected with an inlet of the lithium hexafluorophosphate separation device; the lithium fluoride feeding device is connected with the feed inlet of the pre-reactor, and the liquid outlet of the lithium hexafluorophosphate separating device is connected with the feed inlet of the pre-reactor through a circulating pump. The invention can respectively carry out the pre-reaction and the main reaction of different batches of raw materials in the pre-reactor and the main reactor simultaneously, so that the intermittent reaction further realizes the semi-continuous operation, and the time utilization rate and the reaction efficiency are greatly improved.)

1. The production device of lithium hexafluorophosphate is characterized by comprising a phosphorus pentafluoride feeding device, a lithium fluoride feeding device, a lithium hexafluorophosphate reaction device and a lithium hexafluorophosphate separation device, wherein the lithium hexafluorophosphate reaction device comprises a pre-reactor and a main reactor which are connected in series, and a discharge port of the pre-reactor is connected with a feed port of the main reactor; the phosphorus pentafluoride feeding device is connected to a feeding hole of the main reaction device, and a discharging hole of the main reaction device is connected with an inlet of the lithium hexafluorophosphate separation device; the lithium fluoride feeding device is connected with the feed inlet of the pre-reactor, and the liquid outlet of the lithium hexafluorophosphate separating device is connected with the feed inlet of the pre-reactor through a circulating pump.

2. The apparatus of claim 1, wherein the phosphorus pentafluoride supply apparatus is a phosphorus pentafluoride reactor, and wherein the phosphorus pentafluoride reactor comprises a batch reactor and/or a continuous reactor.

3. The apparatus for producing lithium hexafluorophosphate according to claim 1 or 2, further comprising a hydrogen fluoride purification apparatus comprising a hydrogen fluoride rectification column and an HF storage tank.

4. The apparatus for producing lithium hexafluorophosphate of claim 1 or 2, wherein said lithium hexafluorophosphate separating device comprises a crystallizer and a filter.

5. The apparatus for producing lithium hexafluorophosphate of claim 1, wherein said lithium hexafluorophosphate reaction apparatus comprises a second reaction apparatus and a second separation apparatus connected in parallel with the lithium hexafluorophosphate reaction apparatus and the lithium hexafluorophosphate separation apparatus.

6. The apparatus for producing lithium hexafluorophosphate of claim 5, wherein said second reaction device comprises a second pre-reaction device and a second main reaction device; the second separation device comprises a second crystallizer and a second filter.

7. A method for producing lithium hexafluorophosphate is characterized by comprising the following steps:

feeding in a first batch: charging specified amounts of lithium fluoride and hydrofluoric acid into a pre-reactor to dissolve the lithium fluoride; conveying the solution of lithium fluoride and hydrofluoric acid in the pre-reactor to a main reactor at the downstream of the pre-reactor for reaction;

feeding for the second batch: adding specified amounts of lithium fluoride and hydrofluoric acid into the pre-reactor again for reaction;

the first batch of feed is subjected to main reaction: conveying gaseous phosphorus pentafluoride and/or a mixture of gaseous phosphorus pentafluoride and hydrogen chloride gas to a main reactor, carrying out gas-liquid contact reaction with the solution of lithium fluoride and hydrofluoric acid, and returning unreacted phosphorus pentafluoride gas and/or a mixture of gaseous phosphorus pentafluoride and hydrogen chloride gas in the main reactor to a pre-reactor;

pre-reaction of the second batch of feed: in the pre-reactor, the lithium fluoride and hydrofluoric acid solution added in the second batch of feeding materials is in gas-liquid contact with the unreacted mixture of phosphorus pentafluoride and hydrogen chloride gas returned to the pre-reactor in the main reactor, and the pre-reaction of the second batch of feeding materials is carried out while the pre-reaction of the first batch of feeding materials is carried out;

pre-reaction of the third batch of feed: conveying the liquid of the first batch of feeding main reaction to a lithium hexafluorophosphate separation device, conveying the liquid of the second batch of feeding pre-reaction in a pre-reactor to a main reactor, adding specified amounts of lithium fluoride and hydrofluoric acid feeding into the pre-reactor, carrying out the main reaction of the second batch of feeding in the main reactor, and simultaneously carrying out the third batch of feeding pre-reaction in the pre-reactor;

and (3) product separation: separating the lithium hexafluorophosphate product from the liquid in a lithium hexafluorophosphate separation device, and returning the mother liquid obtained by separation to the pre-reactor for re-reaction.

8. The method for producing lithium hexafluorophosphate of claim 7, wherein the reaction in the pre-reactor and the main reactor is performed under a nitrogen atmosphere, and the pressure in the pre-reactor and the main reactor is 0.8 to 1.2Kg/cm²(g) The reaction temperature is 0-5 ℃, and the reaction time is 4-10 hours.

9. The method for producing lithium hexafluorophosphate according to any one of claims 7 or 8, wherein a second pre-reactor, a second main reactor and a second lithium hexafluorophosphate separation device are connected in parallel with the pre-reactor, the main reactor and the lithium hexafluorophosphate separation device, and the reaction and separation operations are performed in the second pre-reactor, the second main reactor and the second lithium hexafluorophosphate separation device while the pre-reactor and the main reactor are in the feeding operation.

Technical Field

The invention relates to the technical field of lithium battery electrolyte raw material production, in particular to a device and a method for producing lithium hexafluorophosphate for lithium battery production.

Background

The electrolyte is one of three main components of a lithium ion secondary battery and a lithium polymer battery. Inorganic fluoride lithium hexafluorophosphate (LiPF)₆) Is a raw material for producing the anhydrous organic electrolyte. Because lithium hexafluorophosphate is a battery grade product, the manufacturing technical requirement is very high, the general product specification requirement is that the purity is more than 99.9 percent, the moisture content is less than 15ppm, the HF content is less than 70ppm, the content of various metal components is less than 1ppm, the chloride ion content is less than 2ppm, and SO is₄ ^2-The content is less than 5ppm, and the obtained product has uniform particle size. At the same time, the by-products are reduced in the large-scale production processThe conversion rate and the selectivity of the product are improved. In the existing lithium hexafluorophosphate production process, anhydrous hydrofluoric acid is generally reacted with phosphorus pentachloride to generate phosphorus pentafluoride, and then the phosphorus pentafluoride is conveyed to a lithium hexafluorophosphate reactor to be reacted with lithium fluoride to generate phosphorus pentafluoride, wherein the lithium hexafluorophosphate reactor is generally a batch reactor, and if a certain conversion rate is reached and a product with required purity is obtained, the required reaction time is long, and the single-kettle yield is low.

Disclosure of Invention

In order to solve the technical problems, the invention provides the following technical scheme:

a production device of lithium hexafluorophosphate comprises a phosphorus pentafluoride feeding device, a lithium fluoride feeding device, a lithium hexafluorophosphate reaction device and a lithium hexafluorophosphate separation device, wherein the lithium hexafluorophosphate reaction device comprises a pre-reactor and a main reactor which are connected in series, and a discharge port of the pre-reactor is connected with a feed port of the main reactor; the phosphorus pentafluoride feeding device is connected to a feeding hole of the main reaction device, and a discharging hole of the main reaction device is connected with an inlet of the lithium hexafluorophosphate separation device; the lithium fluoride feeding device is connected with the feed inlet of the pre-reactor, and the liquid outlet of the lithium hexafluorophosphate separating device is connected with the feed inlet of the pre-reactor through a circulating pump.

Further, the phosphorus pentafluoride feeding device is a phosphorus pentafluoride reactor, and preferably, the phosphorus pentafluoride reactor comprises a batch reactor and/or a continuous reactor.

Further, the production device of lithium hexafluorophosphate also comprises a hydrogen fluoride refining device, and the hydrogen fluoride refining device comprises a hydrogen fluoride rectifying tower and a hydrogen fluoride storage tank.

Further, the lithium hexafluorophosphate separation device comprises a crystallizer and a filter.

Further, the lithium hexafluorophosphate reaction device comprises a second reaction device and a second separation device which are connected in parallel with the lithium hexafluorophosphate reaction device and the lithium hexafluorophosphate separation device, and preferably, the second reaction device comprises a second pre-reaction device and a second main reaction device; the second separation device comprises a second crystallizer and a second filter.

A method for producing lithium hexafluorophosphate comprises the following steps:

feeding in a first batch: charging specified amounts of lithium fluoride and hydrofluoric acid into a pre-reactor to dissolve the lithium fluoride; conveying the solution of lithium fluoride and hydrofluoric acid in the pre-reactor to a main reactor at the downstream of the pre-reactor for reaction;

feeding for the second batch: adding specified amounts of lithium fluoride and hydrofluoric acid into the pre-reactor again for reaction;

the first batch of feed is subjected to main reaction: conveying gaseous phosphorus pentafluoride and/or a mixture of gaseous phosphorus pentafluoride and hydrogen chloride gas to a main reactor, carrying out gas-liquid contact reaction with the solution of lithium fluoride and hydrofluoric acid, and returning unreacted phosphorus pentafluoride gas and/or a mixture of gaseous phosphorus pentafluoride and hydrogen chloride gas in the main reactor to a pre-reactor;

pre-reaction of the second batch of feed: in the pre-reactor, the lithium fluoride and hydrofluoric acid solution added in the second batch of feeding materials is in gas-liquid contact with the unreacted mixture of phosphorus pentafluoride and hydrogen chloride gas returned to the pre-reactor in the main reactor, and the pre-reaction of the second batch of feeding materials is carried out while the pre-reaction of the first batch of feeding materials is carried out;

pre-reaction of the third batch of feed: conveying the liquid of the first batch of feeding main reaction to a lithium hexafluorophosphate separation device, conveying the liquid of the second batch of feeding pre-reaction in a pre-reactor to a main reactor, adding specified amounts of lithium fluoride and hydrofluoric acid feeding into the pre-reactor, carrying out the main reaction of the second batch of feeding in the main reactor, and simultaneously carrying out the third batch of feeding pre-reaction in the pre-reactor;

and (3) product separation: separating the lithium hexafluorophosphate product from the liquid in a lithium hexafluorophosphate separation device, and returning the mother liquid obtained by separation to the pre-reactor for re-reaction.

Further, the reaction in the pre-reactor and the main reactor is carried out in a nitrogen atmosphere, and the pressure in the pre-reactor and the main reactor is 0.8-1.2 Kg/cm²(g) The reaction temperature is 0-5 ℃, and the reaction time is 4-10 hours.

And when the pre-reactor and the main reactor are subjected to feeding operation, the second pre-reactor, the second main reactor and the second lithium hexafluorophosphate separating device are subjected to reaction and separation operation.

The invention has the beneficial effects that:

the pre-reactor and the main reactor which are arranged in series improve the utilization rate of raw materials, and recycle unreacted raw materials, the raw materials are pre-reacted with unreacted gas returned from the main reactor in the pre-reactor to realize certain conversion, and then the raw materials are conveyed to the main reactor to carry out main reaction with sufficient gas, so that the conversion rate can be greatly improved; in addition, the pre-reaction and the main reaction of different batches of raw materials can be simultaneously carried out in the pre-reactor and the main reactor respectively, so that the intermittent reaction further realizes semi-continuous operation, and the time utilization rate and the reaction efficiency are greatly improved.

Drawings

FIG. 1 is a process flow diagram of a first embodiment of the present invention;

FIG. 2 is a process flow diagram of a second embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Example 1

Fig. 1 schematically shows a first embodiment of a production apparatus and a production method of lithium hexafluorophosphate of the present invention. The lithium hexafluorophosphate production device comprises a phosphorus pentafluoride feeding device 1, a hydrogen fluoride feeding device 2, a lithium hexafluorophosphate reaction device 3 and a lithium hexafluorophosphate separation device 4.

In this embodiment, the phosphorus pentafluoride supply device 1 is a reactive distillation column 11, a phosphorus pentafluoride storage tank 12 is connected to a discharge port of the reactive distillation column 11, and PCl is introduced into the reactive distillation column 11₃And Cl₂，PCl₃And Cl₂Reaction takes place to form PCl₅And then chemically reacted with 5 equivalents of HF from the hydrogen fluoride supply 2 to form PF₅：

PCl₃(l)+Cl₂(l)→PCl₅(l)

PCl₅(l)+5HF(l)→PF₅(g)+5HCl(g)

PF is generated in the reactive distillation column 11₅And 5 equivalents of HCl, which is conveyed to the phosphorus pentafluoride storage tank 12 from the discharge port for storage and conveyed to the lithium hexafluorophosphate reaction device 3 as required.

The hydrogen fluoride supply device 2 includes a hydrogen fluoride refining device including a hydrogen fluoride rectifying tower 21 and hydrogen fluoride storage tanks (22, 22'). The hydrogen fluoride rectifying column 21 is a column for rectifying anhydrous hydrofluoric acid (Fresh AHF) from a Fresh feed and recovered hydrofluoric acid from the phosphorus pentafluoride reaction apparatus 1, further removing water from the raw materials, supplying the raw materials to the reactor as a reaction solvent, and supplying PF₅The generator was used as a feedstock.

The lithium hexafluorophosphate reaction device 3 comprises a pre-reactor 31 and a main reactor 32 which are connected in series, wherein a discharge hole of the pre-reactor 31 is connected with a feed hole of the main reactor 32;

an outlet of the phosphorus pentafluoride feeding storage tank 12 is connected to a feeding hole of a main reaction device 32, and a discharging hole of the main reaction device 32 is connected with an inlet of a lithium hexafluorophosphate separating device 4; the lithium fluoride feeding device 5 is connected with the feed inlet of the pre-reactor 31, and the liquid outlet of the lithium hexafluorophosphate separating device 4 returns to the feed inlet of the pre-reactor 31 through a circulating pump. In the present embodiment, the lithium hexafluorophosphate separation apparatus 4 includes a crystallizer 41 and a filter 42.

The method for preparing lithium hexafluorophosphate by adopting the production device of lithium hexafluorophosphate comprises the following steps:

the LiPF₆The reaction is carried out in a pre-reactor 31 and a main reactor 32 in series.

The reaction formula is as follows: PF (particle Filter)₅/HCl+LiF/HF→LiPF₆+5HCl

Feeding:

first, a first batch of material is fed, and a specified amount of LiF is loaded into the lithium fluoride feeding device 5 at the top of the pre-reactor 31, in this embodiment, the lithium fluoride feeding device 5 is a LiF hopper for feeding the pre-reactor 31. Anhydrous hydrofluoric acid was fed from the hydrogen fluoride feeder 2 to the pre-reactor 31 to dissolve LiF. The dissolved LiF exists in the form of LiF · HF and is slightly exothermic. After the LiF dissolution is complete, the solution is transferred to the downstream main reactor 32.

After the transfer, the prereactor 31 is purged with nitrogen. The above operation is repeated, and a second batch of the feed is again made into the pre-reactor 31, and the prescribed amounts of lithium fluoride and hydrofluoric acid are added and dissolved for reaction.

Reaction:

the pre-reactor 31 and the main reactor 32 were cooled to 1 ℃ with chilled brine, ready for reaction.

Starting the stirrer in each reactor, carrying out the main reaction of the first batch of feed in the main reactor 32, and introducing PF into the main reactor 32 from the phosphorus pentafluoride feed storage tank 12₅The/5 HCl gas is in gas-liquid contact with LiF/HF solution to react to generate LiPF₆. Unreacted PF in the main reactor 32₅The gas and HCl gas are returned to the pre-reactor 31 for re-use in pre-reaction, so as to make PF₅The loss of gas is minimized.

Meanwhile, in the pre-reactor 31, the lithium fluoride and hydrofluoric acid solution added in the second batch of the feed in the pre-reactor 31 and the unreacted phosphorus pentafluoride and hydrogen chloride gas mixture from the main reaction of the first batch of the feed in the main reactor 32 and returned to the pre-reactor 31 are subjected to gas-liquid contact, and the second batch of the feed pre-reaction is simultaneously carried out in the pre-reactor 31.

After the reaction time is reached, the liquid obtained by the main reaction of the first batch of feeding materials in the main reactor 32 is conveyed to a lithium hexafluorophosphate separation device 4 for product separation, the liquid obtained by the pre-reaction of the second batch of feeding materials in the pre-reactor 31 is conveyed to the main reactor 32, and then specified amounts of lithium fluoride and hydrofluoric acid feeding materials are added into the emptied pre-reactor 31 to serve as a third batch of feeding materials, and the pre-reaction of the third batch of feeding materials is prepared. The reaction solution of the pre-reacted second batch of feed material delivered from the pre-reactor 31 to the main reactor 32 is subjected to the main reaction of the second batch of feed material in the main reactor 32, and the unreacted PF in the main reactor 32₅Gas and HCl gas are returned to pre-reactionThe reactor 31 is reused while the pre-reaction of the third charge is carried out in the pre-reactor 31.

The pre-reactor 31 and the main reactor 32 which are arranged in series improve the utilization rate of raw materials, and recycle unreacted raw materials, the raw materials are pre-reacted with unreacted gas returned from the main reactor 32 in the pre-reactor 31 to realize certain conversion, and then the raw materials are conveyed to the main reactor 32 to carry out main reaction with sufficient gas, so that the conversion rate can be greatly improved; in addition, the pre-reaction and the main reaction of different batches of raw materials can be simultaneously carried out in the pre-reactor 31 and the main reactor 32 respectively, so that the intermittent reaction further realizes semi-continuous operation, and the time utilization rate and the reaction efficiency are greatly improved.

In the pre-reactor 31 and the main reactor 32, the reaction conditions are: pressure 1.0Kg/cm²G, temperature 1 ℃ reaction time 6 hours as reference.

And (3) separating and purifying reaction products:

the lithium hexafluorophosphate product is separated from the liquid in the lithium hexafluorophosphate separation device 4, and the mother liquor obtained by separation is returned to the pre-reactor 31 for reaction again. The lithium hexafluorophosphate separation apparatus 4 includes a crystallizer 41 and a filter 42.

And (3) crystallization: after the main reaction in the main reactor 32 is completed, the concentration and purity of the reaction solution are analyzed, if LiPF₆The solution is sent to crystallizer 41 at a concentration below 15.0 wt.%, and if the concentration is above 15.0 wt.%, a new HF adjustment concentration is replenished from hydrogen fluoride storage tank 22'.

The crystallized filtrate is filtered and returned from the buffer tank 43 to the pre-reactor 31 as make-up feed to dissolve LiF.

And (3) filtering: the discharge valve at the bottom of the crystallizer 41 is opened, and LiPF is added₆The crystals/mother liquor are transferred to the filter 42 and solid-liquid separation is carried out. At this time, the pressure of the crystallizer 41 was maintained at 2.0kg/cm²G, the filtrate from the buffer tank 43 is also simultaneously withdrawn and returned to the prereactor 31 as make-up feed.

And (3) drying: introducing nitrogen gas into the filter 42, heating, and purging the LiPF filtered by the filter 42₆Cooling the crystal。

Waste acid treatment:

the filtrate obtained after the end of filtration is stored in the filtrate receiver buffer tank 43. A portion will be disposed of as spent acid. The waste acid treatment is divided into two steps, wherein in the first step, filtrate in the buffer tank 43 passes through the buffer tank 43', and is quantitatively sent to the concentrator 44, and HF is recovered in the concentrator 44; second step LiPF is recovered in the thermal decomposer 45 after HF is secondarily recovered₆PF produced by thermal decomposition₅And recycling the gas, wherein LiF obtained after thermal decomposition contains more metal components and is sent out for treatment as solid waste.

The reaction formula is as follows: LiPF₆(Heat) → LiF (solid) + PF₅(gas)

The conditions of the above reaction formula: heating at 265 deg.C, and maintaining micro-negative pressure in the thermal decomposer.

Acid gas separation:

the gas discharged from the top of the pre-reactor 31 is a mixed gas of HCl and HF, and cannot be directly discharged into the atmosphere. From the viewpoint of preventing environmental pollution and resource regeneration, equipment is designed to separate and use the mixed gas.

In this embodiment, the phosphorus pentafluoride reactor is a reactive distillation column 11, in which reaction and distillation are simultaneously performed, wherein the lower part of the reactive distillation column is a reaction section, the upper part of the reactive distillation column is a distillation section, and the top of the reactive distillation column 11 is connected with a phosphorus pentafluoride storage tank 12. Three raw material feeds, Cl, in a reactive distillation column₂An appropriate excess amount to avoid PF causing side reactions₃And (4) generating.

By rectification, pure PF₅The gas and the HCl gas partially flow back through the condenser, and the discharged material at the top of the tower enters the phosphorus pentafluoride storage tank 12 and then enters the main reactor 32. Owing to adopt the reaction rectifying column as phosphorus pentafluoride feedway, can realize phosphorus pentafluoride's continuous production to collect and preserve in the phosphorus pentafluoride storage tank, on the one hand in the control raw materials index parameter, can satisfy the stable feed of the lithium hexafluorophosphate of prereactor and main reactor in the follow-up technology.

In the reactive distillation column 11, the reaction and the distillation are performed simultaneously. By rectification and inversionHF and Cl contained in the reaction mass₂Going to the bottom of the column, pure PF₅The gas and HCl gas enter the main reactor through the top of the tower.

Example 2

Fig. 2 schematically shows a process flow diagram of a second embodiment of the apparatus for producing lithium hexafluorophosphate of the present invention.

The lithium hexafluorophosphate reaction device comprises a second reaction device and a second separation device which are connected in parallel with the lithium hexafluorophosphate reaction device and the lithium hexafluorophosphate separation device, and preferably, the second reaction device comprises a second pre-reaction device 31 'and a second main reaction device 32'; the second separation device comprises a second crystallizer 41 'and a second filter 42'.

The parallel reaction devices can carry out normal reaction operation when one group is filled or overhauled, thereby further improving the production efficiency.

What has been described above are merely some embodiments of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.