CN115513553B - Method for recovering lithium salt in electrolyte based on continuous flow reactor - Google Patents

Method for recovering lithium salt in electrolyte based on continuous flow reactor Download PDF

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CN115513553B
CN115513553B CN202211464990.5A CN202211464990A CN115513553B CN 115513553 B CN115513553 B CN 115513553B CN 202211464990 A CN202211464990 A CN 202211464990A CN 115513553 B CN115513553 B CN 115513553B
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CN115513553A (en
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吴宇鹏
檀智祥
魏文添
刘雅婷
韩恒
苏俊
黄兵
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Guangzhou Tinci Materials Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/54—Reclaiming serviceable parts of waste accumulators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/40—Mixing liquids with liquids; Emulsifying
    • B01F23/405—Methods of mixing liquids with liquids
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D13/00—Compounds of sodium or potassium not provided for elsewhere
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/08—Carbonates; Bicarbonates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
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    • Y02W30/84—Recycling of batteries or fuel cells

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Abstract

The invention belongs to the field of lithium ion batteries, and discloses a method for recovering lithium salt in electrolyte based on a continuous flow reactor, which is carried out based on a continuous flow reaction system, wherein the continuous flow reaction system comprises a first continuous flow reactor, a first buffer tank, a first pump, a first filter, a second continuous flow reactor, a second buffer tank, a second pump and a second filter which are sequentially connected; the front section of the first continuous flow reactor and the front section of the second continuous flow reactor are connected with one or more filling pipes for injecting a solution containing micro-nano bubbles; the micro-nano bubbles are carbon dioxide bubbles; mixing electrolyte containing lithium hexafluorophosphate and water solution containing soluble carbonate to form mixed solution, adding the mixed solution into a continuous flow reaction system for reaction, wherein the reaction temperature is not lower than 60 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate. The method improves the precipitation efficiency of the continuous flow reactor.

Description

Method for recovering lithium salt in electrolyte based on continuous flow reactor
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a method for recovering lithium salt in electrolyte based on a continuous flow reactor.
Background
The applicant previously proposed patent application CN2022109698418 to disclose a method for recovering electrolyte of a waste lithium ion battery, which comprises the following steps: step 1: mixing and reacting waste electrolyte and soluble carbonate solution or soluble phosphate solution in a continuous flow reactor to obtain an oil phase, a water phase and a precipitate; lithium ions in the waste electrolyte are fixed in the precipitate, and lithium carbonate or lithium phosphate products are obtained through separation; hexafluorophosphate in the waste electrolyte exists in an aqueous phase; the non-aqueous organic solution in the waste electrolyte is the main component of the oil phase; and 2, step: the hexafluorophosphate salt in the aqueous phase is extracted.
When the method adopts soluble carbonate as a precipitator and is based on continuous flow reactor for electrolyte recovery, the recovery rate of Li can reach 94.75 percent.
The phosphate is used as a precipitator, and the recovery efficiency is higher.
In practical applications, lithium carbonate is more desirable as a product, and can be directly and widely used as a cathode material, a lithium salt and other raw materials.
The technical problem solved by the scheme is as follows: how to improve the recovery efficiency of waste electrolyte based on a continuous flow reactor.
Disclosure of Invention
The invention aims to provide a method for recovering lithium salt in electrolyte based on a continuous flow reactor, which is carried out by adopting carbon dioxide micro-nano bubbles and the continuous flow reactor, wherein the micro-nano bubbles are injected into the front section of the continuous flow reactor, tend to be attached to an oil-water intersection interface, the pressure is gradually reduced at the rear section of the continuous flow reactor, the micro-nano bubbles can be gradually broken, higher energy is released at the oil-water phase interface, the oil-water mixing force is improved, and the precipitation efficiency of the continuous flow reactor is improved. Meanwhile, compared with the air micro-nano bubbles, the carbon dioxide micro-nano bubbles have a better precipitation effect on lithium carbonate under the condition of very low bubble consumption.
In order to achieve the purpose, the invention provides the following technical scheme: a method for recovering lithium salt in electrolyte based on a continuous flow reactor is carried out based on a continuous flow reaction system, wherein the continuous flow reaction system comprises a first continuous flow reactor, a first buffer tank, a first pump, a first filter, a second continuous flow reactor, a second buffer tank, a second pump and a second filter which are connected in sequence; the front section of the first continuous flow reactor and the front section of the second continuous flow reactor are connected with one or more filling pipes for injecting a solution containing micro-nano bubbles; the micro-nano bubbles are carbon dioxide bubbles;
mixing electrolyte containing lithium hexafluorophosphate and water solution containing soluble carbonate to form mixed solution, adding the mixed solution into a continuous flow reaction system for reaction, wherein the reaction temperature is not lower than 60 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
If the temperature is too low, the micro-nano carbon dioxide bubbles are easy to react with the sodium carbonate solution to generate sodium bicarbonate, so that the micro-nano bubbles disappear in the long-flow reaction process, and the micro-nano carbon dioxide bubbles are absorbed by the sodium carbonate solution instead of disappearing in a cracking mode.
When the reaction temperature exceeds 60 ℃, sodium bicarbonate is difficult to exist, micro-nano bubbles can maintain higher pressure and are difficult to be absorbed by sodium carbonate, so the reaction temperature should be controlled to be above 60 ℃, preferably above 70 ℃, and more preferably above 80 ℃.
In the above method for recovering lithium salt from an electrolyte solution based on a continuous flow reactor, the mass ratio of the electrolyte solution to an aqueous solution containing soluble carbonate is 1 to 10; the concentration of lithium hexafluorophosphate in the electrolyte is 5-20wt%.
In the invention, the mass ratio of the electrolyte to the water solution containing soluble carbonate can be selected from 1; 1; 1; 1; 1; 1; 1; 1;1, 9; 1; 2; 3, a step of; 4; 5, performing primary filtration and secondary filtration; 6; 7; 8; 9; 10;
the weight ratio of the soluble carbonate and the lithium hexafluorophosphate in the electrolyte is related, and it is sure that no matter how the concentration changes, in the continuous flow reactor, the precipitation efficiency is improved by adding micro-nano carbon dioxide bubbles, and the optimal carbonate concentration can be obtained through experiments for different electrolytes.
In the experimental process, 1.0M lithium hexafluorophosphate electrolyte is adopted, and the soluble carbonate is sodium carbonate with the concentration of 30 percent; according to the trend of the molar ratio of lithium hexafluorophosphate to sodium carbonate from 1.0 to 1.5, the weight ratio thereof varies from 6:1 (oil-water ratio) to 3:1 (oil-water ratio). It should be noted that the ratio of the two does not change the tendency of micro-nano bubbles to precipitate lithium carbonate based on the continuous flow reactor.
In the method for recovering lithium salt from the electrolyte based on the continuous flow reactor, the solution containing the micro-nano bubbles contains soluble carbonate.
In the method for recovering lithium salt from the electrolyte based on the continuous flow reactor, the micro-nano bubble-containing solution has the same composition as the mixed solution; the liquid flow rate in the first continuous flow reactor and the second continuous flow reactor is 0.5-2m/s; the volume ratio of the mixed liquid injected from the first continuous flow reactor to the solution injected from the filling pipe is 10;
preferably, the filling pipe is connected to a micro-nano bubble generation system, and micro-nano bubbles generated by the micro-nano bubble generation system are mainly distributed in the range of 100-500 nm; preferably, the micro-nano bubble generation system comprises the following components connected in sequence: the device comprises a dissolved air pump, a dissolved air tank and a micro-nano bubble generator; the inlet of the dissolved air pump is connected to a sodium carbonate solution storage tank or directly connected to a liquid injection pipe of the first continuous flow reactor, the same mixed liquid as the first continuous flow reactor is adopted, and a pump body of the dissolved air pump is also connected with a carbon dioxide supply pipe; the dissolved air pump mixes carbon dioxide and sodium carbonate solution or mixed solution, and the carbon dioxide gas with larger grain diameter is discharged in the dissolved air tank after mixing; then the liquid enters a micro-nano bubble generator, after the micro-nano bubble generator is subjected to various actions of shock, oscillation, backflow and vortex, the pressure is suddenly released, and a large amount of micro bubbles can be separated out; these micro bubbles have a large energy once they are broken, and can change the two-phase interface balance. The volume ratio of the sodium carbonate solution or the mixed solution flowing through the dissolved air pump to the carbon dioxide gas (normal pressure equivalent) is 100-20, and the pressure of the dissolved air tank 13 is maintained at 5bar.
In the above method for recovering lithium salt from an electrolyte solution based on a continuous flow reactor, the first buffer tank and the second buffer tank are at normal pressure or slightly negative pressure; the micro negative pressure refers to the vacuum degree of 1kPa-10kPa.
In the method for recovering lithium salt from the electrolyte based on the continuous flow reactor, the liquid discharged from the second filter is subjected to liquid separation to obtain a water phase and an oil phase; and obtaining the hexafluorophosphate from the aqueous phase by a crystallization method.
In the method for recovering lithium salt from the electrolyte based on the continuous flow reactor, the particle size of the micro-nano bubbles is 10nm-10 μm.
In the method for recovering lithium salt from the electrolyte based on the continuous flow reactor, the particle size of the micro-nano bubbles is 100-500nm.
In the above method for recovering lithium salt from an electrolyte solution based on a continuous flow reactor, the soluble carbonate is sodium carbonate, potassium carbonate or ammonium carbonate; the ratio of the molar amount of lithium ions in lithium hexafluorophosphate to the molar amount of carbonate in the aqueous solution containing soluble carbonate is 2:1 to 1.5.
In the above-described method for recovering lithium salt from an electrolyte based on a continuous flow reactor, the reaction temperature is 70 to 90 ℃.
Compared with the prior art, the invention has the beneficial effects that:
the method provided by the invention is carried out by adopting carbon dioxide micro-nano bubbles and a continuous flow reactor, wherein the micro-nano bubbles are injected into the front section of the continuous flow reactor, tend to attach to an oil-water intersection interface, the pressure is gradually reduced at the rear section of the continuous flow reactor, the micro-nano bubbles can be gradually broken, higher energy is released at the oil-water phase interface, the oil-water mixing force is improved, and the precipitation efficiency of the continuous flow reactor is realized.
Meanwhile, compared with the air micro-nano bubbles, the carbon dioxide micro-nano bubbles have a better precipitation effect on lithium carbonate under the condition of very low bubble consumption. As a possible corollary, at the instant of explosion of the micro-nano bubbles, the following reversible reaction is in progress:
CO 2 +H 2 O⇌CO 3 2- +H + ；
this reversible reaction promotes the precipitation of Li.
Drawings
FIG. 1 is a piping flow diagram of a continuous flow reaction system of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Introduction to continuous flow reaction systems
The continuous flow reaction system comprises a first continuous flow reactor 1, a first buffer tank 2, a first pump 3, a first filter 4, a second continuous flow reactor 5, a second buffer tank 6, a second pump 7, a second filter 8, a third buffer tank 9 and a liquid distributor 10 which are connected in sequence; the front section of the first continuous flow reactor 1 and the front section of the second continuous flow reactor 5 are connected with one or more filling pipes 11 for injecting a solution containing micro-nano bubbles; in this example, the specifications of the first continuous flow reactor 1 and the second continuous flow reactor 5 are the same; its DN50, length 25m; the positions of 1m, 5m and 10m are respectively connected with a filling pipe 11, and in practical application, the filling pipe 11 can be only one or two in each continuous flow reactor; the filling pipe 11 is connected to a micro-nano bubble generating system, the micro-nano bubble generating system can be realized by any commercially available micro-nano bubble generator 14, and micro-nano bubbles generated by the micro-nano bubble generating system are mainly distributed in the range of 100-500 nm; as an alternative implementation form, it includes the following components connected in sequence: the device comprises a dissolved air pump 12, a dissolved air tank 13 and a micro-nano bubble generator 14; the inlet of the solution gas pump 12 is connected to a sodium carbonate solution storage tank 15 or directly connected to a liquid injection pipe of the first continuous flow reactor, and the inlet of the solution gas pump 12 or the pump body of the solution gas pump 12 is further connected to a carbon dioxide supply pipe 16; the dissolved air pump 12 mixes carbon dioxide and a sodium carbonate solution or a mixed solution, and the carbon dioxide gas with larger grain diameter is discharged in the dissolved air tank 13 after mixing; then the liquid enters the micro-nano bubble generator 14, and after the actions of impact, oscillation, backflow and vortex in the micro-nano bubble generator 14, the pressure is suddenly released, so that a large amount of micro bubbles can be separated out; these micro bubbles have a large energy once they are broken, and can change the two-phase interface balance. The volume ratio of the sodium carbonate solution or the mixed solution flowing through the dissolved air pump to the carbon dioxide gas (normal pressure equivalent) is 100-20, and the pressure of the dissolved air tank 13 is maintained at about 5bar.
Meanwhile, the micro-nano bubble generation system is a normal temperature system generally, in this case, part of carbon dioxide can be dissolved into a sodium carbonate solution to form a small amount of sodium bicarbonate, once the mixed solution passes through the micro-nano bubble generator 14 and enters the continuous flow reactor, more micro-nano bubbles can be additionally formed due to decomposition of the sodium bicarbonate at higher temperature, and therefore, in the continuous flow reactor, the effect of adopting the carbon dioxide micro-nano bubbles is obviously superior to that of non-carbon dioxide micro-nano bubbles, such as air micro-nano bubbles;
the working principle of the system of the invention is as follows: the oil-water mixed phase enters a first continuous flow reactor 1, a sodium carbonate solution containing micro-nano bubbles is supplemented through a filling pipe 11, and along with the reaction of the continuous flow reactor, the pressure is lower when the oil-water mixed phase is closer to a first buffer tank 2, and more micro-nano bubbles can be broken; then the solution enters a first buffer tank 2 for buffering and completely releasing pressure; pressurizing by a first pump 3, filtering by a first filter 4 to obtain lithium carbonate, then entering a second continuous flow reactor 5, enabling the reaction processes of the solution in the first continuous flow reactor 1 and the second continuous flow reactor 5 to be similar, then entering a second buffer tank 6 for buffer storage, pressurizing by a second pump 7, filtering by a second filter 8 to obtain lithium carbonate, buffering by a third buffer tank 9, separating by a liquid separator 10 to obtain an oil phase and a water phase, fractionating the oil phase to obtain different organic solvents, and recrystallizing the water phase to obtain sodium hexafluorophosphate.
Example 1
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, wherein the method is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are at normal pressure;
the method comprises the following steps:
mixing electrolyte containing lithium hexafluorophosphate and aqueous solution containing sodium carbonate to form mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 70 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The concentration of each substance of the electrolyte is as follows: liPF (lithium ion particle Filter) 6 15wt%, EC 28wt%, DMC 28wt%, EMC 28wt%, VC 1wt%; the concentration of sodium carbonate in the aqueous solution is 30wt%; liPF 6 ：CO 3 2- =2:1.1 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 0.8m/s;
the volume ratio of the mixed solution flowing through the dissolved air pump and the carbon dioxide gas is 100. 91% of mixed liquid is injected into the inlet of the first continuous flow reactor, and 9% of mixed liquid is injected through the filling pipe, wherein the filling amount of the filling pipe on the first continuous flow reactor and the filling amount of the filling pipe on the second continuous flow reactor are equally divided, and the following examples are the same.
Example 2
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, which is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are at normal pressure;
the method comprises the following steps:
mixing electrolyte containing lithium hexafluorophosphate and aqueous solution containing sodium carbonate to form mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 80 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The electrolyte was the same as in example 1; the concentration of sodium carbonate in the aqueous solution is 30wt%; liPF 6 ：CO 3 2- =2：13 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 0.7m/s; the volume ratio of the solution containing micro-nano bubbles to the mixed solution of the electrolyte and the sodium carbonate aqueous solution flowing through the dissolved air pump is 100. 94% of the mixed solution is injected into the inlet of the first continuous flow reactor, and 6% of the mixed solution is injected through the filling pipe.
Example 3
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, which is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are under micro-negative pressure; the vacuum degree of the micro negative pressure is 5kPa (atmospheric pressure-absolute pressure in the tank);
the method comprises the following steps:
mixing electrolyte containing lithium hexafluorophosphate and aqueous solution containing sodium carbonate to form mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 90 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The electrolyte was the same as in example 1; the concentration of sodium carbonate in the aqueous solution is 30wt%; liPF 6 ：CO 3 2- =2:1.5 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 0.7m/s; the volume ratio of the sodium carbonate solution flowing through the dissolved air pump to the carbon dioxide gas is 100; the volume ratio of the mixed solution flowing through the dissolved air pump and the carbon dioxide gas is 100. 91% of the mixed solution is injected into the inlet of the first continuous flow reactor, and 9% of the mixed solution is injected through the filling pipe.
Example 4
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, which is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are at normal pressure;
the method comprises the following steps:
mixing an electrolyte containing lithium hexafluorophosphate and an aqueous solution containing sodium carbonate to form a mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 70 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The electrolyte was the same as in example 1; the concentration of sodium carbonate in the aqueous solution is 20wt%; liPF (lithium ion particle Filter) 6 ：CO 3 2- =2:1.2 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 1.2m/s;
the volume ratio of the mixed solution flowing through the dissolved air pump to the carbon dioxide gas is 100. The inlet of the first continuous flow reactor was filled with 85% of the mixed liquor and through the fill pipe with 15% of the mixed liquor.
Example 5
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, wherein the method is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are at normal pressure;
the method comprises the following steps:
mixing electrolyte containing lithium hexafluorophosphate and aqueous solution containing sodium carbonate to form mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 70 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The electrolyte was the same as in example 1; the concentration of sodium carbonate in the aqueous solution is 10wt%; liPF 6 ：CO 3 2- =2:1.3 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 1.5m/s;
the volume ratio of the solution containing micro-nano bubbles to the mixed solution of the electrolyte and the sodium carbonate aqueous solution flowing through the dissolved air pump to the carbon dioxide gas is 100. The inlet of the first continuous flow reactor was filled with 85% of the mixed solution, and 15% of the mixed solution was injected through the fill pipe.
Example 6
A method for recovering lithium salt from an electrolyte based on a continuous flow reactor, which is carried out based on the continuous flow reaction system; the first buffer tank and the second buffer tank are at normal pressure;
the method comprises the following steps:
mixing electrolyte containing lithium hexafluorophosphate and aqueous solution containing sodium carbonate to form mixed solution, and adding the mixed solution into a continuous flow reaction system for reaction at the reaction temperature of 70 ℃; filtering the solution through a first filter and a second filter to obtain lithium carbonate precipitate.
The electrolyte was the same as in example 1; the concentration of sodium carbonate in the aqueous solution is 8wt%; liPF 6 ：CO 3 2- =2:1.1 (molar ratio); the flow rates of the first continuous flow reactor and the second continuous flow reactor are 1.4m/s;
the volume ratio of the solution containing micro-nano bubbles to the mixed solution of the electrolyte and the sodium carbonate aqueous solution flowing through the dissolved air pump to the carbon dioxide gas is 100. The inlet of the first continuous flow reactor was filled with 85% of the mixed solution, and 15% of the mixed solution was injected through the fill pipe.
Comparative example 1
The same as example 1, except that: the fill tube does not fill any liquid and all of the mixed liquor is injected through the inlet of the first continuous flow reactor.
Comparative example 2
The same as example 1, except that: the gas injected into the dissolved air pump is air.
Analysis of results
The lithium carbonate collected on the first filter and the second filter of each example and comparative example was weighed, and the yield of Li was calculated.
The results are given in Table 1 below
TABLE 1 yield results of examples and comparative examples
Figure 195675DEST_PATH_IMAGE001
From the above analysis it can be seen that:
1. compared with the embodiment 1, the comparative example 2 and the comparative example 1, the adoption of the micro-nano bubbles is better than the non-adoption of the micro-nano bubbles; the carbon dioxide micro-nano bubbles are adopted to be superior to the air micro-nano bubbles;
2. as can be seen from comparison of examples 1 to 3, the higher the carbonate amount and the higher the temperature, the higher the lithium carbonate yield;
3. it can be seen from the comparison of examples 1 and 4 to 6 that the higher the concentration and the larger the amount of carbonate used, the higher the yield of lithium carbonate.

Claims (8)

1. The method for recovering the lithium salt in the electrolyte based on the continuous flow reactor is characterized by being carried out based on a continuous flow reaction system, wherein the continuous flow reaction system comprises a first continuous flow reactor, a first buffer tank, a first pump, a first filter, a second continuous flow reactor, a second buffer tank, a second pump and a second filter which are connected in sequence; the front section of the first continuous flow reactor and the front section of the second continuous flow reactor are connected with one or more filling pipes for injecting a solution containing micro-nano bubbles; the micro-nano bubbles are carbon dioxide bubbles;
mixing electrolyte containing lithium hexafluorophosphate and water solution containing soluble carbonate to form mixed solution, adding the mixed solution into a continuous flow reaction system for reaction, wherein the reaction temperature is not lower than 60 ℃; filtering through a first filter and a second filter to obtain lithium carbonate precipitate;
the mass ratio of the electrolyte to the aqueous solution containing soluble carbonate is 1-10, wherein the concentration of the soluble carbonate in the aqueous solution containing soluble carbonate is 1-30wt%; the concentration of lithium hexafluorophosphate in the electrolyte is 5-20wt%;
the first buffer tank and the second buffer tank are under normal pressure or micro negative pressure; the micro negative pressure refers to the vacuum degree of 1kPa-10kPa.
2. The method for recovering lithium salt from the electrolyte based on the continuous flow reactor of claim 1, wherein the micro-nano bubble-containing solution contains soluble carbonate.
3. The method for recovering lithium salt in the electrolyte based on the continuous flow reactor of claim 2, wherein the solution containing micro-nano bubbles has the same composition as the mixed solution; the liquid flow rate in the first continuous flow reactor and the second continuous flow reactor is 0.5-2m/s; the volume ratio of the mixed liquid injected from the first continuous flow reactor to the solution injected from the fill pipe is 10.
4. The method for recovering lithium salt in the electrolyte based on the continuous flow reactor of claim 1, wherein the liquid discharged from the second filter is subjected to liquid separation to obtain a water phase and an oil phase; and obtaining the hexafluorophosphate from the aqueous phase by a crystallization method.
5. The method for recovering lithium salt from an electrolyte solution based on a continuous flow reactor as claimed in any one of claims 1 to 4, wherein the micro-nano bubbles have a particle size of 10nm to 10 μm.
6. The method for recovering lithium salt from the electrolyte solution based on the continuous flow reactor of claim 5, wherein the micro-nano bubbles have a particle size of 100-500nm.
7. The continuous flow reactor based recovery method of lithium salts from electrolyte of claim 1, wherein the soluble carbonate is sodium carbonate, potassium carbonate or ammonium carbonate; the ratio of the molar amount of lithium ions in lithium hexafluorophosphate to the molar amount of carbonate in the aqueous solution containing soluble carbonate is 2:1 1.5.
8. The continuous flow reactor based recovery method of lithium salts from electrolytes of claim 1, wherein the reaction temperature is 70-90 ℃.
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CN114713154B (en) * 2022-04-30 2022-12-16 南京佳华工程技术有限公司 System and process method for preparing lithium hexafluorophosphate
CN115207506A (en) * 2022-08-12 2022-10-18 广州天赐高新材料股份有限公司 Method for recovering electrolyte of waste lithium ion battery

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