阅读说明：本技术 一种从含锂卤水中提取锂的离子液体萃取相及萃取方法 (Ionic liquid extraction phase for extracting lithium from lithium-containing brine and extraction method ) 是由 康锦 卫丽娜 阴彩霞 李恩泽 李虎 程芳琴 于 2020-11-19 设计创作，主要内容包括：本发明公开了一种从含锂卤水中提取锂的离子液体萃取相及萃取方法,属于萃取化学、化工技术领域。萃取相包括10％-40％的萃取剂,余量为稀释剂,其中,所述萃取剂为磷酸酯类离子液体,所述百分比为占萃取相总体积的百分比,所述离子液体在酸的调控下,能够从水相转移到有机相。本发明的离子液体萃取相在萃取段能够与含锂卤水互溶,使离子液体与锂离子充分络合；在分相段通过加入低浓度酸溶液使负载锂的离子液体发生相转移,实现萃取相与卤水分离,然后再用较高浓度的酸反洗最终得到锂盐。本发明的萃取相及萃取方法不需要协萃剂的使用,而且萃取过程中没有第三相的产生。(The invention discloses an ionic liquid extraction phase for extracting lithium from lithium-containing brine and an extraction method, belonging to the technical field of extraction chemistry and chemical engineering. The extraction phase comprises 10-40% of an extracting agent and the balance of a diluent, wherein the extracting agent is phosphate ionic liquid, the percentage is the percentage of the total volume of the extraction phase, and the ionic liquid can be transferred from the water phase to the organic phase under the regulation and control of acid. The ionic liquid extract phase can be mutually soluble with lithium-containing brine in an extraction section, so that the ionic liquid and lithium ions are fully complexed; and adding a low-concentration acid solution in the phase separation section to perform phase transfer on the lithium-loaded ionic liquid, so as to realize the separation of an extraction phase and brine, and then backwashing by using a higher-concentration acid to finally obtain the lithium salt. The extraction phase and the extraction method do not need to use a co-extractant, and a third phase is not generated in the extraction process.)

1. An ionic liquid extract phase for extracting lithium from lithium-containing brine, characterized in that: the extraction phase comprises 10-40% of an extracting agent and the balance of a diluent, wherein the extracting agent is a phosphate ionic liquid extracting agent, and the percentage is the percentage of the total volume of the extraction phase.

2. The ionic liquid extract phase of claim 1 for extracting lithium from lithium-containing brine, wherein: the phosphate ionic liquid is room-temperature ionic liquid, consists of cations and anions, takes phosphate alkyl ester anions as the anions, takes quaternary amines as the cations, and has the following structure:

in the formula R₁、R₂、R₃Represents an alkyl group in the phosphate alkyl ester anion, and the carbon chain length of the alkyl group is 1-9; in the formula R₁’、R₂’、R₃' represents an alkyl group in a quaternary amine.

3. An ionic liquid extract phase for extracting lithium from lithium-containing brine according to claim 2, wherein: the cation of the phosphate ionic liquid is one or a mixture of at least two of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole or 1-butylimidazole cation.

4. An ionic liquid extract phase for extracting lithium from lithium-containing brine according to claim 2, wherein: the anion of the phosphate ionic liquid is one or a mixture of at least two of diethyl phosphate, dipropyl phosphate or dibutyl phosphate.

5. An ionic liquid extract phase for extracting lithium from lithium-containing brine according to claim 1, wherein: the diluent is one or a mixture of at least two of dichloromethane, trichloromethane, carbon tetrachloride or 1, 2-dichloroethane.

6. An ionic liquid extraction method for extracting lithium from lithium-containing brine according to any one of claims 1 to 5, comprising the following steps:

step 1, mixing and stirring an ionic liquid extraction phase for extracting lithium from lithium-containing brine and the lithium-containing brine, and performing extraction operation;

step 2, adding hydrochloric acid to adjust the water phase H⁺The concentration is 0.2-0.6mol/L, so that the lithium-loaded ionic liquid is subjected to phase transfer from the water phase to the organic phase;

and 3, mixing the loaded organic phase with a hydrochloric acid solution for backwashing, and back-extracting lithium to a water phase to obtain a lithium-containing water solution.

7. The ionic liquid extraction process of claim 6 for extracting lithium from lithium-containing brine, characterized in that: the concentration of lithium in the lithium-containing brine in the step 1 is not higher than 2.0 g/L.

8. The ionic liquid extraction process of claim 6 for extracting lithium from lithium-containing brine, characterized in that: in the step 1, the ratio of the organic phase to the aqueous phase of the extraction phase and the lithium-containing brine is 1:2-3:1, and no synergist is added in the extraction.

9. The ionic liquid extraction process of claim 6 for extracting lithium from lithium-containing brine, characterized in that: the stirring temperature in the step 1 is 4-40 ℃, and the extraction time is 2-20 min.

10. The ionic liquid extraction process of claim 6 for extracting lithium from lithium-containing brine, characterized in that: in the step 3, the concentration of hydrochloric acid used for backwashing is 2.0-6.0mol/L, and the washing phase ratio is 1: 1-1: 3.

Technical Field

The invention belongs to the technical field of extraction chemistry and chemical engineering, and particularly relates to an ionic liquid extraction phase for extracting lithium from lithium-containing brine and an extraction method.

Background

Lithium and its compounds are widely used in the fields of electronics, manufacturing, aerospace, etc. In recent years, with the increase of lithium demand of lithium power batteries, the demand of lithium in the international market is rapidly increased, and the price of lithium products is increased by times. As the main type of lithium resources, the lithium resources in salt lake brine account for 91 percent of the total amount of the lithium resources in the world. Because the lithium extraction from the salt lake brine has the advantages of simple process, low cost, strong market competitiveness and the like compared with the traditional solid lithium ore lithium extraction process, the method becomes a main way for lithium industrial development and production of lithium salts at home and abroad. China is a world large lithium resource country, and salt lakes contain abundant lithium resources, which account for 87 percent of the total lithium reserves proven in China, and are an important resource basis for the future development of lithium salt industry in China, so that the development of brine lithium resources in China must be enhanced. However, since the brine contains various metal ions, the separation and extraction of lithium from the brine containing high magnesium and low lithium concentration, namely the brine with high magnesium-lithium ratio, is a recognized worldwide technical problem. The solvent extraction technology is an effective technology for separating and extracting various metals from a solution, has the advantages of high separation efficiency, simple process and equipment, continuous operation, easy realization of automatic control and the like, and is considered to be one of the most promising methods for extracting and separating lithium from brine with a high magnesium-lithium ratio.

The ionic liquid has great application potential in metal separation, is organic salt comprising anions and cations and is liquid at or near room temperature, and has the advantages of low vapor pressure, high heat stability, good dissolving performance, etc. in addition, the anions and cations of the ionic liquid have very good designability. Various ionic liquids have been developed for extracting lithium from salt lake brine, but there are general problems: the extraction efficiency of the hydrophobic ionic liquid is low, but the dissolution loss of the hydrophilic ionic liquid is large, so that the economic cost is increased, and the environment is polluted.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an ionic liquid extraction phase and an extraction method for extracting lithium from lithium-containing brine. The purpose of extracting lithium from lithium-containing brine is realized by utilizing the acid regulation phase transfer property of the phosphate functionalized ionic liquid, so that the efficient extraction of lithium is ensured, and the dissolution loss of the ionic liquid is greatly reduced. The extraction phase does not need to add ferric trichloride and a synergistic agent, so that the complexity of components in the extraction phase is reduced, and the optimization of an extraction process is facilitated.

In order to achieve the purpose, the invention adopts the following technical scheme:

as one aspect of the present invention, there is provided an extract phase for extracting lithium from lithium-containing brine, the extract phase comprising 10% to 40% of an extractant, with the balance being a diluent.

Further, the extracting agent is a phosphate ionic liquid extracting agent, and the percentage is the percentage of the total volume of the extracting phase. The phosphate extractant has higher extraction efficiency and good selectivity to lithium ions.

Furthermore, the phosphate ionic liquid is a room-temperature ionic liquid, is composed of cations and anions, takes phosphate alkyl ester anions as anions, takes quaternary amines as cations, and has the following structure:

in the formula R₁、R₂、R₃Represents an alkyl group in the phosphate alkyl ester anion, and the carbon chain length of the alkyl group is 1-9; in the formula R₁’、R₂’、R₃' represents an alkyl group in a quaternary amine. The anions and cations of the phosphate functionalized ionic liquid have very good designability, and the structure can be designed according to the actual extraction requirement.

Furthermore, the cation of the phosphate ionic liquid is one or a mixture of at least two of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole or 1-butylimidazole cation. The cation is imidazole ionic liquid, the melting point is generally low, the number of optional substituents is large, most of the ionic liquids are liquid at normal temperature, the melting points of other types of ionic liquids are generally high, most of the ionic liquids are solid at normal temperature, and extraction is not facilitated.

Preferably, the cation of the phosphate ionic liquid is any one of 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole or 1-butylimidazole cation.

The anion of the phosphate ionic liquid is one or a mixture of at least two of diethyl phosphate, dipropyl phosphate or dibutyl phosphate. The anion is phosphate with carbon chain length less than 4, has good water solubility, is favorable for combining with lithium ions, has low viscosity and is favorable for extraction.

Preferably, the anion of the phosphate ionic liquid is any one of diethyl phosphate, dipropyl phosphate or dibutyl phosphate.

The diluent is one or a mixture of at least two of dichloromethane, trichloromethane, carbon tetrachloride or 1, 2-dichloroethane. All are low-toxicity and non-flammable solvents, and have safety in the production process.

Preferably, the diluent is any one of dichloromethane, trichloromethane, carbon tetrachloride or 1, 2-dichloroethane.

As another aspect of the present invention, there is provided an extraction method for extracting lithium from lithium-containing brine using the above ionic liquid extraction phase, comprising the steps of:

(1) mixing and stirring an ionic liquid extraction phase for extracting lithium from lithium-containing brine and the lithium-containing brine, and performing extraction operation;

(2) adding hydrochloric acid to adjust water phase H⁺The concentration is 0.2-0.6mol/L, so that the lithium-loaded ionic liquid is subjected to phase transfer from the water phase to the organic phase;

(3) and mixing the loaded organic phase with a hydrochloric acid solution for backwashing, and back-extracting lithium to a water phase to obtain a lithium-containing aqueous solution. The method uses hydrochloric acid for backwashing, and has the advantages of low economic cost and simple and convenient operation.

Further, the concentration of lithium in the lithium-containing brine used in the extraction in the step (1) is not higher than 2.0 g/L. Can be extracted in the brine with lower concentration, and is beneficial to the recovery of lithium ions in the low-grade lithium-containing brine.

Further, the phase ratio (O/A) of the extraction phase to the organic phase and the aqueous phase of the lithium-containing brine in the step (1) is 1:2-3:1, and FeCl is not required to be added in the extraction₃And a synergist. The extraction phase is lower than the water phase, so that the use of organic matters can be reduced, and the risk of environmental pollution is reduced.

Further, the stirring temperature in the step (1) is 4-40 ℃, and the extraction time is 2-20 min. The stirring temperature is 4-40 deg.C, and can be performed at room temperature without strict temperature control. The extraction time is short, which is beneficial to the high-efficiency and rapid extraction.

Further, the concentration of hydrochloric acid used for backwashing in the step (3) is 2.0-6.0mol/L, and the washing phase ratio is 1: 1-1: 3. the higher concentration acid can effectively elute the lithium ions loaded on the extraction phase, and the washing phase ratio is 1: 1-1: 3, the use of acid solution can be reduced.

Compared with the prior art, the invention has the following advantages:

1. the invention controls the ionic liquid to generate phase transfer by acid, realizes the full complexation of the ionic liquid and lithium ions in the extraction section, and controls the ionic liquid to be separated from the brine to enter an organic phase by acid in the phase separation section, thereby ensuring the high-efficiency extraction of lithium, greatly reducing the dissolution loss of the ionic liquid, and being a novel extraction phase and an extraction method.

2. The extraction method of the invention does not need to add ferric trichloride and a synergistic agent, reduces the complexity of components in the extraction phase and is beneficial to the optimization of the extraction process.

3. The method for extracting lithium from the lithium-containing brine adopts the green ionic liquid extracting agent, thereby greatly reducing the pollution to the environment.

Drawings

FIG. 1 is a graph of the effect of initial lithium concentration on extraction yield for an example of the present invention;

FIG. 2 is a graph showing the effect of phase ratio (O/A) on extraction yield for an example of the present invention;

FIG. 3 shows an aqueous phase H according to an embodiment of the present invention⁺The effect of concentration on extraction rate;

FIG. 4 shows the effect of extraction time on extraction rate in the examples of the present invention.

Detailed Description

Example 1

In this example, the extract phase composition was: the ionic liquid is used as an extracting agent, and the dichloromethane is used as a diluting agent. In the lithium-containing brine, the content of lithium is 0.5g/L, the content of magnesium is 4.0g/L, the content of sodium is 6.0g/L, and the content of potassium is 2.5 g/L.

Taking an ionic liquid extraction phase and lithium-containing brine as raw materials, and extracting lithium by the following steps:

(1) mixing the extraction phase with lithium-containing brine at a ratio of 2:1, with the extractant content of 30%, stirring at 25 deg.C for 10min, and performing extraction operation.

(2) After the extraction is finished, hydrochloric acid is added to regulate the water phase H⁺The concentration is 0.2mol/L, the single-stage extraction rate of lithium is 70.6 percent after standing and phase separation. The extraction rates of Mg, Na and K were 0.7%, 0.9% and 0.3%, respectively.

(3) And (3) carrying out countercurrent washing on the extracted loaded organic phase by adopting 3.0mol/L HCl solution, wherein the washing ratio is 1: 1.

Example 2

In this example, the extract phase composition was: the ionic liquid is used as an extracting agent, and the dichloromethane is used as a diluting agent. In the lithium-containing brine, the content of lithium is 1.0g/L, the content of magnesium is 8.0g/L, the content of sodium is 12.0g/L, and the content of potassium is 5.0 g/L.

Taking an ionic liquid extraction phase and lithium-containing brine as raw materials, and extracting lithium by the following steps:

(1) mixing the extraction phase with lithium-containing brine at a ratio of 3:1, wherein the content of the extractant is 40%, stirring at 30 deg.C for 20min, and performing extraction operation.

(2) After extraction, hydrochloric acid is added to adjust the water phase H⁺The concentration is 0.6mol/L, the single-stage extraction rate of lithium is 72.1 percent after standing and phase separation. The extraction rates of Mg, Na and K were 0.8%, 1.0% and 0.4%, respectively.

(3) And (3) carrying out countercurrent washing on the extracted loaded organic phase by adopting a 3.0mol/LHCl solution, wherein the washing phase ratio is 1: 3.

example 3

In this example, the extract phase composition was: the ionic liquid is used as an extracting agent, and the dichloromethane is used as a diluting agent. In the lithium-containing brine, the content of lithium is 0.5g/L, the content of magnesium is 4.0g/L, the content of sodium is 6.0g/L, and the content of potassium is 2.5 g/L.

Taking an ionic liquid extraction phase and lithium-containing brine as raw materials, and extracting lithium by the following steps:

(1) mixing the extraction phase with lithium-containing brine at a ratio of 3:1, and stirring at 25 deg.C for 10min to perform extraction.

(2) After the extraction is finished, hydrochloric acid is added to regulate the water phase H⁺The concentration is 0.2mol/L, the single-stage extraction rate of lithium is 80.6 percent after standing and phase separation. The extraction rates of Mg, Na and K were 1.8%, 1.7% and 0.8%, respectively.

(3) And (3) carrying out countercurrent washing on the extracted loaded organic phase by adopting 3.0mol/L HCl solution, wherein the washing ratio is 1: 1.

Example 4

In this example, the extract phase composition was: the ionic liquid is used as an extracting agent, and the dichloromethane is used as a diluting agent. In the lithium-containing brine, the content of lithium is 0.5g/L, the content of magnesium is 4.0g/L, the content of sodium is 6.0g/L, and the content of potassium is 2.5 g/L.

Taking an ionic liquid extraction phase and lithium-containing brine as raw materials, and extracting lithium by the following steps:

(1) mixing the extraction phase with lithium-containing brine at a ratio of 2:1, with the extractant content of 30%, stirring at 25 deg.C for 20min, and performing extraction operation.

(2) After the extraction is finished, hydrochloric acid is added to regulate the water phase H⁺The concentration is 0.2mol/L, the single-stage extraction rate of lithium is 70.6 percent after standing and phase separation. The extraction rates of Mg, Na and K were 1.1%, 1.4% and 0.5%, respectively.

(3) And (3) carrying out countercurrent washing on the extracted loaded organic phase by adopting 3.0mol/L HCl solution, wherein the washing ratio is 1: 1.

Example 5

In this example, the extract phase composition was: the ionic liquid is used as an extracting agent, and the trichloromethane is used as a diluting agent. In the lithium-containing brine, the content of lithium is 0.5g/L, the content of magnesium is 4.0g/L, the content of sodium is 6.0g/L, and the content of potassium is 2.5 g/L.

Taking an ionic liquid extraction phase and lithium-containing brine as raw materials, and extracting lithium by the following steps:

(1) mixing the extraction phase with lithium-containing brine at a ratio of 2:1, with the extractant content of 30%, and stirring at 25 deg.C for 10 min.

(2) After the extraction is finished, hydrochloric acid is added to regulate the water phase H⁺The concentration is 0.3mol/L, the single-stage extraction rate of lithium is 73.6 percent after standing and phase separation. The extraction rates of Mg, Na and K were 0.9%, 1.0% and 0.4%, respectively.

(3) And (3) carrying out countercurrent washing on the extracted loaded organic phase by adopting 3.0mol/L HCl solution, wherein the washing ratio is 1: 1.

The above-described embodiments are merely preferred embodiments of the present invention, and it should be noted that, for those skilled in the art, various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be construed as the protection scope of the present invention.