An α-diketone lithium ion extractant and extraction system

Abstract

The present invention belongs to the technical field of lithium purification, and relates to an α-diketone lithium ion extractant and an extraction system. The lithium ion extractant includes an α-diketone compound, wherein the α-diketone compound has a general formula as shown in Formula I: #imgabs0# wherein R1 and R2 are each independently H or a C1-C8 alkyl, a C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different; and the α-diketone compound is not the following structure: #imgabs1# The α-diketone compound of the present invention can control the degree of single molecule enolization, realize partial enolization, and solve the problems of large alkali consumption of the extraction system, large dissolution loss of the extractant, poor selectivity for potassium ions, and low removal rate in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of lithium purification, and in particular to an alpha-diketone lithium ion extractant and an extraction system. Background Art

[0002] At present, lithium purification technology mostly adopts extraction. In the existing extraction system, diketone extractants are selected as lithium extractants and lithium ion extractants, which have the following technical defects: on the one hand, in order to ensure the extraction efficiency of lithium in the solution (usually requiring lithium concentration <10mg / L), the pH value at the extraction equilibrium is relatively high, requiring pH>12.5, resulting in increased alkali consumption; at the same time, under high pH conditions, the commonly used diketones (such as Lix54) have large dissolution losses and poor stability of the extractant, which increases the difficulty and cost of wastewater treatment. On the other hand, the existing technology is mostly β-diketone-based extraction systems with low selectivity for lithium, sodium, and potassium in the solution, especially low selectivity for potassium content, which directly affects the quality of purified lithium products. Summary of the invention

[0003] In view of the above analysis, the present invention aims to provide an α-diketone lithium ion extractant and an extraction system to solve at least one of the problems in the prior art: large alkali consumption of the extraction system, large dissolution loss of the extractant, poor selectivity for potassium ions, and low impurity removal rate.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] The present invention provides an α-diketone lithium ion extractant, which has an α-diketone compound of the general formula shown in Formula I:

[0006]

[0007] Wherein, R1 and R2 are each independently H or C1-C8 alkyl, C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different;

[0008] And the α-diketone compound is not the following structure:

[0009]

[0010] Preferably, the α-diketone compound is not any of the following structures:

[0011] 1-Benzoylacetone, 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone, 1-(2-naphthoyl)-3,3,3-trifluoroacetone, 2-methoxy-5-nonylbenzoyltrifluoroacetone, acetylacetone, acetylacetone, acetybutylketone, acetylvanoic acid, hexafluoroacetylacetone, benzoyltrifluoroacetone, 2-thenoyltrifluoroacetone, 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione, 4,4,4-trifluoro-1-(p-tolyl)-1,3-butanedione, (4-(1-(5-(tert-butyl)2-hydroxyphenyl)ethyl)phenyl)dioctylphosphine oxide, 4-(dioctylphosphoryl)1-(4-octylphenyl)butane 1,3-dione.

[0012] Preferably, the substituent group of the substituted phenyl group is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different;

[0013] And / or, the substituent group of the substituted aryl is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of the haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different.

[0014] Preferably, there is at least one hydrogen atom on the carbon atom to which R1 is attached to the carbonyl group, and / or there is at least one hydrogen atom on the carbon atom to which R2 is attached to the carbonyl group.

[0015] Preferably, the α-diketone compound includes any one of the structures shown in A001 to A010:

[0016]

[0017] Preferably, the α-diketone compound comprises any one of the structures shown below:

[0018]

[0019] An extraction system comprises the above-mentioned lithium ion extractant, and also comprises: a co-extractant and a diluent.

[0020] Preferably, the synergistic extractant is one or more of trioctylphosphine oxide (TOPO), tributylphosphine oxide (TBPO), and trialkylphosphine oxide (TRPO).

[0021] Preferably, the diluent is one or more of alkanes, benzenes or alcohol compounds; preferably, the diluent is one or more of No. 260 solvent oil, aviation kerosene, xylene and octanol.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] (1) Compared with the traditional β-diketone compounds, the α-diketone compounds of the present invention can control the degree of enolization of the single molecule and achieve partial enolization based on the special core structure of the α-diketone group and through the selection of substituents, so that the α-diketone compounds can maintain a lower solubility in water while completing the extraction of lithium ions, so that the α-diketone compounds in the extractant have a lower dissolution loss;

[0024] (2) Compared with the conventional β-diketone compounds, the α-diketone compounds of the present invention can control the degree of enolization of a single molecule and achieve partial enolization, thereby reducing the number of hydroxide ions actually required at the phase interface, reducing the amount of alkali used, and achieving enolization and lithium ion extraction in a milder environment;

[0025] (3) The α-diketone compound of the present invention is more likely to bind lithium ions rather than sodium and potassium ions with larger volume due to the steric hindrance of the adjacent β-substituent of the keto carbonyl group and the smaller distance between the two carbonyl groups. Therefore, the extractant has a higher selectivity for the extraction of lithium ions, and reduces the content of sodium and potassium ions as impurities in the extracted product. Under alkaline conditions, the extractant of the present invention can have a high extraction rate and high lithium selectivity for salt lake brine or lithium precipitation mother liquor with different magnesium-lithium ratios.

[0026] (4) The extraction system of the present invention has strong acid resistance, alkali resistance and aging resistance, and remains stable after repeated use.

[0027] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be obvious from the description or understood by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0029] Figure 1 This is the H NMR spectrum of A009. DETAILED DESCRIPTION

[0030] In one aspect, the present invention discloses an α-diketone lithium ion extractant, comprising an α-diketone compound having a general formula as shown in Formula I:

[0031]

[0032] Wherein, R1 and R2 are each independently H or C1-C8 alkyl, C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different;

[0033] And the α-diketone compound is not the following structure:

[0034]

[0035] Specifically, the α-diketone compound is not any of the following structures:

[0036] 1-Benzoylacetone, 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone, 1-(2-naphthoyl)-3,3,3-trifluoroacetone, 2-methoxy-5-nonylbenzoyltrifluoroacetone, acetylacetone, acetylacetone, acetybutylketone, acetylvanoic acid, hexafluoroacetylacetone, benzoyltrifluoroacetone, 2-thenoyltrifluoroacetone, 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione, 4,4,4-trifluoro-1-(p-tolyl)-1,3-butanedione, (4-(1-(5-(tert-butyl)2-hydroxyphenyl)ethyl)phenyl)dioctylphosphine oxide, 4-(dioctylphosphoryl)1-(4-octylphenyl)butane 1,3-dione.

[0037] Specifically, the substituent group of the substituted phenyl is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different;

[0038] And / or, the substituent group of the substituted aryl is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of the haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different.

[0039] Preferably, there is at least one hydrogen atom on the carbon atom to which R1 is attached to the carbonyl group, and / or there is at least one hydrogen atom on the carbon atom to which R2 is attached to the carbonyl group.

[0040] Preferably, the α-diketone compound includes any one of the structures shown in A001 to A010:

[0041]

[0042] Preferably, the α-diketone compound comprises any one of the structures shown below:

[0043]

[0044] It should be noted that the present invention utilizes the enolization effect of α-diketone compounds in an alkaline environment, and the active hydrogen produced by the compounds will exchange with lithium ions, thereby completing the extraction; the applicant has found that the enolization degree of α-diketone compounds, the polarity of the substituents, and the steric hindrance effect of the substituents jointly affect the solubility of the α-diketone compounds in aqueous solution, thereby affecting the dissolution loss of the α-diketone compounds during use: the higher the enolization degree of the α-diketone compound molecules, the greater the solubility in aqueous solution, and the greater the loss of the α-diketone compounds during extraction; The greater the polarity of the β-substituent adjacent to the keto carbonyl, the more difficult it is for the hydrogen of the β-substituent to transfer to the keto carbonyl to undergo enolation, and the lower the solubility of the α-diketone compound in aqueous solution; when the β-substituent adjacent to the keto carbonyl is a benzene ring, a quaternary carbon group or other substituent, the β carbon has no directly connected hydrogen, and thus the enolation reaction cannot occur; at the same time, when the β-substituent adjacent to the keto carbonyl is a secondary carbon or tertiary carbon group with obvious steric hindrance effect, the enolation reaction will also be inhibited due to the presence of the substituent; when the above multiple factors exist at the same time, their effects are difficult to predict.

[0045] The enolization process and extraction process of common β-diketone compounds in the prior art meet the following requirements:

[0046]

[0047] Wherein, A and B are substituents at both ends of the β-diketone compound.

[0048] The difference is that the α-diketone compound of the present invention has no secondary carbon atom containing hydrogen due to the direct connection of two keto groups, so the enolization process and the extraction process meet the following conditions:

[0049]

[0050] Wherein, A and B are substituents at both ends of the α-diketone compound, and the hydrogen source required for enolation comes from A or B, that is, there is at least one hydrogen atom on the carbon atom connected to the carbonyl group of A, and / or there is at least one hydrogen atom on the carbon atom connected to the carbonyl group of B.

[0051] It can be understood that when one of the carbon atoms connected to the carbonyl group of A and B does not contain a hydrogen atom, the enolization intermediate of the α-diketone compound will not contain two hydroxyl groups, and the number of hydroxyl groups can directly affect the solubility of the α-diketone compound; the above setting can reduce the number of hydroxyl groups by achieving partial enolization, thereby reducing the dissolution loss during the extraction of the α-diketone compound.

[0052] For example, the β carbon on the right side of A003 is a tertiary carbon group and the β carbon on the left side of A007 is a benzene ring. Both β carbons do not contain directly connected hydrogen atoms, so the corresponding keto carbonyl groups cannot undergo enolization reaction. Lithium ions can only be extracted by relying on the substituent on the other side and the keto carbonyl group to undergo enolization reaction.

[0053]

[0054] Compared with the prior art, on the one hand, the α-diketone compound of the present invention is based on the special core structure of the α-diketone group and can control the degree of enolization of the single molecule through the selection of substituents to achieve partial enolization, so that it can complete the extraction of lithium ions while maintaining its low solubility in water, so that the α-diketone compound in the extractant has a lower dissolution loss;

[0055] On the other hand, because the extraction occurs at the interface between the aqueous solution and the extractant, the partial enolization of the α-diketone compound leads to a decrease in the number of hydroxide ions actually required at the interface, thereby reducing the amount of base used and achieving enolization and lithium ion extraction in a milder environment.

[0056] At the same time, since the volume of sodium and potassium ions among the impurity ions is much larger than that of lithium ions, the α-diketone compound of the present invention makes it easier for the enolate product of the α-diketone compound to bind to lithium ions rather than sodium and potassium ions with larger volume due to the steric hindrance of the β-substituent adjacent to the ketocarbonyl group and the smaller distance between the two carbonyl groups. Therefore, the extractant has higher selectivity for the extraction of lithium ions, and reduces the content of sodium and potassium ions as impurities in the extraction product.

[0057] In another aspect, the present invention discloses an α-diketone compound satisfying the following structure:

[0058]

[0059] On the other hand, the present invention discloses a method for preparing an α-diketone compound for synthesizing include:

[0060] S001: dissolving a first raw material containing a formyl halide group and a catalyst in an organic solvent;

[0061] S002: Adding a tetraalkyltin containing an α-carbonyl group as a second raw material into an organic solvent to prepare an α-diketone.

[0062] Specifically, the first raw material molecule can be any one of 3-chloro-2-pyridinecarbonyl fluoride, 3-chloro-2-pyridinecarbonyl chloride, 3-chloro-2-pyridinecarbonyl bromide, and 3-chloro-2-pyridinecarbonyl iodide;

[0063] The second raw material can be any one of propionyltriethyltin, propionyltripropyltin, and propionyltributyltin; the catalyst can be PdCl2(PPh3)2, PdCl2 or Pd(OAc)2.

[0064] As an example, 3-chloro-2-pyridinecarbonyl chloride is used as the first raw material, tributyltin propionate is used as the second raw material, tributyltin propionate is used as the second raw material, and PdCl2(PPh3)2 is used as the catalyst; the reaction in S002 satisfies:

[0065]

[0066] Specifically, the organic solvent in S001 can be any one of toluene, benzene, acetonitrile, tetrahydrofuran, and DMF.

[0067] Preferably, the organic solvent in S001 needs to be dehydrated and deoxygenated.

[0068] Specifically, the reaction temperature in S002 is 35°C-120°C, and the reaction time is 0.5h-36h. Under this reaction condition, the reaction can obtain the target compound with a higher yield.

[0069] Preferably, S002 needs to be quenched after the reaction is completed.

[0070] Specifically, the quenching reagent may be a saturated sodium bicarbonate solution.

[0071] Preferably, after the S002 reaction is completed, extraction and purification treatment are also included.

[0072] Specifically, the extraction reagent can be any one of ethyl acetate, dichloromethane, anisole, and tert-butyl methyl ether; and the purification method can be column chromatography purification treatment.

[0073] In another aspect, the present invention discloses a lithium ion extractant, comprising the above-mentioned α-diketone compound.

[0074] On the other hand, the present invention discloses an extraction system, comprising the above-mentioned lithium ion extractant, and further comprising: a co-extractant and a diluent.

[0075] Specifically, the synergistic extractant is one or more of trioctylphosphine oxide (TOPO), tributylphosphine oxide (TBPO), and trialkylphosphine oxide (TRPO).

[0076] Specifically, the diluent is one or more of alkane, benzene or alcohol compounds; preferably, the diluent is one or more of No. 260 solvent oil, aviation kerosene, xylene and octanol.

[0077] In another aspect, the present invention discloses a method for extracting lithium from a low-lithium solution, comprising:

[0078] S101: pretreating the low-lithium solution by adding alkali;

[0079] S102: adding the pretreated lithium-containing raw material solution into an extraction system for extraction;

[0080] S103: Reverse-extract the organic phase after extraction to obtain a lithium-rich stripping solution.

[0081] Specifically, the low-lithium solution can be salt lake brine or lithium precipitation mother liquor.

[0082] Specifically, the lithium content of the low-lithium solution is 0.1g / L~2.5g / L, and the main impurities are cations such as sodium, potassium, magnesium, and calcium, among which the sodium content is 10g / L~130g / L, and the potassium content is 1g / L~70g / L; the anions are chloride ions and sulfate ions, among which the chloride ion content is 5g / L~200g / L, and the sulfate ion content is 1g / L~190g / L.

[0083] The low-lithium solution of the present invention can be salt lake brine, wherein the lithium content of the salt lake brine is 0.1g / L-0.98g / L, and the main impurities are cations such as sodium, potassium, magnesium, calcium, etc., wherein the sodium content is 10g / L-130g / L, and the potassium content is 1g / L-70g / L; the anions include chloride ions and sulfate ions, wherein the chloride ion content is 5g / L-200g / L, and the sulfate ion content is 1g / L-10g / L.

[0084] The low-lithium solution of the present invention can be a lithium precipitation mother liquor, wherein the lithium content of the lithium precipitation mother liquor is 1.5g / L to 2.5g / L, and the main impurities are cationic impurities such as sodium, potassium, magnesium, and calcium, wherein the sodium content is 50g / L to 130g / L, and the potassium content is 5g / L to 50g / L; the anions include chloride ions and sulfate ions, wherein the chloride ion content is 5g / L to 100g / L, and the sulfate ion content is 5g / L to 190g / L.

[0085] Specifically, the alkali added in S101 may be sodium hydroxide or sodium carbonate, and the pretreatment pH value ranges from 8 to 9.

[0086] It should be noted that, on the one hand, the alkaline environment is conducive to the removal of high-valent and divalent ions in the solution; on the other hand, the extraction selectivity of the extraction system for monovalent metal ions can selectively extract lithium from high-concentration sodium and potassium solutions and consume hydroxide in the extraction process.

[0087] Specifically, the extraction system in S102 comprises an α-diketone compound satisfying the following general formula:

[0088]

[0089] Wherein, R1 and R2 are each independently H or C1-C8 alkyl, C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different.

[0090] Preferably, the α-diketone compound is not of the following structure:

[0091]

[0092] Preferably, the α-diketone compound is not of the following structure:

[0093] 1-Benzoylacetone, 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone, 1-(2-naphthoyl)-3,3,3-trifluoroacetone, 2-methoxy-5-nonylbenzoyltrifluoroacetone, acetylacetone, acetylacetone, acetybutyl ketone, acetylvanoic acid, hexafluoroacetylacetone, benzoyltrifluoroacetone, 2-thenoyltrifluoroacetone, 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione, 4,4,4-trifluoro-1-(p-tolyl)-1,3-butanedione, (4-(1-(5-(tert-butyl)-2-hydroxyphenyl)ethyl)phenyl)dioctylphosphine oxide, 4-(dioctylphosphoryl)-1-(4-octylphenyl)butane 1,3-dione.

[0094] Preferably, the substituent group of the substituted phenyl group is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of the haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different.

[0095] Preferably, the substituent group of the substituted aryl is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of the haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different.

[0096] Preferably, the α-diketone compound includes any one of the structures shown in A001 to A010:

[0097]

[0098] Preferably, the α-diketone compound comprises any one of the structures shown below:

[0099]

[0100] It should be noted that the present invention utilizes the enolization effect of α-diketone compounds in an alkaline environment, and the active hydrogen produced by the compounds will exchange with lithium ions, thereby completing the extraction; the applicant has found that the enolization degree of α-diketone compounds, the polarity of the substituents, and the steric hindrance effect of the substituents jointly affect the solubility of the α-diketone compounds in aqueous solution, thereby affecting the dissolution loss of the α-diketone compounds during use: the higher the enolization degree of the α-diketone compound molecules, the greater the solubility in aqueous solution, and the greater the loss of the α-diketone compounds during extraction; The greater the polarity of the β-substituent adjacent to the keto carbonyl, the more difficult it is for the hydrogen of the β-substituent to transfer to the keto carbonyl to undergo enolation, and the lower the solubility of the α-diketone compound in aqueous solution; when the β-substituent adjacent to the keto carbonyl is a benzene ring, a quaternary carbon group or other substituent, the β carbon has no directly connected hydrogen, and thus the enolation reaction cannot occur; at the same time, when the β-substituent adjacent to the keto carbonyl is a secondary carbon or tertiary carbon group with obvious steric hindrance effect, the enolation reaction will also be inhibited due to the presence of the substituent; when the above multiple factors exist at the same time, their effects are difficult to predict.

[0101] For example, the β carbon on the right side of A003 is a tertiary carbon group, and the β carbon on the left side of A007 is a carbon on the benzene ring. Both β carbons do not contain directly connected hydrogen atoms, so the corresponding keto carbonyl groups cannot undergo enolization reaction. Lithium ions can only be extracted by relying on the substituent on the other side and the keto carbonyl group to undergo enolization reaction.

[0102]

[0103] Compared with the prior art, on the one hand, the α-diketone compound of the present invention can control the degree of enolization of a single molecule and achieve partial enolization based on the special core structure of the α-diketone group and the selection of substituents compared with the traditional β-diketone compound, thereby completing the extraction of lithium ions while maintaining a lower solubility in water, so that the α-diketone compound in the extractant has a lower dissolution loss;

[0104] On the other hand, because the extraction occurs at the interface between the aqueous solution and the extractant, relative to traditional β-diketone compounds, based on the special core structure of the α-diketone group and through the selection of substituents, partial enolization can be achieved, resulting in a decrease in the number of hydroxide ions actually required at the interface. This can reduce the amount of alkali used, and enolization and lithium ion extraction can be achieved in a milder environment.

[0105] At the same time, since the volume of sodium and potassium ions among the impurity ions is much larger than that of lithium ions, the α-diketone compound of the present invention is easier to bind to lithium ions rather than sodium and potassium ions with larger volume due to the steric hindrance of the β-substituent adjacent to the keto carbonyl group and the smaller distance between the two carbonyl groups. Therefore, the extractant has higher selectivity for the extraction of lithium ions, and reduces the content of sodium and potassium ions as impurities in the extraction product.

[0106] Preferably, the extraction system in S102 further includes a synergist.

[0107] Specifically, the synergistic extractant is one or more of trioctylphosphine oxide (TOPO), tributylphosphine oxide (TBPO), and trialkylphosphine oxide (TRPO).

[0108] Preferably, the extraction system in S102 further includes a diluent.

[0109] Specifically, the diluent is one or more of alkane, benzene or alcohol compounds.

[0110] Preferably, the diluent is one or more of No. 260 solvent oil, aviation kerosene, xylene and octanol.

[0111] Preferably, the mass percentage of the α-diketone compound in the extraction system in S102 is 5-20%, and the mass percentage of the synergistic agent is 5-40%.

[0112] More preferably, the mass percentage of the α-diketone compound in the extraction system in S102 is 5-15%, and the mass percentage of the synergistic agent is 5-20%.

[0113] It should be noted that temperature affects the effects of extraction mass transfer and separation. If the temperature is low during the extraction process, it will affect the mass transfer efficiency of the extraction, that is, the extraction rate will be low. It will also affect the phase separation rate, that is, the organic phase and the aqueous phase are not separated completely, and the two phases carry a large amount of material, which makes the subsequent treatment of the organic phase and water difficult. The liquid processing volume cannot be increased, which will affect the production capacity; if the extraction temperature is too high, it will increase the volatilization loss of the extractant and increase the economic cost.

[0114] In order to ensure subsequent extraction efficiency and phase separation, the extraction temperature in S102 is 10-50°C, preferably 20-40°C.

[0115] Preferably, the step between S102 and S103 also includes washing and removing impurities from the organic phase after extraction.

[0116] Specifically, pure water or weakly acidic aqueous solution is used as a cleaning agent to wash and remove impurities from the organic phase after extraction.

[0117] Preferably, the amount of the cleaning agent is such that the mixed volume ratio O / A of the organic phase to water after extraction is 10 to 20:1, and the number of washing stages can be selected from 1 to 5.

[0118] Preferably, the washing and impurity removal temperature is between 10 and 50°C, and can be 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, 33°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, or 50°C.

[0119] Preferably, a weakly acidic aqueous solution is used to wash and remove impurities from the organic phase after extraction.

[0120] Specifically, the pH value of the weakly acidic aqueous solution is 0.5 to 2.0.

[0121] It should be noted that the present invention utilizes the enolization effect of α-diketone compounds in an alkaline environment, which produces active hydrogen that will exchange with lithium ions to complete the extraction; at the same time, a very small amount of sodium and potassium will also be co-extracted (the extraction rate is less than 5%); the purpose of washing is to remove the sodium and potassium that are entrained and co-extracted in a small amount during the extraction process; using a weakly acidic aqueous solution for washing and impurity removal can improve the washing efficiency.

[0122] Preferably, the solution after washing and impurity removal is returned to the extraction section to achieve recovery of washed lithium elements, which helps to improve the yield of lithium.

[0123] Specifically, the stripping temperature in S103 is 10-50°C, and can be 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, 33°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, or 50°C.

[0124] Preferably, the amount of the stripping reagent in S103 satisfies: the mixed volume ratio O / A of the organic phase and water after extraction is 10 to 30:1, and the stripping stage can be selected from 1 to 5 stages.

[0125] It should be noted that the acidic environment is conducive to the trans-enolate reaction of α-diketone compounds, which consumes hydrogen ions in the solution and releases the adsorption state of lithium ions by the organic phase, thereby achieving the stripping of lithium ions by the water phase.

[0126] The acid solution used can be sulfuric acid, hydrochloric acid, phosphoric acid or the like. The acid with the same anion can be selected according to the lithium salt anion requirement of the stripping solution, and the concentration range is 0.5 mol / L to 8 mol / L.

[0127] The lithium concentration in the lithium-rich solution is obtained to be 15-30 g / L, preferably, the lithium concentration in the lithium-rich solution is 22-30 g / L, wherein the separation effect of lithium and sodium and potassium is relatively high, the mass ratio of lithium / sodium in the solution is greater than 200, and the mass ratio of lithium / potassium is greater than 500, which meets the requirements of direct lithium precipitation.

[0128] In order to better illustrate the present invention, the present invention sets the following preparation examples and experimental examples:

[0129] Preparation Example

[0130] This preparation example discloses a method for preparing an α-diketone compound A009, comprising:

[0131] S001: Dissolve 0.1 mol of 3-chloro-2-pyridinecarbonyl chloride and 0.01 mol of catalyst PdCl2(PPh3)2 in 500 mL of anhydrous toluene to obtain a mixed solution;

[0132] S002: 0.11 mol of tributyltin propionyl was added to the mixed solution as the second raw material, and the reaction temperature was raised to 80 degrees. The reaction was terminated after 24 hours. Saturated sodium bicarbonate solution was added to the system to quench the reaction, and the reaction system was extracted with ethyl acetate. The organic phases were combined and concentrated, and then purified by column chromatography to obtain the target product with a yield of 75%.

[0133] The target product is A009, adjust the raw material types and process conditions according to the above method to prepare A001~A008 and A010 according to the same reaction mechanism, or prepare A001~A008 and A010 according to other methods in the prior art, or purchase commercially available products of A001~A008 and A010.

[0134] like Figure 1 As shown, A009 contains five characteristic peaks near 9.0PPM, 8.3PPM, 8.05PPM, 2.4PPM and 1.05PPM, indicating that A009 contains five different hydrogen atoms, which is consistent with the structure of A009.

[0135] Experimental example

[0136] This experimental example discloses a method for extracting lithium from a low-lithium solution, using an α-diketone compound comprising A001 to A010. The specific conditions and test results are shown in Tables 1 to 3, including:

[0137] S101: pre-treating the low-lithium solution as a lithium-containing raw material solution by adding alkali;

[0138] S102: adding the pretreated lithium-containing raw material solution into an extraction system for extraction;

[0139] S103: Mixing and washing the organic phase after lithium extraction to remove impurities;

[0140] S104: The organic phase after extraction is back-extracted to obtain a lithium-rich stripping solution, and the organic phase after back-extraction is recovered and recycled as an extractant.

[0141] Table 1 Lithium-containing raw material liquid composition

[0142]

[0143]

[0144] Table 2 Process parameters

[0145]

[0146]

[0147]

[0148]

[0149] Table 3 Test results

[0150]

[0151]

[0152] The results show:

[0153] It can be seen from Examples 1 to 15 that for a lithium content of 0.1 g / L to 2.5 g / L, the main impurities are cations such as sodium, potassium, magnesium, and calcium, wherein the sodium content is 10 g / L to 130 g / L, and the potassium content is 1 g / L to 70 g / L; the anions are chloride ions and sulfate ions, wherein the chloride content is 5 g / L to 200 g / L, and the sulfate content is 1 g / L to 190 g / L of a low-lithium solution. The lithium extraction system and extraction method of the present invention can prepare a lithium concentration of 15 to 30 g / L, a lithium / sodium mass ratio in the solution of >200, and a lithium / potassium mass ratio of >500, which meets the requirements of direct lithium precipitation. A lithium-rich solution.

[0154] It can be seen from Examples 1 to 10 that the extraction system composed of A001-A010 extractants has an extractant hydrolysis loss of less than 0.0032% for the first use, and the extractant hydrolysis loss after 100 recycling cycles of the extraction system is less than 0.0035%, which is significantly reduced compared with the conventional extraction system in the prior art in Comparative Example 5; at the same time, compared with the conventional extraction system in the prior art in Comparative Example 5, the present invention has higher selectivity for lithium ion extraction in the lithium ion / potassium ion separation system (the lithium extraction system and extraction method of the present invention prepare a lithium-rich solution with a lithium / potassium mass ratio of >500, while the lithium ion / potassium ion in the lithium-rich solution in Comparative Example 5 is <460).

[0155] It is understandable that, because the extraction occurs at the interface between the aqueous solution and the extractant, the partial enolization of the α-diketone compound leads to a decrease in the number of hydroxide ions actually required at the interface, thereby reducing the amount of alkali used, and achieving enolization and lithium ion extraction at a lower pH value and a milder environment.

[0156] At the same time, by comparing Examples 1 to 10 with Comparative Examples 1 and 2, it can be seen that the extractants outside the scope of the present invention are significantly inferior to those of Examples 1 to 10 in the lithium ion extraction selectivity in the lithium ion / potassium ion separation system and the hydrolysis loss after multiple recycling of the extractants.

[0157] It can be seen from Example 9, Comparative Example 3 and Comparative Example 4 that the extraction system with limited components and proportions of the present invention has better performance in lithium ion extraction concentration and lithium ion selectivity than the extraction system with components and proportions outside the limited range: Example 9 can prepare a lithium-rich solution with a lithium concentration of 25.8 g / L, a lithium / sodium mass ratio of 223, and a lithium / potassium mass ratio of 676 in the solution; while the lithium concentration, lithium / sodium mass ratio and lithium / potassium mass ratio of the lithium-rich solution of Comparative Examples 3 and 4 are significantly reduced relative to that of Example 9.

[0158] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An application of an α-diketone lithium ion extractant, characterized in that: For the extraction of lithium ions, the α-diketone lithium ion extractant comprises an α-diketone compound having the general formula shown in Formula I: Wherein, R1 and R2 are each independently H or C1-C8 alkyl, C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different; And the α-diketone compound is not the following structure: There is at least one hydrogen atom on the carbon atom to which R1 is attached to the carbonyl group, and / or there is at least one hydrogen atom on the carbon atom to which R2 is attached to the carbonyl group; The α-diketone lithium ion extractant is used to obtain a lithium-rich organic phase from a lithium-containing raw material solution containing sodium and potassium, thereby achieving separation of lithium from sodium and potassium.

2. The use of the lithium ion extractant according to claim 1, characterized in that: The α-diketone compound is not any of the following structures: 1-Benzoylacetone, 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone, 1-(2-naphthoyl)-3,3,3-trifluoroacetone, 2-methoxy-5-nonylbenzoyltrifluoroacetone, acetylacetone, acetylacetone, acetybutylketone, acetylvanoic acid, hexafluoroacetylacetone, benzoyltrifluoroacetone, 2-thenoyltrifluoroacetone, 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione, 4,4,4-trifluoro-1-(p-tolyl)-1,3-butanedione, (4-(1-(5-(tert-butyl)2-hydroxyphenyl)ethyl)phenyl)dioctylphosphine oxide, 4-(dioctylphosphoryl)1-(4-octylphenyl)butane 1,3-dione.

3. The use of the lithium ion extractant according to claim 2, characterized in that: The substituent group of the substituted phenyl group is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different; And / or, the substituent group of the substituted aryl is C1-C 10 Alkyl, C3-C6 cycloalkyl, C1-C 10 Alkoxy, C1-C 10 One or more of the haloalkyl and halogen, when there are multiple, the R1 and R2 are the same or different.

4. The use of the lithium ion extractant according to claim 3, characterized in that: The α-diketone compound includes any one of the structures shown in A001 to A010:

5. The use of the lithium ion extractant according to claim 4, characterized in that: Diketone extractants include any of the following structures:

6. An extraction system, characterized in that: The invention comprises the α-diketone lithium ion extractant, co-extractant and diluent as described in any one of claims 1 to 5; The α-diketone lithium ion extractant comprises an α-diketone compound having the general formula shown in Formula I: Wherein, R1 and R2 are each independently H or C1-C8 alkyl, C6-C 12 Phenyl, C6-C 12 Substituted phenyl, C6-C 20 Aryl, C6-C 20 Substituted aryl or C6-C 20 Heteroaryl, R1 and R2 are the same or different; And the α-diketone compound is not the following structure: There is at least one hydrogen atom on the carbon atom to which R1 is attached to the carbonyl group, and / or there is at least one hydrogen atom on the carbon atom to which R2 is attached to the carbonyl group; The α-diketone lithium ion extractant is used to obtain a lithium-rich organic phase from a lithium-containing raw material solution containing sodium and potassium, thereby achieving separation of lithium from sodium and potassium.

7. The extraction system according to claim 6, characterized in that The synergistic extractant is one or more of trioctylphosphine oxide (TOPO), tributylphosphine oxide (TBPO), and trialkylphosphine oxide (TRPO).

8. The extraction system according to claim 6, characterized in that The diluent is one or more of alkane, benzene or alcohol compounds.

9. The extraction system according to claim 8, characterized in that The diluent is one or more of No. 260 solvent oil, aviation kerosene, xylene and octanol.

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