CN107779612B - Process for extracting lithium from alkaline brine - Google Patents

Process for extracting lithium from alkaline brine Download PDF

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CN107779612B
CN107779612B CN201711298395.8A CN201711298395A CN107779612B CN 107779612 B CN107779612 B CN 107779612B CN 201711298395 A CN201711298395 A CN 201711298395A CN 107779612 B CN107779612 B CN 107779612B
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extraction
organic phase
lithium
washing
phase
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CN107779612A (en
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李丽娟
张利诚
彭小五
时东
宋富根
聂峰
韩文生
曾忠民
姬连敏
宋雪雪
李慧芳
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Qinghai Institute of Salt Lakes Research of CAS
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
    • C22B3/306—Ketones or aldehydes
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Extraction Or Liquid Replacement (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention discloses a process for extracting lithium from alkaline brine, which comprises the following steps: providing an extraction aqueous phase, providing an extraction organic phase, an extraction step, a washing step, a stripping step and a regeneration step. The process provided by the invention adopts an extraction system different from the traditional extraction system, can extract lithium from an alkaline brine system, firstly determines the full-flow process of extraction-washing-back extraction-regeneration, stays on the basic research of extraction sections, finally determines the process parameters such as the grade, the phase ratio and the concentration of each reagent of each section adapted by the extraction system, and provides a basic process route for industrial expanded production; the process for extracting lithium from the alkaline brine is particularly suitable for a filtrate system generated in the process of preparing a lithium carbonate product from a lithium chloride solution, so that lithium is further extracted from the alkaline filtrate brine system saturated by lithium carbonate, thereby realizing the real comprehensive recycling of the salt lake brine and having practical significance.

Description

Process for extracting lithium from alkaline brine
Technical Field
The invention belongs to the technical field of salt lake chemical industry, and particularly relates to a process for extracting lithium from alkaline brine.
Background
Lithium is the lightest metal in nature and has extremely strong electrochemical activity, and the metal and the compound thereof are widely applied to industries and fields of glass, ceramic aluminum smelting, organic chemical industry, aerospace, nuclear fusion and the like as explosives of thermonuclear fusion (hydrogen bomb), high-performance propelling fuels of airplanes, rockets and missiles and shielding materials of nuclear reactors. The lithium battery has 4-30 times higher energy storage than a common battery, has good service performance, and can be used as the driving force of torpedoes, submarines and spacecraft for a long time. The lithium aluminum and lithium magnesium alloy has high strength and light weight, is a good material for aerospace and rocket, and is favored by military industry and aerospace industry. In the 21 st century, with the rising demand for clean energy and the production of low-priced lithium salts, lithium energy will likely deeply affect human lives, and thus lithium is called "energy metal of the 21 st century".
The current effective method for extracting lithium from salt lake brine comprises a solvent extraction method, and FeCl is inevitably adopted in the solvent extraction method3As a co-extractant, the density of an extracted organic phase is increased, the density difference of two phases is reduced, the requirement on extraction separation equipment is higher, the traditional mixer-settler is difficult to meet the process requirement, high-efficiency centrifugal extraction equipment is adopted, and the equipment cost is high; at the same time, FeCl is introduced3Then, the difficulty is high when the extractant is regenerated by alkali, and very accurate flow control is needed, otherwise, the problems of extraction rate reduction or extractant emulsification failure and the like can be caused. In addition, the organic phase contains FeCl as a synergist3The extraction liquid (brine) is required to be kept weakly acidic, otherwise, Fe hydrolysis is caused, the brine entering an extraction working section is required to be subjected to acidification treatment, lithium and boron in the Qinghai salt lake commonly exist in association, boric acid is inevitably separated out in the acidification process, and filtration treatment is required, so that the method has no applicability to extraction of lithium in an alkaline system. Most of the current extracting agents for lithium can only realize lithium-magnesium separation, and have poor extraction effect on an alkali metal system. In conclusion, FeCl was the synergist3The existing method has the disadvantages of complex process flow, great difficulty in process control and great equipment investment. Therefore, there is a need to develop a process suitable for extracting lithium from alkaline brine.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a process for extracting lithium from alkaline brine, which adopts an extraction system different from the traditional extraction system, can extract lithium from the alkaline brine system, determines a full-flow process of extraction-washing-back extraction-regeneration, and provides a process path for industrial production.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
A process for extracting lithium from alkaline brines comprising the steps of:
Providing an extraction aqueous phase: taking lithium-containing alkaline brine as an extraction water phase; wherein the pH value of the lithium-containing alkaline brine is 8-14, and Li is contained in the lithium-containing alkaline brine+The mass concentration of the lithium ion battery is 0.05 g/L-10 g/L, and the total concentration of other metals except lithium is not more than 80 g/L;
Providing an extracted organic phase: mixing an extracting agent, a co-extracting agent and kerosene to prepare an extracted organic phase; wherein, in the extracted organic phase, the quantity concentration of the extracting agent and the co-extracting agent is 0.1 mol/L-0.5 mol/L, the extracting agent is selected from any one of benzoyl trifluoroacetone, thenoyl trifluoroacetone and furoyl trifluoroacetone, and the co-extracting agent is selected from any one of trioctylphosphine oxide, trialkyl phosphine oxide, tributyl phosphate and diethyl hexyl phosphoric acid;
An extraction step: mixing the extraction organic phase and the extraction water phase according to the volume ratio of 1: 10-10: 1, performing 2-10-level countercurrent extraction, and after extraction balance, splitting phases to obtain raffinate and a loaded organic phase;
A washing step: carrying out 2-10-level countercurrent washing or 2-10-level cross-flow washing on the loaded organic phase by taking 0.1-6 mol/L hydrochloric acid solution as a washing solution, and carrying out phase separation to obtain a washing residual solution and a washing organic phase; wherein the volume ratio of the loaded organic phase to the washing liquid is 1: 1-40: 1;
Back extraction: carrying out 2-10-level counter-current back extraction or 2-10-level cross-current back extraction on the washed organic phase by using 1-12 mol/L hydrochloric acid solution as a back extraction solution, and after the back extraction is balanced, carrying out phase splitting to obtain a lithium chloride solution and an empty organic phase; wherein the volume ratio of the washing organic phase to the stripping solution is 1: 1-80: 1;
a regeneration step: carrying out grade 1 regeneration, grade 2-5 countercurrent regeneration or grade 2-5 cross-flow regeneration on the empty organic phase by using water or an alkaline solution as a regeneration solution, and carrying out phase splitting to obtain a regeneration residual liquid and a regeneration organic phase; wherein the volume ratio of the empty organic phase to the regenerated liquid is 1: 5-20: 1.
Further, in the washing step, the concentration of lithium in the washed organic phase is not less than 80% of the concentration of lithium in the loaded organic phase; the concentration of alkali metals except lithium in the washing organic phase is not higher than 5% of the concentration of alkali metals except lithium in the loaded organic phase.
Further, in the regenerating step, the extraction capacity of the regenerated organic phase is not less than 90% of the extraction capacity of the extracted organic phase.
Further, the alkaline solution is any one of a hydroxide solution, an ammonia solution, or a carbonate solution.
Further, in the extraction step, the single-stage extraction time is 2min to 10 min; in the washing step, the single-stage washing time is 2-10 min; in the back extraction step, the single-stage back extraction time is 2min to 10 min; in the regeneration step, the single-stage regeneration time is 10 min-20 min.
Further, the anion in the lithium-containing alkaline brine is selected from Cl-、SO4 2-、CO3 2-、NO3 -At least one of (1).
further, in the step of providing an extraction aqueous phase, the lithium-containing alkaline brine is obtained by adding a sodium hydroxide solution, a sodium carbonate solution, or an ammonia solution to the lithium-containing brine.
Further, the process also includes the cycling step: returning the regenerated organic phase to the extraction step for use as an extracted organic phase, and repeating the extraction step, the washing step, the stripping step, and the regeneration step.
Has the advantages that:
(1) The purpose of extracting lithium from the lithium-containing alkaline brine is realized by adopting the diketone compound as an extracting agent and the neutral phosphorus-oxygen compound as a co-extracting agent; compared with the method for extracting lithium from salt lake brine by using a TBP-based extraction system in the prior art, the method avoids the co-extraction agent FeCl3The use of the method also avoids the problems of small density difference of two phases, high difficulty in process control and the like in the extraction process.
(2) The process realizes the full-flow process of extraction-washing-back extraction-regeneration, not only stays on the basic research of extraction sections, and finally determines the process parameters of the extraction system, such as the grade number, the phase ratio (the volume ratio of an organic phase to a water phase), the concentration of each reagent and the like of each section, thereby providing a basic process route for industrial expanded production, which is the first time for industrial production; the process is particularly suitable for a filtrate system generated in the process of preparing a lithium carbonate product from a lithium chloride solution, so that lithium is further extracted from the alkaline filtrate brine system saturated by the lithium carbonate, and the real comprehensive recycling of the salt lake brine is realized.
(3) According to the process, the water solubility of the extracting agent, the co-extracting agent and the diluent is low, the rest components in the raffinate are basically unchanged, the organic phase can be recycled through the regeneration step, three wastes are not generated, and the lithium recovery rate is more than 90%.
(4) The method has the advantages of simple process, easy control and high operation reliability, can effectively separate and recover lithium from the lithium-containing alkaline brine, has high purity of lithium chloride in the lithium chloride solution obtained by back extraction and less impurities, and can be used for preparing lithium chloride products or lithium carbonate products.
Drawings
The above and other aspects, features and advantages of embodiments of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a process flow diagram of a process for extracting lithium from alkaline brine according to the present invention;
FIG. 2 is a schematic diagram of the extraction principle of the extractant according to the invention;
Fig. 3 is a schematic diagram of the extraction principle of the extraction system according to the invention.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided to explain the principles of the invention and its practical application to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.
The invention provides a process for extracting lithium from alkaline brine, which provides a full-flow process comprising extraction, washing, back extraction and regeneration, and confirms process parameters such as the stage number, the phase ratio (the volume ratio of an organic phase to a water phase), the concentration of each reagent and the like of each section so as to form a process method with good extraction efficiency, thereby providing a process route for industrial expanded production; the process for extracting lithium from the alkaline brine is particularly suitable for a filtrate system generated in the process of preparing a lithium carbonate product from a lithium chloride solution, so that lithium is further extracted from the alkaline filtrate brine system saturated by lithium carbonate, thereby realizing the real comprehensive recycling of the salt lake brine and having practical significance.
Referring to fig. 1, the process for extracting lithium from alkaline brine includes the following steps:
Step S1, providing an extraction water phase.
Specifically, lithium-containing alkaline brine is used as an extraction water phase; wherein the pH of the lithium-containing alkaline brine is 8 to 14, and Li is contained in the lithium-containing alkaline brine+The mass concentration of the lithium ion battery is 0.05 g/L-10 g/L, and the total concentration of other metals except lithium is not more than 80 g/L.
The anion in the lithium-containing alkaline brine may be Cl-、SO4 2-、CO3 2-、NO3 -Main anions representing the type of the salt lake brine or the anions introduced in the comprehensive utilization process of the salt lake brine; when lithium carbonate product is prepared by using lithium chloride solution, sodium carbonate is generally added into the system so as to lead Li in the system to be+precipitating with lithium carbonate precipitate, performing solid-liquid separation to obtain lithium carbonate product, and filtering to obtain filtrate saturated with lithium carbonate and containing Na+And is alkaline, the method of the invention can be used for the filtrate to treat Li therein+Further recovery is carried out to form a lithium chloride solution which can be recycled as a raw material for preparing a lithium carbonate product.
it is worth to be noted that, if the initial pH of the lithium-containing brine cannot meet the above requirements, the lithium-containing alkaline brine with the pH of 9 to 12 can be obtained by adding a sodium hydroxide solution, a sodium carbonate solution or an ammonia solution thereto; the amount and concentration of the substance in the sodium hydroxide solution, sodium carbonate solution or ammonia solution for adjusting the pH are not particularly limited.
Step S2, providing an extracted organic phase.
Specifically, an extraction agent, a synergist and kerosene are mixed to prepare an extraction organic phase.
In the extracted organic phase, the quantity concentration of both the extracting agent and the co-extracting agent is controlled to be 0.1-0.5 mol/L, the extracting agent is selected from any one of benzoyl trifluoroacetone, thenoyl trifluoroacetone and furoyl trifluoroacetone, and the co-extracting agent is selected from any one of trioctylphosphine oxide, trialkyl phosphine oxide, tributyl phosphate and diethyl hexyl phosphoric acid; alkali metals in the first main group of the periodic table are very susceptible to losing the outermost s-electron to M+The ions, alkali metal ions, are hard Lewis acids and these cations are generally capable of forming relatively temperature complexes with oxygen-containing coordinating groups (e.g., strong Lewis bases such as carbonyl, phosphono, etc.). The separation of alkali metals from each other is achieved according to the difference in the degree of stability of the formed Lewis acid-base pairs.
solvent extraction of lithiumThe selective extraction of lithium can be realized by a common extraction system, and a special extracting agent and an extraction system must be searched. Depending on the nature of the lithium, the ligand requirements must satisfy the following aspects in order for an effective extraction effect to occur: satisfy Li+The requirement of tetrahedral coordination structure of (a); with energy of reaction with Li+Chelating functional groups that form stronger primary valency bonds, such as-OH or carbonyl compounds that can appear in the enol form during extraction; an O or N ligand having a hard basicity; with Li+Forming a stable chelate ring.
The extracting agents used in the invention, benzoyl trifluoroacetone, thiophene formyl trifluoroacetone and furan formyl trifluoroacetone, belong to diketone compounds, diketone is an acidic chelating extracting agent, and the mechanism of extracting lithium mainly utilizes hydroxyl interconverted by carbonyl or enol and Li+Combining; specifically, as shown in FIG. 2, in the diketone, there is a tautomeric equilibrium between the keto form (I) and the enol form (II) thereof, and Li is present during extraction+can form a stable chelate structure (III) with diketone; the diketone is neutral after chelating with the metal ion, and the solubility of the inner complex salt in the organic phase is very small, as shown in fig. 3, if the ligand (S) exists, the diketone can be complexed with the inner complex salt to form an extractable neutral extract, and the ligand is called as a synergist, namely trioctylphosphine oxide, trialkylphosphine oxide, tributyl phosphate and diethylhexyl phosphate used in the invention. When the diketone is applied to extracting lithium, a synergistic extraction system is usually formed by the diketone and a neutral synergistic extractant for extraction so as to meet the requirement of Li+A four-coordinate structure of (a); furthermore, enolic bis-ketones with Li+After coordination, a stable six-membered chelate ring is formed. Meanwhile, the coordination chelation mode is mainly directed to Li+、Na+、K+Alkali metal and Ca2+、Mg2+Alkaline earth metals, however, the stability of chelates formed by different cations is different, and the stability of chelates formed by diketones and neutral synergists with different structures is also greatly different, so that not every diketone and every neutral synergist can be applied to the process of the present invention.
In particular, the present inventionThe diketone compounds adopted by the invention as the extracting agents all have trifluoromethyl groups which have stronger electron withdrawing effect, so that the enolization degree of the diketone compounds is enhanced, and the diketone compounds and Li are further reacted+Better bonding is possible; while other compounds with diketone structure, such as benzoylacetone, dibenzoylmethane, etc., do not have electron-withdrawing group, and thus have no electron-withdrawing group to Li+The selectivity of (a) is relatively weak and, correspondingly, lithium extraction is less effective. In other words, even though the diketone compound is used as an extractant for lithium ions, the hydroxyl group interconverted by carbonyl group or enol in the diketone structure is utilized with Li+In combination with the formation of cyclics, not every diketone compound can be a good lithium extractant.
More specifically, the synergist adopted by the invention is a neutral phosphine compound containing phosphine-oxygen double bonds, and has stronger synergic effect due to stronger electron-donating capability; other extracting agents containing carbon-oxygen double bonds or nitrogen-oxygen double bonds and sulfur-oxygen double bonds have relatively weak extracting effect due to the weak electron donating capability.
It is noted that, although based on the above extraction principle, the extractant and synergist will also react with Ca2+、Mg2+The alkaline earth metals are complexed for extraction, but the aqueous phase of the extraction according to the invention is alkaline and therefore contains free Ca2+、Mg2+The alkaline earth metal concentration will be very low; that is, the cation in the extract aqueous phase is mainly an alkali metal.
And step S3, extraction.
Specifically, an extraction organic phase and an extraction aqueous phase are mixed according to the volume ratio (hereinafter referred to as extraction ratio) of 1: 10-10: 1, 2-10 stages of countercurrent extraction are carried out, and phase separation is carried out after extraction balance to obtain raffinate and a loaded organic phase.
Generally, the extraction balance can be achieved by controlling the single-stage extraction time to be 2 min-10 min.
It is worth to be noted that, when a certain extraction organic phase is determined, the single-stage extraction rate of different extraction organic phases under different extraction phase ratios can be determined in advance, and then the extraction balance is combinedAnd determining the theoretical extraction stage number corresponding to the preset extraction effect by using the isotherm, and finally determining the final actual extraction stage number, wherein the fluctuation does not exceed two stages on the basis of the theoretical extraction stage number. It can be seen that, in the multi-stage countercurrent extraction process, the determination of the extraction stage number and the extraction phase ratio is not independent process parameters, but is determined by target ion concentrations (specifically referring to Li in the invention) in the extraction organic phase and the extraction aqueous phase+) A unified, mutually influencing parameter combination determined together; in other words, if the concentration of the target ion in the extraction aqueous phase is changed, the finally determined process parameters of the extraction section may also be changed correspondingly, and the composition of the extraction organic phase and the extraction ratio are changed in the same way, so as to finally form a short-series, low-cost and short-time preferred process with less extraction organic phase.
And step S4, washing.
Specifically, 0.1-6 mol/L hydrochloric acid solution is used as a washing solution to carry out 2-10-stage countercurrent washing or 2-10-stage cross-flow washing on the loaded organic phase, the volume ratio of the loaded organic phase to the washing solution (hereinafter referred to as washing ratio) is controlled to be 1: 1-40: 1, and the washing residual solution and the washing organic phase are obtained by phase separation.
In the extraction of Li+The process of (2) is inevitable to generate entrainment due to competitive extraction of other alkali metal ions, so that the part of the entrained alkali metal ions needs to be washed and removed by multi-stage countercurrent washing or multi-stage cross-flow washing before back extraction is carried out, but obviously, Li is inevitable to be caused in the washing process+So that the single-stage washing time is controlled to be 2min to 10min in the washing process, and Li is used+The loss rate of (a) is less than 20% and the elution rate of the entrained alkali metals other than lithium is not less than 95%; in other words, the concentration of lithium in the washed organic phase is not less than 80% of the concentration of lithium in the loaded organic phase and the concentration of alkali metals other than lithium in the washed organic phase is not more than 5% of the concentration of alkali metals other than lithium in the loaded organic phase by multistage countercurrent washing or multistage cross-flow washing.
Therefore, in the multi-stage counter-current washing or multi-stage cross-current washing, the concentration of the washing liquid and the washing ratio are specifically adjusted according to the content of lithium and alkali metal except lithium in the loaded organic phase and the washing purpose, so that the cation in the washed organic phase is mainly lithium.
And step S5, back extraction.
Specifically, 1-12 mol/L hydrochloric acid solution is used as stripping solution to carry out 2-10-level countercurrent stripping or 2-10-level cross-flow stripping on a washing organic phase, the volume ratio of the washing organic phase to the stripping solution (hereinafter referred to as stripping solution ratio) is controlled to be 1: 1-80: 1, and phase separation is carried out after the stripping balance to obtain a lithium chloride solution and an empty organic phase.
Generally, the back extraction balance can be achieved by controlling the single-stage back extraction time to be 2 min-10 min.
The back extraction process is a process of transferring lithium from an organic phase to a water phase, and is equivalent to a reverse reaction of the extraction process, so that the back extraction process is similar to the extraction step, after the content of the lithium in the washed organic phase is determined, the single-stage back extraction rate of the back extraction solution with different concentrations under different back extraction phase ratios can be determined in advance, then the theoretical back extraction stage number corresponding to the preset back extraction effect is determined by combining a back extraction equilibrium isotherm, and finally the fluctuation is not more than two stages on the basis of the theoretical back extraction stage number, so that the final actual back extraction stage number is determined. It can be seen from this that, although the back extraction process is somewhat simpler than the extraction process and involves somewhat fewer process parameters, in the process of multi-stage counter-current back extraction or multi-stage cross-flow back extraction, the determined solutions of the back extraction stages and the back extraction ratio are not independent process parameters, but rather are the target ion concentrations in the organic phase of the wash (in the present invention, Li is specifically referred to in the specification)+) And a uniform parameter combination with mutual influence jointly determined by the stripping solution; in other words, if the concentration of the target ion in the organic phase is changed, the finally determined process parameters of the stripping section may also be changed correspondingly, and the changes of the concentration of the stripping solution and the stripping ratio are the same, so as to finally form a preferred process with short series, less consumption of the stripping solution, low cost and short time consumption.
And step S6, regeneration.
Because the empty organic phase obtained after the back extraction carries or extracts part of back extraction liquid hydrochloric acid, and the part of hydrochloric acid can bring great influence on the recycling of the part of empty organic phase to a subsequent extraction section if the part of hydrochloric acid is not treated, in order to reduce the waste of the extracted organic phase, the empty organic phase should be regenerated to recover the lithium extraction capability, so that the organic phase can be recycled.
Specifically, water or an alkaline solution is used as a regeneration liquid to carry out 1-stage regeneration, 2-5-stage countercurrent regeneration or 2-5-stage cross-flow regeneration on an empty organic phase, the volume ratio of the empty organic phase to the regeneration liquid (hereinafter referred to as regeneration ratio) is controlled to be 1: 5-20: 1, phase separation is carried out to obtain a regeneration residual liquid and a regeneration organic phase, and thus the regeneration organic phase can be returned to the step S3 to be used as an extraction organic phase for recycling.
More specifically, the concentration of the alkaline solution is not particularly limited; the alkaline solution is preferably any one of a hydroxide solution, an ammonia solution, or a carbonate solution.
Generally, the single-stage regeneration time is controlled to be 10 min-20 min.
It is worth to say that, in the regeneration process, the extraction capacity of the regenerated organic phase is not less than 90% of the extraction capacity of the extracted organic phase as the regeneration target; therefore, during the regeneration, it is necessary to adjust the number of regeneration steps and the type or concentration of the regeneration liquid to meet the above regeneration requirement.
Thus, compared with the extraction system using TBP as the extractant in the prior art, the extraction process does not need to use FeCl as the co-extractant3The problems of small density difference of two phases, high difficulty in process control and the like in the extraction process are avoided; in addition, in the process, the water solubility of the extracting agent, the co-extracting agent and the diluent is low, the rest components in the raffinate are basically unchanged, the organic phase can be recycled through a regeneration step, three wastes are not generated, and the lithium recovery rate is more than 90%; meanwhile, the process is simple, easy to control and high in operation reliability, lithium can be effectively separated and recovered from the lithium-containing alkaline brine, and the lithium chloride solution obtained through back extraction has high purity and few impurities.
The technical effect of the above-described process for extracting lithium from alkaline brine will be shown below by specific examples.
Example 1
To Li+the concentration is 2g/L, Na+Adding 2mol/L sodium hydroxide solution into chloride type brine with the concentration of 20g/L, and adjusting the pH value to 8.5-11.0 to obtain an extraction water phase.
Mixing benzoyl trifluoroacetone (HBTA), trioctylphosphine oxide (TOPO) and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.4 mol/L.
mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 2:3, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking 1-4 mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing and phase splitting to obtain a washing residual solution and a washing organic phase.
And (3) taking a hydrochloric acid solution of 4-8 mol/L as a back extraction solution, carrying out three-stage countercurrent back extraction on the washed organic phase, controlling the back extraction phase ratio to be 20:1, controlling the single-stage back extraction time to be 6min, standing and phase splitting after the back extraction balance is achieved, so as to obtain a lithium chloride solution and an empty organic phase.
And (2) taking water as a regeneration liquid, carrying out two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration ratio to be 1:1, controlling the single-stage regeneration time to be 10min, and standing for phase splitting to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 95.5%, the back extraction rate reaches 98.5%, and the total recovery rate of lithium reaches 94%.
Example 2
To Li+The concentration is 2g/L, Na+Adding 2mol/L sodium hydroxide solution into carbonate type brine with the concentration of 40g/L, and mixing the solutionThe pH was adjusted to 10.0 to obtain an aqueous extract phase.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.3 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking a 2mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 15:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) taking a 2mol/L sodium hydroxide solution as a regeneration liquid, carrying out primary regeneration on the empty organic phase, controlling the regeneration phase ratio to be 10:1, and the regeneration time to be 10min, and standing and phase-splitting to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 98.0%, the back extraction rate reaches 99.0%, and the total recovery rate of lithium reaches 97%.
Example 3
To Li+The concentration is 2g/L, Na+2mol/L sodium carbonate solution was added to sulfate type brine having a concentration of 60g/L to adjust the pH thereof to 11.0, thereby obtaining an extract aqueous phase.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.3 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking 1mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 15:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) performing two-stage countercurrent regeneration on the empty organic phase by taking 1mol/L sodium carbonate solution as a regeneration liquid, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 96.4%, the back extraction rate reaches 97.6%, and the total recovery rate of lithium reaches 94%.
Example 4
The lithium-containing alkaline brine adopted in the embodiment is Li+The concentration is 0.2g/L, Na+The carbonate brine with a concentration of 10g/L, which had a pH of 10.8, was used as the aqueous extraction phase without adjustment.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.15 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking 0.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 10:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) performing two-stage countercurrent regeneration on the empty organic phase by taking 1mol/L sodium carbonate solution as a regeneration liquid, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 96.4%, the back extraction rate reaches 97.6%, and the total recovery rate of lithium reaches 94.1%.
Example 5
The lithium-containing alkaline brine adopted in the embodiment is Li+The ammoniacal brine with concentration of 0.2g/L has pH of 9.98, and is used as extraction water phase without adjustment.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.15 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing two-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
And (3) taking 0.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking a hydrochloric acid solution of 3mol/L as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 10:1, controlling the single-stage stripping time to be 6min, standing and phase-separating after the stripping balance is achieved, thus obtaining a lithium chloride solution and an empty organic phase.
Taking ammonia-ammonium chloride buffer solution with pH of 9.8 as regeneration liquid, performing two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration phase ratio to be 10:1, performing single-stage regeneration for 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 85.5%, the back extraction rate reaches 99.2%, and the total recovery rate of lithium reaches 84.8%.
Example 6
to Li+Adding 1mol/L sodium carbonate solution into brine of trace alkaline earth metal and noble metal with the concentration of 8g/L and the total concentration of alkali metal except lithium of 20g/L, adjusting the pH value to 10.5, and precipitating the alkaline earth metal to obtain an extraction water phase.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.4 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 4:1, performing four-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
And (3) taking 1.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) taking 0.1mol/L sodium carbonate-sodium bicarbonate buffer solution as a regeneration solution, carrying out two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing and phase-splitting to obtain a regeneration residual solution and a regeneration organic phase.
therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 90.2%, the back extraction rate reaches 99.5%, and the total recovery rate of lithium reaches 89.7%.
Example 7
To Li+Adding 1mol/L sodium carbonate solution into 0.5g/L brine with total alkali metal concentration except lithium being 20g/L and trace alkaline earth metal and noble metal, adjusting the pH value to 10.5, and precipitating the alkaline earth metal to obtain an extraction water phase.
Mixing HBTA, TOPO and kerosene to obtain an extracted organic phase; wherein, the concentration of HBTA and TOPO substances in the extracted organic phase is 0.2 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:2, performing four-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
and (3) taking 1.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
and (3) taking a hydrochloric acid solution of 3mol/L as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-separating after the stripping balance is achieved, thus obtaining a lithium chloride solution and an empty organic phase.
And (2) taking 0.1mol/L sodium carbonate-sodium bicarbonate buffer solution as a regeneration solution, carrying out two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing and phase-splitting to obtain a regeneration residual solution and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 96.2%, the back extraction rate reaches 98.5%, and the total recovery rate of lithium reaches 94.76%.
Example 8
The lithium-containing alkaline brine adopted in the embodiment is Li+The 0.2g/L ammoniacal solution, pH 9.98, was used as the aqueous extraction phase without any adjustment.
Mixing furoyl trifluoroacetone (TFTA), TOPO and kerosene to obtain an extracted organic phase; wherein, the mass concentration of HFTA and TOPO in the extracted organic phase is 0.15 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing two-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
And (3) taking 0.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking a hydrochloric acid solution of 3mol/L as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 10:1, controlling the single-stage stripping time to be 6min, standing and phase-separating after the stripping balance is achieved, thus obtaining a lithium chloride solution and an empty organic phase.
Taking ammonia-ammonium chloride buffer solution with pH of 9.8 as regeneration liquid, performing two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration phase ratio to be 10:1, performing single-stage regeneration for 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 92.8%, the back extraction rate reaches 94.6%, and the total recovery rate of lithium is 87.79%.
Example 9
To Li+Adding 1mol/L sodium carbonate solution into brine of trace alkaline earth metal and noble metal with the concentration of 8g/L and the total concentration of alkali metal except lithium of 20g/L, adjusting the pH value to 10.5, and precipitating the alkaline earth metal to obtain an extraction water phase.
Mixing HBTA, tributyl phosphate and kerosene to obtain an extracted organic phase; wherein, the mass concentration of the benzoyl trifluoroacetone and the tributyl phosphate in the extracted organic phase is 0.4 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 4:1, performing four-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
And (3) taking 1.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
and (2) taking 0.1mol/L sodium carbonate-sodium bicarbonate buffer solution as a regeneration solution, carrying out two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing and phase-splitting to obtain a regeneration residual solution and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 80.2%, the back extraction rate reaches 91.5%, and the total recovery rate of lithium is 73.4%.
It is worth to be noted that, according to the principle analysis of the above-mentioned diketone and neutral phosphine oxide substance for extracting lithium, it can be seen that not every diketone and/or every neutral phosphine oxide substance can obtain the above-mentioned extraction effect of the present invention, and therefore, the present invention has performed the following comparative experiments with respect to other diketones as the extractant and/or other neutral phosphine oxide substances as the co-extractant.
Comparative example 1
To Li+The concentration is 2g/L, Na+2mol/L sodium carbonate solution was added to sulfate type brine having a concentration of 60g/L to adjust the pH thereof to 11.0, thereby obtaining an extract aqueous phase.
Mixing 2, 4-pentanedione, 2-ethylhexyl phosphoric acid and kerosene to obtain an extracted organic phase; wherein the mass concentrations of 2, 4-pentanedione and 2-ethylhexyl phosphoric acid in the extracted organic phase were each 0.3 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking 1mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 15:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) performing two-stage countercurrent regeneration on the empty organic phase by taking 1mol/L sodium carbonate solution as a regeneration liquid, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 46.4%, the back extraction rate reaches 97.6%, and the total recovery rate of lithium is 45.3%.
Comparative example 2
To Li+The concentration is 2g/L, Na+2mol/L sodium hydroxide solution was added to 40g/L carbonate-type brine to adjust the pH to 10.0, thereby obtaining an extract aqueous phase.
Mixing dibenzoyl methane, tributyl phosphine oxide and kerosene to obtain an extracted organic phase; wherein, the mass concentration of dibenzoyl methane and tributyl phosphine oxide in the extracted organic phase is 0.3 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking a 2mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 15:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) taking a 2mol/L sodium hydroxide solution as a regeneration liquid, carrying out primary regeneration on the empty organic phase, controlling the regeneration phase ratio to be 10:1, and the regeneration time to be 10min, and standing and phase-splitting to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
The detection shows that the extraction rate of lithium in the alkaline lithium-containing brine is 58.0 percent, the back extraction rate reaches 96.0 percent, and the total recovery rate of lithium reaches 55.7 percent.
Comparative example 3
To Li+The concentration is 2g/L, Na+2mol/L sodium carbonate solution was added to sulfate type brine having a concentration of 60g/L to adjust the pH thereof to 11.0, thereby obtaining an extract aqueous phase.
Mixing thenoylacetone, tributyl phosphate and kerosene to obtain an extracted organic phase; wherein, in the extracted organic phase, the mass concentration of the thiophenecarboxylacetone and the tributyl phosphate are both 0.3 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:1, performing three-stage countercurrent extraction, controlling single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after extraction balance is achieved.
And (3) taking 1mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking 6mol/L hydrochloric acid solution as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 15:1, controlling the single-stage stripping time to be 6min, standing and phase-splitting after the stripping balance is achieved, and thus obtaining a lithium chloride solution and an empty organic phase.
And (2) performing two-stage countercurrent regeneration on the empty organic phase by taking 1mol/L sodium carbonate solution as a regeneration liquid, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing for phase separation to obtain a regeneration residual liquid and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 76.4%, the back extraction rate reaches 95.6%, and the total recovery rate of lithium reaches 73.0%.
Comparative example 4
To Li+Concentration ofAdding 1mol/L sodium carbonate solution into 0.5g/L brine with total alkali metal concentration except lithium being 20g/L and trace alkaline earth metal and noble metal, adjusting pH value to 10.5, and precipitating alkaline earth metal therein to obtain extraction water phase.
Mixing toluylacetone, tributylphosphine oxide and kerosene to obtain an extracted organic phase; wherein, the mass concentration of the toluoylacetone and the tributyl phosphine oxide in the extracted organic phase is 0.2 mol/L.
Mixing the prepared extraction organic phase and extraction water phase according to an extraction ratio of 1:2, performing four-stage countercurrent extraction, controlling the single-stage extraction time to be 6min, and standing for phase separation to obtain raffinate and a loaded organic phase after the extraction balance is achieved.
And (3) taking 1.5mol/L hydrochloric acid solution as a washing solution, carrying out three-stage countercurrent washing on the loaded organic phase, controlling the washing phase ratio to be 20:1, and the single-stage washing time to be 6min, and standing for phase separation to obtain a washing residual solution and a washing organic phase.
And (3) taking a hydrochloric acid solution of 3mol/L as a stripping solution, carrying out three-stage countercurrent stripping on the washed organic phase, controlling the stripping phase ratio to be 20:1, controlling the single-stage stripping time to be 6min, standing and phase-separating after the stripping balance is achieved, thus obtaining a lithium chloride solution and an empty organic phase.
And (2) taking 0.1mol/L sodium carbonate-sodium bicarbonate buffer solution as a regeneration solution, carrying out two-stage countercurrent regeneration on the empty organic phase, controlling the regeneration ratio to be 1: 5-5: 1, controlling the single-stage regeneration time to be 20min, and standing and phase-splitting to obtain a regeneration residual solution and a regeneration organic phase.
Therefore, the regenerated organic phase obtained in the previous step can be reused as the extraction organic phase in the next period for cyclic utilization, so that the purposes of reducing organic reagent consumption, reducing pollution and reducing extraction cost are achieved.
Through detection, the extraction rate of lithium in the alkaline lithium-containing brine is 66.2%, the back extraction rate reaches 98.5%, and the total recovery rate of lithium reaches 65.2%.
it can be seen from the comparison of the examples and the comparative examples that although the same family of diketone extractants or the same family of neutral phosphine oxide synergists, there is still a great difference in the extraction effect between the homologues, so that there is no simple substitution between different extractants and/or different synergists.
Based on the above comparative analysis of different extractants and co-extractants in homologues, it can be seen that a complete extraction process is an integral result of the combined action of multiple factors. In addition, it is worth to be noted that a full-flow process including extraction-washing-stripping-regeneration is more complicated than the process of a general extraction section or extraction-stripping section, and the factors to be considered in the process design are more; this is because the extractant also has a certain extraction effect on the impurity ions contained in the raw material solution (i.e., the extraction aqueous phase) when extracting the target ions, and if the loaded organic phase obtained by extraction is directly subjected to stripping, the impurity ions in the loaded organic phase are also stripped into the stripping product solution (i.e., the lithium chloride solution in the present invention) by the stripping solution, and the purity of the obtained stripping product solution is difficult to ensure. Meanwhile, as the extracted organic phase carries a part of raw material liquid in the extraction process, the part of raw material liquid can enter the counter liquid along with the counter extraction, so that the product purity is reduced and the counter extraction acid liquor is consumed. The washing process provided by the invention not only can maximally elute the impurity ions in the loaded organic phase by adjusting the concentration of the washing acid compared with the washing, but also can separate the extraction section from the back extraction section, thereby maximally reducing the problem of high impurity content of the product caused by entrainment, and further improving the purity and yield of the product. In addition, the regeneration method provided by the invention effectively recovers the extraction capability of the empty organic phase after the back extraction, realizes the recycling of the organic phase, and ensures that the whole extraction flow has a complete flow and has a basic industrial value.
While the invention has been shown and described with reference to certain embodiments, those skilled in the art will understand that: various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims (5)

1. A process for extracting lithium from alkaline brine, comprising the steps of:
Providing an aqueous extraction phase: taking lithium-containing alkaline brine as an extraction water phase; wherein the pH value of the lithium-containing alkaline brine is 8-14, and Li is contained in the lithium-containing alkaline brine+the mass concentration of the lithium ion battery is 0.05 g/L-10 g/L, and the total concentration of other metals except lithium is not more than 80 g/L; the anion in the lithium-containing alkaline brine is selected from Cl-、SO4 2-、CO3 2-、NO3 -At least one of;
Providing an extracted organic phase: mixing an extracting agent, a co-extracting agent and kerosene to prepare an extracted organic phase; wherein, in the extracted organic phase, the quantity concentration of the substances of the extracting agent and the synergistic agent is 0.1-0.5 mol/L, the extracting agent is furyltrifluoroacetone, and the synergistic agent is trioctylphosphine oxide;
An extraction step: mixing the extraction organic phase and the extraction water phase according to the volume ratio of 1: 10-10: 1, performing 2-10-level countercurrent extraction, and after extraction balance, splitting phases to obtain raffinate and a loaded organic phase; in the extraction step, the single-stage extraction time is 2 min-10 min;
A washing step: carrying out 2-10-level countercurrent washing or 2-10-level cross-flow washing on the loaded organic phase by taking 0.05-12 mol/L hydrochloric acid solution as a washing solution, and carrying out phase separation to obtain a washing residual solution and a washing organic phase; wherein the volume ratio of the loaded organic phase to the washing liquid is 1: 1-40: 1; in the washing step, the single-stage washing time is 2-10 min;
Back extraction: carrying out 2-10-level counter-current back extraction or 2-10-level cross-current back extraction on the washed organic phase by taking 0.05-12 mol/L hydrochloric acid solution as a back extraction solution, and after the back extraction is balanced, carrying out phase separation to obtain a lithium chloride solution and an empty organic phase; wherein the volume ratio of the washing organic phase to the stripping solution is 1: 1-80: 1; in the back extraction step, the single-stage back extraction time is 2min to 10 min;
A regeneration step: carrying out grade 1 regeneration, grade 2-5 countercurrent regeneration or grade 2-5 cross-flow regeneration on the empty organic phase by using water or an ammoniacal solution or a carbonate solution as a regeneration solution, and carrying out phase splitting to obtain a regeneration residual liquid and a regeneration organic phase; wherein the volume ratio of the empty organic phase to the regenerated liquid is 1: 5-20: 1; in the regeneration step, the single-stage regeneration time is 10 min-20 min.
2. The process of claim 1 wherein, in the washing step, the concentration of lithium in the washed organic phase is no less than 80% of the concentration of lithium in the loaded organic phase; the concentration of alkali metals except lithium in the washing organic phase is not higher than 5% of the concentration of alkali metals except lithium in the loaded organic phase.
3. The process of claim 1, wherein in the regenerating step, the extraction capacity of the regenerated organic phase is no less than 90% of the extraction capacity of the extracted organic phase.
4. The process of claim 1, wherein in the step of providing an aqueous extraction phase, the lithium-containing alkaline brine is obtained by adding a sodium hydroxide solution, a sodium carbonate solution or an ammonia solution to the lithium-containing brine.
5. The process according to any one of claims 1 to 3, characterized in that it further comprises a recycling step: returning the regenerated organic phase to the extraction step for use as an extracted organic phase, and repeating the extraction step, the washing step, the stripping step, and the regeneration step.
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