Method for extracting, purifying, removing impurities and enriching lithium from lithium-containing aqueous solution

Abstract

The invention relates to a method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution, which comprises the following steps: mixing an organic extractant and a synergistic extractant, saponifying, and pumping into a bubble-supported oil film extractor to obtain oil bubbles coated with the organic extractant; performing countercurrent contact on the oil bubbles and the lithium-containing aqueous solution to obtain an impurity-containing organic phase and an impurity-removed lithium-containing raffinate; pumping the lithium-containing raffinate subjected to impurity removal into a next-stage series-connected bubble-supported oil film extractor, and performing countercurrent contact with the oil bubbles coated with the organic extractant again to obtain a lithium-rich loaded organic phase and raffinate; the washed organic phase is subjected to reverse extraction, and lithium-rich reverse extraction liquid is obtained; and after reverse extraction, regenerating the organic phase and then returning to saponification for recycling. The pH range of the lithium-containing aqueous solution applicable to the method is wide, the difference of the extraction rates of lithium ions and coexisting impurity ions is utilized, an extraction system composed of the same organic extraction agent and a synergistic extraction agent is adopted, various impurity ions coexisting with lithium in the lithium-containing aqueous solution can be effectively removed, and efficient enrichment of low-concentration lithium can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution. Background Art

[0002] Lithium is widely used in many fields such as lithium batteries, aerospace, atomic energy, nuclear power industry and medicine. It is known as the "energy metal that promotes the progress of the world" and is an important strategic resource in the national economy and national defense construction. In nature, lithium resources are mainly found in salt lake brine deposits and granite microcrystalline deposits. There are also reports that lithium is dispersed in clay minerals such as bauxite, kaolinite and illite. In addition, a large number of discarded electronic products, power batteries, etc. are also important lithium-rich secondary resources.

[0003] Solvent extraction has been rapidly developed in recent years in the application of lithium extraction due to its advantages of strong selectivity, high separation efficiency, simple process, small equipment investment, and easy scale-up. At present, the extraction of lithium from salt lake brine has developed into the most promising important method for treating salt lake brine with high magnesium-lithium ratio, in addition to precipitation, calcination leaching, ion exchange (adsorption), electrodialysis membrane, etc. For lithium-containing ores and various lithium-rich secondary resources, lithium is generally extracted by acid or alkali leaching after roasting. However, due to the complex occurrence form of lithium in nature, low grade, and a wide variety of co-existing minerals, the lithium-containing acid leaching solution, alkaline leaching solution or neutral leaching solution obtained from various lithium-containing mineral resources and secondary resources has complex solution composition and large pH differences. Not only does it require different extraction systems to separate and recover lithium, but the entire separation, impurity removal and lithium purification process is lengthy, inefficient, and costly.

[0004] At present, the extraction system for lithium extraction from salt lake brine is mainly phosphate esters, including tributyl phosphate-ferric chloride-kerosene extraction system, tributyl phosphate-amide-ferric chloride extraction system, tributyl phosphate-ionic liquid-extraction system, etc. However, this system often requires the addition of FeCl3 as a co-extractant and requires the Cl in the aqueous phase to be -Lithium can only be extracted when the ion concentration is kept at a high level. The above system is not applicable to sulfuric acid media or alkaline lithium-containing solutions produced by lithium ore leaching and waste lithium battery recovery. For the leachate of lithium ore and secondary resources, the synergistic extraction system composed of β-diketone and neutral or acidic organic phosphine has a good effect, but this system has a good extraction effect on lithium only in an alkaline medium. There is no separation selectivity for coexisting ions such as calcium, magnesium, aluminum, iron, nickel, and cobalt in neutral or acidic leachates, and when the lithium loading in the organic phase is high, it is easy to have phase separation difficulties. In particular, whether it is acidic, neutral or alkaline medium extraction, when there are multiple metal impurity ions coexisting in the leachate, most of the reported extraction systems can only preferentially extract and remove some high-valent metal impurity ions, with low separation efficiency and low product purity. Moreover, while extracting and removing impurities, the co-extraction dispersion loss of lithium is difficult to avoid, resulting in low lithium recovery and high separation cost. Furthermore, when the lithium ion concentration in the leachate is low, the reported extraction system cannot achieve efficient extraction and enrichment of lithium concentration. Before or after extraction and impurity removal, the lithium concentration still needs to be further increased by evaporation and concentration before it can be used for the subsequent preparation of lithium carbonate and other products.

[0005] Chinese patent CN117965906 A discloses a method for recycling lithium from waste ternary lithium batteries. In view of the fact that the lithium mother liquor still contains a high concentration of residual lithium, an extractant (2-ethylhexyl bis (2-ethylhexyl) phosphate and / or tributyl phosphate) that can coordinate with lithium ions has been developed. The extractant can extract lithium from the lithium mother liquor alone, and then strip and precipitate lithium to obtain lithium carbonate, thereby improving the recovery rate of lithium. However, this method still cannot achieve effective separation of lithium and high-price impurity ions such as calcium and magnesium, and a neutralization precipitation method is required to remove impurity ions such as calcium and magnesium in advance. In addition, this method uses precipitation to enrich lithium, and the yield of lithium is low and the precipitation agent consumption is large, which does not have advantages in terms of economy and environmental protection.

[0006] Chinese patent CN 112342405 A discloses a method for extracting lithium from a lithium-containing solution, which can extract lithium again from the lithium-containing solution remaining after lithium extraction, the lithium-containing solution remaining after preparing lithium carbonate or lithium hydroxide by the ore method, the lithium-containing wastewater generated during battery recovery, and the lithium-containing solution remaining after preparing lithium carbonate, and the lithium-containing solution remaining after preparing battery-grade lithium carbonate from industrial-grade lithium carbonate. The method uses phosphates and β-diketones as extractants, and the organic phase loaded with lithium is stripped with carbon dioxide, which effectively slows down or avoids acidic corrosion of the equipment, has high safety, and the lithium carbonate obtained by the method has high purity and low cost. However, similarly, for complex solutions, the system still cannot achieve deep removal of impurity ions, and the scope of use of the method is neutral or alkaline systems. For acidic lithium-containing systems, the method is not applicable.

[0007] Chinese patent CN 115947354 A discloses a method for preparing battery-grade lithium carbonate from lithium-containing wastewater in the production of alumina from fly ash. The method comprises: evaporating and concentrating the lithium-containing wastewater to obtain a lithium-enriched solution; extracting the lithium-enriched solution with an organic phase (phosphate ester) to obtain a lithium-containing organic phase; stripping the lithium-containing organic phase to obtain a stripping solution; precipitating and removing impurities from the stripping solution to obtain a lithium chloride-containing solution; adding sodium carbonate to the lithium chloride-containing solution for precipitation reaction to obtain lithium carbonate. The lithium extraction rate of this method is greater than 94%, and the purity of lithium carbonate is greater than 99.50%. It can effectively recover lithium from industrial wastewater in the production of alumina from fly ash, expand the application scope of solvent extraction of lithium, and realize the effective separation of lithium and impurity aluminum. However, this method cannot avoid the co-extraction of aluminum ions, and can only further precipitate and remove impurities from the lithium stripping solution, which still requires the consumption of a large amount of precipitant.

[0008] In summary, the main problems with the current solvent extraction of lithium are: 1) The reported extractants are applicable to a narrow pH range of the feed solution, and most of them can only be applied to acidic or alkaline systems, and cannot take into account various complex lithium-containing solutions; 2) For low-concentration lithium-containing solutions, the enrichment effect is limited, and lithium enrichment by evaporation and concentration is still required; 3) It is impossible to effectively separate lithium and other impurity ions, and it is necessary to rely on neutralization precipitation and other methods to remove impurities in advance. Summary of the invention

[0009] In order to solve the above problems, the present invention aims to provide a method for full extraction purification, impurity removal and enrichment of lithium ions. According to the difference in extraction rate between lithium ions and impurity ions such as iron, aluminum, calcium, magnesium, sodium, potassium, etc., an extraction system consisting of the same organic extractant and a co-extractant is used, which can not only achieve effective separation of lithium and impurity ions, but also achieve efficient enrichment of low-concentration lithium in lithium-containing solutions.

[0010] In order to achieve this object, the present invention implements the above-mentioned object and method through the following technical solutions:

[0011] The method for extracting, purifying, removing impurities and enriching lithium in a lithium-containing aqueous solution comprises the following steps:

[0012] (1) The organic extractant and the co-extractant are mixed uniformly in a certain volume ratio and then dissolved in a diluent to obtain an extracted organic solution;

[0013] (2) saponifying the extracted organic solution obtained in step (1) with a sodium hydroxide aqueous solution having a concentration of 1 to 10 mol / L or a sodium acetate aqueous solution having a concentration of 1 to 6 mol / L to obtain a saponified organic extractant;

[0014] (3) pumping a lithium-containing aqueous solution into the water inlet of the upper side wall of the bubble supported oil film extractor, and then pumping the saponified organic extractant obtained in step (2) into the oil chamber of the bubble supported oil film extractor, and then spraying it out from the oil spray port of the bottom oil distributor of the bubble supported oil film extractor; at the same time, pumping nitrogen into the air inlet of the bottom end of the bubble supported oil film extractor, and then spraying it out from the air jet port of the bottom oil distributor; controlling the flow rate of the saponified organic extractant sprayed from the oil spray port of the bottom oil distributor of the bubble supported oil film extractor and the nitrogen sprayed from the air jet port to obtain "oil bubbles" containing bubbles and coated with the saponified organic extractant on the surface; the extractant-containing "oil bubbles" move from bottom to top, countercurrently contact with the lithium-containing aqueous solution pumped into the water inlet of the upper side wall of the bubble supported oil film extractor and moving from top to bottom, and then merge at the oil phase overflow port at the upper end of the bubble supported oil film extractor to obtain an impure organic phase; and the lithium-containing raffinate after impurity removal flows out from the water outlet at the lower end of the bubble supported oil film extractor;

[0015] (4) the lithium-containing raffinate after impurity removal flowing out of the water outlet at the lower end of the bubble supported oil film extractor in step (3) is pumped into the water inlet at the upper end side wall of the bubble supported oil film extractor in the next stage connected in series, and then the saponified organic extractant obtained in step (2) is pumped into the oil chamber of the bubble supported oil film extractor of this stage, and then sprayed out from the oil spray port of the bottom oil distributor of this stage; at the same time, nitrogen is pumped into the air inlet at the bottom end of the bubble supported oil film extractor, and then sprayed out from the air jet port of the bottom oil distributor; controlling the air inlet from the bubble supported oil film extractor to flow out of the oil chamber of the bubble supported oil film extractor; The saponified organic extractant sprayed from the oil spray port of the oil distributor at the bottom of the extractor and the nitrogen gas flow rate sprayed from the air jet port obtain "oil bubbles" containing bubbles and coated with the saponified organic extractant on the surface; the "oil bubbles" containing the extractant move from bottom to top, countercurrently contact with the lithium-containing raffinate pumped from the water inlet at the upper end side wall of the bubble-supported oil film extractor of this stage, and then merge at the oil phase overflow port at the upper end of the bubble-supported oil film extractor of this stage, to obtain a lithium-rich loaded organic phase; the raffinate flows out from the water outlet at the lower end of the bubble-supported oil film extractor of this stage;

[0016] (5) The impurity-containing organic phase obtained in step (3) is stirred and mixed with pure water or a 0.1-1 mol / L sulfuric acid aqueous solution or a 0.1-1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10-10:1 for washing, and after phase separation, a washed organic phase and a lithium-containing wash water are obtained; the lithium-containing wash water is combined with the lithium-containing raffinate flowing out of the water outlet at the lower end of the bubble-supported oil film extractor in step (3);

[0017] (6) The washed organic phase obtained in step (5) is mixed with a 0.1-6 mol / L sulfuric acid aqueous solution or a 0.1-8 mol / L hydrochloric acid aqueous solution or a 0.1-4 mol / L water-soluble ethylenediaminetetraacetic acid (EDTA) aqueous solution at a volume ratio of 1:1 to 10:1, and then stripped to obtain a blank stripping organic phase and an impurity-containing stripping solution after phase separation;

[0018] (7) The blank stripping organic phase obtained in step (6) is mixed with a 0.1-2 mol / L sodium hydroxide aqueous solution at a volume ratio of 1:10-10:1 and stirred for regeneration. The regenerated organic phase obtained after phase separation is returned to step (2) for re-saponification and recycling;

[0019] (8) The lithium-rich organic phase obtained in step (4) is stirred, mixed and washed with pure water or a 0.01 to 1 mol / L sulfuric acid aqueous solution or a 0.01 to 1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10 to 10:1, and after phase separation, a washed organic phase and washing water are obtained;

[0020] (9) The washed organic phase obtained in step (8) is mixed with 0.5 to 4 mol / L sulfuric acid aqueous solution or 0.1 to 6 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:1 to 10:1, and then stripped to obtain a lithium-rich stripping solution and a blank stripping organic phase after phase separation;

[0021] (10) The blank stripping organic phase obtained in step (9) is stirred, mixed and washed with pure water, and then stirred and mixed with 0.1 to 2 mol / L sodium hydroxide aqueous solution at a volume ratio of 1:10 to 10:1 for regeneration. The regenerated organic phase obtained after phase separation is returned to step (2) for re-saponification and recycling.

[0022] Further, according to a specific embodiment of the present invention, the lithium-containing aqueous solution in step (3) is a lithium-containing sulfuric acid, hydrochloric acid or nitric acid aqueous solution or a mixed salt solution containing sulfate, chloride and nitrate, or a lithium-containing alkaline aqueous solution with a pH in the range of 0.1 to 14. In the lithium-containing aqueous solution, the initial mass concentration of lithium is 0.05 to 5 g / L.

[0023] Further, according to a specific embodiment of the present invention, the organic extractant in step (1) is a β-diketone compound or an acidic phosphine compound or a mixture of the two in a certain volume ratio. The co-extractant is an amine compound or a neutral phosphine compound or a mixture of the two in a certain volume ratio. The diluent is kerosene or any one of alkanes with a carbon chain length of 6-12 carbons.

[0024] Preferably, when the organic extractant is a β-diketone compound, it is preferably any one or more selected from benzoyltrifluoroacetone (HBTA), 2-thenoyltrifluoroacetone (HTTA) and 1-heptyl-3-phenyl-1,3-propanedione (LIX 54).

[0025] Preferably, when the organic extractant is an acidic phosphine compound, it is preferably any one or more of di-(2-ethylhexyl)phosphoric acid (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), di-(2-ethylhexyl)phosphinic acid (P227), and di-(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272).

[0026] Preferably, when the synergist is an amine compound, it is preferably any one or more of trioctyldecyl tertiary amine (N235) and tri-n-octylamine (TOA).

[0027] Preferably, when the synergist is a neutral phosphine compound, it is preferably any one or more selected from trioctylphosphine oxide (TOPO), trialkylphosphine oxide (Cyanex 923), and tributyl phosphate (TBP).

[0028] Further, according to a specific embodiment of the present invention, when the organic extractant in step (1) is a mixture of a β-diketone compound and an acidic phosphine compound, the mixing volume ratio of the β-diketone compound to the acidic phosphine compound is 1:5 to 5:1.

[0029] Further, according to a specific embodiment of the present invention, the molar concentration of the organic extractant in the extraction organic solution in step (1) is 0.1-2 mol / L, and the saponification degree is 0-70%. Wherein, the saponification degree of the organic extractant in the extraction organic solution is controlled by the volume of the sodium hydroxide aqueous solution with a concentration of 1-10 mol / L or the sodium acetate aqueous solution with a concentration of 1-6 mol / L added in step (2). The extraction organic solution obtained in step (1) is mixed with a certain volume of sodium hydroxide aqueous solution with a concentration of 1-10 mol / L or sodium acetate aqueous solution with a concentration of 1-6 mol / L at room temperature for sufficient reaction to obtain a saponified organic extractant. Then, the mass percentage of the organic extractant that does not participate in the reaction in the saponified organic extractant obtained after the reaction, that is, the residual acid value of the organic phase, is determined by titration analysis.

[0030] Furthermore, according to a specific embodiment of the present invention, the molar concentration and saponification degree of the organic extractant in the saponified organic extractant used in step (3) may be the same as or different from the molar concentration and saponification degree of the organic extractant in the saponified organic extractant used in step (4).

[0031] Further, according to a specific embodiment of the present invention, when the synergistic extractant in step (1) is a mixture of an amine compound and a neutral phosphine compound, the mixing volume ratio of the amine compound to the neutral phosphine compound is 1:5 to 5:1.

[0032] Further, according to a specific embodiment of the present invention, the concentration of the co-extraction agent in the extraction organic solution in step (1) is 0.1-2 mol / L.

[0033] Furthermore, according to a specific embodiment of the present invention, the purpose of step (3) is to preferentially extract and remove high-valent metal ion impurities such as iron, aluminum, calcium, and magnesium in the lithium-containing aqueous solution, inhibit the co-extraction loss of lithium ions, and obtain a residual aqueous solution containing only low-valent cations such as lithium, sodium, and potassium; the purpose of step (4) is to selectively extract and enrich low-concentration lithium ions, inhibit the co-extraction of sodium and potassium impurity ions, and obtain a lithium-rich loaded organic phase.

[0034] Furthermore, according to a specific embodiment of the present invention, the purpose of saponifying the extracted organic solution obtained in step (1) with a sodium hydroxide aqueous solution having a concentration of 1 to 10 mol / L or a sodium acetate aqueous solution having a concentration of 1 to 6 mol / L in step (2) is that when the saponified organic extractant obtained in step (2) is used to perform the extraction and impurity removal in step (3), the saturated load capacity of impurity ions in the organic phase can be increased, and the co-extraction loss of lithium ions can be suppressed; when the saponified organic extractant obtained in step (2) is used to perform the extraction and enrichment of lithium in step (4), the saturated load capacity of lithium ions in the organic phase can be increased, and a higher lithium ion extraction enrichment ratio can be obtained.

[0035] Furthermore, according to a specific embodiment of the present invention, the purpose of saponifying the extracted organic solution obtained in step (1) with a sodium hydroxide aqueous solution having a concentration of 1 to 10 mol / L or a sodium acetate aqueous solution having a concentration of 1 to 6 mol / L in step (2) is that when the saponified organic extractant obtained in step (2) is used to perform the extraction and impurity removal in step (3), when the initial pH of the lithium-containing aqueous solution is in the acidic or neutral range, a neutral lithium-containing raffinate after impurity removal can be obtained, which is beneficial to the subsequent step (4) of extracting and enriching lithium; when the saponified organic extractant obtained in step (2) is used to perform the extraction and enrichment of lithium in step (4), when the initial pH of the lithium-containing raffinate after impurity removal is in the neutral range, low-concentration lithium ions can still be extracted and enriched to obtain a lithium-rich loaded organic phase.

[0036] Furthermore, according to a specific embodiment of the present invention, the lithium-containing aqueous solution in step (3) and the lithium-containing raffinate in step (4) are pumped into the water inlet on the upper side wall of the bubble-supported oil film extractor at a flow rate of 0.1 to 60 mL / min.

[0037] Further, according to a specific embodiment of the present invention, the saponified organic extractant in step (3) and step (4) is sprayed out from the bottom oil distributor nozzle of the bubble supported oil film extractor at a flow rate of 0.1 to 20 mL / min.

[0038] Furthermore, according to a specific embodiment of the present invention, the purpose of controlling the gas flow rate ejected from the bottom oil distributor nozzle of the bubble-supported oil film extractor in step (3) and step (4) is that when the saponified organic extractant is pumped into the oil chamber of the bubble-supported oil film extractor and then ejected from the bottom oil distributor nozzle of the bubble-supported oil film extractor, "oil bubbles" containing bubbles and coated with the saponified organic extractant on the surface can be obtained.

[0039] Further, according to a specific embodiment of the present invention, the flow rate of nitrogen gas ejected from the bottom oil distributor nozzle of the bubble-supported oil film extractor in step (3) and step (4) is 20 to 6000 mL / min. Preferably, the flow rate of nitrogen gas ejected from the bottom oil distributor nozzle of the bubble-supported oil film extractor is 1000 to 4000 mL / min.

[0040] Furthermore, according to a specific embodiment of the present invention, the aspect ratio of the bubble supported oil film extractor in step (3) and step (4) is 10:1 to 40:1.

[0041] Further, according to a specific embodiment of the present invention, the purpose of controlling the height-to-diameter ratio of the bubble-supported oil film extractor in step (3) and step (4) is to control the countercurrent flow contact time of the continuous water phase moving from top to bottom and the "oil bubble" dispersed phase moving from bottom to top in the bubble-supported oil film extractor. The height-to-diameter ratio of the bubble-supported oil film extractor used in step (3) may be the same as or different from the height-to-diameter ratio of the bubble-supported oil film extractor used in step (4). Preferably, the height-to-diameter ratio of the bubble-supported oil film extractor used in step (3) is 20:1 to 40:1; the height-to-diameter ratio of the bubble-supported oil film extractor used in step (4) is 10:1 to 30:1.

[0042] Further, according to a specific embodiment of the present invention, the bubble-supported oil film extractors in step (3) and step (4) can be used alone or in multiple stages in series. Wherein, when the bubble-supported oil film extractors in step (3) are used in multiple stages in series, the purpose is to control the concentration of impurity ions in the lithium-containing raffinate flowing out from the lower water outlet of the bubble-supported oil film extractor after impurity removal, and to remove high-valent impurity metal ions such as iron, aluminum, calcium, and magnesium that coexist with lithium ions in the lithium-containing raffinate as much as possible, so as to obtain a raffinate aqueous solution containing only low-valent cations such as lithium, sodium, and potassium; when the bubble-supported oil film extractors in step (4) are used in multiple stages in series, the purpose is to control the concentration of residual lithium ions in the raffinate flowing out from the lower water outlet of the bubble-supported oil film extractor, so as to obtain a higher lithium extraction yield, and at the same time control the concentration of sodium and potassium ions in the lithium-rich loaded organic phase, elute the co-extracted sodium and potassium impurity ions, and facilitate the subsequent stripping to obtain a high-purity lithium stripping solution.

[0043] Furthermore, according to a specific embodiment of the present invention, in step (5), the impure organic phase is stirred and mixed with pure water or a 0.1-1 mol / L sulfuric acid aqueous solution or a 0.1-1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10-10:1 for washing, the purpose of which is to elute the co-extracted lithium ions in the impure organic phase and reduce the co-extraction loss rate of lithium ions; the obtained lithium-containing wash water is combined with the lithium-containing raffinate flowing out of the lower end water outlet of the bubble-supported oil film extractor in step (3), the purpose of which is to incorporate the eluted lithium ions into the subsequent lithium extraction stage to improve the lithium extraction yield.

[0044] Furthermore, according to a specific embodiment of the present invention, in step (8), the lithium-rich loaded organic phase is stirred and mixed with pure water or 0.01-1 mol / L sulfuric acid aqueous solution or 0.01-1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10 to 10:1 for washing, the purpose of which is to elute the monovalent cations such as sodium and potassium co-extracted in the lithium-rich loaded organic phase to obtain a loaded organic phase containing only lithium ions, so as to improve the lithium purity in the lithium-rich stripping solution obtained in step (9).

[0045] The principle of the method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution described in the present invention is that when a β-diketone compound or an acidic phosphine compound is used as an organic extractant, an amine compound or a neutral phosphine compound is used as a co-extractant, and a co-extractant system is formed with the organic extractant to treat a lithium-containing aqueous solution with a pH in the range of 0.1 to 14, the saponified organic extractant extracts high-valent metal impurity ions such as iron, aluminum, calcium, and magnesium that coexist with lithium ions by a cation exchange mechanism. When a bubble-supported oil film extractor is used, on the one hand, the "oil bubble" coated with the saponified organic extractant on the surface moves from bottom to top and countercurrently contacts with the lithium-containing aqueous solution moving from top to bottom in the bubble-supported oil film extractor. Since the extraction rate of high-valent impurity metal ions such as iron, aluminum, calcium, and magnesium that coexist with lithium ions is faster than that of lithium ions, these impurity ions can be preferentially extracted and removed, and due to the interface effect of the oil film extraction on the bubble surface, the difference in extraction rate between lithium ions and coexisting impurity ions is amplified, which is conducive to efficient extraction and impurity removal. On the other hand, even if lithium ions co-extract from the organic extractant "oil bubbles" moving from bottom to top, the exchange capacity of high-valent impurity metal ions such as iron, aluminum, calcium, and magnesium is greater than that of lithium ions. Under the flushing and washing action of the lithium-containing aqueous solution moving from top to bottom, the lithium ions co-extracted from the surface of the "oil bubbles" will be eluted back to the aqueous phase during the upward process, thereby suppressing the loss of lithium ion co-extraction. Therefore, when a bubble-supported oil film extractor is used, by controlling appropriate operating conditions, water phase flow rate, and the height-to-diameter ratio of the bubble-supported oil film extractor, the effective separation of lithium and high-valent impurity metal ions such as iron, aluminum, calcium, and magnesium in a multi-component complex lithium-containing solution can be achieved, and a residual aqueous solution containing only low-valent cations such as lithium, sodium, and potassium can be obtained. When the lithium-containing raffinate after extraction and impurity removal is pumped into the next-stage bubble-supported oil film extractor in series, since the solution only contains low-valent cations such as lithium, sodium, and potassium, the organic extractant also extracts low-valent cations such as lithium, sodium, and potassium by the cation exchange mechanism. However, since the extraction rate of lithium ions is faster than that of impurity ions such as sodium and potassium, the same organic extractant and co-extractant system can be used to selectively extract lithium first and elute the co-extracted sodium and potassium impurity ions without changing the extractant. On the other hand, the bubble-supported oil film extraction and enrichment of lithium can utilize the extremely small volume of organic extractant coated on the surface of the bubble to achieve ultra-large ratio extraction and enrichment, which is conducive to the efficient dispersion of small volume organic extractants, prevent emulsification, improve the utilization rate of organic extractants, and achieve high enrichment ratio extraction and enrichment of lithium.

[0046] Compared with other disclosed technical solutions, the present invention has the following beneficial effects:

[0047] 1) The present invention adopts a bubble-supported oil film extractor, utilizes the difference in extraction rate between lithium ions and coexisting impurity ions, and adopts an extraction system consisting of the same organic extractant and a synergistic extractant, which can not only realize the effective separation of lithium and impurity ions in a multi-component complex lithium-containing solution, but also realize the efficient enrichment of low-concentration lithium.

[0048] 2) The pH range of the lithium-containing aqueous solution applicable to the present invention is wide, and it is applicable not only to lithium-containing sulfuric acid, hydrochloric acid or nitric acid aqueous solutions, but also to neutral salt water solutions containing sulfate, chloride and nitrate, and also to lithium-containing alkaline aqueous solutions.

[0049] 3) The process of the present invention is simple, the separation efficiency is high, and continuous operation can be easily realized. It can significantly shorten the process flow of extracting and enriching lithium in the existing multi-component complex solution. It can not only be used to replace the current neutralization precipitation impurity removal process to realize the full extraction method for impurity removal and enrichment and extraction of lithium, but also can be used to replace the current evaporation concentration and enrichment process of lithium. After bubble-supported oil film extraction and stripping, low-concentration lithium can be efficiently enriched. The concentration of lithium ions in the obtained stripping solution can meet the feed requirements of the subsequent precipitation of lithium carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a process flow chart of the present invention;

[0051] Figure 2 A schematic structural diagram of a bubble-supported oil film extractor according to a preferred embodiment is shown.

[0052] in,

[0053] 1-gas phase outlet; 2-organic phase overflow outlet; 3-water phase inlet; 4-oil distributor nozzle; 5-oil chamber; 6-organic phase inlet; 7-gas phase inlet; 8-water phase outlet; 9-water phase distributor; 10-organic phase demulsifier

[0054] Figure 3 The present invention is a schematic structural diagram of a bottom oil distributor nozzle of a bubble-supported oil film extractor according to a preferred embodiment.

[0055] in,

[0056] 11-internal jet pipe; 12-fuel injection pipe sleeved outside the jet pipe; 13-jet port; 14-fuel injection port DETAILED DESCRIPTION

[0057] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0058] Embodiment 1:

[0059] (1) Saponification of organic phase

[0060] Weigh 8.5 g of benzoyltrifluoroacetone (HBTA) solid and dissolve it in 100 mL of kerosene, then add 15 mL of tributyl phosphate (TBP) and stir to obtain an unsaponified organic phase. Mix 30 mL of 1.0 mol / L sodium acetate aqueous solution with the organic phase and stir for 3 hours, then separate the phases in a separatory funnel to obtain a saponified organic phase.

[0061] (2) Bubble-supported oil film extraction and impurity removal

[0062] The height-to-diameter ratio of the bubble-supported oil film extractor is 20:1, and two stages are used in series. The sulfuric acid leachate after oxidation roasting of lithium ore with an initial lithium mass concentration of 0.05 g / L and a pH of 0.1 is pumped into the upper side wall water inlet of the first-stage bubble-supported oil film extractor, and the raffinate flowing out from the lower end water outlet of the first-stage bubble-supported oil film extractor is pumped into the upper side wall water inlet of the second-stage bubble-supported oil film extractor; nitrogen is pumped into the air inlet at the bottom end of the two-stage bubble-supported oil film extractor at a flow rate of 40 mL / min and sprayed out from the jet port; the lithium ore leachate is continuously pumped into the water phase inlet at the top of the first-stage bubble-supported oil film extractor at a flow rate of 0.1 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the water phase inlet at a flow rate of 1 The organic phase was pumped into the two-stage bubble-supported oil film extractor from the bottom inlet at a flow rate of mL / min, sprayed out from the oil spray port to form an oil film wrapped around the bubble surface, rising with the bubbles in the extraction column, and then bursting at the top of the extraction column and flowing out through the oil phase overflow port, and the impure organic phase was collected at the oil phase overflow port.

[0063] The impurity-containing organic phase and 1 mol / L hydrochloric acid solution were mixed and stirred at a volume ratio of 10:1 for 10 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions was incorporated into the lithium-containing raffinate;

[0064] Further, the washed impurity-containing organic phase was contacted with 8 mol / L hydrochloric acid solution at a volume ratio of 10:1, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0065] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 1:10;

[0066] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0067] (3) Bubble-supported oil film extraction and enrichment of lithium

[0068] The height-to-diameter ratio of the bubble-supported oil film extractor is 10:1, and it is used in a single stage. The lithium-containing raffinate flowing out from the bottom of the second-stage bubble-supported oil film extractor in (2) is pumped into the third-stage bubble-supported oil film extractor connected in series therewith. Similarly, nitrogen is pumped in from the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 20 mL / min and sprayed out from the jet port; the lithium-containing raffinate is continuously pumped in from the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 1 mL / min; at the same time, the saponified organic phase in step (1) is pumped in from the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 0.1 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then ruptured at the top of the extractor and flowed out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0069] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0070] (4) Washing

[0071] The lithium-rich organic phase was mixed with a 0.01 mol / L hydrochloric acid solution at a volume ratio of 1:10 and stirred for washing for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0072] (5) Stripping

[0073] The washed lithium-rich organic phase was contacted with a 6 mol / L hydrochloric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0074] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be 270 times to 13.5 g / L.

[0075] (6) Organic phase regeneration

[0076] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 10:1;

[0077] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0078] Embodiment 2:

[0079] (1) Saponification of organic phase

[0080] Measure 20 mL of di-(2-ethylhexyl)phosphoric acid (P204), 30 mL of trioctyldecyl tertiary amine (N235), and 50 mL of kerosene solution, stir and mix them evenly to obtain the unsaponified organic phase. Mix 2 mL of 10.0 mol / L NaOH with the organic phase and stir until a uniform and stable organic phase is obtained, which is the saponified organic phase.

[0081] (2) Bubble-supported oil film extraction and impurity removal

[0082] The height-to-diameter ratio of the bubble-supported oil film extractor is 30:1, and it is used in a single stage. A lithium ore hydrochloric acid leachate with an initial lithium mass concentration of 1.0 g / L and a pH of 0.5 is pumped into the water inlet of the upper side wall of the bubble-supported oil film extractor, and then nitrogen is pumped in from the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 60 mL / min and sprayed out from the jet port; the lithium ore leachate is continuously pumped in from the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 2 mL / min; at the same time, the saponified organic phase in step (1) is pumped in from the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 10 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the impurity-containing organic phase is collected at the oil phase overflow port.

[0083] The impurity-containing organic phase was mixed with a 0.1 mol / L sulfuric acid solution at a volume ratio of 1:10 and stirred for 20 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions was incorporated into the lithium-containing raffinate;

[0084] Further, the washed impurity-containing organic phase was contacted with a 4 mol / L water-soluble ethylenediaminetetraacetic acid (EDTA) aqueous solution at a volume ratio of 10:1, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0085] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 1 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0086] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0087] (3) Bubble-supported oil film extraction and enrichment of lithium

[0088] The height-to-diameter ratio of the bubble-supported oil film extractor is 20:1, and two stages are connected in series. The lithium-containing raffinate flowing out of the lower end of the bubble-supported oil film extractor in (2) is pumped into the first-stage bubble-supported oil film extractor connected in series, and then flows out from the bottom end of the second-stage bubble-supported oil film extractor. Similarly, nitrogen is pumped into the air inlet at the bottom end of the two-stage bubble-supported oil film extractor at a flow rate of 100 mL / min and sprayed out from the jet port; the lithium-containing raffinate is continuously pumped into the water phase inlet at the top end of the first-stage bubble-supported oil film extractor at a flow rate of 1 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom end of the two-stage bubble-supported oil film extractor at a flow rate of 1 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top end of the extraction column and flowing out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0089] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0090] (4) Washing

[0091] The lithium-rich organic phase was mixed with 0.01 mol / L sulfuric acid at a volume ratio of 1:10 and stirred for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0092] (5) Stripping

[0093] The washed lithium-rich organic phase was contacted with a 4 mol / L sulfuric acid solution at a volume ratio of 10:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0094] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be approximately 41 times to 40.8 g / L.

[0095] (6) Organic phase regeneration

[0096] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 2 mol / L sodium hydroxide solution at a volume ratio of 10:1;

[0097] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0098] Embodiment 3:

[0099] (1) Saponification of organic phase

[0100] Measure 10 mL of di-(2-ethylhexyl)phosphinic acid (P227), 10 mL of 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), 30 mL of trioctyldecyl tertiary amine (N235), and 50 mL of kerosene solution, stir and mix evenly to obtain an unsaponified organic phase. Mix 2 mL of 10.0 mol / L NaOH with the organic phase and stir until a uniform and stable organic phase is obtained, which is the saponified organic phase.

[0101] (2) Bubble-supported oil film extraction and impurity removal

[0102] The height-to-diameter ratio of the bubble-supported oil film extractor is 40:1, and it is used in a single stage. The nitric acid leachate of the cathode material of the waste lithium battery with an initial lithium mass concentration of 3.0 g / L and pH=1, after extracting nickel and cobalt, is pumped into the water inlet of the upper side wall of the bubble-supported oil film extractor, and then nitrogen is pumped into the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 200 mL / min and sprayed out from the jet port; the nitric acid leachate of the cathode material is continuously pumped into the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 2 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 20 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the impurity-containing organic phase is collected at the oil phase overflow port.

[0103] The impurity-containing organic phase and pure water are mixed and stirred at a volume ratio of 1:10 for 20 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions is incorporated into the lithium-containing raffinate;

[0104] Further, the washed impurity-containing organic phase was contacted with a 0.1 mol / L aqueous solution of water-soluble ethylenediaminetetraacetic acid (EDTA) at a volume ratio of 1:1, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0105] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 2 mol / L sodium hydroxide solution at a volume ratio of 10:1;

[0106] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0107] (3) Bubble-supported oil film extraction and enrichment of lithium

[0108] The height-to-diameter ratio of the bubble-supported oil film extractor is 30:1, and it is used in a single stage. The lithium-containing raffinate flowing out from the bottom of the bubble-supported oil film extractor in (2) is pumped into the next-stage bubble-supported oil film extractor connected in series. Similarly, nitrogen is pumped into the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 200 mL / min and sprayed out from the jet port; the lithium-containing raffinate is continuously pumped into the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 1 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 0.5 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then ruptured at the top of the extractor at this stage and flowed out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0109] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0110] (4) Washing

[0111] The lithium-rich organic phase was mixed with 1 mol / L sulfuric acid at a volume ratio of 10:1 and stirred for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0112] (5) Stripping

[0113] The washed lithium-rich organic phase was contacted with a 0.5 mol / L sulfuric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0114] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be about 10 times to 28.8 g / L.

[0115] (6) Organic phase regeneration

[0116] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 1 mol / L sodium hydroxide solution at a volume ratio of 1:10;

[0117] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0118] Embodiment 4:

[0119] (1) Saponification of organic phase

[0120] Measure 10 mL of 1-heptyl-3-phenyl-1,3-propanedione (LIX 54), 10 mL of di-(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272), 27 g of trioctylphosphine oxide (TOPO), and 50 mL of n-octane solution, stir and mix evenly to obtain an unsaponified organic phase. Mix 5 mL of 5.0 mol / L NaOH with the organic phase and stir until a uniform and stable organic phase is obtained, which is the saponified organic phase.

[0121] (2) Bubble-supported oil film extraction and impurity removal

[0122] The height-to-diameter ratio of the bubble-supported oil film extractor is 36:1, and two stages are connected in series. The sulfuric acid leachate of the waste lithium battery positive electrode material with an initial lithium mass concentration of 5.0 g / L and pH = 4 is pumped into the upper side wall water inlet of the first-stage bubble-supported oil film extractor, and the raffinate flowing out from the lower end water outlet of the first-stage bubble-supported oil film extractor is pumped into the upper side wall water inlet of the second-stage bubble-supported oil film extractor; nitrogen is pumped into the air inlet at the bottom of the two-stage bubble-supported oil film extractor at a flow rate of 1000 mL / min, and sprayed out from the jet nozzle; The sulfuric acid leaching solution of the positive electrode material is continuously pumped into the water phase inlet at the top of the first-stage bubble-supported oil film extractor at a flow rate of mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the two-stage bubble-supported oil film extractor at a flow rate of 10 mL / min, sprayed out from the oil spray port to form an oil film wrapped on the bubble surface, rising with the bubble in the extraction column, and then bursting at the top of the extraction column and flowing out through the oil phase overflow port, and the impure organic phase is collected at the oil phase overflow port.

[0123] The impurity-containing organic phase and 1 mol / L sulfuric acid solution were mixed and stirred at a volume ratio of 1:1 for 20 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions was incorporated into the lithium-containing raffinate;

[0124] Further, the washed impurity-containing organic phase was contacted with a 6 mol / L sulfuric acid solution at a volume ratio of 1:1, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0125] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.5 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0126] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0127] (3) Bubble-supported oil film extraction and enrichment of lithium

[0128] The height-to-diameter ratio of the bubble-supported oil film extractor is 12:1, and two stages are connected in series. The lithium-containing raffinate flowing out of the lower end of the second-stage bubble-supported oil film extractor in (2) is pumped into the third-stage bubble-supported oil film extractor connected in series therewith, and then flows out from the fourth-stage bubble-supported oil film extractor connected in series; similarly, nitrogen is pumped into the air inlet at the bottom of the third and fourth bubble-supported oil film extractors at a flow rate of 2000 mL / min, respectively, and sprayed out from the jet port; the lithium-containing raffinate is continuously pumped into the water phase inlet at the top of the third-stage bubble-supported oil film extractor at a flow rate of 50 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the third and fourth bubble-supported oil film extractors at a flow rate of 10 mL / min, respectively, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0129] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0130] (4) Washing

[0131] The lithium-rich organic phase was mixed with 1 mol / L hydrochloric acid at a volume ratio of 5:1 and stirred for washing for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0132] (5) Stripping

[0133] The washed lithium-rich organic phase was contacted with a 0.1 mol / L hydrochloric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0134] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be about 6 times to 31.2 g / L.

[0135] (6) Organic phase regeneration

[0136] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 2 mol / L sodium hydroxide solution at a volume ratio of 1:5;

[0137] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0138] Embodiment 5:

[0139] (1) Saponification of organic phase

[0140] Measure 20 mL of 1-heptyl-3-phenyl-1,3-propanedione (LIX 54), 30 mL of tri-n-octylamine (TOA), and 50 mL of n-hexane solution, stir and mix evenly to obtain an unsaponified organic phase. Mix 5 mL of 5.0 mol / L NaOH with the organic phase and stir until a uniform and stable organic phase is obtained, which is the saponified organic phase.

[0141] (2) Bubble-supported oil film extraction and impurity removal

[0142] The height-to-diameter ratio of the bubble-supported oil film extractor is 40:1, and it is used in a single stage. A neutral water leaching solution of lithium sulfate roasted with an initial lithium mass concentration of 0.1 g / L and a pH of 6 is pumped into the water inlet of the upper side wall of the bubble-supported oil film extractor, and then nitrogen is pumped into the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 2000 mL / min and sprayed out from the jet port; the lithium ore leaching solution is continuously pumped into the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 60 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 20 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the impurity-containing organic phase is collected at the oil phase overflow port.

[0143] The impurity-containing organic phase was mixed with a 0.1 mol / L sulfuric acid solution at a volume ratio of 1:10 and stirred for 20 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions was incorporated into the lithium-containing raffinate;

[0144] Further, the washed impurity-containing organic phase was contacted with a 0.1 mol / L sulfuric acid solution at a volume ratio of 1:10, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0145] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 1 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0146] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0147] (3) Bubble-supported oil film extraction and enrichment of lithium

[0148] The height-to-diameter ratio of the bubble-supported oil film extractor is 10:1, and it is used in a single stage. The lithium-containing raffinate flowing out from the bottom of the bubble-supported oil film extractor in (2) is pumped into the next-stage bubble-supported oil film extractor connected in series; similarly, nitrogen is pumped in from the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 4000 mL / min and ejected from the jet port; the lithium-containing raffinate is continuously pumped in from the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 60 mL / min; at the same time, the saponified organic phase in step (1) is pumped in from the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 1 mL / min, ejected from the oil jet port and forms an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0149] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0150] (4) Washing

[0151] The lithium-rich organic phase was mixed with 1 mol / L hydrochloric acid in a 1:1 volume ratio and stirred for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0152] (5) Stripping

[0153] The washed lithium-rich organic phase was contacted with a 4 mol / L sulfuric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0154] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be about 420 times to 42.1 g / L.

[0155] (6) Organic phase regeneration

[0156] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.5 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0157] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0158] Embodiment 6:

[0159] (1) Saponification of organic phase

[0160] Weigh 30 g of 2-thiophenecarbonyltrifluoroacetone (HTTA) solid and dissolve it in 100 mL of kerosene, then add 50 mL of tributyl phosphate (TBP) and stir to obtain an unsaponified organic phase. Mix 60 mL of 1.0 mol / L NaOH with the organic phase and stir for 3 hours, then separate the phases in a separatory funnel to obtain a saponified organic phase.

[0161] (2) Bubble-supported oil film extraction and impurity removal

[0162] The height-to-diameter ratio of the bubble-supported oil film extractor is 30:1, and it is used in a single stage. The lithium ore sulfuric acid leachate with an initial lithium mass concentration of 2.0 g / L and pH=14 is purified and impurities are removed, evaporated and concentrated, and then the carbon precipitation mother liquor of lithium carbonate is precipitated by sodium carbonate and pumped into the water inlet of the upper side wall of the bubble-supported oil film extractor, and then nitrogen is pumped into the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 6000 mL / min and sprayed out from the jet port; the lithium precipitation mother liquor is continuously pumped into the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 30 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 20 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped on the surface of the bubble, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the impurity-containing organic phase is collected at the oil phase overflow port.

[0163] The impurity-containing organic phase and 0.1 mol / L hydrochloric acid solution were mixed and stirred at a volume ratio of 1:1 for 20 minutes to wash away the co-extracted lithium, and the washing water containing lithium ions was incorporated into the lithium-containing raffinate;

[0164] Further, the washed impurity-containing organic phase was contacted with a 0.1 mol / L hydrochloric acid solution at a volume ratio of 1:10, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0165] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0166] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0167] (3) Bubble-supported oil film extraction and enrichment of lithium

[0168] The height-to-diameter ratio of the bubble-supported oil film extractor is 15:1, and it is used in a single stage. The lithium-containing raffinate flowing out from the bottom of the bubble-supported oil film extractor in (2) is pumped into the next-stage bubble-supported oil film extractor connected in series; similarly, nitrogen is pumped in from the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 6000 mL / min and sprayed out from the jet port; the lithium-containing raffinate is continuously pumped in from the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 3 mL / min; at the same time, the saponified organic phase in step (1) is pumped in from the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 0.5 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0169] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0170] (4) Washing

[0171] The lithium-rich organic phase was mixed with pure water at a volume ratio of 1:10 and stirred for washing for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0172] (5) Stripping

[0173] The washed lithium-rich organic phase was contacted with a 4 mol / L sulfuric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0174] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be about 16 times to 33.5 g / L.

[0175] (6) Organic phase regeneration

[0176] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 1:10;

[0177] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0178] Embodiment 7:

[0179] (1) Saponification of organic phase

[0180] Weigh 30 g of benzoyltrifluoroacetone (HBTA) solid and dissolve it in 100 mL of n-dodecane, then add 25 mL of trioctyldecyl tertiary amine (N235) and 25 mL of trialkylphosphine oxide (Cyanex 923), stir and mix evenly to obtain an unsaponified organic phase. Mix 60 mL of 6.0 mol / L sodium acetate aqueous solution with the organic phase and stir for 3 hours, then separate the phases in a separatory funnel to obtain a saponified organic phase.

[0181] (2) Bubble-supported oil film extraction and impurity removal

[0182] The height-to-diameter ratio of the bubble-supported oil film extractor is 25:1, and it is used in a single stage. The purified liquid of the lithium ore sulfuric acid leachate with an initial lithium mass concentration of 1.5 g / L and a pH of 12 after neutralization, precipitation and impurity removal is pumped into the water inlet of the upper side wall of the bubble-supported oil film extractor, and then nitrogen is pumped into the air inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 100 mL / min and sprayed out from the jet port; the purified liquid is continuously pumped into the water phase inlet at the top of the bubble-supported oil film extractor at a flow rate of 0.1 mL / min; at the same time, the saponified organic phase in step (1) is pumped into the organic phase inlet at the bottom of the bubble-supported oil film extractor at a flow rate of 0.1 mL / min, sprayed out from the oil jet port and formed into an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top of the extraction column and flowing out through the oil phase overflow port, and the impurity-containing organic phase is collected at the oil phase overflow port.

[0183] The impurity-containing organic phase was mixed with 0.5 mol / L sulfuric acid solution at a volume ratio of 1:5 and stirred for washing for 20 minutes to wash away the co-extracted lithium;

[0184] Further, the washed impurity-containing organic phase was contacted with a 4 mol / L sulfuric acid solution at a volume ratio of 1:1, and stirred for stripping for 30 minutes to obtain a blank organic phase;

[0185] Furthermore, the blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0186] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0187] (3) Bubble-supported oil film extraction and enrichment of lithium

[0188] The height-to-diameter ratio of the bubble-supported oil film extractor is 25:1, and it is used in a single stage. The lithium-containing raffinate flowing out of the bottom end of the bubble-supported oil film extractor in (2) is pumped into the next-stage bubble-supported oil film extractor connected in series; similarly, nitrogen is pumped in from the air inlet at the bottom end of the bubble-supported oil film extractor at a flow rate of 200 mL / min and ejected from the jet port; the lithium-containing raffinate is continuously pumped in from the water phase inlet at the top end of the bubble-supported oil film extractor at a flow rate of 30 mL / min; at the same time, the saponified organic phase in step (1) is pumped in from the organic phase inlet at the bottom end of the bubble-supported oil film extractor at a flow rate of 20 mL / min, ejected from the oil jet port and forms an oil film wrapped around the bubble surface, rising with the bubble in the extraction column, and then breaking at the top end of the extraction column and flowing out through the oil phase overflow port, and the lithium-rich organic phase is collected at the oil phase overflow port.

[0189] Detection of Li in the raffinate + Ion content, calculated Li + The extraction rate of ions is 99.9%;

[0190] (4) Washing

[0191] The lithium-rich organic phase was mixed with 1 mol / L stream acid at a volume ratio of 10:1 and stirred for 10 minutes to wash away the co-extracted sodium and potassium ions.

[0192] (5) Stripping

[0193] The washed lithium-rich organic phase was contacted with a 4 mol / L sulfuric acid solution at a volume ratio of 1:1, and stripped with stirring for 30 minutes to obtain a blank organic phase and a lithium-rich stripping solution;

[0194] The lithium-rich stripping solution was tested and the lithium enrichment factor was calculated to be about 30 times to 45.8 g / L.

[0195] (6) Organic phase regeneration

[0196] The blank organic phase was washed with pure water until the aqueous phase was nearly neutral, and then regenerated with 0.1 mol / L sodium hydroxide solution at a volume ratio of 1:1;

[0197] Furthermore, the regenerated organic phase is re-saponified according to step (1) and then recycled.

[0198] The present invention has been described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and implementation methods of the present invention, all of which fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution, It is characterized in that The method comprises the following steps: (1) The organic extractant and the co-extractant are mixed uniformly in a certain volume ratio and then dissolved in a diluent to obtain an extracted organic solution; (2) saponifying the extracted organic solution obtained in step (1) with a sodium hydroxide aqueous solution having a concentration of 1 to 10 mol / L or a sodium acetate aqueous solution having a concentration of 1 to 6 mol / L to obtain a saponified organic extractant; (3) pumping a lithium-containing aqueous solution into the water inlet of the upper side wall of the bubble supported oil film extractor, then pumping the saponified organic extractant obtained in step (2) into the oil chamber of the bubble supported oil film extractor, and then spraying it out from the oil spray port of the bottom oil distributor of the bubble supported oil film extractor; at the same time, pumping nitrogen into the air inlet of the bottom end of the bubble supported oil film extractor, and then spraying it out from the air jet port of the bottom oil distributor; controlling the flow rate of the saponified organic extractant sprayed from the oil spray port of the bottom oil distributor of the bubble supported oil film extractor and the nitrogen sprayed from the air jet port to obtain "oil bubbles" containing bubbles and coated with the saponified organic extractant on the surface; the extractant-containing "oil bubbles" move from bottom to top, countercurrently contact with the lithium-containing aqueous solution pumped into the water inlet of the upper side wall of the bubble supported oil film extractor and moving from top to bottom, and then merge at the oil phase overflow port at the upper end of the bubble supported oil film extractor to obtain an impure organic phase; and the lithium-containing raffinate after impurity removal flows out from the water outlet at the lower end of the bubble supported oil film extractor; (4) the lithium-containing raffinate after impurity removal flowing out of the water outlet at the lower end of the bubble supported oil film extractor in step (3) is pumped into the water inlet at the upper end side wall of the bubble supported oil film extractor in the next stage connected in series, and then the saponified organic extractant obtained in step (2) is pumped into the oil chamber of the bubble supported oil film extractor of this stage, and then sprayed out from the oil spray port of the bottom oil distributor of this stage; at the same time, nitrogen is pumped into the air inlet at the bottom end of the bubble supported oil film extractor, and then sprayed out from the air jet port of the bottom oil distributor; controlling the air inlet from the bubble supported oil film extractor to flow out of the oil chamber of the bubble supported oil film extractor; The saponified organic extractant sprayed from the oil spray port of the oil distributor at the bottom of the extractor and the nitrogen gas flow rate sprayed from the air jet port obtain "oil bubbles" containing bubbles and coated with the saponified organic extractant on the surface; the "oil bubbles" containing the extractant move from bottom to top, countercurrently contact with the lithium-containing raffinate pumped from the water inlet at the upper end side wall of the bubble-supported oil film extractor of this stage, and then merge at the oil phase overflow port at the upper end of the bubble-supported oil film extractor of this stage, to obtain a lithium-rich loaded organic phase; the raffinate flows out from the water outlet at the lower end of the bubble-supported oil film extractor of this stage; (5) The impurity-containing organic phase obtained in step (3) is mixed with pure water or a 0.1-1 mol / L sulfuric acid aqueous solution or a 0.1-1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10-10:1 by stirring and washing, and after phase separation, a washed organic phase and a lithium-containing wash water are obtained; the lithium-containing wash water is combined with the lithium-containing raffinate flowing out of the water outlet at the lower end of the bubble-supported oil film extractor in step (3); (6) The washed organic phase obtained in step (5) is mixed with a 0.1-6 mol / L sulfuric acid aqueous solution or a 0.1-8 mol / L hydrochloric acid aqueous solution or a 0.1-4 mol / L water-soluble ethylenediaminetetraacetic acid (EDTA) aqueous solution at a volume ratio of 1:1 to 10:1, and then stripped to obtain a blank stripping organic phase and an impurity-containing stripping solution after phase separation; (7) The blank stripping organic phase obtained in step (6) is mixed with a 0.1-2 mol / L sodium hydroxide aqueous solution at a volume ratio of 1:10-10:1 and stirred for regeneration. The regenerated organic phase obtained after phase separation is returned to step (2) for re-saponification and recycling; (8) The lithium-rich organic phase obtained in step (4) is stirred and mixed with pure water or a 0.01 to 1 mol / L sulfuric acid aqueous solution or a 0.01 to 1 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:10 to 10:1 for washing, and after phase separation, a washed organic phase and washing water are obtained; (9) The washed organic phase obtained in step (8) is mixed with 0.5 to 4 mol / L sulfuric acid aqueous solution or 0.1 to 6 mol / L hydrochloric acid aqueous solution at a volume ratio of 1:1 to 10:1, and then stripped to obtain a lithium-rich stripping solution and a blank stripping organic phase after phase separation; (10) The blank stripping organic phase obtained in step (9) is stirred, mixed and washed with pure water, and then stirred and mixed with 0.1 to 2 mol / L sodium hydroxide aqueous solution at a volume ratio of 1:10 to 10:1 for regeneration. The regenerated organic phase obtained after phase separation is returned to step (2) for re-saponification and recycling.

2. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The lithium-containing aqueous solution in step (3) is a lithium-containing sulfuric acid, hydrochloric acid or nitric acid aqueous solution with a pH in the range of 0.1 to 14, or a mixed salt solution containing sulfate, chloride and nitrate, or a lithium-containing alkaline aqueous solution; the initial mass concentration of lithium in the lithium-containing aqueous solution is 0.05 to 5 g / L.

3. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The organic extractant in step (1) is a β-diketone compound or an acidic phosphine compound or a mixture of the two in a certain volume ratio, the concentration of the organic extractant in the extraction organic solution is 0.1-2 mol / L, and the saponification degree is 0-70%; the synergistic extractant is an amine compound or a neutral phosphine compound or a mixture of the two in a certain volume ratio, the concentration of the synergistic extractant in the extraction organic solution is 0.1-2 mol / L; the diluent is kerosene or any one of alkanes with a carbon chain length of 6-12 carbons.

4. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1 or 3, It is characterized in that The organic extractant β-diketone compound is selected from any one or more of benzoyltrifluoroacetone (HBTA), 2-thenoyltrifluoroacetone (HTTA) and 1-heptyl-3-phenyl-1,3-propanedione (LIX 54); the organic extractant acidic phosphine compound is selected from any one or more of di-(2-ethylhexyl) phosphoric acid (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), di-(2-ethylhexyl) phosphinic acid (P227), di-(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272); the synergist amine compound is selected from any one or more of trioctyldecyl tertiary amine (N235) and tri-n-octylamine (TOA); the synergist neutral phosphine compound is selected from trioctylphosphine oxide (TOPO), trialkylphosphine oxide (Cyanex 923), tributyl phosphate (TBP) Any one or two or more of the following.

5. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The lithium-containing aqueous solution in step (3) and the lithium-containing raffinate in step (4) are pumped into the water inlet on the upper side wall of the bubble-supported oil film extractor at a flow rate of 0.1 to 60 mL / min.

6. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The saponified organic extractant in step (3) and step (4) is sprayed from the oil spray port of the bottom oil distributor of the bubble supported oil film extractor at a flow rate of 0.1 to 20 mL / min.

7. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that In step (3) and step (4), the nitrogen flow rate ejected from the bottom oil distributor nozzle of the bubble-supported oil film extractor is 20 to 6000 mL / min.

8. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The height-to-diameter ratio of the bubble-supported oil film extractor in step (3) and step (4) is 10:1 to 40:

1.

9. A method for extracting, purifying, removing impurities and enriching lithium from a lithium-containing aqueous solution as claimed in claim 1, It is characterized in that The bubble-supported oil film extractors in step (3) and step (4) can be used alone or in multiple stages in series.

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