A multi-component lithium-strengthening extraction cycle system and method of use thereof

Abstract

This invention belongs to the fields of extraction chemistry and chemical engineering, and discloses a multi-component enhanced cyclic lithium extraction system and its application method. The extraction system provided by this invention includes an extractant and a co-extractant; the extractant includes aliphatic hydrocarbon phosphates and acidic phosphine extractants; the co-extractant is Fe(III). This invention employs the separate addition of Fe(III) to both phases to enhance the separation effect of lithium from impurity elements Ca and Na during the extraction process. The lithium extraction method provided solves the problem of maintaining a high concentration of chloride ions in the extraction system to prevent Fe(III) loss. The washing and back-extraction processes have also been optimized, but no additional acid or alkali solutions are used, which improves the system's stability and has broad industrial application prospects.

Description

Technical Field

[0001] This invention relates to the fields of extraction chemistry and chemical engineering, and in particular to a multi-component enhanced cyclic lithium extraction system and its application method. Background Technology

[0002] Solvent extraction for lithium extraction offers significant advantages such as high yield, low investment, and low cost. In particular, the triisobutyl phosphate (TIBP) extraction system allows lithium to be extracted into the system as LiFeCl4, forming the LiFeCl4·2TIBP complex ion. Therefore, in the presence of a co-extractant Fe... 3+ In the presence of TIBP in a large amount of Mg 2+ Na + K + High-efficiency extraction of Li in chlorination system + The method, which separates lithium from impurity ions, has been used in lithium extraction processes from high-magnesium salt lakes. Currently, existing Chinese invention patents include: (1) a composite extraction system and extraction method for extracting lithium from lithium-containing brine (CN107502741B) and (2) a method for back-extracting lithium from the loaded organic phase after extraction from lithium-containing brine (201810750237.X). These patents utilize long-chain phosphates with the same functional group structure, such as tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, and trioctyl phosphate, all of which can efficiently extract lithium from high-magnesium salt lake brines. Furthermore, by combining this system with acidic phosphine reagents, lithium can be back-extracted in water or low-acid (<2M HCl). Unlike traditional high-acid back-extraction (>6M), this invention significantly reduces acid and alkali consumption, stabilizes the extraction system, and improves extraction efficiency, thereby reducing operating costs and mitigating environmental pollution. This method has replaced previous lithium extraction technologies and has been applied in industrial production, becoming the only extraction technology currently used in the industrial production of lithium extraction from salt lakes. The extraction system mentioned in the aforementioned patent uses phosphate triesters composed of long-chain aliphatic hydrocarbons as the extraction system and acidic phosphine extractants or amides as co-extractants. This system has a drawback in extracting Li: the extraction time is too long. Summary of the Invention

[0003] To address the problem of excessively long extraction times, the present invention aims to provide a multi-component cyclic enhanced lithium extraction system and extraction method. The extraction system provided by the present invention is suitable for a mixture of the multi-component cyclic enhanced lithium extraction system and the lithium-containing brine in which the molar ratio of iron ions to lithium ions is (1-5):1.

[0004] To achieve the above objectives, the first aspect of the present invention provides a multi-component enhanced cyclic lithium extraction system, comprising a co-extractant and an extractant; the co-extractant is Fe(III), the Fe(III) source is ferric chloride, and the ferric chloride loading is 5-20 g / L; by volume, the extractant comprises 20-40 parts of aliphatic hydrocarbon phosphate and 5-10 parts of acidic phosphine extractant.

[0005] Preferably, the multi-component enhanced lithium extraction system also includes a hydrocarbon diluent. Preferably, the aliphatic hydrocarbon phosphate is any one or more of tributyl phosphate, tributyl phosphate, tripentyl phosphate, triisopentyl phosphate, trihexyl phosphate, triisohexyl phosphate, triheptyl phosphate, triisoheptyl phosphate, trioctyl phosphate, or triisooctyl phosphate.

[0006] Preferably, the acidic phosphine extractant is any one or more of di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507), or bis(2,4,4-trimethylpentyl)phosphite. In this invention, the addition of the acidic phosphine extractant can reduce the back-extraction acidity of the system.

[0007] Preferably, the hydrocarbon diluent is any one or more of kerosene, tetradecane, hexadecane, octadecane, tetramethylbenzene, p-tert-butylbenzene, octylbenzene, or laurylbenzene. In this invention, adding a hydrocarbon diluent can reduce the viscosity of the system.

[0008] Preferably, the multi-component enhanced lithium extraction system consists of a co-extractant and an extractant; the co-extractant is Fe(III); the loading of ferric chloride is 5-20 g / L; the extractant includes 20%-40% aliphatic hydrocarbon phosphate, 5%-10% acidic phosphine extractant, and the remainder is a hydrocarbon diluent; the percentages are the volume percentages of each component in the extractant.

[0009] The second aspect of this invention provides a method for extracting lithium from lithium-containing brine using a multi-component enhanced lithium extraction system based on the first aspect described above, comprising the following steps: (1) Add a portion of ferric chloride to the organic phase formed by the extractant and diluent, and add another portion of ferric chloride to the aqueous phase of the lithium brine; (2) The multi-component enhanced cyclic lithium extraction system was mixed with lithium-containing brine containing ferric chloride and extracted to obtain a loaded organic phase; (3) Mix the loaded organic phase with the washing solution, extract, and wash to obtain the washed organic phase; (4) The washed organic phase is back-extracted to obtain LiCl enriched back-extract solution.

[0010] Preferably, in step (1), the organic phase formed by the extractant and the diluent and the aqueous phase of the lithium brine are mixed with ferric chloride in a ratio of [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0011] Preferably, in step (2), the molar ratio of iron ions to lithium ions in the mixture of the multi-component cyclic enhanced lithium extraction system and the lithium-containing brine with added ferric chloride is (1-5):1; the volume ratio of the multi-component cyclic enhanced lithium extraction system to the lithium-containing brine is (1-10):1; the extraction adopts a multi-stage countercurrent method, and the number of extraction stages is 3-8.

[0012] Preferably, in step (3), the washing liquid is water and / or LiCl solution; in the mixture of the loaded organic phase and the washing liquid, the volume ratio of the organic phase to the aqueous phase is (70-100):1; the washing adopts a multi-stage countercurrent method, and the number of washing stages is 3-8 stages.

[0013] Preferably, in step (4), the reagent used for back-extraction is water and / or acid solution; in back-extraction, the volume ratio of organic phase to aqueous phase is (10-30):1; back-extraction adopts a multi-stage countercurrent method, and the number of back-extraction stages is 5-15.

[0014] The role and effect of invention This invention addresses the industry pain points of traditional extraction systems for lithium extraction from high magnesium-to-lithium ratio salt lake brines, such as severe Fe(III) loss, poor impurity separation, insufficient system stability, and high consumption of acid and alkali reagents. It develops a multi-component enhanced cyclic lithium extraction system and supporting extraction methods. Through synergistic compounding design of extractants, optimization of the Fe(III) phase-separation addition process, and innovative back-extraction process without additional acid and alkali washing, it achieves highly efficient and selective lithium extraction, stable cyclic extraction system, and reduced operating costs and environmental impact. The core functions and technical effects are specifically reflected in the following aspects: The extraction system achieves synergistic enhancement, fundamentally improving lithium extraction performance and stability. This invention constructs a composite system of aliphatic hydrocarbon phosphate ester and acidic phosphine extractant, fully leveraging the synergistic effect of the two types of extractants: it retains the effect of aliphatic hydrocarbon phosphate ester on Li... + The high selective complexation ability enables efficient lithium extraction; furthermore, the strong chelating effect of acidic phosphine extractant on Fe(III) stabilizes [FeCl4] in the extraction system. - The use of complexed anions fundamentally solves the problems of easy dissociation of complexes, easy degradation of extractants, and significant loss of water solubility in the organic phase in traditional single-component extraction systems. Compared with the traditional TBP / FeCl3 system, this system significantly improves lithium extraction efficiency and organic phase cycle stability, providing a fundamental guarantee for long-term continuous operation.

[0015] This invention innovatively employs a two-phase Fe(III) addition process, separately adding Fe(III) to the aqueous and organic phases. This enhances the interfacial complexation reaction during the extraction process. On one hand, it completely breaks the technical limitation of traditional extraction systems that require maintaining ultra-high chloride concentrations to prevent Fe(III) hydrolysis and loss. Stable Fe(III) retention can be achieved without relying on a high chloride environment, fundamentally solving the industry problem of large-scale Fe(III) loss with the raffinate and significantly reducing the replenishment cost of co-extractants. On the other hand, the phase-separated addition of Fe(III) allows for precise control of the extraction reaction process, significantly enhancing the separation effect of lithium from impurity elements such as Ca and Na, and greatly reducing the co-extraction rate of impurity ions. This reduces the operating load of subsequent washing processes and improves the purity of the final lithium product from the source.

[0016] This invention optimizes the entire process of washing and back-extraction without requiring additional acid or alkali additions, thus improving system stability and environmental friendliness. It eliminates the need for such additions, avoiding problems caused by excessive acid or alkali additions in traditional processes, such as drastic pH fluctuations, accelerated extractant degradation, and equipment corrosion. This significantly improves the operational stability of the entire extraction-washing-back-extraction process and extends the lifespan of the organic phase and production equipment. Furthermore, the absence of additional acid or alkali significantly reduces the generation of saline wastewater and waste acids and alkalis, lowering environmental treatment costs and reducing the pressure of waste disposal, perfectly aligning with the industrial development requirements for the green development of salt lake resources.

[0017] With strong closed-loop adaptability and excellent industrial application value, the extraction system of this invention can realize the closed-loop recycling and reuse of organic phase and Fe(III). The lithium extraction efficiency and impurity separation effect do not significantly decrease during multiple cycles, greatly reducing the long-term consumption of extractant and co-extractant. At the same time, this system can be directly adapted to existing mainstream industrial equipment for lithium extraction from salt lakes, such as centrifugal extraction and mixing clarification tanks, without the need for large-scale equipment modification. The process is simple to operate, has a high parameter tolerance, and can be adapted to salt lake brine raw materials with different magnesium-to-lithium ratios and different impurity contents. It takes into account lithium extraction efficiency, operating costs, and industrial adaptability, and provides a new and mature technical solution for large-scale, low-cost lithium extraction from salt lake brine with high magnesium-to-lithium ratio. Attached Figure Description

[0018] Figure 1 The different volume fractions of triisobutyl phosphate in the embodiments of the present invention affect Li + Statistical chart of extraction effect; Figure 2 The different dioctyl phosphate volume fractions in the embodiments of the present invention affect Li + Statistical chart of extraction effect; Figure 3 Fe is an example of the present invention.3+ / Li + molar ratio of Li + Extraction efficiency statistics chart; Figure 4 Fe is an example of the present invention. 3+ Adding method for Li + Extraction efficiency statistics chart; Figure 5 In the embodiments of the present invention, compared to R(O / A) for Li + Extraction efficiency statistics chart; Figure 6 In the embodiments of the present invention, the extraction time affects Li + Extraction efficiency statistics chart; Figure 7 This is a schematic diagram of the extraction and back-extraction mechanism of the system in an embodiment of the present invention.

[0019] Attached image description: Figures 1-6 In the diagram, the three lines represent three sets of parallel experiments. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0021] Unless otherwise specified, the raw materials and materials used in the embodiments of the present invention were purchased through general commercial channels.

[0022] The source information of the raw materials, materials, and instruments involved in the following embodiments or comparative examples is as follows: Table 1 Main reagents and raw materials for the experiment

[0023] Table 2 Main Instruments and Equipment for the Experiment

[0024] like Figure 7 As shown, the mechanism of this invention is that in a highly chlorinated medium, lithium ions (Li...) + It can react with the ferric(III) tetrachlorophosphate anion ([FeCl4]). - [FeCl4] forms a neutral ion pair, enabling efficient co-extraction into the organic phase. This ion pair is solubilized by the neutral organophosphorus extractant TIBP (triisobutyl phosphate). Subsequent stripping with deionized water or a low-chloride aqueous solution significantly reduces the chloride ion concentration, promoting the extraction of [FeCl4]. - Dissociate and release Fe 3+ When the acidic extractant P204 (dioctyl phosphate) is present, the released Fe...3+ It will be immediately chelated through cation exchange to form FeA3—this highly hydrophobic and stable six-coordinate chelate (where A represents the deprotonated form of P2O4) will remain firmly embedded in the organic phase. Meanwhile, due to Li + Due to its weak coordination with TIBP and high hydration energy, it is preferentially stripped into the aqueous phase. This method utilizes chloride ion concentration as a switch to regulate metal morphology, and through the complementary functions of TIBP (as a solvator) and P2O4 (as a chelating agent), it achieves Li... + with Fe 3+ Highly efficient separation.

[0025] <Example 1> In this embodiment, during the small-scale test, 50 mL each of the organic phase and the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 40% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0026] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 87%.

[0027] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 98%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 85.4%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0028] <Example 2> In this embodiment, during the small-scale test, 50 mL of each of the organic and aqueous phases were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0029] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 85.0%.

[0030] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 96%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 83.45%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0031] <Example 3> In this embodiment, during the small-scale test, 50 mL each of the organic phase and the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 15% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.63 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0032] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 80.45%.

[0033] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 88.10%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 78.98%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0034] <Example 4> In this embodiment, during the small-scale test, 50 mL each of the organic phase and aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0035] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. Iron was added to the organic phase and the aqueous phase at a ratio of 1:2, respectively, and pre-loaded. After 5 stages of countercurrent extraction, the lithium extraction rate reached 88.88%.

[0036] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 98%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 87.8%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0037] <Example 5> In this embodiment, during the small-scale test, 50 mL of the organic phase and 100 mL of the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, by volume fraction, consisted of: 36% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0038] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 60%.

[0039] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 59%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 55.58%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0040] <Example 6> In this embodiment, during the small-scale test, 50 mL of the organic phase and 100 mL of the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, by volume fraction, consisted of: 38% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0041] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 80%.

[0042] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 95%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 79%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0043] <Example 7> In this embodiment, during the small-scale test, 50 mL each of the organic phase and the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 40% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0044] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction, the lithium extraction rate reached 87.3%.

[0045] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 30:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 95%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 86%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0046] <Example 8> In this embodiment, during the pilot-scale test, 50 L each of the organic phase and aqueous phase were added to a centrifugal extractor. The multi-component enhanced lithium extraction system, by volume fraction, consisted of: 40% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0047] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, with the total iron to total lithium equivalent ratio being 1.6. After 5 stages of countercurrent extraction for 18 minutes, the lithium extraction rate reached 85.90%.

[0048] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 97%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 84%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0049] <Example 9> In this embodiment, during the pilot-scale test, 50 L each of the organic phase and aqueous phase were added to a centrifugal extractor. The multi-component enhanced lithium extraction system, by volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0050] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1:1, wherein the total iron to total lithium equivalent ratio was 1.6. After 5 stages of countercurrent extraction for 20 min, the lithium extraction rate reached 87.00%.

[0051] (3) The loaded organic phase after extraction was washed with water in a 5-stage countercurrent process with a washing ratio of 70:1. (4) The washed loaded organic phase was back-extracted with pure water at a ratio of 40:1. After 10 stages of countercurrent back-extraction, the lithium back-extraction rate was 97.5%, and the iron back-extraction rate was close to 0. The total lithium yield during the extraction and back-extraction process was 85.5%. After precipitation with sodium carbonate, lithium carbonate with a purity of 99% was obtained.

[0052] <Example 10> In this embodiment, during the small-scale test, 50 mL each of the organic phase and aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 10 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10 g / L. During extraction, the total ferric chloride loading was 10 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportion according to [nFe (organic phase) / nFe (aqueous phase) = 1:1].

[0053] (2) The extraction system is mixed with lithium-containing brine containing ferric chloride at a 1:1 ratio, where the total iron to total lithium equivalent ratio is 2, and pre-loaded. Then, single-stage extraction is performed, such as... Figure 1 As shown, the horizontal axis represents the volume fraction of triisobutyl phosphate, and the vertical axis represents the lithium extraction efficiency. When the volume fraction of triisobutyl phosphate is 35%, the lithium single-stage extraction efficiency is optimal, at 58.87%.

[0054] <Example 11> In this embodiment, during the small-scale test, 50 mL each of the organic phase and the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 5% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 5 g / L. During extraction, the total ferric chloride loading was 5 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportion according to [nFe (organic phase) / nFe (aqueous phase) = 1:1].

[0055] (2) The extraction system is mixed with lithium-containing brine containing ferric chloride at a 1:1 ratio, where the total iron to total lithium equivalent ratio is 1, and pre-loaded. Then, single-stage extraction is performed, such as... Figure 2 As shown, the horizontal axis represents the volume fraction of dioctyl phosphate, and the vertical axis represents the lithium extraction efficiency. When the volume fraction of dioctyl phosphate is 5%, the lithium single-stage extraction efficiency is optimal, at 50.98%.

[0056] <Example 12> In this embodiment, during the small-scale test, 50 mL of each of the organic and aqueous phases were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 5% P2O4 as the extractant + the remainder sulfonated kerosene, with an organic phase loading of 8 g / L ferric chloride. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with an aqueous phase loading of 8 g / L ferric chloride. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportion according to [nFe (organic phase) / nFe (aqueous phase) = 1:1].

[0057] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a 1:1 ratio, with a total iron to total lithium equivalent ratio of 1.6, and pre-loaded. Then, single-stage extraction was performed, such as... Figure 3 As shown, the horizontal axis represents Fe. 3+ / Li + The molar ratio, with the vertical axis representing lithium extraction efficiency, is calculated when Fe... 3+ / Li + At a molar ratio of 1.6, ferric chloride consumption is low, and the single-stage lithium extraction efficiency is optimal at 56.90%.

[0058] <Example 13> In this embodiment, during the small-scale test, 50 mL each of the organic phase and the aqueous phase were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 5% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 8 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0059] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a 1:1 ratio, with a total iron to total lithium equivalent ratio of 1.6, and pre-loaded. Then, single-stage extraction was performed, such as... Figure 4 As shown, the horizontal axis represents the method of iron addition, and the vertical axis represents the lithium extraction efficiency. When iron is added to the organic phase and the aqueous phase in a ratio of 1:2, the single-stage lithium extraction efficiency is optimal, at 63.89%.

[0060] <Example 14> In this embodiment, during the small-scale test, 50 mL of each of the organic and aqueous phases were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 7.47 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0061] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1.5:1, with a total iron to total lithium equivalent ratio of 1.6, and pre-loaded. Then, single-stage extraction was performed, such as... Figure 5 As shown, the horizontal axis represents the ratio of organic phase to aqueous phase, and the vertical axis represents lithium extraction efficiency. When the ratio is 1.5, the single-stage lithium extraction efficiency is optimal, at 55.48%.

[0062] <Example 15> In this embodiment, during the small-scale test, 50 mL of each of the organic and aqueous phases were added to a separatory funnel. The multi-component enhanced lithium extraction system, based on volume fraction, consisted of: 35% triisobutyl phosphate + 10% P2O4 as the extractant + the remainder sulfonated kerosene, with a ferric chloride organic phase loading of 5.33 g / L. The lithium-containing brine contained 0.43 g / L lithium, 58.33 g / L magnesium, 1.84 g / L sodium, and 0.78 g / L potassium, with a ferric chloride aqueous phase loading of 10.67 g / L. During extraction, the total ferric chloride loading was 7.47 g / L. Using the multi-component enhanced lithium extraction system and the lithium-containing brine as raw materials, lithium was extracted through the following steps: (1) The organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

[0063] (2) The extraction system was mixed with lithium-containing brine containing ferric chloride at a ratio of 1.5:1, with a total iron to total lithium equivalent ratio of 1.6, and pre-loaded. Then, single-stage extraction was performed, such as... Figure 6 As shown, the horizontal axis represents extraction time, and the vertical axis represents lithium extraction efficiency. When the time is 5 minutes, the single-stage lithium extraction efficiency is the best, which is 53.71%.

[0064] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A multi-component enhanced cyclic lithium extraction system, characterized in that, It includes a co-extractant and an extractant; wherein the co-extractant is Fe(III), the Fe(III) source is ferric chloride, and the ferric chloride loading is 5-10 g / L; the extractant includes 20-40 parts by volume of aliphatic hydrocarbon phosphate and 5-10 parts by volume of acidic phosphine extractant.

2. The multi-component enhanced cyclic lithium extraction system according to claim 1, characterized in that, It also includes hydrocarbon diluents.

3. The multi-component enhanced cyclic lithium extraction system according to claim 1 or 2, characterized in that, The aliphatic hydrocarbon phosphate ester is any one or more of tributyl phosphate, triisobutyl phosphate, tripentyl phosphate, triisopentyl phosphate, trihexyl phosphate, triisohexyl phosphate, triheptyl phosphate, triisoheptyl phosphate, trioctyl phosphate, or triisooctyl phosphate.

4. The multi-component enhanced cyclic lithium extraction system according to claim 1 or 2, characterized in that, The acidic phosphine extractant is any one or more of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, or bis(2,4,4-trimethylpentyl) hypophosphite.

5. The multi-component enhanced cyclic lithium extraction system according to claim 2, characterized in that, The hydrocarbon diluent is any one or more of kerosene, tetradecane, hexadecane, octadecane, tetramethylbenzene, p-tert-butylbenzene, octylbenzene, or laurylbenzene.

6. A method for extracting lithium from lithium-containing brine using a multi-component enhanced cyclic lithium extraction system, characterized in that, Includes the following steps: (1) Add a portion of ferric chloride to the organic phase formed by the extractant and diluent, and add another portion of ferric chloride to the aqueous phase of the lithium brine; (2) The multi-component enhanced cyclic lithium extraction system is mixed with lithium-containing brine containing ferric chloride, and extracted to obtain a loaded organic phase; (3) The loaded organic phase is mixed with the washing solution, extracted, and washed to obtain the washed organic phase; (4) The washed organic phase is back-extracted to obtain LiCl enriched back-extract; Wherein, the extractant is the extractant according to any one of claims 1 to 5; the diluent is any one or more of kerosene, tetradecane, hexadecane, octadecane, tetramethylbenzene, p-tert-butylbenzene, octylbenzene or laurylbenzene.

7. The method according to claim 6, characterized in that, In step (1), the organic phase formed by the extractant and diluent and the aqueous phase of lithium brine are mixed with ferric chloride in the corresponding proportions according to [nFe (organic phase) / nFe (aqueous phase) = 1:2].

8. The method according to claim 6, characterized in that, In step (1), the molar ratio of iron ions to lithium ions in the mixture of the multi-component cyclic enhanced lithium extraction system and the lithium-containing brine is (1-5):1; the volume ratio of the multi-component cyclic enhanced lithium extraction system to the lithium-containing brine is (1-10):1; the extraction adopts a multi-stage countercurrent method, and the number of extraction stages is 3-8.

9. The method according to claim 6, characterized in that, In step (2), the washing liquid is water and / or LiCl solution; in the mixture of the supported organic phase and the washing liquid, the volume ratio of the organic phase to the aqueous phase is (70-100):1; the washing adopts a multi-stage countercurrent method, and the number of washing stages is 3-8 stages.

10. The method according to claim 6, characterized in that, In step (3), the reagent used for back-extraction is water and / or acid solution; in the back-extraction, the volume ratio of organic phase to aqueous phase is (10-30):1; the back-extraction adopts a multi-stage countercurrent method, and the number of back-extraction stages is 5-15.

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