Method for extracting lithium from high-aluminum lithium-containing solution and lithium carbonate

Abstract

The invention relates to the technical field of lithium material preparation, in particular to a method for extracting lithium from a high-aluminum lithium-containing solution and lithium carbonate. The method comprises the following steps: extracting a high-aluminum lithium-containing solution by using a composite extracting agent to obtain a loaded organic phase; wherein the composite extraction agent comprises a ketone extraction agent and an organic phosphine extraction agent; the amount of substance n1 of the ketone extraction agent and the amount of substance n2 of the organic phosphine extraction agent meet the condition that n1: n2 is greater than or equal to 1: 2; washing the loaded organic phase by using a washing agent to obtain a washing water phase; and carrying out back extraction on the washing water phase by using a back extraction agent to obtain a lithium-rich solution. According to the method, the process is shortened by optimizing an extraction agent combination (particularly preferentially removing aluminum by a high-proportion organic phosphine extraction agent), and meanwhile, the extraction rate of lithium and the quality of the final lithium-rich liquid are remarkably improved through the synergistic effect of all the steps (synergistic extraction, washing purification and efficient reverse extraction).

Description

Technical Field

[0001] This application relates to the field of lithium material preparation technology, and in particular to a method for extracting lithium from a high-alumina lithium-containing solution and lithium carbonate. Background Technology

[0002] Lithium is a critical strategic metal, but traditional lithium ore resources are insufficient to meet the ever-increasing market demand. Therefore, there is an urgent need to develop non-brine-grade lithium resources to broaden the sources of lithium raw materials. Currently, sedimentary lithium resources are abundant, primarily enriched in claystone-type lithium resources, especially lithium deposits associated with bauxite. These deposits are characterized by large reserves and wide distribution. However, these lithium deposits enter the alumina production process along with the bauxite, allowing for lithium recovery from the waste liquid. However, current methods for extracting lithium from sodium aluminate solutions formed from bauxite have the following drawbacks: low lithium separation and enrichment efficiency, lengthy extraction process, and difficulty in recovering lithium from the mother liquor. This results in low overall lithium yield and production efficiency through the alumina production process. In addition, the main raw materials for extracting lithium from lithium-containing solutions are currently salt lake brine and lithium precipitation mother liquor. However, the technology for extracting lithium from high-alumina lithium-containing solutions obtained after desorption of aluminum-based lithium concentrate has the disadvantages of long extraction process and low extraction rate.

[0003] To address the aforementioned deficiencies, the current methods for extracting lithium from lithium-containing solutions include: (1) A process for efficiently extracting lithium from lithium-containing solutions and preparing high-purity lithium carbonate, the steps of which include: adding a regulator to the lithium-containing solution for homogenization to obtain homogenized effluent; mixing the homogenized effluent with the extraction organic phase to extract lithium components to obtain the extraction organic phase; washing the extraction organic phase, and then back-extracting the washed extraction organic phase under heat and pressure to obtain a blank organic phase, concentrated lithium carbonate solution and carbon dioxide gas; removing the entrained organic matter from the concentrated lithium carbonate solution by degreasing to obtain a purified lithium carbonate solution; filtering and drying the purified lithium carbonate solution sequentially to obtain a high-purity lithium carbonate product. (2) An extraction system and extraction method for extracting lithium from alkaline lithium-containing solutions, using a mixed extraction system containing ester compounds to achieve the extraction and separation of lithium from other alkali metal ions in alkaline lithium-containing solutions. (3) A method for extracting and separating lithium from high-aluminum-lithium solutions, comprising the following steps: S1. Preparing a mixed extractant; S2. Adjusting the iron-lithium atomic ratio of the aqueous solution to be extracted; S3. Adjusting the pH value of the aqueous solution to be extracted; S4. Determining the volume ratio of the extractant to the aqueous solution to be extracted; S5. Shaking the extractant and the aqueous solution to be extracted to promote mixing and obtain an extraction mixture; S6. Allowing the mixture to stand and separate into layers to obtain a loaded organic phase; S7. Mixing the loaded organic phase with hydrochloric acid solution to obtain a lithium-containing mixture; S8. Shaking and allowing the lithium-containing mixture to stand sequentially to obtain an aqueous solution; S9. The obtained aqueous solution is a LiCl solution. This method uses a tributyl phosphate (TBP)-methyl isobutyl alcohol (MIBK) extraction system, and by controlling the process parameters of the extraction process, efficient extraction and separation of lithium from high-lithium and aluminum solutions can be achieved.

[0004] However, most of the existing methods for extracting lithium from lithium-containing solutions have long processes and low extraction rates, making it difficult to meet the demand for extracting lithium from lithium-containing solutions with high aluminum content. Summary of the Invention

[0005] This application provides a method for extracting lithium from a high-alumina lithium-containing solution and lithium carbonate, in order to solve the following technical problem: how to improve the extraction rate of lithium from a high-alumina lithium-containing solution under short extraction process conditions. In a first aspect, embodiments of this application provide a method for extracting lithium from a high-alumina lithium-containing solution, the method comprising: A high-alumina lithium-containing solution was extracted using a composite extractant to obtain a supported organic phase; wherein the composite extractant includes a ketone extractant and an organophosphorus extractant; the amount of substance n1 of the ketone extractant and the amount of substance n2 of the organophosphorus extractant satisfy: n1:n2≥1:2; The loaded organic phase was washed with detergent to obtain a washing aqueous phase; The washing aqueous phase was back-extracted using a back-extraction agent to obtain a lithium-rich solution.

[0006] Optionally, the amount of substance n1 of the ketone extractant and the amount of substance n2 of the organophosphorus extractant satisfy the following: n1:n2=1:(0.2 to 2).

[0007] Optionally, the ketone extractant may include at least one of the following: benzoyltrifluoroacetone, 2-furanoyltrifluoroacetone, and 2-thiophenoyltrifluoroacetone.

[0008] Optionally, the types of organophosphorus extractants include trialkylphosphine oxide, tri-n-octylphosphine oxide, 2,4,4-trimethylpentylphosphine, trihexyl(tetradecyl)phosphine bromide, and hexadecylphosphine bromide.

[0009] Optionally, the volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following: V1:V2=1:(0.2 to 10).

[0010] Optionally, the composite extractant further includes a diluent, the volume of which is 60% to 90% of the volume of the composite extractant.

[0011] Optionally, the detergent includes a first nitric acid solution having a molar concentration of 0.05 mol / L to 1 mol / L; and / or The stripping agent includes a second nitric acid solution with a molar concentration of 2 mol / L to 5 mol / L.

[0012] Optionally, the volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4 = 1:(0.05 to 2); and / or The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following: V5:V6=1:(0.02 to 0.2).

[0013] Secondly, embodiments of this application provide a lithium carbonate, wherein the raw material for the lithium carbonate includes a lithium-rich solution obtained by the method described in the first aspect; the lithium-rich solution has a lithium mass concentration of 15 g / L to 25 g / L.

[0014] Thirdly, embodiments of this application provide a method for preparing the lithium carbonate described in the second aspect, the method comprising: The lithium-rich solution obtained by the method described in the first aspect is subjected to lithium precipitation using a lithium precipitation agent to obtain a crude lithium carbonate mixture; wherein the volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy: V7:V8 = (0.5 to 1.5):10; The crude lithium carbonate mixture was separated to obtain a solid lithium carbonate phase; The lithium carbonate solid phase is dried and crushed sequentially to obtain the lithium carbonate product.

[0015] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for extracting lithium from a high-alumina lithium-containing solution. The method uses a composite extractant formed by a ketone extractant and an organophosphorus extractant. The oxygen atoms in the enol structure of the ketone extractant selectively capture lithium ions from the high-alumina lithium-containing solution, forming a stable six-membered ring chelate. The organophosphorus extractant, used in a molar ratio ≥1:2 with the ketone extractant, effectively absorbs aluminum ions from the high-alumina lithium-containing solution, significantly reducing the aluminum content and inhibiting the reaction of aluminum and lithium ions on the ketone extractant. The method employs competitive adsorption to improve the selectivity of ketone extractants in adsorbing lithium ions, reduce the likelihood of ketone extractants adsorbing impurity ions, and increase the adsorption capacity of ketone extractants for aluminum ions. This increases the lithium content in the supported organic phase, thereby improving the lithium extraction rate. Washing removes weakly bound impurity ions from the supported organic phase, improving the purity of lithium in the supported organic phase. Finally, a back-extraction agent specifically disrupts lithium-ketone complexes, efficiently releasing lithium from the washing aqueous phase, resulting in a lithium-rich solution with high lithium content. Therefore, this method, through only three steps—extraction, washing, and back-extraction—can improve the lithium extraction rate from high-aluminum lithium-containing solutions and obtain a lithium-rich solution under short extraction conditions. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This application provides a schematic flowchart of a method for extracting lithium from a high-alumina lithium-containing solution. Figure 2 This is a schematic diagram of a method for preparing lithium carbonate provided in an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.

[0021] It should be noted that, regarding the prior art (1) described in the background art, the inventors found that although the lithium carbonate prepared by this process has a high purity, the process has defects such as a long process flow, high equipment requirements, and low total lithium yield. Furthermore, the lithium-containing solution needs to be adjusted before extraction, and the back-extraction process requires complex operations such as heating and pressurization. Finally, in the process of pyrolyzing the concentrated lithium bicarbonate solution to prepare carbonic acid, the lithium pyrolysis rate is low due to limitations in the pyrolysis equipment and process. Regarding the prior art (2) described in the background art, the inventors found that although using a mixed extraction system containing ester compounds can shorten the extraction process, this mixed extraction system has relatively low selectivity for lithium extraction, resulting in a low lithium extraction rate. Regarding the prior art (3) described in the background art, the inventors found that the process flow of this method is long, and the lithium extraction rate is low.

[0022] Therefore, existing extraction methods using extractants or systems have limited applicability to the extraction and recovery of lithium from high-alumina lithium-containing solutions. Furthermore, these extractants or systems exhibit poor selectivity for lithium during extraction, and some extraction processes are quite lengthy. In addition, research on short-process recovery and extraction of lithium from aluminum-based lithium concentrate desorption solutions is insufficient. Therefore, it is currently difficult to achieve effective lithium extraction from high-alumina lithium-containing solutions using a short-process approach.

[0023] Figure 1 An exemplary schematic diagram of a method for extracting lithium from a high-alumina lithium-containing solution provided in an embodiment of this application is shown. like Figure 1 As shown in the embodiments of this application, a method for extracting lithium from a high-alumina lithium-containing solution is provided, the method comprising: S1. A high-aluminum lithium-containing solution is extracted using a composite extractant to obtain a supported organic phase; wherein the composite extractant includes a ketone extractant and an organophosphorus extractant; the amount of the ketone extractant n1 and the amount of the organophosphorus extractant n2 satisfy: n1:n2≥1:2; S2. The loaded organic phase is washed with detergent to obtain a washing aqueous phase; S3. The washing aqueous phase is back-extracted using a back-extraction agent to obtain a lithium-rich solution.

[0024] It should be noted that the high-alumina lithium-containing solution can be the desorption solution obtained after hydrothermal desorption of aluminum-based lithium concentrate. The components of this high-alumina lithium-containing solution include: lithium ion concentrations of 0.1 g / L to 3 g / L, aluminum ion concentrations of 0.02 g / L to 5 g / L, sodium ion concentrations of 1 g / L to 5 g / L, and carbonate ion concentrations of 0.1 g / L to 5.0 g / L. The pH of this high-alumina lithium-containing solution can be 8.0 to 12.0.

[0025] It should be noted that the ketone extractant in this composite extractant exhibits low solubility in alkaline solutions with low pH, but remains stable in alkaline solutions with high pH. This reduces the loss of the extractant due to water solubility or saponification in high-alumina lithium-containing solutions. Furthermore, the ketone extractant can form stable six-membered ring chelates with lithium in high-alumina lithium-containing solutions through its enol-structured oxygen atoms, while showing low affinity for other alkali metal ions (sodium ions, potassium ions) or alkaline earth metal ions (magnesium ions, calcium ions). This indicates that the ketone extractant has strong selectivity for lithium extraction.

[0026] It should be noted that, in addition to directly participating in the assisted extraction process of ketone extractants, the organophosphorus extractants in this composite extractant can also modify, modify, transport, and compatibilize the ketone extractants, thereby promoting the formation of a more stable six-membered ring chelate between the ketone extractants and lithium. Furthermore, the addition of electronic groups to the organophosphorus extractants can accelerate the extraction reaction process of the composite extractant.

[0027] It should be noted that this composite extractant more readily forms stable extractables, thus improving extraction efficiency. Furthermore, the differences between different extractants can significantly enhance separation performance, resulting in superior extraction compared to single-extraction methods. Simultaneously, if carbonate ions are present in the high-alumina lithium-containing solution, the diketone structure in the ketone extractants of these composite extractants transforms into an enol structure under the influence of carbonate ions, inhibiting hydrogen bonding in the ketone extractants. The lone pair electrons on the oxygen atoms of these enol structures can form stable six-membered ring chelates with lithium, thereby improving the extraction efficiency of the composite extractant.

[0028] It should be noted that in addition to obtaining the supported organic phase, the extraction process can also yield a raffinate aqueous phase, which can be purified and reused as industrial water.

[0029] It should be noted that the method for extracting lithium from a high-alumina lithium-containing solution provided in this application embodiment achieves the core objective of efficient lithium extraction under short-process conditions through innovations in the optimization of composite extractant components and synergistic process design. Its core mechanism is as follows: 1. Synergistic effect of composite extractants: the core of efficient aluminum-lithium separation: (1) Ketone extractants: mainly responsible for the extraction of lithium ions (Li... + Complexation extraction of ketone extractants. These are based on the oxygen atom of the enol structure of ketone extractants, which can form stable six-membered ring chelates with lithium. This makes ketone extractants generally selective for alkali metal ions, but their performance is poor when used alone in high-alumina environments.

[0030] (2) Organophosphorus extractants: These extractants (acidic phosphorus type) are effective against high-valence metal ions (especially Al). 3+ It possesses extremely strong selectivity and high extraction capacity, making it key to achieving aluminum-lithium separation.

[0031] (3) Synergistic mechanism (n1:n2≥1:2): This specific molar ratio requirement (with a larger proportion of phosphine) is key: 1) Preferential "capture" of aluminum: Organophosphorus extractants, when present in a high proportion, can selectively extract the vast majority of aluminum ions (Al) in the solution with extremely high efficiency. 3+ This significantly reduces the aluminum concentration in the aqueous phase.

[0032] 2) Reduced competition and co-extraction: After a large amount of aluminum is extracted, the competition for Al is greatly reduced. 3+ With Li + Competition among ketone extractants. Ketone extractants can extract lithium ions more specifically and efficiently.

[0033] 3) Reduced impurities in the organic phase: Since aluminum is mainly fixed by organophosphorus extractants, the amount of aluminum impurities entering the organic phase is relatively reduced (although the organophosphorus extractants themselves are loaded with aluminum). This relatively improves the purity of lithium in the loaded organic phase and reduces the washing burden.

[0034] 4) Improved extraction kinetics and phase separation: Composite systems may have better extraction kinetics and phase separation performance than single ketones.

[0035] 2. Washing steps: Deep purification of the loaded organic phase (1) Purpose: Although the composite extractant improves selectivity, the supported organic phase may still contain a small amount of aqueous phase or trace amounts of co-extracted / entrained impurity ions (such as sodium, potassium, residual aluminum, etc.).

[0036] (2) Function: Use a specific detergent (usually an aqueous solution with controlled composition and acidity) to contact the supported organic phase.

[0037] 1) Eluting impurities: Wash impurity ions (especially residual trace amounts of aluminum and other cations) that are entrained or weakly bound to the extractant (relative to lithium) back into the aqueous phase.

[0038] 2) Lithium retention: Ensure that lithium-ketone complexes remain stable during washing and are not washed away.

[0039] 3) Improved lithium purity after back-extraction: The washed organic phase (washing aqueous phase) is relatively pure, with a higher lithium concentration and fewer impurities. This directly improves the purity of the lithium-rich solution obtained from subsequent back-extraction and the lithium recovery rate (because it reduces the interference of impurities on the back-extraction process and the lithium loss pathways).

[0040] 3. Back-extraction step: Efficiently releases lithium Use a suitable back-extraction agent (usually an acidic aqueous solution) to contact the wash water phase.

[0041] Because the organic phase has fewer impurities after washing, the lithium-ketone extractant complex is relatively "pure". The stripping agent can more efficiently and selectively destroy the lithium-ketone complex, releasing lithium ions into the aqueous phase to form a lithium-rich solution.

[0042] The lower impurity load also reduces the consumption of stripping agent and the concentration of impurities in the stripping solution, which is beneficial for the direct treatment of the subsequent lithium-rich solution (such as concentration or lithium precipitation).

[0043] Therefore, this method mainly achieves the goal of efficient lithium extraction under short-process conditions through the following mechanism: (1) Source suppression co-extraction, achieving deep separation of aluminum and lithium in one step: Traditional extraction methods may require complex pretreatment such as multiple precipitation and ion exchange steps to remove aluminum ions, resulting in a long process and significant lithium loss. This method utilizes a high proportion of organophosphorus extractants to powerfully remove most of the aluminum in one extraction step, directly extracting lithium efficiently and selectively against a high-aluminum background, eliminating the lengthy and cumbersome aluminum removal pretreatment steps and greatly shortening the process.

[0044] (2) Synergistic extraction enhances lithium selectivity: The composite system (especially organophosphorus extractants that eliminate aluminum competition) significantly improves the lithium extraction selectivity of ketone extractants, reducing the amount of lithium lost in the aqueous phase due to competition or low efficiency in the extraction stage.

[0045] (3) Washing ensures purity and reduces subsequent losses: The washing step effectively removes entrained and weakly bound impurities within a short process, preventing these impurities from entering the lithium-rich liquid with lithium in the back-extraction stage or interfering with the back-extraction process. This reduces the risk of lithium loss due to entrained impurities or incomplete back-extraction, and ensures efficient conversion from the loaded organic phase to the lithium-rich liquid.

[0046] (4) The overall process is compact and efficient: The main process consisting of three steps, namely extraction (composite synergistic aluminum removal and lithium extraction) → washing (deep impurity removal) → back-extraction (efficient lithium extraction), is very simple. Each step specifically addresses key issues (aluminum interference, impurity purification, and lithium release), avoiding lithium loss and process extension caused by repeated processing and recycling of intermediate products.

[0047] In summary, the method for extracting lithium from a high-alumina lithium-containing solution provided in this application has a core breakthrough in utilizing a composite extraction system with n1:n2 ≥ 1:2 (mainly organophosphorus extractants). This system achieves efficient and deep separation of aluminum and lithium in the initial extraction stage, completely eliminating the greatest interference of the high-alumina environment on lithium extraction. This efficient source control, combined with subsequent targeted washing, purification, and back-extraction, allows the entire process to maintain lithium ion concentration even with fewer steps and shorter time (short process). (1) It can efficiently and selectively enter the organic phase from the high-alumina solution during the extraction stage (reducing the residual loss of the aqueous phase).

[0048] (2) It can be effectively retained in the organic phase during the washing stage (reducing elution loss).

[0049] (3) It can be released into the aqueous phase efficiently and purely during the back-extraction stage (reducing incomplete back-extraction loss and impurity dilution).

[0050] Therefore, this method shortens the process by optimizing the extractant combination (especially by using a high proportion of organophosphorus extractants to preferentially remove aluminum), and significantly improves the lithium extraction rate and the quality of the final lithium-rich solution through the synergistic effect of each step (synergistic extraction → washing and purification → high-efficiency back-extraction).

[0051] In some optional embodiments, the amount of the ketone extractant n1 and the amount of the organophosphorus extractant n2 satisfy: n1:n2=1:(0.2 to 2).

[0052] In these embodiments, the ratio of ketone extractant to organophosphorus extractant (1:0.2 to 2) ensures that the composite extractant contains an excess of organophosphorus extractant and a sufficient amount of ketone extractant. The excess organophosphorus extractant can effectively adsorb aluminum ions from the high-aluminum lithium-containing solution, thereby significantly reducing the aluminum content of the high-aluminum lithium-containing solution, inhibiting the competitive adsorption of aluminum ions and lithium ions on the ketone extractant, and increasing the amount of aluminum ions adsorbed by the ketone extractant, which is beneficial for subsequently improving the lithium extraction rate.

[0053] The molar amount n2 of the organophosphorus extractant can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5 or 2.0.

[0054] In some alternative embodiments, the ketone extractant includes at least one of the following: benzoyltrifluoroacetone, 2-furanoyltrifluoroacetone, and 2-thiophenoyltrifluoroacetone.

[0055] In these embodiments, the use of ketone extractants, including benzoyltrifluoroacetone, 2-furanoyltrifluoroacetone and 2-thiophenoyltrifluoroacetone, can cover most ketone extractants. The oxygen atoms of the enol structure of these ketone extractants can form stable six-membered ring chelates with lithium in high-aluminum lithium-containing solutions, thereby improving the extraction effect of high-aluminum lithium-containing solutions.

[0056] In some alternative embodiments, the organophosphorus extractant includes trialkylphosphine oxide, tri-n-octylphosphine oxide, 2,4,4-trimethylpentylphosphine, trihexyl(tetradecyl)phosphine bromide, and hexadecylphosphine bromide.

[0057] In these embodiments, organophosphorus extractants, including trialkylphosphine oxide, tri-n-octylphosphine oxide, 2,4,4-trimethylpentylphosphine, trihexyl(tetradecyl)phosphine bromide, and hexadecylphosphine bromide, are used. These organophosphorus extractants can adequately adsorb aluminum ions from high-aluminum lithium-containing solutions to suppress the competitive adsorption of aluminum ions and lithium ions on ketone extractants, improve the selectivity of ketone extractants in adsorbing lithium ions, and increase the amount of lithium ions adsorbed by ketone extractants. This can increase the lithium content in the supported organic phase and improve the lithium extraction rate.

[0058] In some optional embodiments, the volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy: V1:V2=1:(0.2 to 10).

[0059] In these embodiments, a volume ratio of 1:(0.2 to 10) of composite extractant and high-aluminum lithium-containing solution can ensure that the high-aluminum lithium-containing solution has sufficient composite extractant. Through the synergistic effect between ketone extractant and organophosphorus extractant, these composite extractants achieve efficient and deep separation of aluminum and lithium in the initial extraction stage, completely solving the biggest interference of the high-aluminum environment on lithium extraction.

[0060] The volume V2 of the high-alumina lithium-containing solution can be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, or 10.

[0061] It should be noted that when the volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the ratio V1:V2 < 1:10, this indicates that the amount of high-aluminum lithium-containing solution used is relatively high. In this case, the organophosphorus extractant in the composite extractant will preferentially bind lithium and inhibit the co-extraction of aluminum. However, since the ketone extractant and organophosphorus extractant in the composite extractant are a quantitative extraction system, excessive high-aluminum lithium-containing solution will affect the extraction efficiency of the composite extractant. When the volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the ratio V1:V2 > 1:0.2, the amount of composite extractant added is too large. Although this is beneficial for the binding of organophosphorus extractant with aluminum in the high-aluminum lithium-containing solution and increases the difference in aluminum partition coefficient to achieve the separation of aluminum and lithium, too much composite extractant will passivate the extraction process and reduce the extraction rate.

[0062] In some optional embodiments, the composite extractant further includes a diluent, the volume of which is 60% to 90% of the volume of the composite extractant.

[0063] In these embodiments, a diluent is introduced into the composite extractant, and the volume of dilution is controlled to be 60% to 90% of the volume of the composite extractant. The diluent can increase the dispersion of ketone extractants and organophosphorus extractants in the composite extractant, which is beneficial to the synergistic extraction between ketone extractants and organophosphorus extractants, thereby increasing the adsorption capacity of aluminum ions by the composite extractant and improving the subsequent lithium extraction rate.

[0064] The volume of the diluent can be 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the volume of the composite extractant.

[0065] It should be noted that the diluent can be kerosene.

[0066] In some optional embodiments, the detergent comprises a first nitric acid solution having a molar concentration of 0.05 mol / L to 1 mol / L; and / or The stripping agent includes a second nitric acid solution with a molar concentration of 2 mol / L to 5 mol / L.

[0067] In these embodiments, a first nitric acid solution with a molar concentration of 0.05 mol / L to 1 mol / L can effectively remove impurity ions such as sodium, iron, and chloride ions from the loaded organic phase due to the high impurity solubility of nitric acid solutions. This facilitates the purification and recovery of the target lithium in the subsequent washing aqueous phase, ensuring the purity of the final lithium-rich solution. Furthermore, a second nitric acid solution with a molar concentration of 2 mol / L to 5 mol / L can exert its oxygen reduction-driven effect, directly displacing lithium in the six-membered ring chelate, causing lithium to transform from the chelate into a free liquid phase. This improves the efficiency of back-extraction while reducing the consumption of the second nitric acid solution.

[0068] The molar concentration of the first nitric acid solution can be 0.05 mol / L, 0.06 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.20 mol / L, 0.30 mol / L, 0.40 mol / L, 0.50 mol / L, or 1 mol / L.

[0069] The molar concentration of the second nitric acid solution can be 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, or 5.0 mol / L.

[0070] In some optional embodiments, the volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4 = 1:(0.05 to 2); and / or The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following: V5:V6=1:(0.02 to 0.2).

[0071] In these embodiments, a detergent with a volume ratio of 1:(0.05 to 2) to the supported organic phase can effectively wash away impurity ions such as sodium, iron, and chloride ions from the supported organic phase, which is beneficial for the purification and recovery of lithium in the subsequent washing aqueous phase and ensures the purity of the final lithium-rich solution. Additionally, a stripping agent with a volume ratio of 1:(0.02 to 0.2) to the washing aqueous phase can selectively break down lithium-ketone complexes, releasing lithium ions into the aqueous phase to form a lithium-rich solution and improving the purity of the lithium-rich solution.

[0072] The volume V4 of the supported organic phase can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.50, 1.0, 1.5 or 2.0.

[0073] The volume V6 of the washing aqueous phase can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.50, 1.0, 1.5 or 2.0.

[0074] Based on a general inventive concept, embodiments of this application provide a lithium carbonate, wherein the raw material for the lithium carbonate includes a lithium-rich solution obtained by the method; the lithium-rich solution has a lithium mass concentration of 15 g / L to 25 g / L.

[0075] The lithium carbonate is produced based on the above method. The specific steps of the method can be referred to the above embodiments. Since the lithium carbonate adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0076] It should be noted that a lithium-rich solution with a mass concentration of 15 g / L to 25 g / L indicates that this method can effectively extract and enrich the lithium component in high-alumina lithium-containing solutions, which is beneficial for the direct use of the lithium-rich solution. The mass concentration of lithium in this lithium-rich solution can be 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, or 25 g / L.

[0077] It should be noted that when the lithium mass concentration in the lithium-rich solution is less than 15 g / L, the lithium mass fraction in the lithium-rich solution is too low, which is not conducive to the subsequent lithium precipitation or direct use of the lithium-rich solution; when the lithium mass concentration in the lithium-rich solution is greater than 25 g / L, the lithium mass fraction in the lithium-rich solution is too high, which will cause the salts in the lithium-rich solution to co-crystallize with lithium and precipitate prematurely, resulting in lithium loss.

[0078] Figure 2 An exemplary schematic diagram of a method for preparing the lithium carbonate provided in an embodiment of this application is shown; Based on a general inventive concept, such as Figure 2 As shown in the embodiments of this application, a method for preparing the lithium carbonate is provided, the method comprising: S1. Lithium is precipitated in the lithium-rich solution obtained by the method using a lithium precipitation agent to obtain a crude lithium carbonate mixture; wherein the volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy: V7:V8 = (0.5 to 1.5):10; S2. Separate the crude lithium carbonate mixture to obtain a solid lithium carbonate phase; S3. The lithium carbonate solid phase is dried and crushed sequentially to obtain the lithium carbonate product.

[0079] This method relates to the preparation method of the lithium carbonate described above. The specific composition of the lithium carbonate can be referred to in the above embodiments. Since this method adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0080] It should be noted that a lithium precipitant with a volume ratio of (0.5 to 1.5):10 to the lithium-rich solution can effectively promote the binding of lithium with the lithium precipitant in the lithium-rich solution, ultimately yielding a high-purity lithium carbonate solid phase.

[0081] The volume V7 of the lithium precipitation agent can be 0.5, 0.6, 0.7, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0082] It should be noted that the lithium precipitation agent can be a carbonate or a bicarbonate, such as any one of sodium carbonate, sodium bicarbonate, and ammonium bicarbonate.

[0083] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0084] Example 1 The high-alumina lithium-containing solution has the following components: lithium ion concentration of 0.1 g / L, aluminum ion concentration of 0.02 g / L, sodium ion concentration of 1 g / L, and carbonate ion concentration of 0.1 g / L. The pH of this high-alumina lithium-containing solution is 8.0.

[0085] like Figure 1 As shown, a method for extracting lithium from a high-alumina lithium-containing solution includes: S1. A high-aluminum lithium-containing solution is extracted using a composite extractant to obtain a supported organic phase; wherein the composite extractant includes a ketone extractant and an organophosphorus extractant; the amount of the ketone extractant n1 and the amount of the organophosphorus extractant n2 satisfy: n1:n2≥1:2; S2. The loaded organic phase is washed with detergent to obtain a washing aqueous phase; S3. The washing aqueous phase is back-extracted using a back-extraction agent to obtain a lithium-rich solution.

[0086] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:0.2.

[0087] The type of ketone extractant is benzoyltrifluoroacetone.

[0088] The type of organophosphorus extractant is trialkylphosphine oxide.

[0089] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:10.

[0090] The composite extractant also includes kerosene as a diluent, and the volume of the diluent is 90% of the volume of the composite extractant.

[0091] The detergent includes a first nitric acid solution with a molar concentration of 0.05 mol / L; The stripping agent includes a second nitric acid solution with a molar concentration of 2 mol / L.

[0092] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following ratio: V3:V4=1:2; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.02.

[0093] A lithium carbonate, wherein the raw material for the lithium carbonate includes a lithium-rich solution obtained by the above method; the lithium-rich solution has a lithium mass concentration of 20 g / L.

[0094] like Figure 2 As shown in the embodiments of this application, a method for preparing lithium carbonate is provided, comprising: S1. Using ammonium carbonate as a lithium precipitant, lithium is precipitated in the lithium-rich solution obtained by the method to obtain a crude lithium carbonate mixture; wherein, the volume V7 of the lithium precipitant and the volume V8 of the lithium-rich solution satisfy: V7:V8=0.5:10. S2. Separate the crude lithium carbonate mixture to obtain a solid lithium carbonate phase; S3. The lithium carbonate solid phase is dried and crushed sequentially to obtain the lithium carbonate product.

[0095] Example 2 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 0.5 g / L, aluminum ion concentration of 0.05 g / L, sodium ion concentration of 2 g / L, and carbonate ion concentration of 1.0 g / L. The pH of this high-alumina lithium-containing solution is 8.0.

[0096] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:0.5.

[0097] The type of ketone extractant is benzoyltrifluoroacetone.

[0098] The organophosphorus extractant is tri-n-octylphosphine oxide.

[0099] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:3.

[0100] The volume of the diluent is 85% of the volume of the composite extractant.

[0101] The molar concentration of the first nitric acid solution is 0.1 mol / L; The molar concentration of the second nitric acid solution is 2 mol / L.

[0102] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4=1:1; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.1.

[0103] The lithium concentration in the lithium-rich solution is 23 g / L.

[0104] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following condition: V7:V8=0.8:10.

[0105] Example 3 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 1 g / L, aluminum ion concentration of 1 g / L, sodium ion concentration of 2 g / L, and carbonate ion concentration of 2.0 g / L. The pH of this high-alumina lithium-containing solution is 9.0.

[0106] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:1.

[0107] The type of ketone extractant is benzoyltrifluoroacetone.

[0108] The organophosphorus extractant is 2,4,4-trimethylpentylphosphonic acid.

[0109] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:2.

[0110] The volume of the diluent is 80% of the volume of the composite extractant.

[0111] The molar concentration of the first nitric acid solution is 0.2 mol / L; The molar concentration of the second nitric acid solution is 3 mol / L.

[0112] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4=1:1; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.1.

[0113] The lithium concentration in the lithium-rich solution is 25 g / L.

[0114] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=1:10.

[0115] Example 4 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 1 g / L, aluminum ion concentration of 2 g / L, sodium ion concentration of 3 g / L, and carbonate ion concentration of 2.0 g / L. The pH of this high-alumina lithium-containing solution is 10.0.

[0116] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:1.

[0117] The type of ketone extractant is 2-furanoyltrifluoroacetone.

[0118] The type of organophosphorus extractant is trihexyl(tetradecyl)phosphine bromide.

[0119] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:1.

[0120] The volume of the diluent is 75% of the volume of the composite extractant.

[0121] The molar concentration of the first nitric acid solution is 0.5 mol / L; The molar concentration of the second nitric acid solution is 3 mol / L.

[0122] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following ratio: V3:V4=1:0.5; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.05.

[0123] The lithium concentration in the lithium-rich solution is 20 g / L.

[0124] The lithium precipitation agent is sodium bicarbonate.

[0125] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=1:10.

[0126] Example 5 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 2 g / L, aluminum ion concentration of 3 g / L, sodium ion concentration of 4 g / L, and carbonate ion concentration of 3.0 g / L. The pH of this high-alumina lithium-containing solution is 11.0.

[0127] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:1.5.

[0128] The type of ketone extractant is 2-furanoyltrifluoroacetone.

[0129] The organophosphorus extractant is hexadecylphosphine bromide.

[0130] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following condition: V1:V2=1:0.25.

[0131] The volume of the diluent is 70% of the volume of the composite extractant.

[0132] The molar concentration of the first nitric acid solution is 0.5 mol / L; The molar concentration of the second nitric acid solution is 4 mol / L.

[0133] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following condition: V3:V4=1:0.1; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.02.

[0134] The lithium concentration in the lithium-rich solution is 25 g / L.

[0135] The lithium precipitation agent is sodium bicarbonate.

[0136] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following: V7:V8=1.2:10.

[0137] Example 6 Compared to Example 1, the differences in this example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 3 g / L, aluminum ion concentration of 5 g / L, sodium ion concentration of 5 g / L, and carbonate ion concentration of 5.0 g / L. The pH of this high-alumina lithium-containing solution is 12.0.

[0138] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:2.

[0139] The type of ketone extractant is 2-thiophenecarboxylic acid trifluoroacetone.

[0140] The type of organophosphorus extractant is trialkylphosphine oxide.

[0141] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following condition: V1:V2=1:0.2.

[0142] The volume of the diluent is 60% of the volume of the composite extractant.

[0143] The molar concentration of the first nitric acid solution is 1 mol / L; The molar concentration of the second nitric acid solution is 5 mol / L.

[0144] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following condition: V3:V4=1:0.05; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.04.

[0145] The lithium concentration in the lithium-rich solution is 15 g / L.

[0146] The lithium precipitation agent is ammonium bicarbonate.

[0147] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following: V7:V8=1.5:10.

[0148] Comparative Example 1 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following components: lithium ion concentration of 1 g / L, aluminum ion concentration of 2 g / L, sodium ion concentration of 2 g / L, and carbonate ion concentration of 2 g / L. The pH of this high-alumina lithium-containing solution is 9.0.

[0149] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:5.

[0150] The type of ketone extractant is benzoyltrifluoroacetone.

[0151] The type of organophosphorus extractant is trialkylphosphine oxide.

[0152] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:20.

[0153] The volume of the diluent is 70% of the volume of the composite extractant.

[0154] The detergent includes a first hydrochloric acid solution with a molar concentration of 0.5 mol / L; The stripping agent includes a second hydrochloric acid solution with a molar concentration of 2 mol / L.

[0155] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following condition: V3:V4=1:0.1; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.1.

[0156] The lithium concentration in the lithium-rich solution is 10 g / L.

[0157] The lithium precipitation agent is sodium carbonate.

[0158] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=0.5:10.

[0159] Comparative Example 2 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 2 g / L, aluminum ion concentration of 3 g / L, sodium ion concentration of 4 g / L, and carbonate ion concentration of 3 g / L. The pH of this high-alumina lithium-containing solution is 13.0.

[0160] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:1.

[0161] The type of ketone extractant is benzoyltrifluoroacetone.

[0162] The organophosphorus extractant is tri-n-octylphosphine oxide.

[0163] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following ratio: V1:V2=1:2.

[0164] The volume of the diluent is 75% of the volume of the composite extractant.

[0165] The detergent includes a first sulfuric acid solution with a molar concentration of 0.2 mol / L; The stripping agent includes a second sulfuric acid solution with a molar concentration of 4 mol / L.

[0166] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following ratio: V3:V4=1:0.5; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.1.

[0167] The lithium concentration in the lithium-rich solution is 10 g / L.

[0168] The lithium precipitation agent is sodium bicarbonate.

[0169] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=1:10.

[0170] Comparative Example 3 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following components: lithium ion concentration of 1.5 g / L, aluminum ion concentration of 0.5 g / L, sodium ion concentration of 2 g / L, and carbonate ion concentration of 2 g / L. The pH of this high-alumina lithium-containing solution is 10.0.

[0171] In the composite extractant, only benzoyltrifluoroacetone is used as a ketone extractant.

[0172] The volume of the diluent is 70% of the volume of the composite extractant.

[0173] The detergent includes a first nitric acid solution with a molar concentration of 0.1 mol / L; The stripping agent includes a second nitric acid solution with a molar concentration of 3 mol / L.

[0174] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4=1:1; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.15.

[0175] The lithium concentration in the lithium-rich solution is 8 g / L.

[0176] The lithium precipitation agent is sodium carbonate.

[0177] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=1:10.

[0178] Comparative Example 4 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 1 g / L, aluminum ion concentration of 2 g / L, sodium ion concentration of 3 g / L, and carbonate ion concentration of 3 g / L. The pH of this high-alumina lithium-containing solution is 11.0.

[0179] In the composite extractant, only trialkylphosphine oxide is used as an organophosphine extractant.

[0180] The volume of the diluent is 70% of the volume of the composite extractant.

[0181] The detergent includes a first nitric acid solution with a molar concentration of 0.5 mol / L; The stripping agent includes a second nitric acid solution with a molar concentration of 5 mol / L.

[0182] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following ratio: V3:V4=1:2; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.05.

[0183] The lithium concentration in the lithium-rich solution is 6 g / L.

[0184] The lithium precipitation agent is ammonium bicarbonate.

[0185] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following: V7:V8=1.5:10.

[0186] Comparative Example 5 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 2 g / L, aluminum ion concentration of 3 g / L, sodium ion concentration of 4 g / L, and carbonate ion concentration of 4 g / L. The pH of this high-alumina lithium-containing solution is 12.0.

[0187] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:1.

[0188] The type of ketone extractant is benzoyltrifluoroacetone.

[0189] The type of organophosphorus extractant is trialkylphosphine oxide.

[0190] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following condition: V1:V2=1:0.5.

[0191] The volume of the diluent is 75% of the volume of the composite extractant.

[0192] The detergent includes a first nitric acid solution with a molar concentration of 0.02 mol / L; The stripping agent includes a second nitric acid solution with a molar concentration of 1 mol / L.

[0193] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy the following ratio: V3:V4=1:0.8; The volume V5 of the stripping agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.01.

[0194] The lithium concentration in the lithium-rich solution is 7 g / L.

[0195] The lithium precipitation agent is sodium carbonate.

[0196] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following: V7:V8=1.2:10.

[0197] Comparative Example 6 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The high-alumina lithium-containing solution has the following composition: lithium ion concentration of 2.5 g / L, aluminum ion concentration of 4 g / L, sodium ion concentration of 5 g / L, and carbonate ion concentration of 5 g / L. The pH of this high-alumina lithium-containing solution is 12.0.

[0198] The amounts of ketone extractant n1 and organophosphorus extractant n2 satisfy the following ratio: n1:n2 = 1:0.5.

[0199] The type of ketone extractant is benzoyltrifluoroacetone.

[0200] The organophosphorus extractant is tri-n-octylphosphine oxide.

[0201] The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following condition: V1:V2=1:0.2.

[0202] The volume of the diluent is 65% of the volume of the composite extractant.

[0203] The detergent includes a first nitric acid solution with a molar concentration of 2 mol / L; The stripping agent includes a second nitric acid solution with a molar concentration of 10 mol / L.

[0204] The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4=1:80; The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following condition: V5:V6=1:0.1.

[0205] The lithium concentration in the lithium-rich solution is 12 g / L.

[0206] The lithium precipitation agent is sodium carbonate.

[0207] The volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy the following ratio: V7:V8=0.5:10.

[0208] Relevant experimental and effect data: The purity and total lithium recovery rate of the lithium carbonate products obtained in each embodiment and comparative example were statistically analyzed, and the results are shown in Table 1.

[0209] Table 1. Lithium carbonate product purity and lithium recovery rate for each example and comparative example.

[0210] As shown in Table 1, the method for extracting lithium from a high-alumina lithium-containing solution provided in this application utilizes a composite extraction system with n1:n2 ≥ 1:2 (mainly organophosphorus extractants, supplemented by ketone extractants). This system achieves efficient and deep separation of aluminum and lithium in the initial extraction stage, completely eliminating the greatest interference of the high-alumina environment on lithium extraction. This efficient source control, combined with subsequent targeted washing, purification, and back-extraction, significantly improves the quality of the final lithium-rich solution and the lithium extraction rate to over 99.50% while minimizing steps and time (short process). Simultaneously, lithium carbonate products with a purity of over 99.50% can be obtained.

[0211] Compared to Example 1, Comparative Example 1 used more organophosphorus extractants, and hydrochloric acid was used as the detergent and back-extraction agent. However, hydrochloric acid could not effectively wash away impurity ions or facilitate the back-extraction process, resulting in a lower lithium extraction rate and lower purity of the obtained lithium carbonate. Comparative Example 2 used sulfuric acid instead of nitric acid, which made it difficult for the washing and back-extraction processes to proceed smoothly, resulting in a lower lithium extraction rate and lower purity of the obtained lithium carbonate.

[0212] Compared to Example 1, Comparative Example 3 used a single ketone extractant as the extractant, while Comparative Example 4 used a single organophosphorus extractant as the extractant. This resulted in insufficient extraction, a significant reduction in the lithium extraction rate, and lower purity of the obtained lithium carbonate.

[0213] Compared to Example 1, Comparative Example 5 uses a lower concentration of nitric acid solution as both the washing and extraction agent. To ensure the stability of the nitric acid molecule's mass, a large amount of nitric acid solution needs to be added. This requires a larger container for the overall washing and back-extraction system and also affects the washing and back-extraction efficiency, resulting in a lower lithium extraction rate and lower purity of the obtained lithium carbonate. In contrast, Comparative Example 6 uses a higher concentration of nitric acid solution as both the washing and extraction agent. To ensure the stability of the nitric acid molecule's mass, a small amount of nitric acid solution needs to be added. This allows the washing and back-extraction processes to proceed rapidly, making it difficult to effectively remove impurities during the washing stage and affecting the subsequent lithium ion release during back-extraction, resulting in a lower lithium extraction rate and lower purity of the obtained lithium carbonate.

[0214] In summary, the embodiments of this application provide a method for extracting lithium from a high-aluminum lithium-containing solution. This method shortens the process by optimizing the extractant combination (especially by using a high proportion of organophosphorus extractants to preferentially remove aluminum), and significantly improves the lithium extraction rate and the quality of the final lithium-rich solution through the synergistic effect of each step (synergistic extraction → washing and purification → high-efficiency back-extraction).

[0215] In addition, this application provides a method for extracting lithium from a high-alumina lithium-containing solution. This method uses a composite extraction system formed by organophosphorus extractants and ketone extractants to directly extract lithium from the high-alumina lithium-containing solution without the need for pretreatment, solution alkalinity adjustment, or solution acidity adjustment for impurity removal. This solves the problem of low lithium ion extraction rate of ketone extractants in high-alumina lithium-containing solutions and improves the extraction efficiency and selectivity of lithium ions in high-alumina lithium-containing solutions.

[0216] In addition, this application provides a method for extracting lithium from a high-alumina lithium-containing solution. This method can directly use the high-alumina lithium-containing solution produced in the Bayer process for alumina production as raw material. Through a composite extraction system formed by organophosphorus extractants and ketone extractants, lithium-rich solutions can be directly extracted. These lithium-rich solutions have high purity and can be used to prepare high-purity lithium carbonate products. Moreover, the lithium recovery rate in the high-alumina lithium-containing solution is as high as 99.50% or more.

[0217] In addition, the embodiments of this application provide a method for extracting lithium from a high-alumina lithium-containing solution. This method only requires three steps: synergistic extraction with a composite extractant, washing and purification with a detergent, and efficient back-extraction with a back-extraction agent. The overall process is relatively short, and the final lithium recovery rate is high, which can achieve efficient lithium extraction from a high-alumina lithium-containing solution.

[0218] Furthermore, the embodiments of this application provide a lithium carbonate product with a purity of over 99.50% prepared by using the lithium-rich liquid obtained by the above method as raw material. These lithium carbonate products can be widely used in the preparation of battery-grade lithium carbonate.

[0219] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A method for extracting lithium from a high-alumina lithium-containing solution, the method comprising: A high-alumina lithium-containing solution was extracted using a composite extractant to obtain a supported organic phase; wherein the composite extractant includes a ketone extractant and an organophosphorus extractant; the amount of substance n1 of the ketone extractant and the amount of substance n2 of the organophosphorus extractant satisfy: n1:n2≥1:2; The loaded organic phase was washed with detergent to obtain a washing aqueous phase; The washing aqueous phase was back-extracted using a back-extraction agent to obtain a lithium-rich solution.

2. The method according to claim 1, characterized in that, The amount of substance n1 of the ketone extractant and the amount of substance n2 of the organophosphorus extractant satisfy the following: n1:n2=1:(0.2 to 2).

3. The method according to claim 1 or 2, characterized in that, The ketone extractant includes at least one of the following: benzoyltrifluoroacetone, 2-furanoyltrifluoroacetone, and 2-thiophenoyltrifluoroacetone.

4. The method according to claim 1 or 2, characterized in that, The types of organophosphorus extractants include trialkylphosphine oxide, tri-n-octylphosphine oxide, 2,4,4-trimethylpentylphosphine, trihexyl(tetradecyl)phosphine bromide, and hexadecylphosphine bromide.

5. The method according to claim 1, characterized in that, The volume V1 of the composite extractant and the volume V2 of the high-aluminum lithium-containing solution satisfy the following condition: V1:V2=1:(0.2 to 10).

6. The method according to claim 1, characterized in that, The composite extractant also includes a diluent, the volume of which is 60% to 90% of the volume of the composite extractant.

7. The method according to claim 1, characterized in that, The detergent includes a first nitric acid solution with a molar concentration of 0.05 mol / L to 1 mol / L; and / or The stripping agent includes a second nitric acid solution with a molar concentration of 2 mol / L to 5 mol / L.

8. The method according to claim 7, characterized in that, The volume V3 of the detergent and the volume V4 of the supported organic phase satisfy: V3:V4 = 1:(0.05 to 2); and / or The volume V5 of the back-extraction agent and the volume V6 of the washing aqueous phase satisfy the following: V5:V6=1:(0.02 to 0.2).

9. A lithium carbonate, wherein the raw material for the lithium carbonate comprises a lithium-rich liquid obtained by the method according to any one of claims 1 to 8; the lithium-rich liquid has a lithium mass concentration of 15 g / L to 25 g / L.

10. A method for preparing lithium carbonate according to claim 9, the method comprising: The lithium-rich solution obtained by the method according to any one of claims 1 to 8 is subjected to lithium precipitation using a lithium precipitation agent to obtain a crude lithium carbonate mixture; wherein the volume V7 of the lithium precipitation agent and the volume V8 of the lithium-rich solution satisfy: V7:V8 = (0.5 to 1.5):10; The crude lithium carbonate mixture was separated to obtain a solid lithium carbonate phase; The lithium carbonate solid phase is dried and crushed sequentially to obtain the lithium carbonate product.

Images