Method for extracting lithium from lithium-containing sodium aluminate solution and preparing lithium carbonate

Abstract

The invention relates to a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate, and belongs to the technical field of lithium recovery. The method comprises the following steps: adding an extracting agent into a lithium-containing sodium aluminate solution, and carrying out extraction reaction to obtain a lithium-removed sodium aluminate solution and a lithium-rich extracting solution; carrying out reverse extraction on the lithium-rich extraction liquid by taking water as a reverse extraction agent to obtain a lithium-containing solution; adding activated aluminum oxide into the lithium-containing solution, and carrying out adsorption reaction to obtain solid-phase aluminum oxide; eluting the solid-phase aluminum oxide with acid to obtain a lithium-rich solution; and adding a carbon source into the lithium-rich solution, and sequentially precipitating, separating and washing to obtain lithium carbonate. According to the method, a complex impurity removal process does not need to be carried out on the lithium-containing sodium aluminate solution, the high-concentration lithium salt solution is obtained after the lithium ions are directly extracted from the lithium-containing sodium aluminate solution and then are subjected to reverse extraction, adsorption and desorption, and industrial-grade lithium carbonate can be obtained by supplementing a carbon source, so that the preparation cost of the lithium carbonate is greatly reduced. The method has the advantages of good selectivity, high recovery rate, cyclic continuous production, economy and environmental protection.

Description

Technical Field

[0001] The present application relates to the field of lithium recovery technology, and in particular to a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate. Background Art

[0002] Lithium, a traditional high-quality energy storage material with excellent energy density and power efficiency, is widely used in new energy vehicles, electronic information, and energy storage systems. Demand for lithium salts continues to increase, but traditional lithium mineral resources are unable to meet the demand. my country's external dependence on lithium exceeds 70%, necessitating the urgent need to develop and utilize new lithium mineral resources. Bauxite, with its large reserves of lithium, could be a promising source of lithium demand if appropriate methods are employed.

[0003] Currently, lithium exists primarily in isomorphous forms in bauxite. During the Bayer process's alkaline dissolution process, lithium is leached into a sodium aluminate solution. Current methods for enriching lithium carbonate from alumina production processes primarily involve preparing a lithium-enriching carrier suitable for sodium aluminate environments. Then, process conditions are controlled to enrich and precipitate lithium from the sodium aluminate solution produced by the Bayer process or sintering process, thereby separating the lithium from the solution. A specific dissociation process is then used to dissociate the lithium from the carrier, producing a lithium solution. Finally, the lithium solution is purified, impurities removed, and concentrated, and a carbon source is added to produce lithium carbonate. However, this method suffers from high impurity removal costs, significant equipment investment, a lengthy process, and high energy consumption.

[0004] Solvent extraction technology has the advantages of high efficiency, strong continuity, simple operation, and low fixed cost investment. At present, there are no reports in the existing technology on extracting lithium from sodium aluminate solution and preparing high-grade lithium carbonate. Summary of the Invention

[0005] The present application provides a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate, in order to solve the following technical problem: how to extract lithium from the lithium resources associated with the existing alumina production process.

[0006] The present invention provides a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate, the method comprising:

[0007] adding an extractant to a lithium-containing sodium aluminate solution to carry out an extraction reaction to obtain a lithium-depleted sodium aluminate solution and a lithium-rich extract;

[0008] stripping the lithium-rich extract using water as a stripping agent to obtain a lithium-containing solution;

[0009] adding activated alumina to the lithium-containing solution to perform an adsorption reaction to obtain solid-phase alumina;

[0010] eluting the solid phase alumina with acid to obtain a lithium-rich solution;

[0011] adding a carbon source to the lithium-rich solution, and sequentially performing precipitation, separation, and washing to obtain lithium carbonate;

[0012] The temperature of the extraction reaction is 75° C. to 100° C., and the time of the extraction reaction is 15 min to 60 min.

[0013] Optionally, the mass concentration of lithium ions in the lithium-containing sodium aluminate solution is 0.3 g / L to 1.5 g / L.

[0014] Optionally, the extractant is a mixture of alkyl diphenols with a carbon chain length between C7 and C15, fluoroalcohols with a carbon chain length between C9 and C13, and fatty alcohols with a carbon chain length between C8 and C20.

[0015] Optionally, the volume ratio of the lithium-containing sodium aluminate solution to the extractant is (1-5):1.

[0016] Optionally, the volume ratio of the stripping agent to the lithium-rich extract is 1:(0.2-0.5).

[0017] Optionally, the stripping temperature is 40° C. to 60° C., and the stripping time is 10 min to 30 min.

[0018] Optionally, the specific surface area of the activated alumina is 350m 2 / g~480m 2 / g, and the added amount of the activated alumina is 5g / L to 50g / L.

[0019] Optionally, the temperature of the adsorption reaction is 80° C. to 100° C., and the time of the adsorption reaction is 60 min to 120 min.

[0020] Optionally, the acid is any one of sulfuric acid, hydrochloric acid and nitric acid, the concentration of the acid is 0.5 mol / L to 3 mol / L, and the elution time is 5 min to 30 min.

[0021] Optionally, the carbon source is any one of sodium carbonate, ammonium carbonate and potassium carbonate.

[0022] Optionally, the method can achieve: the purity of the prepared lithium carbonate is greater than 98.5%, and the lithium recovery rate is greater than 80%.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] An embodiment of the present application provides a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate. The method comprises: adding an extractant to the lithium-containing sodium aluminate solution to carry out an extraction reaction. The extractant is composed of a mixture of alkyl diphenols, fluoroalcohols, and fatty alcohols of a specific carbon chain length. Its molecular structure is highly selective for lithium ions and can effectively avoid the co-extraction of impurities such as aluminum, iron, calcium, and magnesium. Through the extraction reaction, lithium is transferred from the high-alkalinity sodium aluminate system to the organic phase, forming a lithium-rich extract; water is used as a stripping agent to strip the lithium-rich extract. Water can quickly transfer lithium ions from the organic extract phase (oil phase) to the aqueous phase through polarity, achieving efficient lithium separation and obtaining a lithium-containing solution; activated alumina is added to the lithium-containing solution for an adsorption reaction. The activated alumina, through its high specific surface area and surface active sites, can efficiently and selectively adsorb lithium ions in the solution while avoiding co-adsorption of impurities such as aluminum, iron, calcium, and magnesium; the adsorbed activated alumina is eluted and regenerated with acid, which can be reused, significantly reducing material costs, and obtaining a lithium-rich solution; a carbon source is added to the lithium-rich solution, and the carbonate ions (CO32-) in the carbon source react with the lithium ions (Li+) in the lithium-rich solution to form an insoluble lithium carbonate (Li2CO3) precipitate. This reaction is highly selective and can avoid co-precipitation of other co-existing impurities (such as aluminum and iron ions), thereby ensuring product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 A schematic flow chart of a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate is provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0029] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0030] Figure 1 A schematic flow chart of a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate is provided in an embodiment of the present application.

[0031] See Figure 1 The present invention provides a method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate, the method comprising:

[0032] S1, adding an extractant to a lithium-containing sodium aluminate solution to perform an extraction reaction to obtain a lithium-depleted sodium aluminate solution and a lithium-rich extract;

[0033] The extractant is a mixture of alkyl diphenols, fluoroalcohols, and fatty alcohols of specific carbon chain lengths. Its molecular structure is highly selective for lithium ions, effectively preventing the co-extraction of impurities such as aluminum, iron, calcium, and magnesium. Through the extraction reaction, lithium is transferred from the highly alkaline sodium aluminate system to the organic phase, forming a lithium-rich extract. The delithiation solution (containing sodium aluminate) can be returned to the main alumina process for recycling, avoiding the waste of lithium resources.

[0034] In some embodiments, the extractant is a mixture of alkyl diphenols with carbon chain lengths ranging from C7 to C15, fluoroalcohols with carbon chain lengths ranging from C9 to C13, and fatty alcohols with carbon chain lengths ranging from C8 to C20.

[0035] The long carbon chains of alkyl diphenols (C7-C15) form a stable hydrophobic structure. The coordination ability of their phenolic hydroxyl groups forms a specific chelation effect with lithium ions, inhibiting the co-extraction of metal ions such as aluminum, iron, calcium, and magnesium. The strong electronegativity of the fluorine atoms in fluoroalcohols (C9-C13) enhances the molecular polarity, enhancing the extraction efficiency of lithium through an ion exchange mechanism. At the same time, the chemical inertness of the fluorinated group can reduce the risk of extractant degradation. Fatty alcohols (C8-C20) act as co-extractants to regulate interfacial tension, improve the efficiency of oil-water phase separation, and reduce the entrainment of impurity ions through steric hindrance. The combination of the three as an extractant can synergistically improve lithium ion selectivity.

[0036] In some embodiments, the volume ratio of the lithium-containing sodium aluminate solution to the extractant is (1-5):1.

[0037] The volume ratio of the lithium-containing sodium aluminate solution and the extractant is (1-5):1. By controlling the contact area between the two phases, it is ensured that the lithium ions react fully with the extractant, while suppressing the co-extraction of impurity ions such as aluminum, iron, calcium, and magnesium. When the ratio exceeds 5:1, it may cause the viscosity of the solution to increase and phase separation to be difficult; when it is lower than 1:1, the mass transfer efficiency of lithium will be reduced. Selecting the interval of (1-5:1) ensures the rapid separation of the oil and water phases and avoids emulsification caused by excessive extractant. For example, the volume ratio of the lithium-containing sodium aluminate solution and the extractant can be 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0038] In some embodiments, the mass concentration of lithium ions in the lithium-containing sodium aluminate solution is 0.3 g / L to 1.5 g / L.

[0039] The mass concentration of lithium ions in the lithium-containing sodium aluminate solution is 0.3g / L to 1.5g / L, which can ensure the effective complexation of the extractant with lithium ions while suppressing the co-extraction of impurity ions such as aluminum and iron. In addition, this range covers the typical leachate concentration of lithium resources associated with bauxite (lithium dissolution under the Bayer process system is about 0.2g / L to 1.8g / L), and can be directly connected to the alumina production process without additional concentration or dilution, reducing intermediate processing costs. For example, the mass concentration of lithium ions in the lithium-containing sodium aluminate solution can be 0.3g / L, 0.6g / L, 0.9g / L, 1.2g / L, 1.5g / L, etc.

[0040] In some embodiments, the extraction reaction temperature is 75° C. to 100° C., and the extraction reaction time is 15 min to 60 min.

[0041] Temperatures between 75°C and 100°C enhance the interaction between extractant molecules and lithium ions, promoting the efficient mass transfer of lithium from the sodium aluminate solution to the organic phase. Furthermore, this temperature range effectively inhibits complexation reactions between aluminum, iron, calcium, and magnesium ions and the extractant, reducing co-extraction of impurities and ensuring the extraction system's selectivity for lithium. The extraction time window of 15 to 60 minutes balances mass transfer rate with energy costs. Furthermore, the temperature range of 75 to 100°C matches the thermal stability of the extractant, ensuring that it maintains its performance during repeated use. For example, the extraction reaction temperature can be 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C, and the extraction reaction time can be 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes. In the embodiments of the present application, stirring is performed during the extraction process. This stirring can forcefully mix the oil-water phases formed by the lithium-containing sodium aluminate solution and the extractant, increasing the contact area between the phases and accelerating the migration of lithium ions from the aqueous phase (sodium aluminate solution) to the organic phase (extractant). Secondly, stirring can avoid stratification caused by the density difference between the extractant and the solution, ensuring sufficient contact between the two phases, reducing the diffusion resistance of lithium ions, and increasing the speed at which the thermodynamic equilibrium of the reaction system is reached. Finally, through dynamic mixing, the mass transfer process that originally relied on natural diffusion can be shortened, significantly improving production efficiency.

[0042] S2, stripping the lithium-rich extract with water as a stripping agent to obtain a lithium-containing solution;

[0043] Water can quickly transfer lithium ions from the organic extraction phase (oil phase) to the water phase through polarity, achieving efficient separation of lithium. During the stripping process, when water comes into contact with the lithium-rich extract, lithium ions are redistributed to the water phase through interfacial mass transfer to form a lithium-containing solution. Water as a pure solvent does not contain other ions (such as Na + , Cl-, etc.), it is possible to avoid the introduction of new impurities during the stripping process, ensure the purity of the subsequent lithium solution, and reduce the cost of impurity removal. Compared with acidic or alkaline stripping agents, water is more suitable for scenarios with high requirements for the purity of the solution system. After stripping, the oil phase (extraction agent) can be recycled back to the extraction tank for reuse after separation from the aqueous phase, which significantly reduces the cost of extractant consumption. In the embodiment of the present application, stirring is performed during the stripping process, which can forcibly mix the oil phase (lithium-rich extract) and the aqueous phase (stripping agent), break the interfacial tension between the two phases through mechanical action, and significantly increase the contact area between the phases. This mechanism accelerates the migration speed of lithium ions from the organic phase to the aqueous phase and shortens the time required to reach dynamic equilibrium. In addition, dynamic stirring can suppress premature stratification caused by the difference in oil and water density, ensure that the two phases are fully in contact, and at the same time reduce the boundary layer resistance through turbulent disturbance, so that the lithium ion desorption process is more thorough, and the aqueous phase (lithium-containing solution) after the final phase separation has a higher purity.

[0044] In some embodiments, the volume ratio of the stripping agent to the lithium-rich extract is 1:(0.2-0.5).

[0045] The volume ratio of the stripping agent to the lithium-rich extract is 1: (0.2-0.5). By increasing the relative amount of the stripping agent (water), the efficient transfer of lithium ions from the organic phase (lithium-rich extract) to the aqueous phase is promoted. While ensuring the stripping effect, the problem of subsequent solution volume expansion caused by excessive stripping agent is avoided, which not only reduces the energy consumption of evaporation and concentration, but also prevents the concentration of the diluted lithium solution from being too low, which is beneficial to the material balance of the subsequent activated alumina adsorption step. In addition, by controlling the volume ratio of the two phases, the emulsification tendency of the oil-water mixed system can be reduced and the phase separation process can be accelerated. The separated oil phase can be directly returned to the extraction tank for reuse, reducing the loss of the extractant. For example, the volume ratio of the stripping agent to the lithium-rich extract can be 1: 0.2, 1: 0.3, 1: 0.4, 1: 0.5, etc.

[0046] In some embodiments, the stripping temperature is 40° C. to 60° C., and the stripping time is 10 min to 30 min.

[0047] In the embodiment of the present application, a stripping temperature of 40°C to 60°C helps to improve the stripping efficiency, because appropriate temperature increase can enhance molecular thermal motion, accelerate the mass transfer process, and promote the release of lithium ions from the organic phase to the aqueous phase. At the same time, this temperature range will not cause thermal decomposition or volatilization loss of the extractant. The stripping time of 10min to 30min can not only ensure the full desorption of lithium ions, but also avoid the increased energy consumption and potential side reactions (such as co-desorption of impurity ions) caused by too long a time. Exemplarily, the stripping temperature can be 40°C, 44°C, 48°C, 52°C, 56°C, 60°C, etc.; the stripping time can be 10min, 14min, 18min, 22min, 26min, 30min, etc.

[0048] S3, adding activated alumina to the lithium-containing solution to perform an adsorption reaction to obtain solid-phase alumina;

[0049] Activated alumina can efficiently adsorb lithium ions in the solution through its high specific surface area and surface active sites. This step is crucial for improving the purity of subsequent lithium carbonate products. After the adsorption reaction, lithium ions are enriched on the solid-phase alumina to form lithium-rich solid-phase alumina, which is conducive to the subsequent further extraction and purification of lithium ions through acid elution and other steps, providing a high-concentration lithium source for the preparation of lithium carbonate. Compared with traditional impurity removal methods, the use of activated alumina for adsorption reaction does not require complex impurity removal equipment and processes, and is simple to operate and easy to control, which helps to reduce production costs and improve production efficiency. The solid-phase alumina after the adsorption reaction can be regenerated by acid elution and other methods for recycling, which not only reduces material costs, but also reduces the generation of solid waste, which is beneficial to environmental protection.

[0050] In some embodiments, the specific surface area of the activated alumina is 350 m 2 / g~480m 2 / g, and the added amount of the activated alumina is 5g / L to 50g / L.

[0051] Specific surface area is one of the important indicators to measure the performance of adsorbents. The specific surface area of activated alumina reaches 350m 2 / g~480m 2 / g, which means that its surface provides more active sites and can accommodate more lithium ions, thereby increasing the lithium adsorption capacity of the unit mass adsorbent. In addition, the specific surface area is 350m 2 / g~480m 2 / g of activated alumina has more pores and channels, which are beneficial to the diffusion and transmission of lithium ions inside the adsorbent, thereby accelerating the adsorption rate and shortening the time required to reach adsorption equilibrium. The amount of activated alumina added is controlled in the range of 5g / L to 50g / L, which helps to achieve a dynamic balance between adsorption and desorption in the adsorption reaction. This equilibrium state ensures that lithium ions can be fully adsorbed, and avoids the increased difficulty of desorption and waste of resources caused by excessive adsorbent. In addition, by controlling the amount of activated alumina added in the range of 5g / L to 50g / L, the cost of using the adsorbent can be reduced while ensuring the lithium recovery efficiency. An amount less than 5g / L may lead to incomplete adsorption, while an amount more than 50g / L will increase unnecessary material consumption and the difficulty of subsequent processing. For example, the specific surface area of activated alumina can be 350m 2 / g、370m 2 / g、390m 2 / g、410m 2 / g, 430m 2 / g, 450m 2 / g, 470m 2 / g, 490m 2 / g, etc.; the added amount of activated alumina can be 5g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, etc.

[0052] In some embodiments, the temperature of the adsorption reaction is 80° C. to 100° C., and the time of the adsorption reaction is 60 min to 120 min.

[0053] The temperature range of 80℃ to 100℃ can accelerate the diffusion rate of lithium ions on the surface of activated alumina, while enhancing the reaction activity of the adsorption active sites. This is conducive to shortening the adsorption equilibrium time, increasing the lithium adsorption capacity per unit mass of alumina, and thus enhancing the overall adsorption efficiency. The upper temperature limit design of 100℃ can avoid the attenuation of specific surface area caused by the collapse of the activated alumina structure. The adsorption reaction time of 60min to 120min provides a sufficient contact cycle for ion exchange. For example, the temperature of the adsorption reaction can be 80℃, 84℃, 88℃, 92℃, 96℃, 100℃, etc.; the time of the adsorption reaction can be 60min, 70min, 80min, 90min, 100min, 110min, 120min, etc.

[0054] S4, eluting the solid phase alumina with acid to obtain a lithium-rich solution;

[0055] The activated alumina after adsorption is regenerated through acid elution to release high-purity lithium solution, which can be reused itself, thereby significantly reducing material costs. At the same time, this also reduces the generation of solid waste and is beneficial to environmental protection.

[0056] In some embodiments, the acid is any one of sulfuric acid, hydrochloric acid and nitric acid, the concentration of the acid is 0.5 mol / L to 3 mol / L, and the elution time is 5 min to 30 min.

[0057] Sulfuric acid, hydrochloric acid and nitric acid, as strong acids, can effectively destroy the binding force between lithium ions and the surface of activated alumina, allowing the lithium adsorbed on the activated alumina to be quickly desorbed into the solution, forming a high-concentration lithium-rich solution. This step is crucial for the subsequent precipitation and preparation of lithium carbonate. The acid elution effect ensures that the lithium ions adsorbed on the activated alumina are fully released, thereby improving the overall recovery rate of lithium. In an acidic environment, the dissolution of impurity ions such as aluminum is suppressed, which helps to improve the selective separation efficiency of lithium and ensure the purity of the final product, lithium carbonate.

[0058] The acid concentration is controlled within the range of 0.5mol / L to 3mol / L, which can effectively destroy the binding force between lithium and the surface of activated alumina, allowing the adsorbed lithium to be quickly desorbed into the solution to form a lithium-rich solution. At the same time, the acidic environment can inhibit the dissolution of impurity ions such as aluminum, thereby improving the selective separation efficiency of lithium. Controlling the acid concentration within the range of 0.5mol / L to 3mol / L can not only ensure the elution rate of lithium, but also avoid the destruction of the crystal structure of activated alumina by strong acid, ensure the stability of its specific surface area and adsorption performance, and thus achieve recycling. For example, the acid concentration can be 0.5mol / L, 1.0mol / L, 1.5mol / L, 2.0mol / L, 2.5mol / L, 3mol / L, etc.

[0059] The elution time is set to 5 to 30 minutes. This allows for sufficient lithium release through kinetic equilibrium, ensuring thorough elution while avoiding increased acid consumption and equipment corrosion risks associated with excessive elution times, thereby improving overall elution efficiency. For example, the elution time can be 5, 10, 15, 20, 25, or 30 minutes.

[0060] S5, adding a carbon source to the lithium-rich solution, and sequentially performing precipitation, separation, and washing to obtain lithium carbonate;

[0061] Adding a carbon source to a lithium-rich solution for precipitation, separation, and washing not only helps to prepare high-purity lithium carbonate efficiently and selectively, but also simplifies the process flow, improves product quality, and has environmentally friendly advantages.

[0062] In some embodiments, the carbon source is any one of sodium carbonate, ammonium carbonate and potassium carbonate.

[0063] Sodium carbonate (Na2CO3), ammonium carbonate ((NH4)2CO3) and potassium carbonate (K2CO3) are all strongly alkaline carbonates, and their carbonate ions (CO32-) react with lithium ions (Li+) in lithium-rich solutions to form insoluble lithium carbonate (Li2CO3) precipitates. This reaction is highly selective and can avoid the co-precipitation of other coexisting impurities, thereby ensuring product purity. By adding a carbon source and controlling the precipitation conditions, the lithium ions in the solution can be efficiently converted into solid lithium carbonate, achieving effective lithium recovery and significantly improving the utilization rate of lithium resources. Using carbonate as a carbon source, the precipitation reaction conditions are relatively mild, the operation is simple, and no complex equipment or extreme conditions are required, which is conducive to reducing production costs and reducing energy consumption. At the same time, the precipitated product, lithium carbonate, is easy to separate and wash, further simplifying subsequent processing steps. Carbon sources such as sodium carbonate, ammonium carbonate and potassium carbonate are widely available, relatively low in cost, and no harmful by-products are produced during the reaction, making them environmentally friendly.

[0064] In some embodiments, the method can achieve: the purity of the prepared lithium carbonate is greater than 98.5%, and the lithium recovery rate is greater than 80%.

[0065] In the embodiments of the present application, by optimizing the synergistic effect of extraction, stripping, adsorption and precipitation process parameters, a significant technical effect of lithium carbonate purity greater than 98.5% and lithium recovery rate greater than 80% can be achieved.

[0066] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0067] Example 1

[0068] Place 50L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.3g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 75℃, and the extraction time is 30min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 10L of pure water, the stripping temperature is 50℃, and the stripping time is 10min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 480m 2 / g) 10g, the adsorption temperature was controlled at 80°C, and the adsorption time was 60min; after adsorption, the activated alumina was eluted with 0.5L of hydrochloric acid (0.5mol / L) for 30min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation, with a purity of 98.6% and a lithium recovery rate of 81%.

[0069] Example 2

[0070] Place 30L of lithium-containing sodium aluminate solution with a lithium ion concentration of 1.0g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 85℃, and the extraction time is 60min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 5L of pure water, the stripping temperature is 60℃, and the stripping time is 20min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 350m 2 / g) 50g, the adsorption temperature was controlled at 100°C, and the adsorption time was 100min; after adsorption, the activated alumina was eluted with 0.5L of sulfuric acid (3mol / L) for 5min; after the elution was completed, the solid-liquid separation was completed, potassium carbonate was added to the liquid phase, and lithium carbonate was precipitated and separated, with a purity of 99.0% and a lithium recovery rate of 82%.

[0071] Example 3

[0072] Place 10L of lithium-containing sodium aluminate solution with a lithium ion concentration of 1.5g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 100℃, and the extraction time is 15min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 2L of pure water, the stripping temperature is 50℃, and the stripping time is 30min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 400m 2 / g) 100g, the adsorption temperature was controlled at 95°C, and the adsorption time was 120min; after adsorption, the activated alumina was eluted with 1.0L of nitric acid (0.5mol / L), and the elution time was 10min; after the elution was completed, the solid-liquid separation was completed, ammonium carbonate was added to the liquid phase, and lithium carbonate was precipitated and separated, with a purity of 98.7% and a lithium recovery rate of 81%.

[0073] Example 4

[0074] Place 25L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.3g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 85℃, and the extraction time is 30min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 3L of pure water, the stripping temperature is 50℃, and the stripping time is 15min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 380m 2 / g) 60g, the adsorption temperature was controlled at 90°C, and the adsorption time was 120min; after adsorption, the activated alumina was eluted with 0.5L of hydrochloric acid (0.5mol / L) for 30min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation. The purity of the lithium carbonate was 98.6%, and the recovery rate of lithium was 80%.

[0075] Example 5

[0076] Place 40L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.6g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 95℃, and the extraction time is 60min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 3L of pure water, the stripping temperature is 55℃, and the stripping time is 20min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 450m 2 / g) 120g, the adsorption temperature was controlled at 80°C, and the adsorption time was 50min; after adsorption, the activated alumina was eluted with 0.5L of hydrochloric acid (2.0mol / L) for 20min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation. The purity of the lithium carbonate was 99.6%, and the recovery rate of lithium was 84%.

[0077] Comparative Example 1

[0078] Place 50L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.3g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 45℃, and the extraction time is 30min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 10L of pure water, the stripping temperature is 50℃, and the stripping time is 10min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 350m 2 / g) 10g, the adsorption temperature was controlled at 80°C, and the adsorption time was 60min; after adsorption, the activated alumina was eluted with 0.5L of hydrochloric acid (0.5mol / L) for 30min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation, with a purity of 98.7% and a lithium recovery rate of 56%.

[0079] Comparative Example 2

[0080] Place 40L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.6g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 95℃, and the extraction time is 60min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 3L of pure water, the stripping temperature is 55℃, and the stripping time is 5min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 450m 2 / g) 120g, the adsorption temperature was controlled at 80°C, and the adsorption time was 50min; after adsorption, the activated alumina was eluted with 0.5L of hydrochloric acid (2.0mol / L) for 20min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation. The purity of the lithium carbonate was 99.4%, and the recovery rate of lithium was 43%.

[0081] Comparative Example 3

[0082] Place 25L of lithium-containing sodium aluminate solution with a lithium ion concentration of 0.3g / L in an extraction tank, add 10L of extractant, stir and mix evenly, the extraction temperature is 85℃, and the extraction time is 30min; after phase separation, transfer the lithium-rich extract to the stripping tank, pass 1L of pure water, the stripping temperature is 50℃, and the stripping time is 15min. After phase separation, the extractant can continue to extract repeatedly with the lithium-containing sodium aluminate solution. Add activated alumina (specific surface area of 380m 2 / g) 60g, the adsorption temperature was controlled at 90°C, and the adsorption time was 45min; after adsorption, the activated alumina was eluted with 0.3L of hydrochloric acid (0.5mol / L) for 30min; after the elution was completed, the solid-liquid separation was completed, sodium carbonate was added to the liquid phase, and lithium carbonate was separated by precipitation. The purity of the lithium carbonate was 98.5%, and the recovery rate of lithium was 44%.

[0083] By comparing Example 1 with Comparative Example 1, it can be seen that lowering the extraction temperature will result in a lower recovery rate; by comparing Example 5 with Comparative Example 2, it can be seen that lowering the stripping time will result in a lower recovery rate; by comparing Example 4 with Comparative Example 3, it can be seen that lowering the acid concentration will result in a lower recovery rate.

[0084] One or more technical solutions in the embodiments of the present invention may have at least the following technical effects or advantages:

[0085] In the embodiment of the present invention, the lithium extraction solution has high selectivity, which can prevent aluminum, iron, calcium, magnesium and other ions in the lithium-containing sodium aluminate solution from entering the extraction solution.

[0086] The lithium carbonate obtained in the embodiment of the present invention is not only high in purity, but also easy to operate and non-corrosive to equipment.

[0087] In the embodiment of the present invention, the extractant and the adsorbent can be recycled, which greatly reduces the production cost and avoids environmental pollution.

[0088] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present 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 the present application. Therefore, the present application is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for extracting lithium from a lithium-containing sodium aluminate solution and preparing lithium carbonate, the method comprising: adding an extractant to a lithium-containing sodium aluminate solution to carry out an extraction reaction to obtain a lithium-depleted sodium aluminate solution and a lithium-rich extract; stripping the lithium-rich extract using water as a stripping agent to obtain a lithium-containing solution; adding activated alumina to the lithium-containing solution to perform an adsorption reaction to obtain solid-phase alumina; eluting the solid phase alumina with acid to obtain a lithium-rich solution; adding a carbon source to the lithium-rich solution, and sequentially performing precipitation, separation, and washing to obtain lithium carbonate; The temperature of the extraction reaction is 75° C. to 100° C., and the time of the extraction reaction is 15 min to 60 min.

2. The method according to claim 1, characterized in that The mass concentration of lithium ions in the lithium-containing sodium aluminate solution is 0.3 g / L to 1.5 g / L.

3. The method according to claim 1, characterized in that The extractant is a mixture of alkyl diphenols with a carbon chain length between C7 and C15, fluoroalcohols with a carbon chain length between C9 and C13, and fatty alcohols with a carbon chain length between C8 and C20.

4. The method according to claim 1, wherein The volume ratio of the lithium-containing sodium aluminate solution to the extractant is (1-5):

1.

5. The method according to claim 1, wherein The volume ratio of the stripping agent to the lithium-rich extract is 1:(0.2-0.5).

6. The method according to claim 1, characterized in that The stripping temperature is 40° C. to 60° C., and the stripping time is 10 min to 30 min.

7. The method according to claim 1, characterized in that The specific surface area of the activated alumina is 350m 2 / g~480m 2 / g, the added amount of the activated alumina is 5g / L to 50g / L; and / or, The temperature of the adsorption reaction is 80° C. to 100° C., and the time of the adsorption reaction is 60 min to 120 min.

8. The method according to claim 1, characterized in that The acid is any one of sulfuric acid, hydrochloric acid and nitric acid, the concentration of the acid is 0.5 mol / L to 3 mol / L, and the elution time is 5 min to 30 min.

9. The method according to claim 1, characterized in that The carbon source is any one of sodium carbonate, ammonium carbonate and potassium carbonate.

10. The method according to claim 1, wherein The method can achieve: the purity of the prepared lithium carbonate is greater than 98.5%, and the lithium recovery rate is greater than 80%.

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