Method for efficiently extracting lithium from strongly alkaline lithium-containing system and application

Abstract

The invention discloses a method for efficiently extracting lithium from a strongly basic lithium-containing system, which comprises the following steps: adding a regulator into a strongly basic lithium-containing solution, uniformly mixing, respectively adding an inducer and a reaction aid, applying ultrasonic microwaves to the obtained mixture for reaction, and performing solid-liquid separation after the reaction is finished to obtain a lithium-rich solution and a lithium-rich solid; s2, adsorbing and extracting the lithium-rich solution obtained in the step S1 by adopting a lithium adsorbent to obtain a high-quality lithium-rich solution; s2, dispersing the lithium-rich solid obtained in the step S1 into the lithium extraction enrichment liquid, carrying out solid-liquid separation after full reaction to obtain high-quality lithium-rich liquid and residual lithium solid, and returning the residual lithium solid to the step S1 for reaction again; and S3, mixing the high-quality lithium-rich liquid obtained in the steps S2 and S3, concentrating, and removing impurities to obtain the purified lithium-rich liquid. The method is suitable for lithium resource recovery of the strongly alkaline lithium-containing solution containing macro associated ions, the technological operation is simple and convenient, zero waste discharge is realized, and efficient lithium ion whole-process complete recovery can be realized.

Description

Technical Field

[0001] This invention relates to the field of lithium resource recovery technology, and in particular to a method and application for efficient lithium extraction from a strongly alkaline lithium-containing system. Background Technology

[0002] Lithium, as a core strategic resource in the new energy industry, is a key raw material for lithium-ion batteries, energy storage devices, and new energy vehicles. With the advancement of the "dual-carbon" goals, the scale of the new energy industry continues to expand, leading to a surge in demand for lithium resources. However, global lithium reserves are limited and their distribution is highly uneven, resulting in an increasingly prominent supply-demand imbalance. Simultaneously, a significant portion of lithium resources are found in the large quantities of strongly alkaline lithium-containing materials generated during industrial production (such as alkaline leaching solutions from ores, lithium-containing mother liquor from salt lakes, and industrial lithium-containing wastewater). Failure to recycle these resources not only wastes lithium but also leads to soil pollution from solid waste accumulation and water pollution from wastewater discharge due to the highly alkaline environment, contradicting the principles of green development. Therefore, developing efficient lithium resource recovery technologies for highly alkaline systems is crucial.

[0003] However, the unique chemical environment of strongly alkaline systems presents multiple challenges to conventional lithium resource recovery. Existing technologies generally suffer from poor adaptability, low recovery rates, and severe interference from impurities. Conventional precipitation methods exhibit poor selectivity, low lithium recovery rates, and significant purification difficulties, while also generating substantial amounts of solid waste. Existing lithium adsorbents exhibit poor stability in strongly alkaline environments, are prone to structural collapse, and suffer from poor adsorption selectivity. In extraction methods, conventional lithium extractants are susceptible to hydrolysis and failure in strongly alkaline systems, leading to reagent waste and secondary pollution. If membrane recovery is employed, the strongly alkaline environment can corrode conventional organic membranes, causing membrane flux decline, and the high concentration of impurity ions in the system can cause membrane fouling, resulting in extremely high maintenance costs.

[0004] There is an urgent need to develop a lithium resource recovery process that is adaptable to strongly alkaline systems, has a high recovery rate, and is environmentally friendly, so as to realize the resource utilization of industrial lithium-containing alkaline materials. Summary of the Invention

[0005] The purpose of this invention is to provide a highly efficient lithium resource recovery technology for strongly alkaline lithium-containing systems. This technology is applicable to the recovery of lithium resources in strongly alkaline lithium-containing solutions containing a large amount of associated ions. The process is simple to operate, produces zero waste, conforms to the principles of green chemistry, and can achieve efficient and complete lithium ion recovery throughout the entire process.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for efficiently extracting lithium from a strongly alkaline lithium-containing system includes the following steps: S1. Add a regulator to a strongly alkaline lithium-containing solution, mix well, and then add an inducer and a reaction aid. Apply ultrasonic microwave to the mixture to carry out the reaction. After the reaction is completed, perform solid-liquid separation to obtain a lithium-rich solution and a lithium-rich solid. The regulator is a mixture of lithium salt and aluminum salt, and the inducer is a Li / Al-LDHs seed crystal. S2. The lithium-rich solution obtained in step S1 is adsorbed and extracted using a lithium adsorbent to obtain a high-quality lithium-rich solution. S3. Disperse the lithium-rich solid obtained in step S1 in the lithium enrichment solution. After the reaction is complete, separate the solid and liquid to obtain the high-quality lithium-rich solution and residual lithium solid. Return the residual lithium solid to step S1 and add it back to the reaction. S4. The high-quality lithium-rich solution obtained by mixing steps S2 and S3 is concentrated and purified to obtain a purified lithium-rich solution.

[0007] In this invention, the strongly alkaline lithium-containing solution mainly refers to waste materials generated during industrial production that are accompanied by large quantities of strongly alkaline lithium-containing materials, such as alkaline leaching solutions from ores, lithium precipitation mother liquor from salt lakes, and industrial lithium-containing wastewater. Their pH range is generally 9-14, and the lithium ion concentration is typically 0.1-15 g / L, containing various impurity cations and anions. Impurity cations include, but are not limited to, Na+. + K + 、Rb + Cs + Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ Pb 2+ Sn 2+ Bi 3+ Cr 3+ Sn 4+ It may contain one or more of the following, for example, two, three, four, five, six or more impurity cations. Impurity anions include, but are not limited to, Cl. - CO3 2- NO3 - SO4 2- PO4 3- F - ,Br - B4O7 2- It may contain one or more of the following, for example, two, three, four, five, six or more impurity anions.

[0008] In step S1 of this invention, the regulator used is a mixture of lithium and aluminum salts, such as a mixed solution of lithium and aluminum salts. In a further preferred embodiment, the aluminum salt in step S1 includes, but is not limited to, one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, polyaluminum sulfate, and aluminum silicate; the lithium salt includes, but is not limited to, one or more of lithium nitrate, lithium sulfate, lithium chloride, lithium hydroxide, and lithium perchlorate. The lithium-aluminum molar ratio of the mixed solution obtained after adding the regulator is 1:0.2-10. For example, the ratio interval step can be adjusted in increments of 0.1, such as 1:0.2, 1:0.3, 1:0., ..., 1:10. The purpose of adding the regulator is to increase the proportion of lithium-aluminum bimetallic hydroxides (Li / Al-LDHs) in the solid phase generated in step S1, reduce the formation of other hydroxides, and improve the selective extraction of lithium in subsequent processes.

[0009] In a further preferred embodiment, the inducer in step S1 is a Li / Al-LDHs seed crystal, such as one or more of LiCl·2Al(OH)3, LiNO3·2Al(OH)3, Li2SO4·4Al(OH)3, and Li2CO3·4Al(OH)3. The total amount of inducer added is 0.1%-5% by weight of the strongly alkaline lithium-containing solution. The inducer is used to precisely induce the directional reaction between lithium ions and the aluminum source in the solution by adding specific seed crystals to the lithium-containing mixed solution, thereby achieving the desired reaction of Li... + The precise capture of lithium generates Li / Al-LDHs, which greatly promotes the subsequent efficient lithium extraction reaction and further facilitates the selective extraction of lithium.

[0010] To promote the reaction, in step S1, during the addition of regulators and other materials, and in each reaction process, one or more of the following methods can be used to ensure that the added regulators are fully mixed with the strong alkaline solution, the inducer with the reaction solution, and the reaction aid with the reaction solution, or to promote the rapid progress of the reaction.

[0011] In a further preferred embodiment, the reaction aid in step S1 is at least one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, and acetic acid, and the feed flow rate is preferably 2~100 mL / min.

[0012] In a further preferred embodiment, in step S1, the applied microwave power is preferably 100-800 W, the reaction temperature is preferably 30-60 ℃, the applied ultrasonic power is preferably 100-500 W, the reverse working interval is preferably 1-20 s, and the total reaction time is preferably 0.5-4 h. The ultrasonic and microwave treatment can be applied by placing the obtained mixture in a microwave reactor or by other methods known in the art. By applying ultrasonic + microwave-assisted reaction, instantaneous and uniform heating of the reaction system is achieved, significantly enhancing the mass transfer and reaction kinetics of the reaction system, laying the foundation for efficient delithiation of lithium-rich solids.

[0013] In a further preferred embodiment, in step S2, the process of extracting lithium using a lithium adsorbent mainly involves adsorption and desorption. During adsorption, the selected lithium adsorbent is brought into contact with a lithium-rich solution, allowing lithium ions in the solution to be adsorbed onto the adsorbent. During desorption, a desorption solution is used to desorb the lithium ions adsorbed onto the adsorbent into the desorption solution, thereby achieving lithium ion extraction. The adsorption and desorption processes can be implemented using various methods known in the art, such as using a single or multiple adsorption columns filled with lithium adsorbent, or using a continuous ion exchange device, or more simply, directly adding the lithium adsorbent to the lithium-rich solution for adsorption (preferably, stirring or other operations can be used to promote the adsorption reaction), and then separating the adsorbent for desorption, etc. To achieve the desired adsorption and desorption effects of this invention, the lithium adsorbent is preferably one or more of manganese-based ion sieves, titanium-based ion sieves, aluminum-based adsorbents, or chelating resins. Preferably, the desorption solution is deionized water, ultrapure water, a lithium-containing solution, hydrochloric acid, etc. The conventional parameters used in the adsorption and desorption processes can be reasonably adjusted according to actual conditions, such as the feed flow rate and feed temperature of the lithium-rich solution to be adsorbed and the desorption solution. In this application, the feed flow rate is less than 20 mL / min, and the feed temperature is room temperature or less than 50°C. Depending on the selected adsorption and desorption method, appropriate parameters are chosen as indicators of the completion of adsorption and desorption. For example, when using a single or multiple adsorption columns, the completion of adsorption or desorption can be considered a sign that the solution concentration has stopped, and the operation can be stopped.

[0014] In a further preferred embodiment, in step S3, the lithium extraction enrichment solution is deionized water or ultrapure water, and the feeding ratio of lithium-rich solid to lithium extraction enrichment solution is 1g:10-500mL.

[0015] In a further preferred embodiment, in step S3, saturated steam or high-temperature steam at 100-300°C can be introduced into the reactor to assist the reaction, such as saturated steam at 100°C, steam at 200°C, steam at 300°C, etc., with a steam flow rate of 0.1-10 mL / s, a reaction stirring rate of 300-1000 rpm, and a reaction time of 0.5-8 h. The saturated steam or high-temperature steam can be continuously or pulsedly introduced from the bottom of the reactor using an external steam source. By adding high-temperature steam or saturated steam, firstly, instantaneous high-temperature heating of the lithium-rich solid can be achieved (the heating of traditional water systems is limited by the boiling point of water), accelerating the delithiation rate and strengthening the delithiation intensity; secondly, the intense micro-turbulence and disturbance effect generated by the rising steam flow makes the contact between the lithium extraction enrichment solution and the lithium-rich solid more sufficient, greatly promoting the extraction and enrichment of lithium.

[0016] In a further preferred embodiment, the solid-liquid separation method used in steps S1 and S3 is not limited and may include various solid-liquid separation methods known in the art, such as at least one of vacuum filtration, decantation, centrifugation, and gravity sedimentation.

[0017] In a further preferred technical solution, the concentration method described in step S4 includes, but is not limited to, one or a combination of two or more of the following: reverse osmosis concentration, electrodialysis concentration, multi-effect evaporation concentration, rotary evaporation concentration, and MVR concentration.

[0018] In a further preferred embodiment, the impurity removal method described in step S4 includes, but is not limited to, one or a combination of two or more of nanofiltration, electrodialysis, reverse osmosis, ion exchange, adsorption, and chemical precipitation. By removing impurity metal ions from the solution through impurity removal treatment, a purified lithium-rich solution is obtained, with a purity of over 99%.

[0019] To verify the overall effectiveness of each step of the method and the overall technical solution of the present invention, after steps S1, S2, S3, and S4, the lithium content in lithium-containing solids and / or lithium-containing solutions, as known in the art, is determined using ICP technology, and the lithium recovery effect is calculated and evaluated. Specifically, for lithium-rich solids, the lithium-rich solids are first dissolved into a solution using acid, then the lithium concentration is measured using ICP, and then converted into lithium content; for lithium-containing solutions, the lithium concentration is directly measured using ICP, and then converted into lithium content. The present invention relates to the following calculation formula: 1. For the lithium-rich solid obtained after processing in step S1 of the method of the present invention, the solid-phase lithium enrichment rate of the lithium-rich solid is calculated using formula A: Solid-phase lithium enrichment rate (%) = Lithium content in lithium-rich solid / Lithium content in initial strongly alkaline lithium-containing solution * 100% A 2. For the high-quality lithium-rich solution after adsorption treatment in step S2 of this invention, the lithium adsorption extraction rate is calculated using formula B: Lithium adsorption extraction rate (%) = Lithium content of the high-quality lithium-rich liquid obtained in step S2 / Lithium content of the lithium-rich solution obtained in step S1 * 100% 3. For the high-quality lithium-rich liquid obtained in step S3, calculate the liquid phase lithium enrichment rate using formula C: Liquid phase lithium enrichment rate (%) = High-quality lithium-rich liquid lithium content obtained in step S3 / Lithium-rich solid lithium content * 100% C 4. For the purified lithium-rich solution obtained in step S4, calculate the total lithium recovery rate using formula D: Total lithium recovery rate (%) = Lithium content of purified lithium-rich solution / Lithium content of initial strongly alkaline lithium-containing solution * 100% The present invention also relates to the application of the above-mentioned method for efficiently extracting lithium from a strongly alkaline lithium-containing system in the recovery of lithium ions from a strongly alkaline lithium-containing system.

[0020] In a further preferred embodiment, the purified lithium-rich solution obtained in step S4 can be processed into lithium products using various techniques or methods known in the art. For example, a precipitation method can be used to precipitate lithium from a high-concentration lithium solution, followed by washing and drying to obtain the corresponding lithium product. In this case, for the purified lithium-rich solution obtained in step S4, the amount of precipitant added during the precipitation process is preferably (1-3):2, based on the molar ratio of carbonate to lithium ions in the purified lithium-rich solution. The reaction temperature is preferably 50-90℃, and the reaction time is preferably 0.5-5h. The washing is preferably done with pure water, and the washing temperature is preferably 30-100℃. Preferred drying methods include vacuum drying, forced-air drying, conduction drying, and spray drying. Alternatively, the purified lithium-rich solution obtained in step S4 can be processed into lithium hydroxide using causticization, membrane methods, etc., or processed into desired lithium-containing products, such as lithium phosphate, lithium dihydrogen phosphate, etc., using other methods known in the art.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention successfully constructs a lithium resource recovery technology adapted to complex systems with strong alkalinity and a large number of associated ions. By employing a simple and easy-to-operate reaction process and readily available raw materials and reagents, it achieves efficient and highly selective separation and recovery of lithium ions from other impurity ions. Through solid-phase and liquid-phase lithium enrichment, a high-quality purified lithium-rich solution is obtained. The overall lithium recovery rate in a single reaction reaches over 97.5%, with a maximum of 99.5%. Furthermore, since the residual lithium solid obtained from the reaction is returned to the initial strong alkaline lithium-containing solution for further recovery, no actual lithium element is lost. If the entire reaction process is repeated sufficiently, the overall lithium recovery rate can theoretically approach 100%. Simultaneously, the lithium-containing product obtained from the purified lithium-rich solution has a purity exceeding 99.5%. This invention achieves zero waste discharge, is environmentally friendly, and green economical, realizing the resource utilization of strongly alkaline industrial lithium-containing materials, and has significant economic and environmental value. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the X-ray diffraction patterns of the lithium-rich solid and the residual lithium solid obtained by solid-phase enrichment of the strongly alkaline lithium-containing solution in Example 1.

[0023] Figure 2 This is a scanning electron microscope (SEM) schematic diagram of the lithium-rich solid obtained by solid-phase enrichment of the strongly alkaline lithium-containing solution in Example 1.

[0024] Figure 3 This is a schematic diagram of the particle size distribution of the lithium-rich solid obtained by solid-phase enrichment of a strongly alkaline lithium-containing solution in Example 1. Detailed Implementation

[0025] To facilitate understanding of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Those skilled in the art should understand that the described embodiments are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0026] Example 1 This embodiment focuses on lithium resource recovery from an alkaline leaching solution of ore. The solution has a pH of 13.8 and a lithium ion concentration of 12.6 g / L. Its main impurities are Na, K, Si, and Ca, with Cl- as the anion. - For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Aluminum chloride and lithium chloride were added to a strongly alkaline lithium-containing solution, and the solution was ultrasonically treated for 30 min to obtain a mixed solution with a lithium-aluminum ratio of 1:2. 0.1% LiCl·2Al(OH)3 seed crystals were then added. Hydrochloric acid was pumped into the alkaline mixed solution at a feed rate of 10 mL / min using a peristaltic pump. The resulting slurry was placed in a microwave reactor with a microwave power of 100 W, a reaction temperature of 40 °C, an ultrasonic power of 200 W, a reverse working interval of 3 s, and a total reaction time of 2 h. After the reaction, a vacuum filtration pump was used for solid-liquid separation to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step was 96.3%.

[0027] (2) The lithium-rich solution obtained in step (1) is passed through an adsorption column with aluminum-based adsorbent at 40°C and a flow rate of 15 mL / min for lithium adsorption. Deionized water is then passed through the adsorption column at 40°C and a flow rate of 15 mL / min for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step is 97.5%.

[0028] (3) The lithium-rich solid obtained in step (1) was dispersed in deionized water at a rate of 100 mL / g solid, and high-temperature steam at 150°C was continuously introduced at a flow rate of 2 mL / s. The stirring rate was 500 rpm, and the reaction time was 1 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back into the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 97.4%.

[0029] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is then subjected to nanofiltration, reverse osmosis, ion adsorption for impurity removal, and MVR evaporation to obtain a purified lithium-rich solution with a purity of 99.7%. According to formula D, the overall lithium recovery rate of the entire process after this step is 97.8%.

[0030] The purified lithium-rich liquid obtained in step (4) and the precipitant were fed into the lithium precipitation reactor for reaction at a temperature of 75°C for 1 hour to obtain lithium carbonate slurry. After solid-liquid separation, the slurry was washed at a temperature of 75°C and then vacuum dried to obtain lithium carbonate product with a purity greater than 99.5%.

[0031] Figure 1 This is a schematic diagram of the X-ray diffraction patterns of the lithium-rich solid and residual lithium solid obtained from the solid-phase enrichment of the strongly alkaline lithium-containing solution in Example 1. Figure 1It can be seen that the characteristic peak of LiCl·2Al(OH)3·nH2O appears in the lithium-rich solid, indicating that lithium ions are enriched in the lithium-rich solid. After lithium extraction and enrichment, the characteristic peak of Al(OH)3 appears in the residual lithium solid, indicating that lithium ions enter the liquid phase from the solid phase, resulting in a lithium-rich solution. Figure 2 This is a scanning electron microscope (SEM) schematic diagram of the lithium-rich solid obtained by solid-phase enrichment of the strongly alkaline lithium-containing solution in Example 1. From... Figure 2 It can be seen that the solid has a plate-like structure, indicating that LiCl·2Al(OH)3·nH2O is present in the precipitate. Figure 3 The schematic diagram shows the particle size distribution of lithium-rich solids obtained by solid-phase enrichment of a strongly alkaline lithium-containing solution. It can be seen that the particle size distribution of the solids obtained after treatment by the method of this invention is relatively narrow. This is beneficial for enhancing mass transfer when the solids are dispersed in the lithium extraction enrichment solution for subsequent enrichment, promoting the entry of lithium from the solid phase into the liquid phase, reducing the loss of lithium remaining in the residual lithium solid after a single treatment, and increasing the lithium recovery rate of a single reaction process.

[0032] Example 2 This embodiment focuses on lithium resource recovery from lithium-containing wastewater generated in industry. The solution has a pH of 9.3 and a lithium ion concentration of 0.2 g / L; its main impurity components are Na, K, Co, and Ni, and its anion is SO42-. 2- For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Aluminum sulfate and lithium sulfate were added to a strongly alkaline lithium-containing solution, and the solution was ultrasonically treated for 50 min to obtain a mixed solution with a lithium-aluminum ratio of 1:0.2. 1% Li2SO4·4Al(OH)3 seed crystals were then added. Sulfuric acid was pumped into the alkaline mixed solution at a feed flow rate of 25 mL / min using a peristaltic pump. The resulting slurry was placed in a microwave reactor with a microwave power of 200 W, a reaction temperature of 50 °C, an ultrasonic power of 300 W, a reverse working interval of 5 s, and a total reaction time of 3 h. After the reaction, solid-liquid separation was performed using a vacuum filtration pump to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step was 95.7%.

[0033] (2) The lithium-rich solution obtained in step (1) is passed through an adsorption column with aluminum-based adsorbent at a rate of 15 mL / min at 40°C for lithium adsorption, and deionized water is passed through the adsorption column at a rate of 15 mL / min at 30°C for desorption, thus obtaining a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step is 97.6%.

[0034] (3) The lithium-rich solid obtained in step (1) was dispersed in deionized water at a rate of 300 mL / g solid, and high-temperature steam at 130°C was continuously introduced at a flow rate of 5 mL / s. The stirring rate was 500 rpm, and the reaction time was 0.5 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back into the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 98.6%.

[0035] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is mixed and then subjected to nanofiltration, reverse osmosis, adsorption for impurity removal and multi-effect evaporation to obtain a purified lithium-rich solution with a purity of 99.1%. According to formula D, the overall lithium recovery rate after this step is 98.6%.

[0036] The purified lithium-rich liquid obtained in step (4) and the precipitant were fed into the lithium precipitation reactor for reaction. The reaction temperature was 60℃ and the reaction time was 1h to obtain lithium carbonate slurry. After solid-liquid separation, the slurry was washed at 60℃ and then vacuum dried to obtain lithium carbonate product. The purity of the lithium carbonate product was greater than 99.0%.

[0037] Example 3 This embodiment focuses on lithium resource recovery from lithium precipitation mother liquor. The solution has a pH of 11.9, a lithium ion concentration of 2.6 g / L, and its main impurities are Na and K, with Cl- as the anion. - CO3 2- For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Add aluminum chloride and lithium chloride to a strongly alkaline lithium-containing solution and stir magnetically for 60 min to obtain a mixed solution with a lithium-aluminum ratio of 1:4. Add 2% LiCl·2Al(OH)3 seed crystals. Under the action of a peristaltic pump, hydrochloric acid is pumped into the alkaline mixed solution at a feed flow rate of 30 mL / min. The resulting slurry is placed in a microwave reactor with a microwave power of 300 W, a reaction temperature of 60 °C, an ultrasonic power of 300 W, a reverse working interval of 5 s, and a total reaction time of 2 h. After the reaction is completed, solid-liquid separation is performed using a vacuum filtration pump to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step is 96.6%.

[0038] (2) The lithium-rich solution obtained in step (1) is passed through an adsorption column with aluminum-based adsorbent at 40°C and a flow rate of 10 mL / min for lithium adsorption. Deionized water is then passed through the adsorption column at 30°C and a flow rate of 15 mL / min for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step is 98.3%.

[0039] (3) The lithium-rich solid obtained in step (1) was dispersed in deionized water at a rate of 400 mL / g solid, and high-temperature steam at 200°C was continuously introduced at a flow rate of 1.5 mL / s. The stirring rate was 600 rpm, and the reaction time was 2 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back to the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 99.3%.

[0040] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is mixed and then subjected to nanofiltration, reverse osmosis and MVR evaporation to obtain a purified lithium-rich solution with a purity of 99.6%. According to formula D, the overall lithium recovery rate after this step is 99.2%.

[0041] The purified lithium-rich liquid obtained in step (4) and the precipitant were fed into the lithium precipitation reactor for reaction at a temperature of 75°C for 1 hour to obtain lithium carbonate slurry. After solid-liquid separation, the slurry was washed at a temperature of 75°C and then dried by blowing air to obtain lithium carbonate product with a purity greater than 99.5%.

[0042] Example 4 This embodiment focuses on lithium resource recovery from lithium precipitation mother liquor. The solution has a pH of 12.3, a lithium ion concentration of 1.4 g / L, and its main impurities are Na, K, Ca, Rb, and Cs, with Cl- as the anion. - CO3 2- For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Add aluminum chloride, polyaluminum chloride, lithium carbonate, and lithium chloride to a strongly alkaline lithium-containing solution, and mechanically stir for 120 min to obtain a mixed solution with a lithium-aluminum ratio of 1:5. Add 5% LiCl·2Al(OH)3 seed crystals. Under the action of a peristaltic pump, hydrochloric acid is pumped into the alkaline mixed solution at a feed flow rate of 100 mL / min. The resulting slurry is placed in a microwave reactor with a microwave power of 500 W, a reaction temperature of 40 °C, an ultrasonic power of 300 W, a reverse working interval of 10 s, and a total reaction time of 3 h. After the reaction, solid-liquid separation is performed by centrifugation to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step is 97.3%.

[0043] (2) The lithium-rich solution obtained in step (1) was passed through an adsorption column using a manganese-based ion sieve as the lithium adsorbent at a rate of 12 mL / min at 30 °C for lithium adsorption. Then, 0.3 mol / L hydrochloric acid was passed through the adsorption column at a rate of 12 mL / min at 30 °C for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step was 98.4%.

[0044] (3) The lithium-rich solid obtained in step (1) was dispersed in deionized water at a rate of 50 mL / g solid, and high-temperature steam at 230°C was continuously introduced at a flow rate of 5 mL / s. The stirring rate was 300 rpm, and the reaction time was 5 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back into the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 98.3%.

[0045] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is mixed and then subjected to nanofiltration, reverse osmosis, resin impurity removal and multi-effect evaporation to obtain a purified lithium-rich solution with a purity of 99.3%. According to formula D, the overall lithium recovery rate after this step is 98.3%.

[0046] The purified lithium-rich liquid obtained in step (4) and the precipitant are fed into the lithium precipitation reactor for reaction. The reaction temperature is 80℃ and the reaction time is 1h to obtain lithium carbonate slurry. After solid-liquid separation, it is washed at 80℃ and then dried by blowing air to obtain lithium carbonate product. The purity of the lithium carbonate product is greater than 99.0%.

[0047] Example 5 This embodiment focuses on lithium resource recovery from an alkaline leaching solution of ore. The solution has a pH of 11.3 and a lithium ion concentration of 14.5 g / L; its main impurity components are Na and K, and the anion is SO42-. 2- Cl - For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Aluminum sulfate, aluminum chloride, lithium sulfate, and lithium chloride were added to a strongly alkaline lithium-containing solution, and the solution was ultrasonically treated for 30 min to obtain a mixed solution with a lithium-aluminum ratio of 1:8. 0.5% Li₂SO₄·4Al(OH)₃ and 0.5% LiCl·2Al(OH)₃ seed crystals were then added. Hydrochloric acid was pumped into the alkaline mixed solution at a feed rate of 40 mL / min using a peristaltic pump. The resulting slurry was placed in a microwave reactor with a microwave power of 300 W, a reaction temperature of 45 ℃, an ultrasonic power of 200 W, a reverse working interval of 3 s, and a total reaction time of 4 h. After the reaction, solid-liquid separation was performed using a vacuum filtration pump to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step was 98.4%.

[0048] (2) The lithium-rich solution obtained in step (1) was passed through an adsorption column using a manganese-based ion sieve as the lithium adsorbent at a rate of 10 mL / min at 30 °C for lithium adsorption. Then, 0.5 mol / L hydrochloric acid was passed through the adsorption column at a rate of 10 mL / min at 30 °C for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step was 98.9%.

[0049] (3) The lithium-rich solid obtained in step (1) was dispersed in ultrapure water at a rate of 80 mL / g solid, and high-temperature steam at 250°C was continuously introduced at a flow rate of 5 mL / s. The stirring rate was 500 rpm, and the reaction time was 8 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back into the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 98.2%.

[0050] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is mixed and then subjected to nanofiltration, reverse osmosis, ion adsorption for impurity removal and MVR evaporation to obtain a purified lithium-rich solution with a purity of 99.5%. According to formula D, the overall lithium recovery rate after this step is 98.2%.

[0051] The purified lithium-rich solution obtained in step (4) can be processed by membrane method to obtain lithium hydroxide.

[0052] Example 6 This embodiment focuses on lithium resource recovery from lithium-containing wastewater generated during industrial production. The solution has a pH of 12.3 and a lithium ion concentration of 10.3 g / L. Its main impurities are Na, K, Zn, and Cr, and the anion is NO3. - Cl - For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Aluminum nitrate, aluminum chloride, and lithium chloride were added to a strongly alkaline lithium-containing solution and mechanically stirred for 40 min to obtain a mixed solution with a lithium-aluminum ratio of 1:10. 0.5% LiNO3·2Al(OH)3 and 1.5% LiCl·2Al(OH)3 seed crystals were then added. Nitric acid was pumped into the alkaline mixed solution at a feed rate of 8 mL / min using a peristaltic pump. The resulting slurry was placed in a microwave reactor with a microwave power of 300 W, a reaction temperature of 50 ℃, and an ultrasonic power of 200 W. The reaction was carried out with a 3-second reverse interval, and the total reaction time was 3 h. After the reaction, a vacuum filtration pump was used for solid-liquid separation to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step was 98.6%.

[0053] (2) The lithium-rich solution obtained in step (1) is fed into an adsorption column using a titanium-based ion sieve as the lithium adsorbent at 30°C and a flow rate of 15 mL / min for lithium adsorption. Then, 0.3 mol / L hydrochloric acid is fed through the adsorption column at 30°C and a flow rate of 10 mL / min for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step is 98.4%.

[0054] (3) The lithium-rich solid obtained in step (1) was dispersed in deionized water at a rate of 10 mL / g solid, and high-temperature steam at 250°C was continuously introduced at a flow rate of 5 mL / s. The stirring rate was 500 rpm, and the reaction time was 2 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back into the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 98.1%.

[0055] (4) The high-quality lithium-rich solution obtained from steps (2) and (3) is mixed and then subjected to nanofiltration, reverse osmosis, ion adsorption for impurity removal and MVR evaporation to obtain a purified lithium-rich solution with a purity of 99.3%. According to formula D, the overall lithium recovery rate after this step is 98.1%.

[0056] The purified lithium-rich solution obtained in step (4) can be used to obtain lithium hydroxide product by causticization.

[0057] Example 7 This embodiment focuses on lithium resource recovery from lithium-containing wastewater generated during industrial production. The solution has a pH of 12.1 and a lithium ion concentration of 6.7 g / L. Its main impurities are Na, K, Pb, and Sr, and its anion is SO42-. 2- Cl - For this strongly alkaline lithium-containing solution, this embodiment employs the following steps for lithium resource recovery: (1) Aluminum sulfate, aluminum chloride, and lithium chloride were added to a strongly alkaline lithium-containing solution, and the solution was ultrasonically treated for 30 min to obtain a mixed solution with a lithium-aluminum ratio of 1:10. 0.5% Li₂SO₄·4Al(OH)₃ seed crystals and 2.5% LiCl·2Al(OH)₃ seed crystals were then added. Hydrochloric acid was pumped into the alkaline mixed solution at a feed rate of 50 mL / min using a peristaltic pump. The resulting slurry was placed in a microwave reactor. The microwave power was 400 W, the reaction temperature was 50 ℃, the ultrasonic power was 200 W, the reverse working interval was 3 s, and the total reaction time was 2 h. After the reaction, a vacuum filtration pump was used for solid-liquid separation to obtain a lithium-rich solid and a lithium-rich solution. According to formula A, the solid-phase lithium enrichment rate of the lithium-rich solid obtained after this step was 98.8%.

[0058] (2) The lithium-rich solution obtained in step (1) is fed into an adsorption column using a manganese-based ion sieve as the lithium adsorbent at 30°C and a flow rate of 15 mL / min for lithium adsorption. Then, 0.5 mol / L hydrochloric acid is fed into the adsorption column at 30°C and a flow rate of 12 mL / min for desorption, resulting in a high-quality lithium-rich solution. According to formula B, the lithium adsorption extraction rate obtained in this step is 98.9%.

[0059] (3) The lithium-rich solid obtained in step (1) was dispersed in ultrapure water at a rate of 500 mL / g solid, and high-temperature steam at 300°C was continuously introduced at a flow rate of 5 mL / s. The stirring rate was 500 rpm, and the reaction time was 6 h. Then, solid-liquid separation was performed to obtain a high-quality lithium-rich solution and residual lithium solid. The residual lithium solid was returned to the strongly alkaline solution in step S1 for dissolution and then added back to the reaction cycle. According to formula C, the lithium enrichment rate of the liquid phase obtained after this step was 99.5%.

[0060] (4) The high-quality lithium-rich solutions obtained in steps (2) and (3) are mixed and then purified into a lithium-rich solution by nanofiltration, reverse osmosis and MVR evaporation. The purity of the purified lithium-rich solution is 99.2%. According to formula D, the overall lithium recovery rate after this step is 99.5%.

[0061] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various equivalent substitutions and modifications made without departing from the spirit and scope of the present invention as defined by the claims and their equivalents are all covered within the scope of protection of the present invention.

Claims

1. A method for efficiently extracting lithium from a strongly alkaline lithium-containing system, characterized in that, Includes the following steps: S1. Add a regulator to a strongly alkaline lithium-containing solution, mix well, and then add an inducer and a reaction aid. Apply ultrasonic microwave to the mixture to carry out the reaction. After the reaction is completed, perform solid-liquid separation to obtain a lithium-rich solution and a lithium-rich solid. The regulator is a mixture of lithium salt and aluminum salt, and the inducer is a Li / Al-LDHs seed crystal. S2. The lithium-rich solution obtained in step S1 is adsorbed and extracted using a lithium adsorbent to obtain a high-quality lithium-rich solution. S3. Disperse the lithium-rich solid obtained in step S1 in the lithium extraction enrichment solution. After the reaction is complete, separate the solid and liquid to obtain a high-quality lithium-rich solution and residual lithium solid. Return the residual lithium solid to step S1 and add it back to the reaction. S4. The high-quality lithium-rich solution obtained by mixing steps S2 and S3 is concentrated and purified to obtain a purified lithium-rich solution.

2. The method according to claim 1, wherein in step S1, the aluminum salt is one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, polyaluminum sulfate, and aluminum silicate; and the lithium salt is one or more of lithium nitrate, lithium sulfate, lithium chloride, lithium hydroxide, and lithium perchlorate.

3. The method according to claim 1, wherein the lithium-aluminum molar ratio of the mixed solution obtained after adding the regulator is 1:0.2-10.

4. The method according to claim 1, wherein the inducing agent in step S1 is one or more of LiCl·2Al(OH)3, LiNO3·2Al(OH)3, Li2SO4·4Al(OH)3, and Li2CO3·4Al(OH)3, and the amount added is 0.1%-5% of the weight of the strongly alkaline lithium-containing solution.

5. The method according to claim 1, wherein the reaction aid in step S1 is at least one selected from hydrochloric acid, sulfuric acid, nitric acid, citric acid, and acetic acid.

6. The method according to claim 1, wherein in step S1, the applied microwave power is 100-800 W, the reaction temperature is 30-60 °C, the applied ultrasonic power is 100-500 W, and the total reaction time is 0.5-4 h.

7. The method according to claim 1, wherein in step S2, the lithium adsorbent is one or more of manganese-based ion sieves, titanium-based ion sieves, aluminum-based adsorbents, or chelating resins, wherein the adsorption extraction can be carried out using an adsorption column, a continuous ion exchange device, or by adding the lithium adsorbent to a lithium-rich solution for adsorption extraction.

8. The method according to claim 1, wherein in step S3, the lithium extraction enrichment solution is deionized water or ultrapure water, and the feeding ratio of lithium-rich solid to lithium extraction enrichment solution is 1g:10-500mL.

9. The method according to claim 1, wherein in step S3, saturated steam or high-temperature steam is introduced into the reactor to assist the reaction.

10. The application of the method according to any one of claims 1-10 in the recovery of lithium ions from a strongly alkaline lithium-containing system.

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