Method for extracting lithium from sulfate-type salt lake brine

Abstract

The present application relates to a lithium extraction method from sulfate-type salt lake brine, comprising the following steps: step 1, dividing the sulfate-type salt lake brine to be treated into several portions; step 2, performing first nanofiltration treatment on one portion of the sulfate-type salt lake brine, collecting first concentrated water and first dilute water; step 3, mixing the first concentrated water and a chlorine salt solution, performing second nanofiltration treatment, and collecting second dilute water; step 4, mixing the first dilute water and the second dilute water, performing third nanofiltration treatment, and collecting third concentrated water and third dilute water; step 5, mixing the third concentrated water and another portion of the sulfate-type salt lake brine, repeating steps 2-4 until the mass percentage of sulfate ions in the third dilute water accounts for less than or equal to 10% of the total anions, and the concentration of lithium ions is between 0.05 g / L and 5 g / L; and step 6, extracting lithium ions in the third dilute water obtained in step 5 by using an adsorption method. The above method can overcome the difficulty of low adsorption capacity of adsorbents for lithium ions in the original brine, and improve the applicability of the adsorption method in lithium extraction from sulfate-type salt lake brine.

Description

Technical Field

[0001] This invention relates to the technical field of lithium extraction from brine, and particularly to a method for lithium extraction from sulfuric acid type salt lake brine. Background Technology

[0002] Lithium, as the most reactive metal and the most negative electrode potential known, has extremely broad application prospects in the field of new energy. Currently, more than 80% of the world's lithium carbonate production comes from salt lake brines, making the development of efficient, low-energy-consumption, and low-pollution lithium extraction processes from salt lakes a key issue.

[0003] Sulfate-type salt lakes refer to lakes with a high sulfate content in their water. With the continuous expansion of demand for lithium resources, low-cost mining technology for lithium extraction from sulfate-type salt lake brine is urgently needed.

[0004] Compared to methods such as calcination and extraction, adsorption has advantages such as low cost, simple operation, and wide applicability, and has gradually become an important technology for lithium extraction from salt lake brines. However, the adsorbents used in adsorption methods have a low adsorption capacity for lithium ions in sulfuric acid-type salt lake brines, which limits the application of adsorption methods in lithium extraction from sulfuric acid-type salt lake brines. Summary of the Invention

[0005] Based on this, the present invention provides a method for lithium extraction from sulfuric acid-type salt lake brine to solve the problem of low adsorption capacity of lithium ions in adsorbents in sulfuric acid-type salt lake brine. The technical solution is as follows:

[0006] A method for lithium extraction from sulfuric acid-type salt lake brine includes the following steps:

[0007] Step 1: Divide the sulfuric acid brine to be treated into several portions;

[0008] Step 2: Perform the first nanofiltration treatment on a sample of sulfuric acid-type salt lake brine, and collect the first concentrated water and the first fresh water;

[0009] Step 3: Mix the first concentrated water and the chloride solution, perform a second nanofiltration process, and collect the second fresh water;

[0010] Step 4: Mix the first and second fresh water, perform a third nanofiltration process, and collect the third concentrate and the third fresh water;

[0011] Step 5: Mix the third concentrated water with another part of sulfate-type salt lake brine, and repeat steps 2 to 4 until the mass percentage of sulfate ions in the third fresh water is less than or equal to 10% of the total anions, and the concentration of lithium ions is between 0.05 g / L and 5 g / L.

[0012] Step 6: Extract lithium ions from the third freshwater obtained in Step 5 using an adsorption method.

[0013] In some embodiments, the sulfate-type brine to be treated includes lithium ions, sodium ions, magnesium ions, and sulfate ions, wherein the concentration of lithium ions is between 0.05 g / L and 5 g / L, the concentration of sodium ions is between 0.05 g / L and 200 g / L, the concentration of magnesium ions is between 0.05 g / L and 150 g / L, and the mass percentage of sulfate ions in the total anions is greater than 10% and less than 50%.

[0014] In some embodiments, the first nanofiltration process, the second nanofiltration process, and the third nanofiltration process each independently include one or more of the following features:

[0015] (1) The water production rate of the first nanofiltration treatment is 60%~70%;

[0016] (2) The operating pressure of the first nanofiltration treatment is ≤3.5 MPa;

[0017] (3) The water production rate of the second nanofiltration treatment is 60%~70%;

[0018] (4) The operating pressure of the second nanofiltration treatment is ≤4 MPa;

[0019] (5) The water production rate of the third nanofiltration treatment is 80%~90%;

[0020] (6) The operating pressure of the third nanofiltration process is 2.5 MPa.

[0021] In some embodiments, the chloride salt solution includes one or more of the following characteristics:

[0022] (1) The chloride salt in the chloride salt solution accounts for 5% to 10% by mass, and the mass ratio of the chloride salt solution to the third concentrated water is 1 to 3;

[0023] (2) The chloride salt in the chloride salt solution is one or more of sodium chloride, potassium chloride, and magnesium chloride;

[0024] (3) The solvent in the chloride salt solution is water.

[0025] In some embodiments, the extraction of lithium ions from the third freshwater obtained in step 5 using adsorption includes the following steps:

[0026] Step 61: Divide the third fresh water obtained in step 5 into several portions;

[0027] Step 62: Adsorb lithium ions in a sample of third fresh water using an adsorbent;

[0028] Step 63: Desorb the lithium ions adsorbed by the adsorbent using a desorbent to obtain an desorbent solution;

[0029] Step 64: Repeat steps 62 to 63 until the extraction of lithium ions from several portions of the third freshwater is completed.

[0030] In some embodiments, the adsorbent is an aluminum-based adsorbent; and / or

[0031] The desorbent is water or a lithium-containing eluent.

[0032] In some embodiments, at least one repetition cycle of step 64 further includes the step of rinsing the adsorbent containing lithium ions with a reviving agent between steps 62 and 63.

[0033] In some embodiments, the resuscitator comprises a divalent cationic chloride salt.

[0034] In some embodiments, step 63 further includes one or more of the following steps:

[0035] (1) Before desorbing the lithium ions adsorbed by the adsorbent using a desorbent, a rapid washing step is also included to remove impurity ions;

[0036] (2) After desorbing the lithium ions adsorbed by the adsorbent using a desorbent, the process further includes rinsing to remove residual desorbent.

[0037] The adsorption parameters of the adsorbent satisfy one or more of the following: (1) temperature of -5℃ to 85℃; (2) flow rate of 0.5 BV / h to 60 BV / h; and / or

[0038] The desorption parameters of the desorbent satisfy one or more of the following: (1) temperature of 15℃ to 60℃; (2) flow rate of 0.5 BV / h to 20 BV / h; and / or

[0039] The parameters for the rinsing with the resuscitator meet one or more of the following: (1) temperature of 0℃ to 30℃; (2) flow rate of 1 BV / h to 20 BV / h; and / or

[0040] The parameters for the rapid wash to remove impurity ions meet one or more of the following: (1) temperature is 0℃~30℃; (2) flow rate is 0.5BV / h~20BV / h; and / or

[0041] The parameters for rinsing to remove residual desorbed liquid are satisfied by one or more of the following: (1) temperature is 0℃~30℃; (2) flow rate is 0.5BV / h~20BV / h.

[0042] In some embodiments, the step of collecting the desorption solution that meets the following conditions is also included:

[0043] (1) The concentration ratio of sodium ions to lithium ions is (0.05~1):1; (2) The concentration ratio of magnesium ions to lithium ions is (0.1~10):1.

[0044] Compared with traditional solutions, the present invention has the following advantages:

[0045] This invention utilizes nanofiltration technology to treat sulfate-type brine from salt lakes, significantly reducing the sulfate content and increasing the adsorption capacity for lithium ions when using adsorbents. However, generally, reducing sulfate content also carries away some lithium ions, which is detrimental to the already low-quality brine. The nanofiltration process of this invention, while reducing sulfate content, ensures that lithium ions are not significantly lost. Specifically, a second nanofiltration process involves mixing a first concentrated solution with a chloride solution to drive the permeation of monovalent ions, reducing lithium ion loss in the first concentrated solution and minimizing the loss of monovalent ions due to cation-anion imbalance. Simultaneously, the chloride ion content in the second desalinated solution is increased, replacing sulfate ions and reducing sulfate ion content. A third concentrated solution and another portion of sulfate-type brine are then used for a first nanofiltration process to retain more lithium ions. By repeatedly performing the above steps, a third type of freshwater with low sulfate content and high lithium ion content can be obtained. When using adsorption to adsorb lithium ions from this third type of freshwater, not only is the adsorption capacity high, overcoming the difficulty of low adsorption capacity of adsorbents for lithium ions in the original brine, but the risk of sulfate poisoning of the adsorbent is also reduced. Furthermore, the lithium ion recovery rate is high, significantly improving the applicability of adsorption methods in lithium extraction from sulfate-type salt lake brines, reducing mining difficulty, and removing obstacles hindering its rapid promotion. Moreover, this invention, through nanofiltration technology to treat sulfate-type salt lake brines, can achieve a third type of freshwater recovery rate of over 70% under suitable conditions, resulting in high production efficiency. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention and to more completely understand the present invention and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A schematic flowchart illustrating a method for lithium extraction from sulfuric acid-type salt lake brine according to one embodiment;

[0048] Figure 2 This is a flowchart illustrating an adsorption and desorption cycle in step 6 of one embodiment.

[0049] Figure 3This is a flowchart illustrating another adsorption and desorption cycle in step 6 of one embodiment. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0052] the term

[0053] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0054] In this invention, the selection range of "and / or", "or / and", and "and / or" includes any one of two or more related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that the technical solution undoubtedly includes technical solutions connected by "logical AND", and also undoubtedly includes technical solutions connected by "logical OR". For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0055] In this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined. In this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0056] In this invention, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they are selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0057] In this invention, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous, and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges included therein.

[0058] Unless otherwise specified, the temperature parameters in this invention can be either constant temperature treatment or variations within a certain temperature range. It should be understood that the constant temperature treatment allows temperature fluctuations within the precision range controlled by the instrument. Fluctuations are permitted within ranges such as ±5℃, ±4℃, ±3℃, ±2℃, and ±1℃.

[0059] In this invention, percentage content refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures, unless otherwise specified.

[0060] In this invention, percentage concentrations, unless otherwise specified, refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0061] To address the issue of low adsorption capacity of adsorbents used in adsorption methods for lithium ions in sulfuric acid-type brine, one embodiment of the present invention provides a method for lithium extraction from sulfuric acid-type brine. Please refer to [link to relevant documentation]. Figure 1 This includes the following steps:

[0062] Step 1: Divide the sulfuric acid brine to be treated into several portions.

[0063] Understandably, the sulfated brine to be treated is divided into several portions, and these portions have similar or identical compositions. These portions of sulfated brine can be fed continuously. This embodiment is capable of treating sulfated brine with a wide pH range.

[0064] Optionally, the sulfate-type brine to be treated includes lithium ions, sodium ions, magnesium ions, and sulfate ions, wherein the concentration of lithium ions is between 0.05 g / L and 5 g / L, the concentration of sodium ions is between 0.05 g / L and 200 g / L, the concentration of magnesium ions is between 0.05 g / L and 150 g / L, and the mass percentage of sulfate ions in the total anions is greater than 10% and less than 50%.

[0065] The sulfate content in the sulfate-type salt lake brine to be treated is high. If an adsorbent is added directly to adsorb lithium ions, the adsorption capacity is low and sulfate poisoning is likely to occur.

[0066] Step 2: Perform the first nanofiltration treatment on a sample of sulfuric acid-type salt lake brine to collect the first concentrated water and the first fresh water.

[0067] Optionally, the water production rate of the first nanofiltration treatment is 60% to 70%.

[0068] Optionally, the operating pressure of the first nanofiltration process is ≤3.5 MPa.

[0069] The first nanofiltration process separates monovalent and divalent ions. The first desalinated water contains more monovalent ions, while the first concentrated water contains more divalent ions and some monovalent ions. In this embodiment, the first concentrated water and chloride salt are mixed for a second nanofiltration process to improve the recovery rate of monovalent ions.

[0070] Step 3: Mix the first concentrated water and the chloride solution, perform a second nanofiltration process, and collect the second fresh water.

[0071] Optionally, the chloride salt in the chloride salt solution is one or more of sodium chloride, potassium chloride, and magnesium chloride.

[0072] Optionally, the solvent in the chloride salt solution is water.

[0073] Optionally, the chloride salt in the chloride salt solution accounts for 5% to 10% by mass, and the mass ratio of the chloride salt solution to the third concentrated water is 1 to 3.

[0074] Optionally, the water production rate of the second nanofiltration treatment is 60% to 70%.

[0075] Optionally, the operating pressure of the second nanofiltration process is ≤4 MPa.

[0076] The second nanofiltration process also separates monovalent and divalent ions. Through the second nanofiltration process, monovalent ions are driven to pass through to reduce the loss of lithium ions in the first concentrate and reduce the loss of monovalent ions in the first concentrate due to the balance of anions and cations. At the same time, the chloride ion content in the second desalination is increased, and chloride ions and sulfate ions are used to replace them to reduce the sulfate ion content in the second desalination.

[0077] The second nanofiltration process yields a second concentrate and a second desalinated water. The second desalinated water is collected, while the second concentrate is discharged.

[0078] Step 4: Mix the first and second fresh water, perform a third nanofiltration process, and collect the third concentrate and the third fresh water.

[0079] Optionally, the third nanofiltration treatment has a water production rate of 80% to 90%.

[0080] Optionally, the operating pressure of the third nanofiltration process is 2.5 MPa.

[0081] The third nanofiltration process also separates monovalent and divalent ions, and further removes sulfate ions through the third nanofiltration process.

[0082] Step 5: Mix the third concentrated water with another part of sulfate-type salt lake brine, and repeat steps 2 to 4 until the mass percentage of sulfate ions in the third fresh water is less than or equal to 10% of the total anions, and the concentration of lithium ions is between 0.05 g / L and 5 g / L.

[0083] To prevent the loss of lithium ions in the third concentrate, the third concentrate is mixed with another portion of sulfate-type brine from a salt lake. Steps 2 to 4 are repeated, followed by the first, second, and third nanofiltration treatments. This process yields a third freshwater solution with sulfate ions accounting for less than 10% of the total anions by mass and a lithium ion concentration between 0.05 g / L and 5 g / L.

[0084] Understandably, in the third freshwater, the mass percentage of sulfate ions in the total anions can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1%. The concentration of lithium ions can be 0.05 g / L, 0.1 g / L, 0.5 g / L, 1 g / L, or 5 g / L.

[0085] Optionally, the pH range of the third freshwater is 4 to 9.

[0086] Step 6: Extract lithium ions from the third freshwater obtained in Step 5 using an adsorption method.

[0087] Optionally, the extraction of lithium ions from the third freshwater obtained in step 5 using the adsorption method includes the following steps:

[0088] Step 61: Divide the third fresh water obtained in step 5 into several portions.

[0089] Considering the limited adsorption capacity of the adsorbent, this embodiment divides the third freshwater into several portions to fully extract lithium, and these portions of third freshwater can be fed continuously.

[0090] Step 62: Use an adsorbent to adsorb lithium ions in a sample of third fresh water.

[0091] Optionally, the adsorbent is an aluminum-based adsorbent. Aluminum-based adsorbents have the advantages of fast adsorption rate and no need to consume acid for desorption. Due to their relatively mature preparation and application processes, if their compatibility with sulfuric acid-type salt lake brines can be solved from the source, it will bring a very significant boost to the efficiency of lithium resource mining worldwide.

[0092] In this embodiment, the aluminum-based adsorbent has a better adsorption capacity for the third freshwater with a pH value of around 6.

[0093] Please see Figure 2 This is a schematic diagram of an adsorption and desorption cycle. In this embodiment, an aluminum-based adsorbent is uniformly filled into a fixed-bed resin column. A portion of third-generation freshwater is passed through the resin column in a top-in, bottom-out manner. Lithium ions in the third-generation freshwater are adsorbed under conditions of -5℃ to 85℃ and a flow rate of 0.5 BV / h to 60 BV / h (BV refers to the volume of a unit fixed-bed resin column). Understandably, adsorption can continue until the adsorbent is saturated. After adsorption, the adsorption tailwater flows out.

[0094] Step 63: Desorb the lithium ions adsorbed by the adsorbent using a desorbent to obtain an desorbent solution.

[0095] In this embodiment, the desorbent is flowed through the resin column in a top-in, bottom-out manner, and the lithium ions adsorbed by the adsorbent are desorbed under conditions of temperature of 15℃~60℃ and flow rate of 0.5BV / h~10BV / h.

[0096] Optionally, the desorbent is water or a lithium-containing eluent.

[0097] During desorption, the temperature is high, the flow rate is slow, and the desorption dose is large, allowing lithium ions to be released slowly and fully into the desorption solution.

[0098] In this embodiment, testing the content of sodium ions, magnesium ions, potassium ions, and lithium ions in the desorption solution further includes the following step: collecting the desorption solution that meets the following conditions:

[0099] (1) The concentration ratio of sodium ions to lithium ions is (0.05~1):1; (2) The concentration ratio of magnesium ions to lithium ions is (0.1~10):1.

[0100] If the above conditions are not met, the desorbed solution that does not meet the conditions will be flowed through the resin column in the subsequent rapid washing step, or re-adsorbed.

[0101] Step 64: Repeat steps 62 to 63 until the extraction of lithium ions from several portions of the third freshwater is completed.

[0102] As the adsorbent undergoes repeated adsorption and desorption, its adsorption capacity decreases. Optionally, at least one repetition cycle in step 64 further includes the step of rinsing the adsorbent adsorbed with lithium ions with a reviving agent between steps 62 and 63.

[0103] In this embodiment, when the adsorption capacity of the adsorbent for lithium ions in the third fresh water decreases to less than or equal to 70% of the initial adsorption capacity, the adsorbent adsorbed with lithium ions can be rinsed with a revival agent between steps 62 and 63 to restore the adsorption capacity and maintain it in a stable state. Please refer to [link to previous instructions]. Figure 3 This is a schematic diagram of another adsorption and desorption cycle. In this embodiment, the resuscitator flows through the resin column in a top-in, bottom-out manner, and the adsorbent containing lithium ions is washed under conditions of 0℃~30℃ and flow rate of 1BV / h~20BV / h.

[0104] Optionally, the resuscitator comprises a divalent cationic chloride salt.

[0105] Further, optionally, the resuscitator includes one or more of magnesium chloride and calcium chloride.

[0106] Divalent magnesium ions drive the adsorption and desorption processes of aluminum-based adsorbents. High magnesium conditions help reduce the binding force between sulfate and lithium ions, thereby reducing the probability of aluminum-based adsorbents adsorbing lithium sulfate molecules and converting them to lithium chloride. At the same time, magnesium ions drive the replacement of lithium sulfate inside the adsorbent, which can be used in the detoxification process of aluminum-based adsorbents poisoned by sulfate to release the adsorbent's adsorption capacity.

[0107] Optionally, the resuscitator is an aqueous solution of magnesium chloride or calcium chloride. The magnesium chloride aqueous solution contains 5% to 10% magnesium chloride by mass. The calcium chloride aqueous solution contains 5% to 10% calcium chloride by mass.

[0108] Optionally, the pH value of the resuscitator is between 4 and 6.

[0109] The liquid that flows out after rinsing with resuscitation agent is called resuscitation fluid, which can be repeatedly used as a resuscitation agent.

[0110] Optionally, in step 63, before desorbing the lithium ions adsorbed by the adsorbent using a desorbent, a rapid washing step is also included to remove impurity ions, wherein the impurity ions include magnesium, sodium, etc. in the pore gaps of the adsorbent.

[0111] Alternatively, the quick-washing agent can be water or a desorption solution that does not meet the above conditions. Please see below. Figure 2 and Figure 3 The quick-washing agent is fed through the resin column in a top-in, bottom-out manner, and the adsorbent containing lithium ions is quickly washed under the conditions of 0℃~10℃ and flow rate of 10BV / h~20BV / h.

[0112] Optionally, the amount of quick-washing agent can be 0.5 BV to 1 BV. By controlling the amount of quick-washing solution, the quality of the desorption solution can be improved.

[0113] During quick wash, the temperature is lower, the flow rate is faster, and the dosage is smaller, mainly to remove impurities.

[0114] The liquid that flows out after a quick wash is called quick wash solution, which can be returned to the third fresh water for re-absorption.

[0115] Between steps 62 and 63, after rinsing the adsorbent containing lithium ions with a resuscitator, the amount of quick wash solution used in step 63 can be increased by 1 BV to 1.5 BV to reduce the impact of the resuscitator on the quality of the desorption solution.

[0116] Optionally, in step 63, after desorbing the lithium ions adsorbed by the adsorbent using a desorbent, the step further includes rinsing to remove residual desorbent.

[0117] Alternatively, the leaching agent can be water, adsorbed tailwater, or sulfate-type brine from a salt lake. Please see below. Figure 2 and Figure 3 The eluent is fed through the resin column in a top-in, bottom-out manner, and the desorbed adsorbent is eluented under conditions of 0℃~30℃ and flow rate of 0.5BV / h~20BV / h.

[0118] Optionally, the effluent after rinsing is a lithium-containing rinsing solution, which contains a low concentration of lithium ions and can be used as a desorbent to enrich the lithium ions, thus outputting a qualified desorbent solution.

[0119] This embodiment utilizes nanofiltration technology to treat sulfate-type brine, significantly reducing the sulfate content and increasing the adsorption capacity for lithium ions when using adsorbents. However, generally, reducing sulfate content also carries away some lithium ions, which is detrimental to the already low-quality brine. The nanofiltration step in this embodiment, while reducing sulfate content, ensures that lithium ions are not significantly lost. Specifically: a second nanofiltration process involves mixing a first concentrated solution and a chloride solution to drive monovalent ions through, reducing lithium ion loss in the first concentrated solution and minimizing the loss of monovalent ions due to cation-anion imbalance. Simultaneously, the chloride ion content in the second desalinated solution is increased, replacing sulfate ions and reducing sulfate ion content. A third concentrated solution and another portion of sulfate-type brine are then used for a first nanofiltration process to retain more lithium ions. By repeatedly performing the above steps, a third type of freshwater with low sulfate content and high lithium ion content can be obtained. When using adsorption to adsorb lithium ions from this third type of freshwater, not only is the adsorption capacity high, overcoming the difficulty of low adsorption capacity of adsorbents for lithium ions in the original brine, but the risk of sulfate poisoning of the adsorbent is also reduced. Furthermore, the lithium ion recovery rate is high, significantly improving the applicability of adsorption methods in lithium extraction from sulfate-type salt lake brines, reducing mining difficulty, and removing obstacles hindering its rapid promotion. Moreover, this invention, through nanofiltration technology to treat sulfate-type salt lake brines, can achieve a third type of freshwater recovery rate of over 70% under suitable conditions, resulting in high production efficiency.

[0120] In addition, this embodiment also proposes a method for extracting lithium ions from the third freshwater obtained in step 5 using adsorption. The desorption solution has low impurity ion content, high lithium ion yield, and good quality.

[0121] Furthermore, this embodiment proposes an effective method for adsorbent capacity recovery, resulting in good adsorbent regeneration. It avoids the impact of sulfate ion accumulation on the adsorbent's adsorption capacity. After 100 cycles of adsorption and desorption, the adsorbent's adsorption capacity remains above 90% of its initial capacity, enabling the adsorbent's adsorption capacity to remain stable for a relatively long period.

[0122] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0123] Example 1

[0124] This embodiment provides a method for lithium extraction from sulfuric acid-type salt lake brine, the steps of which are as follows:

[0125] Step 1: Provide the sulfated salt lake brine to be treated, which includes lithium ions at a concentration of 0.656 g / L, sodium ions at a concentration of 92.45 g / L, magnesium ions at a concentration of 21.22 g / L, and sulfate ions accounting for 26.34% of the total anions by mass. Divide the brine into several portions.

[0126] Step 2: Perform the first nanofiltration treatment on a sample of sulfuric acid-type salt lake brine to collect the first concentrated water and the first fresh water.

[0127] Step 3: Mix the first concentrated water and the chloride solution, perform a second nanofiltration process, and collect the second fresh water.

[0128] Step 4: Mix the first and second fresh water, perform a third nanofiltration process, and collect the third concentrate and the third fresh water.

[0129] Step 5: Mix the third concentrated water with another part of sulfate-type salt lake brine, and repeat steps 2 to 4. After the water production rate stabilizes, a third freshwater is obtained with a sulfate ion content of 8.46% of the total anions and a lithium ion concentration of 0.625 g / L.

[0130] Step 6: Extract lithium ions from the third freshwater obtained in Step 5 using an adsorption method.

[0131] Step 61: Divide the third fresh water obtained in step 5 into several portions;

[0132] Step 62: The aluminum-based adsorbent is uniformly filled into the fixed-bed resin column. A portion of the third fresh water is passed through the resin column in a top-in, bottom-out manner to adsorb lithium ions in the third fresh water until saturation. The initial adsorption capacity of the aluminum-based adsorbent for lithium ions in the third fresh water is 2.165 g / L, as shown in Table 1.

[0133] Step 63: Using a top-in, bottom-out flow of pure water through the resin column, the adsorbent containing lithium ions is quickly washed; using a top-in, bottom-out flow of desorbent through the resin column, the lithium ions adsorbed by the adsorbent are desorbed to obtain an desorption solution; the contents of sodium ions, magnesium ions, lithium ions, and potassium ions in the desorption solution are tested, and the results are shown in Table 1; using a top-in, bottom-out flow of pure water through the resin column, the desorbed adsorbent is rinsed.

[0134] Step 64: Repeat steps 62 to 63. Between steps 62 and 63 in the 65th repetition cycle, allow the magnesium chloride aqueous solution to flow through the resin column in a top-in, bottom-out manner, and use a resuscitator to wash the adsorbent containing lithium ions.

[0135] The adsorption capacity of aluminum-based adsorbents for lithium ions in the third freshwater and the contents of sodium, magnesium, lithium and potassium ions in the desorption solution were recorded after 120 and 240 cycles. The results are shown in Table 1.

[0136] Example 2

[0137] This embodiment provides a method for lithium extraction from sulfuric acid-type salt lake brine, which is basically the same as that in embodiment 1. The main difference is that in step 64, when repeating steps 62 to 63, the adsorbent adsorbed with lithium ions is not rinsed with a reviving agent.

[0138] The adsorption capacity of aluminum-based adsorbents for lithium ions in the third freshwater, and the contents of sodium, magnesium, lithium, and potassium ions in the desorption solution were recorded after the initial cycle, 120 cycles, and 240 cycles. The results are shown in Table 1.

[0139] Comparative Example 1

[0140] This comparative example provides a method for lithium extraction from sulfuric acid-type salt lake brine, which is basically the same as that in Example 1. The main difference is that steps 2 to 5 are not performed. In step 62, aluminum-based adsorbent is uniformly filled into a fixed-bed resin column, and a portion of sulfuric acid-type salt lake brine is allowed to flow through the resin column in a top-in, bottom-out manner.

[0141] The adsorption capacity of aluminum-based adsorbents for lithium ions in the third freshwater, and the contents of sodium, magnesium, lithium, and potassium ions in the desorption solution were recorded after the initial cycle, 120 cycles, and 240 cycles. The results are shown in Table 1.

[0142] Comparative Example 2

[0143] This comparative example provides a method for lithium extraction from sulfuric acid-type salt lake brine, the steps of which are as follows:

[0144] Step 1: Provide the sulfate-type salt lake brine to be treated, wherein the sulfate-type salt lake brine to be treated includes lithium ions at a concentration of 0.656 g / L, sodium ions at a concentration of 92.45 g / L, magnesium ions at a concentration of 21.22 g / L, and sulfate ions accounting for 26.34% of the total anions by mass.

[0145] Step 2: Perform nanofiltration on the sulfate-type salt lake brine to obtain fresh water with a sulfate ion content of 6.5% of the total anions and a lithium ion concentration of 0.32 g / L.

[0146] Step 3 is the same as step 6 in Example 1.

[0147] The adsorption capacity of aluminum-based adsorbents for lithium ions in fresh water, and the contents of sodium, magnesium, lithium, and potassium ions in the desorption solution were recorded after the initial cycle, 120 cycles, and 240 cycles. The results are shown in Table 1.

[0148] Table 1

[0149]

[0150] It is evident that appropriate nanofiltration treatment of sulfuric acid-type brine can improve the adsorption capacity of adsorbents. Using a regenerating agent to elute adsorbents containing lithium ions results in good adsorption-regeneration effects.

[0151] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0152] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for lithium extraction from sulfuric acid-type salt lake brine, characterized in that, Includes the following steps: Step 1: Divide the sulfuric acid brine to be treated into several portions; Step 2: Perform the first nanofiltration treatment on a sample of sulfuric acid-type salt lake brine, and collect the first concentrated water and the first fresh water; Step 3: Mix the first concentrated water and the chloride solution, perform a second nanofiltration process, and collect the second fresh water. The chloride solution contains one or more of sodium chloride, potassium chloride, and magnesium chloride. Step 4: Mix the first and second fresh water, perform a third nanofiltration process, and collect the third concentrate and the third fresh water; Step 5: Mix the third concentrated water with another part of sulfate-type salt lake brine, and repeat steps 2 to 4 until the mass percentage of sulfate ions in the third fresh water is less than or equal to 10% of the total anions, and the concentration of lithium ions is between 0.05 g / L and 5 g / L. Step 6: Extract lithium ions from the third freshwater obtained in Step 5 using an adsorption method.

2. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 1, characterized in that, The sulfate-type brine to be treated includes lithium ions, sodium ions, magnesium ions, and sulfate ions. The concentration of lithium ions is between 0.05 g / L and 5 g / L, the concentration of sodium ions is between 0.05 g / L and 200 g / L, the concentration of magnesium ions is between 0.05 g / L and 150 g / L, and the mass percentage of sulfate ions in the total anions is greater than 10% and less than 50%.

3. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 1, characterized in that, The first nanofiltration process, the second nanofiltration process, and the third nanofiltration process include one or more of the following features: (1) The water production rate of the first nanofiltration treatment is 60%~70%; (2) The operating pressure of the first nanofiltration treatment is ≤3.5 MPa; (3) The water production rate of the second nanofiltration treatment is 60%~70%; (4) The operating pressure of the second nanofiltration treatment is ≤4 MPa; (5) The water production rate of the third nanofiltration treatment is 80%~90%; (6) The operating pressure of the third nanofiltration process is 2.5 MPa.

4. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 1, characterized in that, The chloride salt solution includes one or more of the following characteristics: (1) The chloride salt in the chloride salt solution accounts for 5% to 10% by mass, and the mass ratio of the chloride salt solution to the first concentrated water is 1 to 3; (2) The solvent in the chloride salt solution is water.

5. The method for lithium extraction from sulfuric acid-type brine according to any one of claims 1 to 4, characterized in that, The method of extracting lithium ions from the third freshwater obtained in step 5 using adsorption includes the following steps: Step 61: Divide the third fresh water obtained in step 5 into several portions; Step 62: Adsorb lithium ions in a sample of third fresh water using an adsorbent; Step 63: Desorb the lithium ions adsorbed by the adsorbent using a desorbent to obtain an desorbent solution; Step 64: Repeat steps 62 to 63 until the extraction of lithium ions from several portions of the third freshwater is completed.

6. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 5, characterized in that, The adsorbent is an aluminum-based adsorbent; and / or The desorbent is water or a lithium-containing eluent.

7. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 5, characterized in that, In at least one repetition cycle of step 64, the step further includes the following step: between steps 62 and 63, rinsing the adsorbent containing lithium ions with a reviving agent; the reviving agent comprising a divalent cationic chloride salt.

8. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 7, characterized in that, Step 63 also includes one or more of the following steps: (1) Before desorbing the lithium ions adsorbed by the adsorbent using a desorbent, a rapid washing step is also included to remove impurity ions; (2) After desorbing the lithium ions adsorbed by the adsorbent using a desorbent, the process further includes rinsing to remove residual desorbent.

9. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 8, characterized in that, The adsorption parameters of the adsorbent satisfy one or more of the following: (1) temperature is -5℃ to 85℃; (2) flow rate is 0.5 BV / h to 60 BV / h; and / or The desorption parameters of the desorbent satisfy one or more of the following: (1) temperature of 15℃ to 60℃; (2) flow rate of 0.5 BV / h to 20 BV / h; and / or The parameters for the rinsing with the resuscitator meet one or more of the following: (1) temperature is 0℃~30℃; (2) flow rate is 1BV / h~20BV / h; and / or The parameters for the rapid wash to remove impurity ions meet one or more of the following: (1) temperature is 0℃~30℃; (2) flow rate is 0.5BV / h~20BV / h; and / or The parameters for rinsing to remove residual desorbed liquid are satisfied by one or more of the following: (1) temperature is 0℃~30℃; (2) flow rate is 0.5BV / h~20BV / h.

10. The method for lithium extraction from sulfuric acid-type salt lake brine according to claim 5, characterized in that, It also includes the following steps: Collect the desorption solution that meets the following conditions: (1) The concentration ratio of sodium ions to lithium ions is (0.05~1):1; (2) The concentration ratio of magnesium ions to lithium ions is (0.1~10):1.

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