Method for producing lithium-containing compounds using chloride-type low-lithium brine

Abstract

The application provides a method for producing lithium-containing compounds by using chloride type low-lithium brine, comprising: a first adsorption stage to obtain a first purified liquid, a second purified liquid and a third purified liquid; a second adsorption stage to obtain an adsorption purified liquid; and sequentially performing reverse osmosis concentration, extraction and back extraction and post-treatment on the adsorption purified liquid to obtain the lithium-containing compounds. The method is used for preparing high-purity lithium-containing compounds at low cost and in a short process, the second adsorption stage in the lithium extraction process of the brine is designed, the lithium yield is greatly improved, the sodium, potassium and magnesium impurities are effectively removed, the concentration of lithium ions is significantly improved, and the purposes of enriching and concentrating lithium ions in the ultra-low salt lake brine and removing impurities are achieved.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction from brine, and more specifically, to a method for producing lithium-containing compounds using chloride-type low-lithium brine. Background Technology

[0002] Lithium is a crucial inorganic element with important industrial applications. Currently, lithium is mainly derived from salt lake brines, ores, and recycled lithium metal. In particular, salt lake brines contain significant amounts of lithium, but extracting lithium from brine is costly and results in low-grade lithium.

[0003] Currently, lithium extraction from salt lake brines mainly employs methods such as adsorption, extraction, precipitation, and membrane methods. Among these, adsorption is one of the primary methods for lithium extraction from brine. It mainly utilizes ion exchange resins or ion sieves to selectively adsorb lithium from the brine. After washing and desorption, a solution with low levels of impurities such as magnesium is obtained. Then, boron, calcium, magnesium, and other associated impurities in the salt lake brine are further removed, followed by concentration and lithium precipitation with sodium carbonate.

[0004] However, the adsorption method for extracting lithium from brine has drawbacks. The brine contains low-grade and low-content lithium. Furthermore, the adsorption capacity of the adsorbents used is generally small, resulting in a long process flow, high energy consumption, low lithium recovery rate, and relatively high cost.

[0005] Therefore, optimizing the adsorption method for lithium extraction from salt lake brine to improve lithium recovery rate, shorten process flow, reduce preparation cost, and obtain high-purity lithium compound products is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0006] The main objective of this invention is to provide a method for producing lithium-containing compounds using chloride-type low-lithium brine, as well as the lithium-containing compounds themselves, to solve the problems of long process flow and high cost in the existing technology of lithium extraction from chloride-type low-lithium brine.

[0007] To achieve the above objectives, the present invention provides a method for producing lithium-containing compounds using chloride-type low-lithium brine, comprising: Step S1, a first adsorption stage: Step S1-1, pumping chloride-type low-lithium brine into a first adsorption column for first adsorption to obtain a second adsorption column; Step S1-2, using water as a first top feed liquid to top the second adsorption column to obtain a first waste liquid and a third adsorption column; Step S1-3, using water as a first desorption liquid to sequentially perform first desorption, second desorption, and third desorption on the third adsorption column to obtain a fourth adsorption column; wherein the first desorption, second desorption, and third desorption respectively yield a first purified solution, a second purified solution, and a third purified solution; Step S1-4, pumping fresh chloride-type low-lithium brine into the fourth adsorption column for displacement to obtain a third purified solution. Five adsorption columns; Step S2, second adsorption stage: Step S2-1, the first purified solution, the second purified solution, and the third purified solution are used together as the second top feed liquid to perform the second top feed on the fifth adsorption column, resulting in the second waste liquid and the sixth adsorption column; Step S2-2, water is used as the second eluent to perform the fourth, fifth, and sixth desorption sequentially on the sixth adsorption column; wherein the fourth, fifth, and sixth desorptions respectively yield the fourth, fifth, and sixth purified solutions, which are then mixed to obtain the adsorption purified solution; Step S3, the adsorption purified solution is concentrated by reverse osmosis to obtain the concentrate; Step S4, the concentrate is sequentially extracted and back-extracted to obtain a lithium-containing solution; Step S5, the lithium-containing solution is post-treated to obtain a lithium-containing compound.

[0008] Further, in the chloride-type low-lithium brine, the lithium ion concentration is 60 mg / L to 900 mg / L, the sodium ion concentration is 1000 mg / L to 90000 mg / L, the potassium ion concentration is 1000 mg / L to 18000 mg / L, and the magnesium ion concentration is 40000 mg / L to 120000 mg / L; preferably, in step S1-1, the chloride-type low-lithium brine is pumped into the first adsorption column at a flow rate of 10 Bv / h to 12 Bv / h; and / or, the first adsorption time is 12 ± 2 min.

[0009] Further, in steps S1-3, during the first desorption, second desorption, and third desorption processes, the pump flow rate of the first desorption solution is independently 3.5 Bv / h to 5.0 Bv / h, and the temperature is independently 35℃ to 40℃; preferably, the time for the first desorption, second desorption, and third desorption is independently 12±2 min; more preferably, in the first purified solution, the lithium ion concentration is 200 mg / L to 500 mg / L, the sodium ion concentration is 30 mg / L to 100 mg / L, the potassium ion concentration is 5 mg / L to 10 mg / L, and the magnesium ion concentration is 100 mg / L. The concentrations of lithium ions in the second purified solution are: 300 mg / L to 700 mg / L, sodium ions are: 20 mg / L to 30 mg / L, potassium ions are: 5 mg / L to 15 mg / L, and magnesium ions are: 150 mg / L to 300 mg / L; and / or the concentrations of lithium ions in the third purified solution are: 400 mg / L to 700 mg / L, sodium ions are: 20 mg / L to 30 mg / L, potassium ions are: 5 mg / L to 15 mg / L, and magnesium ions are: 100 mg / L to 300 mg / L.

[0010] Further, in steps S1-4, the replacement includes: pumping the chloride-type low-lithium brine into the fourth adsorption column at a flow rate of 1 Bv / h to 2 Bv / h for the first replacement; pumping the chloride-type low-lithium brine into the fourth adsorption column again at a flow rate of 11 Bv / h to 12 Bv / h for the second replacement; preferably, the time for the first replacement and the second replacement are each 12 ± 2 min independently.

[0011] Further, step S2-1 also includes: mixing the first purified solution, the second purified solution and the third purified solution in a volume ratio of (4-5):1:1 to obtain a mixed purified solution, and using the mixed purified solution as the second top feed solution; preferably, the pumping flow rate of the second top feed solution is 6 Bv / h to 8 Bv / h; more preferably, the time for the second top feed solution is 12±2 min.

[0012] Further, in step S2-2, during the fourth, fifth, and sixth desorption processes, the pump flow rate of the second desorption solution is independently 3.5 Bv / h to 5.0 Bv / h, and the temperature is independently 40 ± 2 °C; preferably, the time for the fourth, fifth, and sixth desorption processes is independently 12 ± 2 min; more preferably, in the fourth purification solution, the lithium ion concentration is 400 mg / L to 1700 mg / L, the sodium ion concentration is 100 mg / L to 200 mg / L, the potassium ion concentration is 15 mg / L to 40 mg / L, and the magnesium ion concentration is 500 mg / L. mg / L~800mg / L; and / or, in the fifth purification solution, the lithium ion concentration is 500mg / L~700mg / L, the sodium ion concentration is 20mg / L~70mg / L, the potassium ion concentration is 5mg / L~15mg / L, and the magnesium ion concentration is 150mg / L~300mg / L; and / or, in the sixth purification solution, the lithium ion concentration is 700mg / L~800mg / L, the sodium ion concentration is 20mg / L~70mg / L, the potassium ion concentration is 5mg / L~15mg / L, and the magnesium ion concentration is 150mg / L~300mg / L.

[0013] Furthermore, in step S3, the pressure for reverse osmosis concentration is 3.5 MPa to 4.5 MPa.

[0014] Further, step S4 includes: adjusting the pH of the concentrate to 12-13 and filtering to obtain a filtrate, then subjecting the filtrate to extraction and back-extraction in sequence to obtain a lithium-containing solution; preferably, during the extraction process, the weight ratio of the filtrate to the extractant is (3-4):1; and / or, during the back-extraction process, the back-extraction agent used is one of carbon dioxide, hydrochloric acid solution and phosphoric acid solution.

[0015] Furthermore, the back-extraction agent is carbon dioxide, and the post-treatment in step S5 is heating and filtration; and / or, the back-extraction agent is hydrochloric acid solution or phosphoric acid solution, and the post-treatment in step S5 is evaporation and crystallization.

[0016] The present invention provides a method for preparing high-purity lithium compounds from low-lithium-concentration salt lake brine in a low-cost, short-process manner. By designing the secondary adsorption stage in the lithium extraction process of the brine, the lithium yield is greatly improved, impurities such as sodium, potassium, and magnesium are effectively removed, and the lithium ion concentration is significantly increased. This achieves the purpose of enriching, concentrating, and removing impurities from ultra-low-lithium salt lake brine, and reduces the cost of preparing lithium compound products from chloride-type low-lithium salt lake brine as raw material. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0018] As described in the background art, existing technologies suffer from the difficulty of using chloride-type low-lithium brine as a raw material for adsorption and recovery to obtain high-purity lithium-containing compounds. To address this technical problem, the present invention provides a method for producing lithium-containing compounds using chloride-type low-lithium brine, comprising: Step S1, a first adsorption stage: Step S1-1, pumping chloride-type low-lithium brine into a first adsorption column for first adsorption to obtain a second adsorption column; Step S1-2, using water as a first top feed liquid to top the second adsorption column to obtain a first waste liquid and a third adsorption column; Step S1-3, using water as a first desorption liquid to sequentially perform first desorption, second desorption, and third desorption on the third adsorption column to obtain a fourth adsorption column; wherein the first desorption, second desorption, and third desorption yield a first purified solution, a second purified solution, and a third purified solution, respectively; Step S1-4, pumping fresh chloride-type low-lithium brine into the fourth adsorption column for displacement to obtain... Fifth adsorption column; Step S2, second adsorption stage: Step S2-1, the first purified solution, the second purified solution, and the third purified solution are used together as the second top feed liquid to perform the second top feed on the fifth adsorption column, resulting in the second waste liquid and the sixth adsorption column; Step S2-2, water is used as the second eluent to perform the fourth, fifth, and sixth desorption sequentially on the sixth adsorption column; wherein the fourth, fifth, and sixth desorptions respectively yield the fourth, fifth, and sixth purified solutions, which are then mixed to obtain the adsorption purified solution; Step S3, the adsorption purified solution is concentrated by reverse osmosis to obtain the concentrate; Step S4, the concentrate is sequentially extracted and back-extracted to obtain a lithium-containing solution; Step S5, the lithium-containing solution is post-treated to obtain a lithium-containing compound.

[0019] This invention uses chloride-type low-lithium brine as raw material, and sequentially performs a series of secondary adsorption, reverse osmosis concentration, extraction, and back-extraction to obtain a lithium-containing solution. Further post-processing yields a high-purity lithium-containing compound. Particularly noteworthy is the design of the secondary adsorption series. In the first adsorption stage, using chloride-type low-lithium brine as raw material (hereinafter referred to as the original brine), adsorption, top-feeding, desorption, and displacement are performed to obtain a first purified solution, a second purified solution, and a third purified solution with higher lithium content. Simultaneously, a fifth adsorption column refilled with the original brine is obtained. Specifically:

[0020] In the first adsorption process, the raw brine is pumped into the first adsorption column containing the adsorbent. When it comes into contact with the adsorbent, lithium ions undergo chemical or physical adsorption with the active sites on the adsorbent surface, thus being adsorbed from the brine. Simultaneously, because the adsorbent has a weak adsorption capacity for sodium, potassium, and magnesium ions, they are essentially not adsorbed and instead flow out of the adsorption column with the tail liquid during the first top-feeding process. Then, a higher concentration of lithium-containing solution is used to re-adsorb the third adsorption column, which already contains a large number of lithium ions, resulting in a fourth adsorption column. This yields the first, second, and third purified solutions sequentially. During this process, water, i.e., the first desorption solution, is pumped into the third adsorption column and comes into contact with the adsorbent. Lithium ions desorb from the adsorbent surface and enter the column, forming a high-concentration lithium solution. In particular, this invention incorporates sequential first, second, and third desorption processes to more thoroughly desorb and carry away lithium ions from the adsorption column.

[0021] In the first adsorption process, using the first, second, and third purified solutions obtained above together as the second feed solution can significantly improve the lithium recovery rate in the original brine and the lithium content in the desorbate, reduce its loss, lower the impurity content, and also save water consumption while maintaining the stability of the adsorbent in the adsorption column. In particular, after the first adsorption stage, the lithium ion concentration in the three purified solutions obtained is much higher than that in the original brine. When used as the feed solution, its higher lithium ion concentration can effectively promote the re-adsorption of lithium ions on the adsorbent, thereby improving the total lithium recovery rate and the lithium concentration in the desorbate. Compared with using pure water, the lithium ion concentration in pure water is close to zero, and it cannot provide additional driving force to promote the re-adsorption of lithium ions on the adsorbent. At the same time, since the concentrations of impurities such as sodium, potassium, and magnesium in the three purified solutions have been significantly reduced, they can further replace residual impurities on the adsorbent, reducing the impurity content in subsequent processing. Compared with using water as the second feed solution, although pure water is clean, it is not as effective as purified solutions containing certain impurities in replacing impurities. Therefore, using the purified solution as the second feed solution can more effectively improve the lithium yield and the lithium concentration in the desorption solution. Combined with subsequent reverse osmosis concentration, extraction, back-extraction and post-treatment, it can yield lithium-containing compounds with higher purity and lower preparation cost.

[0022] In summary, the method provided by this invention significantly reduces impurities such as sodium, potassium, and magnesium in chloride-type low-lithium brine, significantly increases the concentration of lithium ions in the desorption liquid, achieves the purpose of enriching, concentrating, and removing impurities from lithium ions, significantly reduces the cost of preparing lithium-containing compound products using salt lake chloride-type low-lithium brine as raw material, shortens the process of preparing lithium salt compounds, and also produces high-purity lithium-containing compound products.

[0023] In practical applications, the adsorption column used in the above method is filled with an aluminum-based adsorbent, specifically LiCl·nAl(OH)3·mH2O. The coefficients n and m represent the molar amounts of aluminum hydroxide and water in the adsorbent, respectively, and vary depending on the preparation process, typically ranging from 1 to 3 independently. The adsorption column is a commonly used adsorption vessel, which usually contains a liquid distributor to uniformly distribute the liquid within the column and prevent adsorbent loss.

[0024] Furthermore, in the chloride-type low-lithium brine, the lithium ion concentration is 60 mg / L to 900 mg / L, the sodium ion concentration is 1000 mg / L to 90000 mg / L, the potassium ion concentration is 1000 mg / L to 18000 mg / L, and the magnesium ion concentration is 40000 mg / L to 120000 mg / L. The above-mentioned control and optimization of the original brine composition is more suitable for the method provided by this invention, thereby more effectively promoting the efficient execution of the secondary adsorption and desorption processes, while reducing the interference of impurity ions at each stage on lithium ion recovery, thus improving the recovery effect. In practical applications, the treated chloride-type low-lithium brine comes from the intercrystalline brine (i.e., high-concentration brine filling the pores of the salt layer in the Qarhan Salt Lake of the Qaidam Basin) in the Qaidam Basin.

[0025] In several more typical embodiments, the chloride-type low-lithium brine has a lithium ion concentration of 60 mg / L to 900 mg / L, a sodium ion concentration of 1000 mg / L to 90000 mg / L, a potassium ion concentration of 1000 mg / L to 18000 mg / L, and a magnesium ion concentration of 40000 mg / L to 120000 mg / L. To improve the adsorption efficiency in the first adsorption process and enhance the adsorption effect of lithium ions, the flow rate and adsorption time of the original brine when pumped into the first adsorption column are preferred, i.e., preferably: in step S1-1, the chloride-type low-lithium brine is pumped into the first adsorption column at a flow rate of 10 Bv / h to 12 Bv / h; and / or, the first adsorption time is 12 ± 2 min.

[0026] Furthermore, regarding the desorption process in the first adsorption stage, the inventors, through extensive experiments, optimized the pump flow rate of the first desorption liquid to be independently 3.5 Bv / h to 5.0 Bv / h and the temperature to be independently 35℃ to 40℃ for each of the first, second, and third desorption processes. This control of the flow rate and temperature of the first desorption liquid can more effectively improve the desorption rate of lithium ions in the first adsorption stage, reduce lithium ion loss during desorption, and yield a first, second, and third purified solution with higher lithium ion content and lower impurity content. These three solutions are then used as the top feed liquid in the second adsorption stage in a certain proportion, thereby increasing the lithium ion concentration and purity of the final lithium-containing desorption solution. Simultaneously, the optimal desorption times for the first, second, and third desorption processes are each 12±2 min, thereby promoting the full progress of the first desorption process and reducing lithium ion loss due to over-desorption.

[0027] In several typical embodiments, the first purification solution contains lithium ion concentrations of 200 mg / L to 500 mg / L, sodium ion concentrations of 30 mg / L to 100 mg / L, potassium ion concentrations of 5 mg / L to 10 mg / L, and magnesium ion concentrations of 100 mg / L to 300 mg / L; and / or, the second purification solution contains lithium ion concentrations of 300 mg / L to 700 mg / L, sodium ion concentrations of 20 mg / L to 30 mg / L, potassium ion concentrations of 5 mg / L to 15 mg / L, and magnesium ion concentrations of 150 mg / L to 300 mg / L; and / or, the third purification solution contains lithium ion concentrations of 400 mg / L to 700 mg / L, sodium ion concentrations of 20 mg / L to 30 mg / L, potassium ion concentrations of 5 mg / L to 15 mg / L, and magnesium ion concentrations of 100 mg / L to 300 mg / L. By optimizing the parameters in the first desorption process as described above, a first purified solution, a second purified solution, and a third purified solution with the aforementioned component contents were obtained. The lithium ion concentration in these three solutions increases sequentially, while the contents of other types of impurity ions gradually decrease. Preferably, these three solutions with the aforementioned component contents are used together in a certain proportion as the second feed solution. This better utilizes their advantages of high lithium concentration and low impurity concentration, thereby achieving a higher recovery rate for lithium extraction from the original brine and ultimately preparing a lithium-containing compound product with higher purity.

[0028] In the displacement process during the first adsorption stage, in order to further improve the lithium ion recovery rate, reduce the waste of brine, and also obtain a substrate adsorption column with a larger amount of lithium ions again, the displacement includes: pumping chloride-type low-lithium brine into the fourth adsorption column at a flow rate of 1 Bv / h to 2 Bv / h for the first displacement; pumping chloride-type low-lithium brine into the fourth adsorption column again at a flow rate of 11 Bv / h to 12 Bv / h for the second displacement; and / or, the time for the first displacement and the second displacement are each 12 ± 2 min independently.

[0029] Further, step S2-1 also includes: mixing the first purified solution, the second purified solution, and the third purified solution in a volume ratio of (4-5):1:1 to obtain a mixed purified solution, and using the mixed purified solution as the second top feed solution. As mentioned above, by mixing the three purified solutions in the first adsorption stage as the top feed solution in the second adsorption stage, this invention can further improve the recovery rate of lithium in the original brine and the lithium ion concentration in the lithium-containing desorption solution, while reducing the impurity content. Based on the composition of the obtained first, second, and third purified solutions, the inventors further optimized the volume ratio of the above-mentioned mixture through numerous experiments, thereby achieving lithium extraction from the original brine with a higher recovery rate, and also preparing lithium-containing compound samples with higher purity.

[0030] In several typical embodiments, the lithium ion concentration in the mixed purification solution is 200 mg / L to 400 mg / L, the sodium ion concentration is 20 mg / L to 150 mg / L, the potassium ion concentration is 5 mg / L to 20 mg / L, and the magnesium ion concentration is 200 mg / L to 800 mg / L. Optimizing the composition of the mixed purification solution as described above can further promote the efficient recovery of lithium ions and improve the purity of the final lithium-containing compound.

[0031] The preferred pump flow rate of the second top feed solution is 6 Bv / h to 8 Bv / h, and the preferred top feeding time is 12 ± 2 min. This allows the top feeding process in the second adsorption stage to proceed more fully, improving top feeding efficiency and reducing lithium ion loss during the top feeding process. Furthermore, the above parameter settings can better adapt to the component concentration of the mixed purification solution, i.e., the second top feed solution, thereby more effectively leveraging the effect of the mixed purification solution in improving lithium recovery.

[0032] Furthermore, in step S2-2, during the fourth, fifth, and sixth desorption processes, the pump flow rate of the second desorption liquid is independently 3.5 Bv / h to 5.0 Bv / h, and the temperature is independently 40 ± 2 °C; and / or, the time for the fourth, fifth, and sixth desorption processes is independently 12 ± 2 min. Optimizing the parameters in the final desorption process to obtain the adsorption purification solution, including the flow rate of the desorption liquid used for each desorption and the temperature and time used, can more effectively improve the lithium ion desorption rate, reduce lithium ion loss during desorption, and yield an adsorption purification solution with higher lithium content and lower impurities, thereby preparing a lithium-containing compound with higher purity.

[0033] In several typical embodiments, in the fourth purification solution, the lithium ion concentration is 400 mg / L to 1700 mg / L, the sodium ion concentration is 100 mg / L to 200 mg / L, the potassium ion concentration is 15 mg / L to 40 mg / L, and the magnesium ion concentration is 500 mg / L to 800 mg / L; and / or, in the fifth purification solution, the lithium ion concentration is 500 mg / L to 700 mg / L, the sodium ion concentration is 20 mg / L to 70 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 150 mg / L to 300 mg / L; and / or, in the sixth purification solution, the lithium ion concentration is 700 mg / L to 800 mg / L, the sodium ion concentration is 20 mg / L to 70 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 150 mg / L to 300 mg / L. The adsorption and purification solutions obtained through the above steps have a higher lithium-ion content, thus more effectively improving the purity of the final lithium-containing compounds. In several more typical embodiments, the lithium-ion concentration in the adsorption and purification solution is 300 mg / L to 700 mg / L, the sodium-ion concentration is 40 mg / L to 250 mg / L, the potassium-ion concentration is 5 mg / L to 20 mg / L, and the magnesium-ion concentration is 200 mg / L to 1300 mg / L. The adsorption and purification solution obtained through the above-mentioned optimized conditions has this component content, which is better suited to the subsequent reverse osmosis concentration and extraction processes, making them more efficient, while also reducing the interference of impurities on lithium-ion recovery, making it more suitable for the high-purity production of lithium compounds.

[0034] In order to more effectively improve the concentration efficiency of lithium ions, reduce energy consumption during the concentration process, and obtain lithium compound products with higher purity, the reverse osmosis concentration pressure in step S3 is further optimized to be 3.5MPa to 4.5MPa.

[0035] Further, step S4 includes: adjusting the pH of the concentrate to 12-13 and filtering to obtain a filtrate, then subjecting the filtrate to extraction and back-extraction sequentially to obtain a lithium-containing solution. Precise pH adjustment and filtration of the filtrate before extraction can more effectively remove impurities from the filtrate through extraction and back-extraction, improving the purity of lithium ions and thus enhancing the purity of the subsequently prepared lithium compounds.

[0036] In order to achieve more efficient enrichment of lithium ions and deeper impurity removal during extraction, and to obtain lithium compound products with higher purity, the preferred weight ratio of filtrate to extractant is (3-4):1. Specifically, the extractant is a special lithium extractant of crown ether or ionic liquid, whose structure includes crown ether host, diluent and co-extractant or functional groups such as cations such as quaternary ammonium salts, anions such as phosphates and phosphate esters.

[0037] In the back-extraction process, one of the following back-extraction agents is carbon dioxide, hydrochloric acid solution, or phosphoric acid solution, to obtain lithium carbonate, lithium chloride, lithium phosphate, or lithium dihydrogen phosphate products. Furthermore, if the back-extraction agent is carbon dioxide, the post-processing in step S5 is heating and filtration, and the lithium-containing compound is lithium carbonate; and / or, if the back-extraction agent is hydrochloric acid solution, the post-processing in step S5 is evaporation and crystallization, and the lithium-containing compound is lithium chloride; and / or, if the back-extraction agent is phosphoric acid solution, the post-processing in step S5 is filtration or evaporation and crystallization, and the lithium-containing compound is lithium phosphate or lithium dihydrogen phosphate. By using carbon dioxide as the back-extraction agent combined with heating and filtration post-processing, high-purity lithium carbonate can be obtained. By using hydrochloric acid solution as the back-extraction agent combined with evaporation and crystallization post-processing, high-purity lithium chloride can be obtained. By using phosphoric acid solution as the back-extraction agent combined with filtration or evaporation and crystallization post-processing, high-purity lithium phosphate or lithium dihydrogen phosphate can be obtained. The selection of back-extraction agents and corresponding post-processing methods can be flexibly adjusted according to different production needs and conditions, making it suitable for customized production of lithium compounds.

[0038] Furthermore, the method described in this application greatly shortens the process flow, reduces product preparation costs, and can be widely applied in the field of lithium extraction.

[0039] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0040] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0041] Example 1

[0042] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0043] The treated chloride-type low-lithium brine comes from the Qarhan Salt Lake brine, and its concentrations are: lithium ion 80 mg / L, sodium ion 50400 mg / L, potassium ion 8200 mg / L, and magnesium ion 42000 mg / L.

[0044] The adsorption column used is filled with a special lithium adsorbent with the structural formula LiCl·nAl(OH)3·mH2O, where n=2 and m=1.5~8.

[0045] (1) First adsorption stage:

[0046] (1-1) The above-mentioned chloride-type low-lithium brine was filtered and then pumped into the first adsorption column at a flow rate of 11.25 Bv / h for a first adsorption time of 12 min to obtain the second adsorption column.

[0047] (1-2) Water was used as the first top feed liquid and pumped into the second adsorption column at a flow rate of 6.9 Bv / h. The second adsorption column was subjected to the first top feed for 12 min to obtain the first waste liquid and the third adsorption column.

[0048] (1-3) Using water at 35℃ as the first desorption solution, the third adsorption column was subjected to the first desorption, the second desorption and the third desorption in sequence to obtain the fourth adsorption column.

[0049] In the first, second, and third desorption processes, the first desorption solution was sequentially pumped into the third adsorption column at a flow rate of 4.5 Bv / h for 12 minutes each time. After three desorption processes, the first purified solution, the second purified solution, and the third purified solution were obtained sequentially. Among them:

[0050] In the first purified solution, the lithium ion concentration was 315 mg / L, the sodium ion concentration was 30 mg / L, the potassium ion concentration was 8.2 mg / L, and the magnesium ion concentration was 277 mg / L.

[0051] In the second purification solution, the lithium ion concentration was 370 mg / L, the sodium ion concentration was 22 mg / L, and the potassium ion concentration was...

[0052] 8.15 mg / L, magnesium ion concentration is 172 mg / L;

[0053] In the third purification solution, the lithium ion concentration was 397 mg / L, the sodium ion concentration was 21 mg / L, and the potassium ion concentration was...

[0054] 8.02 mg / L, magnesium ion concentration is 116 mg / L;

[0055] (1-4) The original brine, i.e., chloride-type low-lithium brine, was pumped into the fourth adsorption column again at a flow rate of 1.5 Bv / h for a first displacement of 12 min; then the chloride-type low-lithium brine was pumped into the fourth adsorption column again at a flow rate of 11.25 Bv / h for a second displacement of 12 min, to obtain the fifth adsorption column.

[0056] (2) Second adsorption stage:

[0057] (2-1) The first purified solution, the second purified solution and the third purified solution are mixed in a volume ratio of 4:1:1 to obtain a mixed purified solution. The mixed purified solution is used as the second top feed solution and pumped into the fifth adsorption column at a flow rate of 6 Bv / h for 12 min to obtain the second waste liquid and the sixth adsorption column.

[0058] (2-2) Using water at 40℃ as the second desorption solution, the solution was pumped into the sixth adsorption column at a flow rate of 4.5 Bv / h, and then subjected to the fourth, fifth, and sixth desorption processes sequentially to obtain the fourth adsorption column. The time for each of these three desorption processes was 12 min, and the fourth, fifth, and sixth purified solutions were obtained sequentially. These were then mixed to obtain the final purified adsorption solution. Wherein:

[0059] In the fourth purification solution, the lithium ion concentration was 449 mg / L, the sodium ion concentration was 128 mg / L, the potassium ion concentration was 15 mg / L, and the magnesium ion concentration was 567 mg / L.

[0060] In the fifth purification solution, the lithium ion concentration was 670 mg / L, the sodium ion concentration was 22 mg / L, and the potassium ion concentration was...

[0061] 8.15 mg / L, magnesium ion concentration is 172 mg / L;

[0062] In the sixth purification solution, the lithium ion concentration was 727 mg / L, the sodium ion concentration was 21 mg / L, and the potassium ion concentration was...

[0063] 7.02 mg / L, magnesium ion concentration is 156 mg / L;

[0064] (3) The adsorption purified solution obtained from the above adsorption process is concentrated using a reverse osmosis membrane system, and the pressure of the high-pressure pump is controlled at 3.5 MPa to obtain a concentrated solution;

[0065] (4) Adjust the pH of the concentrated solution obtained from reverse osmosis to 12, and filter the precipitate to obtain a filtrate. Then, mix the obtained filtrate with a lithium extractant (dibutyl phosphate) for ionic liquids at a weight ratio of 4:1 (filtrate: extractant) and extract to obtain an extract. The obtained extract is then back-extracted using carbon dioxide to obtain a lithium-containing solution, namely a lithium bicarbonate solution.

[0066] (5) Heat the obtained lithium-containing solution to 80°C, then filter, wash and dry the lithium carbonate precipitate to obtain the lithium carbonate product, i.e., the lithium-containing compound.

[0067] Example 2

[0068] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0069] The chloride-type low-lithium brine treated and the type of adsorption column used were consistent with those in Example 1.

[0070] (1) First adsorption stage:

[0071] (1-1) The above-mentioned chloride-type low-lithium brine was filtered and then pumped into the first adsorption column at a flow rate of 12 Bv / h for a first adsorption time of 12 min to obtain the second adsorption column.

[0072] (1-2) Water was used as the first top feed liquid and pumped into the second adsorption column at a flow rate of 7.7 Bv / h. The second adsorption column was subjected to the first top feed for 12 min to obtain the first waste liquid and the third adsorption column.

[0073] (1-3) Using water at 40℃ as the first desorption liquid, the third adsorption column was subjected to the first desorption, the second desorption and the third desorption in sequence to obtain the fourth adsorption column.

[0074] In each of the first, second, and third desorption processes, the first desorption solution was sequentially pumped into the third adsorption column at a flow rate of 5.0 Bv / h for 12 minutes. After three desorption processes, the first purified solution, the second purified solution, and the third purified solution were obtained sequentially. Among them:

[0075] In the first purified solution, the lithium ion concentration was 320 mg / L, the sodium ion concentration was 30 mg / L, the potassium ion concentration was 9 mg / L, and the magnesium ion concentration was 280 mg / L.

[0076] In the second purification solution, the lithium ion concentration was 375 mg / L, the sodium ion concentration was 20 mg / L, the potassium ion concentration was 8.5 mg / L, and the magnesium ion concentration was 178 mg / L.

[0077] In the third purification solution, the lithium ion concentration was 420 mg / L, the sodium ion concentration was 20.5 mg / L, and the potassium ion concentration was...

[0078] 7.9 mg / L, magnesium ion concentration is 120 mg / L;

[0079] (1-4) The original brine, i.e. chloride-type low-lithium brine, was pumped into the fourth adsorption column again at a flow rate of 1.7 Bv / h for a displacement time of 12 min. Then, the chloride-type low-lithium brine was pumped into the fourth adsorption column again at a flow rate of 12 Bv / h for a second displacement time of 12 min, to obtain the fifth adsorption column.

[0080] (2) Second adsorption stage:

[0081] (2-1) The first purified solution, the second purified solution and the third purified solution are mixed in a volume ratio of 5:1:1 to obtain a mixed purified solution. The mixed purified solution is used as the second top feed solution and pumped into the fifth adsorption column at a flow rate of 7.3 Bv / h for 12 min to obtain the second waste liquid and the sixth adsorption column.

[0082] (2-2) Using water at 40℃ as the second desorption solution, the solution was pumped into the sixth adsorption column at a flow rate of 5.0 Bv / h, and then subjected to the fourth, fifth, and sixth desorption processes sequentially to obtain the fourth adsorption column. The time for each of these three desorption processes was 12 min, and the fourth, fifth, and sixth purified solutions were obtained sequentially. These were then mixed to obtain the final purified adsorption solution. Wherein:

[0083] In the fourth purification solution, the lithium ion concentration was 489 mg / L, the sodium ion concentration was 138 mg / L, the potassium ion concentration was 20 mg / L, and the magnesium ion concentration was 537 mg / L.

[0084] In the fifth purification solution, the lithium ion concentration was 690 mg / L, the sodium ion concentration was 45 mg / L, the potassium ion concentration was 13 mg / L, and the magnesium ion concentration was 202 mg / L.

[0085] In the sixth purification solution, the concentration of lithium ions was 738 mg / L, the concentration of sodium ions was 25 mg / L, the concentration of potassium ions was 6.5 mg / L, and the concentration of magnesium ions was 160 mg / L.

[0086] (3) The adsorption purified solution obtained from the above adsorption process is concentrated using a reverse osmosis membrane system, and the pressure of the high-pressure pump is controlled at 4.5 MPa to obtain a concentrated solution;

[0087] (4) Adjust the pH of the concentrated solution obtained from reverse osmosis to 12, and filter the precipitate to obtain a filtrate. Then, mix the obtained filtrate with a lithium extractant (quaternary ammonium salt N263) for ionic liquids at a weight ratio of 3:1 (filtrate: extractant) and extract to obtain an extract. Wash the obtained extract with fresh water and then back-extract it with hydrochloric acid solution to obtain a lithium-containing solution, i.e., a lithium chloride solution.

[0088] (5) The lithium-containing solution is evaporated and crystallized to precipitate lithium chloride. After filtration, washing and drying, lithium chloride product, i.e. lithium-containing compound, is obtained.

[0089] Example 3

[0090] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0091] The only difference between this embodiment and Embodiment 1 is that:

[0092] In step (1-1), the flow rate of the chloride-type low-lithium brine pumped into the first adsorption column is changed to 8 Bv / h, and the first adsorption time is changed to 20 min. At the same time, in step (1-4), the flow rate of the chloride-type low-lithium brine pumped into the fourth adsorption column is changed to 0.8 Bv / h, and the displacement time is changed to 20 min.

[0093] Using the above-mentioned adsorption and displacement conditions in steps (1-1) and (1-4), high-purity lithium carbonate products can also be obtained. However, due to the decrease in adsorption efficiency, the yield of the obtained products is slightly lower, resulting in slightly lower economic benefits and production value.

[0094] Example 4

[0095] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0096] The only difference between this embodiment and Embodiment 2 is that:

[0097] In step (1-1), the flow rate of the chloride-type low-lithium brine pumped into the first adsorption column is changed to 15 Bv / h, and the first adsorption time is changed to 5 min. At the same time, in step (1-4), the flow rate of the chloride-type low-lithium brine pumped into the fourth adsorption column is changed to 0.5 Bv / h, and the displacement time is changed to 5 min.

[0098] Example 5

[0099] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0100] The difference between this embodiment and embodiment 2 lies only in steps (1-3), specifically:

[0101] Using water at 20°C as the first desorption solvent, the third adsorption column was subjected to first, second, and third desorption processes sequentially to obtain a fourth adsorption column. Simultaneously, during each of the first, second, and third desorption processes, the first desorption solvent was pumped into the third adsorption column at a flow rate of 2 Bv / h for 12 minutes. After three desorption processes, the first purified solution, the second purified solution, and the third purified solution were obtained sequentially.

[0102] The subsequent steps are the same as in Example 2.

[0103] Example 6

[0104] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0105] The difference between this embodiment and embodiment 2 lies only in step (2-1), specifically:

[0106] The first, second, and third purified solutions were mixed in a volume ratio of 6:1:1 to obtain a mixed purified solution. This mixed purified solution was then used as the second top feed solution and pumped into the fifth adsorption column at a flow rate of 3 Bv / h for 20 min, resulting in the second waste liquid and the sixth adsorption column.

[0107] Example 7

[0108] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0109] The difference between this embodiment and Embodiment 1 lies only in step (2-1), specifically:

[0110] The first, second, and third purified solutions were mixed in a volume ratio of 3:2:2 to obtain a mixed purified solution. This mixed purified solution was then used as the second top feed solution and pumped into the fifth adsorption column at a flow rate of 10 Bv / h for 5 minutes to obtain the second waste liquid and the sixth adsorption column.

[0111] In this embodiment, by changing the volume ratio of the first purified solution, the second purified solution, and the third purified solution, as well as the flow rate and time of the mixed pump, a high-purity lithium carbonate product can be obtained, but the lithium recovery rate is slightly reduced, and the yield is slightly lower than that of Example 1.

[0112] Comparative Example 1

[0113] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0114] The only difference between this comparative example and Example 1 is that:

[0115] In step (2-1), water is used again as the second top feed liquid and pumped into the second adsorption column at a flow rate of 6 Bv / h for the first top feed of the second adsorption column for 12 min. Then, it is pumped into the fifth adsorption column at a flow rate of 6 Bv / h for the second top feed for 12 min, resulting in the second waste liquid and the sixth adsorption column.

[0116] The remaining steps are performed in accordance with Example 1.

[0117] In this comparative example, pure water was used instead of the mixed purification solution in Example 1. Although a high-purity lithium carbonate product was still obtained, the amount of pure water used was too large, and the recovery rate of lithium in the mixed purification solution was significantly reduced. Therefore, the yield was significantly reduced, the economic benefits were also significantly reduced, and it was difficult to have practical application value.

[0118] Comparative Example 2

[0119] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0120] The only difference between this comparative example and Example 2 is that:

[0121] In steps (1-3), the second and third desorption processes are not performed, and only the first purified solution is obtained. In the subsequent step (2-1), the first purified solution is directly used as the second feed solution.

[0122] The remaining steps are performed in accordance with Example 2.

[0123] Comparative Example 3

[0124] A method for producing lithium-containing compounds using chloride-type low-lithium brine:

[0125] The only difference between this comparative example and Example 1 is that:

[0126] In steps (1-3), a third desorption is not performed, and only the first purified solution and the second purified solution are obtained. In the subsequent step (2-1), the first purified solution and the second purified solution are mixed in a 1:1 volume ratio to form the second top feed solution.

[0127] The remaining steps are performed in accordance with Example 1.

[0128] The contents of each ion in the mixed purification solution used in the top liquid process of the second adsorption stage, the adsorption purification solution obtained in the desorption process, and the concentrate obtained in the reverse osmosis concentration stage of the above embodiments and comparative examples are shown in Table 1. The purity of the final lithium-containing compound is also shown in Table 1.

[0129] Table 1

[0130]

[0131]

[0132] As can be seen from the above description, the above embodiments of the present invention achieve the preparation of high-purity lithium-containing compounds by using chloride-type low-lithium brine as raw material, through first adsorption, first top feed, first desorption, first replacement, second top feed, second desorption, reverse osmosis concentration, extraction and back extraction, and post-treatment.

[0133] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0134] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing lithium-containing compounds using chloride-type low-lithium brine, characterized in that, include: Step S1, First Adsorption Stage: Step S1-1: The chloride-type low-lithium brine is pumped into the first adsorption column for first adsorption to obtain the second adsorption column. Step S1-2: Water is used as the first top feed liquid to top the second adsorption column, resulting in the first waste liquid and the third adsorption column. Steps S1-3: Using water as the first desorption liquid, the third adsorption column is subjected to first desorption, second desorption and third desorption in sequence to obtain a fourth adsorption column; wherein the first desorption, second desorption and third desorption respectively yield a first purified solution, a second purified solution and a third purified solution; Steps S1-4: Fresh chloride-type low-lithium brine is pumped into the fourth adsorption column for displacement to obtain the fifth adsorption column. Step S2, second adsorption stage: Step S2-1: The first purified solution, the second purified solution, and the third purified solution are used together as the second top feed solution to the fifth adsorption column to obtain the second waste liquid and the sixth adsorption column; Step S2-2: Using water as the second desorption solution, the sixth adsorption column is subjected to fourth desorption, fifth desorption and sixth desorption in sequence; wherein the fourth desorption, the fifth desorption and the sixth desorption respectively yield a fourth purified solution, a fifth purified solution and a sixth purified solution, and the fourth purified solution, the fifth purified solution and the sixth purified solution are mixed to obtain an adsorption purified solution; Step S3: The adsorption purification solution is concentrated by reverse osmosis to obtain a concentrated solution; Step S4: The concentrate is subjected to extraction and back-extraction sequentially to obtain a lithium-containing solution; Step S5: The lithium-containing solution is post-processed to obtain the lithium-containing compound.

2. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 1, characterized in that, In the chloride-type low-lithium brine, the lithium ion concentration is 60 mg / L to 900 mg / L, the sodium ion concentration is 1000 mg / L to 90000 mg / L, the potassium ion concentration is 1000 mg / L to 18000 mg / L, and the magnesium ion concentration is 40000 mg / L to 120000 mg / L.

3. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 2, characterized in that, In step S1-1, the chloride-type low-lithium brine is pumped into the first adsorption column at a flow rate of 10 Bv / h to 12 Bv / h; and / or, the first adsorption time is 12 ± 2 min.

4. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, In steps S1-3, during the first desorption, the second desorption, and the third desorption, the pump flow rate of the first desorption liquid is independently 3.5 Bv / h to 5.0 Bv / h, and the temperature is independently 35℃ to 40℃.

5. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 4, characterized in that, The time for the first desorption, the second desorption, and the third desorption is each 12 ± 2 min independently.

6. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 4, characterized in that, In the first purification solution, the lithium ion concentration is 200 mg / L to 500 mg / L, the sodium ion concentration is 30 mg / L to 100 mg / L, the potassium ion concentration is 5 mg / L to 10 mg / L, and the magnesium ion concentration is 100 mg / L to 300 mg / L; and / or, in the second purification solution, the lithium ion concentration is 300 mg / L to 700 mg / L, the sodium ion concentration is 20 mg / L to 30 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 150 mg / L to 300 mg / L; and / or, in the third purification solution, the lithium ion concentration is 400 mg / L to 700 mg / L, the sodium ion concentration is 20 mg / L to 30 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 100 mg / L to 300 mg / L.

7. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, In steps S1-4, the replacement includes: pumping the chloride-type low-lithium brine into the fourth adsorption column at a flow rate of 1 Bv / h to 2 Bv / h for a first replacement; and pumping the chloride-type low-lithium brine into the fourth adsorption column again at a flow rate of 11 Bv / h to 12 Bv / h for a second replacement.

8. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 7, characterized in that, The time for the first substitution and the second substitution is 12 ± 2 min each independently.

9. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, Step S2-1 further includes: mixing the first purified solution, the second purified solution and the third purified solution in a volume ratio of (4~5):1:1 to obtain a mixed purified solution, and using the mixed purified solution as the second top feed solution.

10. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 9, characterized in that, The pumping flow rate of the second top feed liquid is 6 Bv / h to 8 Bv / h.

11. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 9, characterized in that, The time for the second top material is 12±2 min.

12. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, In step S2-2, during the fourth, fifth, and sixth desorption processes, the pump flow rate of the second desorption liquid is independently 3.5 Bv / h to 5.0 Bv / h, and the temperature is independently 40 ± 2℃.

13. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 12, characterized in that, The time for the fourth desorption, the fifth desorption, and the sixth desorption is each 12 ± 2 min independently.

14. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 12, characterized in that, In the fourth purification solution, the lithium ion concentration is 400 mg / L to 1700 mg / L, the sodium ion concentration is 100 mg / L to 200 mg / L, the potassium ion concentration is 15 mg / L to 40 mg / L, and the magnesium ion concentration is 500 mg / L to 800 mg / L; and / or, in the fifth purification solution, the lithium ion concentration is 500 mg / L to 700 mg / L, the sodium ion concentration is 20 mg / L to 70 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 150 mg / L to 300 mg / L; and / or, in the sixth purification solution, the lithium ion concentration is 700 mg / L to 800 mg / L, the sodium ion concentration is 20 mg / L to 70 mg / L, the potassium ion concentration is 5 mg / L to 15 mg / L, and the magnesium ion concentration is 150 mg / L to 300 mg / L.

15. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, In step S3, the pressure of the reverse osmosis concentration is 3.5 MPa to 4.5 MPa.

16. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to any one of claims 1 to 3, characterized in that, Step S4 includes: adjusting the pH of the concentrate to 12-13 and filtering to obtain a filtrate, then subjecting the filtrate to extraction and back-extraction to obtain the lithium-containing solution.

17. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 16, characterized in that, During the extraction process, the weight ratio of the filtrate to the extractant is (3~4):1; and / or, during the back-extraction process, the back-extraction agent used is one of carbon dioxide, hydrochloric acid solution and phosphoric acid solution.

18. The method for producing lithium-containing compounds using chloride-type low-lithium brine according to claim 17, characterized in that, The back-extraction agent is the carbon dioxide, and the post-treatment in step S5 is heating and filtration; and / or... The back-extraction agent is the hydrochloric acid solution or the phosphoric acid solution, and the post-treatment in step S5 is evaporation crystallization.

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