Lithium adsorbent and forming method thereof

Abstract

According to the lithium adsorbent and the forming method thereof, in the process of preparing granulation slurry, multiple alternating mixing operation and shearing emulsification operation are carried out, lithium adsorbent powder is promoted to be evenly dispersed in a premixed solution through mechanical force, meanwhile, shearing force is beneficial to further scattering and agglomeration, and therefore the lithium adsorbent can be formed. The pore-forming agent and the binder fully wrap the powder, so that the binder, the pore-forming agent and the lithium adsorbent powder can effectively form a stable pore-diameter particle structure on the surface and inside of the lithium adsorbent through physical or chemical bond action, the exposure of active sites of the lithium adsorbent is increased, the specific surface area of the lithium adsorbent is increased, and the specific surface area of the lithium adsorbent is increased. The adsorption capacity and the adsorption rate on Li < + > are favorably improved. Besides, the lithium adsorbent precursor is washed by using an aqueous solution of chlorine salt and / or lithium salt, so that excessive lithium removal can be avoided, the adsorbent can keep original structural characteristics and adsorption properties, and further improvement of mechanical compressive strength and adsorption performance of the lithium adsorbent is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium adsorption, and in particular to a lithium adsorbent and a molding method thereof. Background Art

[0002] Lithium is the lightest known metal element and is known as the "new energy metal of the 21st century." Due to its excellent properties such as high specific heat and low expansion coefficient, it is widely used in new energy vehicles, catalysis, aerospace and other fields. It is an indispensable key raw material for the development of various industries.

[0003] my country's salt lake brine has the characteristics of high magnesium-lithium ratio, high magnesium content and low lithium content. The lithium resource reserves in it account for about 70-80% of the country's total lithium resources. Therefore, how to extract lithium from salt lake brine efficiently and at low cost is the key to fully utilizing lithium resources. However, due to the Li + and Mg 2+ The atomic radius is similar, so their physical and chemical properties are also very similar, which makes it possible to separate Li from salt lake brine. + Becomes more difficult.

[0004] Among the many lithium extraction technologies, adsorption is particularly suitable for treating low-grade salt lake brines with a high magnesium-to-lithium ratio due to its high selectivity, simple process flow, and environmental and economic advantages. Currently, the lithium adsorbents used in the adsorption method are primarily inorganic materials, which can be categorized as aluminum-based lithium adsorbents and ion sieve-based lithium adsorbents, represented by manganese oxide ion sieves and titanium oxide ion sieves. Aluminum-based lithium adsorbents are considered to be highly promising adsorbent materials for future lithium extraction due to their simple preparation process, lack of acid washing requirements, and chemical stability.

[0005] However, aluminum-based lithium adsorbents in powder form have numerous shortcomings in practical industrial applications: poor fluidity, limited permeability, low recycling efficiency, significant pressure drop during column operation, and severe powder loss. These issues limit the performance and economic benefits of the adsorbents. To address these issues, granulation technology has emerged, aiming to improve the physical properties of the adsorbent and enhance its performance in lithium extraction processes.

[0006] While granulation technology has addressed the limitations of powdered adsorbents to some extent, existing suspension polymerization granulation methods, such as those described in patent CN116809013A, involve mixing coupled-modified lithium ion sieve powder with specific polymer monomers, initiators, crosslinkers, and porogens. The mixture is then dispersed into an aqueous phase via an oil phase, and polymerization is initiated under controlled conditions to produce lithium ion sieve particles. While this process can produce granular adsorbents with certain performance characteristics, it is complex and requires extremely high process conditions, resulting in high production costs and difficulty in large-scale implementation.

[0007] In view of the above technical problems, there is an urgent need to develop a method for forming lithium adsorbent particles with strong adsorption capacity, good wear resistance, simple preparation method and low cost, so as to provide support for the development of the salt lake lithium extraction industry. Summary of the Invention

[0008] The main purpose of the present invention is to provide a lithium adsorbent and a molding method thereof, so as to solve the problems of poor adsorption capacity, poor compression and wear resistance, complex molding method and high cost of lithium adsorbents in the prior art, thereby providing support for the development of the salt lake lithium extraction industry.

[0009] The forming method of the lithium adsorbent provided by the present invention comprises the following steps: dissolving a binder and a pore-forming agent in an organic solvent to obtain a premixed solution; adding lithium adsorbent powder to the premixed solution, and performing multiple alternating mixing operations and shear emulsification operations on the obtained mixed slurry to obtain a granulated slurry; adding the granulated slurry to an anti-solvent to precipitate solid particles in the anti-solvent; separating the solid particles after standing to obtain a lithium adsorbent precursor; and washing and drying the lithium adsorbent precursor in sequence to obtain the lithium adsorbent; wherein the washing solvent used in the washing process is an aqueous solution of a chloride salt and / or a lithium salt.

[0010] Furthermore, the mixing operation and the shear emulsification operation are performed alternately 2 to 5 times; preferably, the mixing operation includes: mechanically mixing the mixed slurry using a stirring device at a stirring speed of 200 to 400 rpm; the shear emulsification operation includes: using a handheld emulsifier or a fixed emulsifier to perform shear emulsification; preferably, the time for each mixing operation is 10 to 30 minutes; the time for each shear emulsification operation is 1 to 30 minutes.

[0011] Furthermore, the weight ratio of the binder to the pore-forming agent is (1-1.5):1; preferably, the weight ratio of the binder to the lithium adsorbent powder is 1:(3-7).

[0012] Furthermore, the washing solvent is a lithium chloride aqueous solution and / or a sodium chloride aqueous solution; preferably, the concentration of the washing solvent is 100-500 mg / L; preferably, the weight ratio of the washing solvent to the lithium adsorbent precursor is (3-10):1; preferably, the number of washing times is 3-5 times.

[0013] Furthermore, the granulation slurry is added to the anti-solvent at a rate of 0.8 to 2.5 mL / min; preferably, when the granulation slurry is added, the distance between the granulation slurry and the anti-solvent is controlled to be 20 to 40 cm; preferably, the temperature of the anti-solvent is 20 to 50°C; preferably, the weight of the anti-solvent and the granulation slurry is (3 to 6):1; preferably, the standing time is 2 to 12 h; preferably, the temperature of the granulation slurry is 20 to 50°C.

[0014] Furthermore, the step of dissolving the binder and the pore-forming agent in the organic solvent includes: first dissolving the binder in the organic solvent, performing a first mixing, and then adding the pore-forming agent thereto for a second mixing to obtain a premixed solution; preferably, the temperature of the first mixing and the second mixing is 20 to 50° C.; preferably, the time of the first mixing is 30 to 360 minutes, and the time of the second mixing is 20 to 120 minutes; preferably, in the premixed solution, the mass concentration of the binder is 0.06 to 0.2 g / mL.

[0015] Furthermore, the binder is one or more of polyvinyl chloride, polysulfone, polystyrene and polymethyl methacrylate; preferably, the binder is polysulfone; preferably, the pore-forming agent is a water-soluble polymer or an inorganic salt aqueous solution; preferably, the mass concentration of the inorganic salt aqueous solution is 1 to 5%; preferably, the water-soluble polymer is one or more of PVP-K15, PVP-K30, PEG-600, PEG-2000, PEG-6000 and PEG-10000; preferably, the pore-forming agent is one or more of PVP-K15, PVP-K30 and PEG-600; preferably, the inorganic salt aqueous solution is a sodium chloride aqueous solution; preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dichloromethane; further preferably, the organic solvent is N-methylpyrrolidone.

[0016] Furthermore, the lithium adsorbent powder is at least one of an aluminum-based lithium adsorption powder or a doped aluminum-based lithium adsorption powder; preferably, the lithium adsorbent powder is a doped aluminum-based lithium adsorption powder; preferably, the aluminum-based lithium adsorption powder is xLiCl·2Al(OH)3·nH2O, wherein x is 0.2 to 0.9 and n is 0.3 to 2; preferably, the doped aluminum-based lithium adsorption powder is LiAlZn-LDH and / or LiAlMg-LDH; preferably, the molar ratio of Zn to Al in LiAlZn-LDH is (0.05 to 0.15):1; preferably, the molar ratio of Mg to Al in LiAlMg-LDH is (0.05 to 0.15):1; preferably, the particle size of the lithium adsorbent powder is <200 mesh.

[0017] Furthermore, the anti-solvent is one or more of an aqueous sodium chloride solution, an aqueous lithium chloride solution, an ethanol solution of sodium chloride, an ethanol solution of lithium chloride, a mixed solution of sodium chloride, ethanol and water, and a mixed solution of lithium chloride, ethanol and water; preferably, the anti-solvent is an aqueous lithium chloride solution; preferably, the concentration of the anti-solvent is 100-500 mg / L; preferably, the molding process also includes an activation operation on the lithium adsorbent, and the activation operation includes: mixing and stirring the washed and dried lithium adsorbent precursor with water at a solid-liquid ratio of 10-20 g / L; preferably, the activation time is 1-3 h, and the activation temperature is 20-50°C; further preferably, in the activation process, the solid-liquid ratio is 15 g / L, the activation time is 2 h, and the activation temperature is 40°C; preferably, the drying temperature is 15-50°C, and the drying time is 3-12 h.

[0018] According to another aspect of the present invention, a lithium adsorbent is provided, which is prepared by the above-mentioned lithium adsorbent molding method; preferably, the particle size of the lithium adsorbent is 1.5 to 2.5 mm, the water contact angle of the lithium adsorbent is less than 76°, and the mechanical compressive strength of the lithium adsorbent is ≥5.8 MPa.

[0019] The present invention provides a method for forming a lithium adsorbent, wherein the method comprises mixing a binder, a pore-forming agent and a lithium adsorbent powder to form a granulation slurry; then using an anti-solvent method, the granulation slurry is mixed with an anti-solvent to precipitate solid particles, thereby achieving the purpose of forming the lithium adsorbent; and finally washing, drying and activating the granulation slurry to obtain the lithium adsorbent. On the one hand, in the process of preparing the granulation slurry, the method performs multiple alternating mixing operations and shear emulsification operations, and mechanical force is used to promote the uniform dispersion of the lithium adsorbent powder in the premixed solution. At the same time, the shear force helps to further break up the agglomeration, so that the pore-forming agent and the binder can fully wrap the powder, and then the binder and the pore-forming agent can effectively interact with the lithium adsorbent powder through physical or chemical bonds, forming a stable pore size particle structure on the surface and inside of the lithium adsorbent, increasing the exposure of the active sites of the lithium adsorbent, and increasing the specific surface area of ​​the lithium adsorbent, which is beneficial to improving Li + Furthermore, using aqueous solutions of chloride and / or lithium salts to treat the lithium adsorbent precursor avoids excessive delithiation, allowing the adsorbent to maintain its original structural stability and adsorption properties, further improving the mechanical compressive strength and adsorption performance of the lithium adsorbent. These effects synergistically result in the prepared lithium adsorbent particles possessing not only excellent adsorption capacity and adsorption rate, but also superior mechanical properties. This preparation method is simple and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 A physical picture of the lithium adsorbent prepared according to Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0022] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0023] As described in the background section, my country's salt lake brines are characterized by a high magnesium-to-lithium ratio, high magnesium content, and low lithium content. Their lithium reserves account for approximately 70-80% of the nation's total lithium resources. Therefore, efficiently and cost-effectively extracting lithium from salt lake brines is crucial for fully utilizing these resources. Using adsorbent materials to extract lithium is a viable approach, but existing lithium adsorbents suffer from poor adsorption capacity, poor wear resistance, complex molding methods, and high production costs, hindering their large-scale production and application.

[0024] In order to solve the above problems, the present invention provides a forming method of a lithium adsorbent, which comprises the following steps: dissolving a binder and a pore-forming agent in an organic solvent to obtain a premixed solution; adding lithium adsorbent powder to the premixed solution, and performing multiple alternating mixing operations and shear emulsification operations on the obtained mixed slurry to obtain a granulation slurry; adding the granulation slurry to an anti-solvent to precipitate solid particles in the anti-solvent; after standing, separating the solid particles to obtain a lithium adsorbent precursor; and washing and drying the lithium adsorbent precursor in sequence to obtain a lithium adsorbent; wherein the washing solvent used in the washing process is an aqueous solution of a chloride salt and / or a lithium salt.

[0025] The present invention provides a lithium adsorbent forming method, which comprises mixing a binder and a pore-forming agent to form a premixed solution, then mixing the premixed solution with lithium adsorbent powder, and performing multiple alternating mixing operations and shear emulsification operations on the obtained mixed slurry to form a granulation slurry; then mixing the granulation slurry with an anti-solvent, utilizing the effect of solubility difference to precipitate solid particles, thereby achieving the purpose of forming the lithium adsorbent and obtaining a lithium adsorbent precursor; finally, washing and drying the lithium adsorbent precursor to obtain the lithium adsorbent.

[0026] In the lithium adsorbent molding method provided by the present invention, after the premixed solution and the lithium adsorbent powder are mixed, the resulting mixed slurry is subjected to multiple alternating mixing operations and shear emulsification operations to form a granulation slurry. Mechanical force is used to promote the uniform dispersion of the lithium adsorbent powder in the premixed solution, while the shear force helps to further break up the agglomeration, so that the pore-forming agent and the binder fully wrap the powder, and then the binder and the pore-forming agent can be effectively dispersed with the lithium adsorbent powder through physical action or chemical bonding. The above operation is not only conducive to a more uniform and stable structure of the solid particle component precipitated after the granulation slurry is mixed with the anti-solvent, but also can form internal mesopores of 10 to 50 nm inside the lithium adsorbent and a multi-level pore structure of 50 to 120 nm on the surface of the lithium adsorbent, so that the formed lithium adsorbent has better pore size distribution parameters, which is conducive to further improving the specific surface area of ​​the formed lithium adsorbent and improving the adsorption characteristics of the prepared lithium adsorbent for lithium. In addition, the above operation can also increase the exposure of the active sites of the lithium adsorbent. Under the synergistic effect of the exposure of the active sites and the increase in the specific surface area, it is beneficial to better improve the absorption of Li + adsorption capacity and adsorption rate.

[0027] Furthermore, in the lithium adsorbent forming method provided by the present invention, an aqueous solution of a chloride salt and / or a lithium salt is used to wash the lithium adsorbent precursor. Using a salt solution containing chloride or lithium to wash the lithium adsorbent precursor can avoid excessive lithium removal during the washing process, which could adversely affect the adsorption properties of the lithium adsorbent, thereby improving the mechanical compressive strength and adsorption capacity of the lithium adsorbent.

[0028] In summary, the lithium adsorbent molding method provided by the present invention is beneficial to increase the exposure of the active sites of the lithium adsorbent, increase the specific surface area of ​​the lithium adsorbent, and improve the Li + The adsorption capacity and mechanical strength of the lithium adsorbent are improved, thereby improving the overall performance of the lithium adsorbent. The preparation method is simple to operate, low in cost, and suitable for large-scale production.

[0029] In a preferred embodiment, the mixing operation and the shear emulsification operation are performed alternately 2 to 5 times. The alternating mixing and shear emulsification operations can make the lithium adsorbent powder more fully contacted and evenly mixed with the binder and pore-forming agent in the premixed solution, avoid local agglomeration, and form a more uniform particle structure, which is beneficial to further improve the adsorption capacity and mechanical strength of the particles, while also controlling the molding efficiency. Preferably, the mixing operation includes: mechanically mixing the mixed slurry using a stirring device such as a magnetic stirring device or an ultrasonic stirring device, and the stirring speed is 200 to 400 rpm; the shear emulsification operation includes: using a handheld emulsifier or a fixed emulsifier for shear emulsification; preferably, the time for each mixing operation is 10 to 30 minutes; the time for each shear emulsification operation is 1 to 30 minutes. Controlling the specific parameters of the mixing operation and the shear emulsification operation within the above range can further increase the number of active sites in the lithium adsorbent, which is beneficial to better improve the adsorption capacity and stability of the lithium adsorbent.

[0030] In a preferred embodiment, the weight ratio of the binder to the pore-forming agent is (1-1.5):1, specifically 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or any weight ratio between any two of the above. Preferably, the weight ratio of the binder to the lithium adsorbent powder is 1:(3-7); specifically 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, or any weight ratio between any two of the above. Controlling the usage ratio of the binder, pore-forming agent, and lithium adsorbent powder within the above range can enable the lithium adsorbent to have good adsorption performance and good mechanical strength. At the same time, controlling the usage ratio within the above range can also avoid pore clogging caused by excessive use of the binder or low porosity of the lithium adsorbent due to insufficient use of the pore-forming agent, which is conducive to better improving the comprehensive performance of the lithium adsorbent.

[0031] In a preferred embodiment, the washing solvent is a lithium chloride aqueous solution and / or a sodium chloride aqueous solution; preferably, the concentration of the washing solvent is 100-500 mg / L, specifically, for example, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, 400 mg / L, 450 mg / L, 500 mg / L, or any concentration between any two of the above; preferably, the weight ratio of the washing solvent to the lithium adsorbent precursor is (3-10):1, specifically, for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any ratio between any two of the above; preferably, the number of washing times is 3 to 5 times. Washing the prepared lithium adsorbent precursor can remove the organic solvent and a small amount of pore-forming agent attached to the surface of the lithium adsorbent precursor. Using a chloride salt and a lithium salt such as a lithium chloride aqueous solution and / or a sodium chloride aqueous solution to wash the lithium adsorbent precursor can help avoid delithiation caused by the washing process, allowing the adsorbent to maintain its original structural characteristics and adsorption properties, thereby further improving the overall performance of the lithium adsorbent. Preferably, the washing process includes: mixing the lithium adsorbent precursor and a washing solvent, stirring at a stirring speed of 100 to 200 rpm, and then separating the washed lithium adsorbent precursor into a solid-liquid state.

[0032] In a preferred embodiment, the granulation slurry is added to the antisolvent at a rate of 0.8 to 2.5 mL / min; preferably, when the granulation slurry is added, the distance between the granulation slurry and the antisolvent is controlled to be 20 to 40 cm; preferably, the temperature of the antisolvent is 20 to 50° C.; preferably, the weight ratio of the antisolvent to the granulation slurry is (3 to 6):1; preferably, the standing time is 2 to 12 hours; preferably, the temperature of the granulation slurry is 20 to 50° C. Controlling the parameters of the antisolvent molding process within the above range can increase the molding speed of the lithium adsorbent precursor, which is conducive to better controlling the formation of a uniform multi-level pore structure of the formed lithium adsorbent, thereby further improving the adsorption efficiency and selectivity of the lithium adsorbent.

[0033] In a preferred embodiment, the step of dissolving the binder and the pore-forming agent in an organic solvent includes: first dissolving the binder in the organic solvent, performing a first mixing, and then adding the pore-forming agent thereto for a second mixing to obtain a premixed solution; preferably, the temperature of the first mixing and the second mixing is 20 to 50°C; preferably, the time of the first mixing is 30 to 360 minutes, and the time of the second mixing is 20 to 120 minutes; preferably, the mass concentration of the binder in the premixed solution is 0.06 to 0.2 g / mL. Sequentially mixing and dissolving the binder and the pore-forming agent in the organic solvent is beneficial to further improve the uniformity and stability of the granulation slurry, thereby improving the overall performance of the lithium adsorbent. Preferably, the stirring speed of the first mixing and the second mixing is 100 to 500 rpm.

[0034] In a preferred embodiment, the binder is one or more of polyvinyl chloride, polysulfone, polystyrene, and polymethyl methacrylate; preferably, the binder is polysulfone; preferably, the pore-forming agent is a water-soluble polymer or an inorganic salt solution; preferably, the mass concentration of the inorganic salt solution is 1-5%; preferably, the water-soluble polymer is one or more of PVP-K15, PVP-K30, PEG-600, PEG-2000, PEG-6000, and PEG-10000; preferably, the pore-forming agent is one or more of PVP-K15, PVP-K30, and PEG-600; preferably, the inorganic salt solution is a sodium chloride solution; preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dichloromethane; further preferably, the organic solvent is N-methylpyrrolidone. Selecting the above specific types of binder, pore-forming agent, and organic solvent is beneficial to further improve the adsorption capacity and comprehensive properties of the lithium adsorbent, such as mechanical strength.

[0035] In a preferred embodiment, the lithium adsorbent powder is at least one of aluminum-based lithium adsorbent powder and doped aluminum-based lithium adsorbent powder. Preferably, the lithium adsorbent powder is doped aluminum-based lithium adsorbent powder. Using doped aluminum-based lithium adsorbent powder to prepare the lithium adsorbent powder results in a lithium adsorbent powder with improved performance. Preferably, the aluminum-based lithium adsorption powder is xLiCl·2Al(OH)3·nH2O, where x is 0.2-0.9 and n is 0.3-2.0; preferably, the doped aluminum-based lithium adsorption powder is LiAlZn-LDH (lithium-aluminum-zinc layered double hydroxide) and / or LiAlMg-LDH (lithium-aluminum-magnesium layered double hydroxide); preferably, the molar ratio of Zn to Al in LiAlZn-LDH is (0.05-0.15):1; preferably, the molar ratio of Mg to Al in LiAlMg-LDH is (0.05-0.15):1; controlling the molar ratio of Zn to Al and the molar ratio of Mg to Al in the doped aluminum-based lithium adsorption powder within the above range is beneficial to further improve the comprehensive performance of the lithium adsorbent. Preferably, the particle size of the lithium adsorbent powder is <200 mesh. It should be further explained here that the aluminum-based lithium adsorption powder or doped aluminum-based lithium adsorption powder can be purchased or prepared by oneself.

[0036] In a preferred embodiment, the antisolvent is one or more of an aqueous sodium chloride solution, an aqueous lithium chloride solution, an ethanolic sodium chloride solution, an ethanolic lithium chloride solution, a mixed solution of sodium chloride, ethanol, and water, and a mixed solution of lithium chloride, ethanol, and water. Preferably, the antisolvent is an aqueous lithium chloride solution. Preferably, the antisolvent concentration is 100-500 mg / L. Controlling the antisolvent parameters within the above ranges can further improve the formation rate and specific surface area of ​​the lithium adsorbent precursor, thereby further improving the adsorption performance of the lithium adsorbent. Preferably, the formation process also includes an activation operation for the lithium adsorbent. The activation operation comprises mixing and stirring the washed and dried lithium adsorbent precursor with water at a solid-to-liquid ratio of 10-20 g / L. Preferably, the activation time is 1-3 hours and the activation temperature is 20-50°C. More preferably, the solid-to-liquid ratio is 15 g / L, the activation time is 2 hours, and the activation temperature is 40°C. The lithium adsorbent prepared from the slurry can be activated in the above manner. Preferably, the drying temperature is 15-50°C and the drying time is 3-12 hours. Preferably, the stirring speed during the activation process is 200-400 rpm. Preferably, in the mixed solution of sodium chloride, ethanol and water and the mixed solution of lithium chloride, ethanol and water, the volume ratio of ethanol to water is (0.1-2):1.

[0037] It should be noted that due to the specificity of the materials field and the limitations of existing testing and characterization methods, it is impossible to fully characterize the lithium adsorbent particles obtained by the above preparation method. However, experiments have confirmed that the lithium adsorbent particles have the beneficial effect of improving adsorption performance and mechanical strength, demonstrating the improvement of the preparation method of the present invention on the material itself.

[0038] According to another aspect of the present invention, a lithium adsorbent is provided, which is prepared by the above-mentioned lithium adsorbent molding method; preferably, the particle size of the lithium adsorbent is 1.5 to 2.5 mm, the water contact angle of the lithium adsorbent is less than 76°, and the mechanical compressive strength of the lithium adsorbent is ≥5.8 MPa.

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

[0040] It should be further explained that the doped aluminum-based lithium adsorption powders used were all prepared, and the salt lake brine used in the examples was from the same batch. The preparation method of the doped aluminum-based lithium adsorption powder comprises: dissolving m(LiCl)=84.8g, m(AlCl3)=161g, and m(ZnCl2)=9.08g in 1000mL of deionized water to obtain a salt solution, wherein c(LiCl) in the salt solution is 1.37g. +)=2mol / L, and the molar ratio of Li ions, Al ions and Zn ions is 3:1:0.1. 88g of NaOH is dissolved in 1100mL of deionized water to obtain a 2mol / L alkaline solution. Under room temperature, the salt solution is stirred at a speed of 450r / min, and the alkaline solution is added dropwise at a uniform rate until the pH of the system is 7, and the addition is stopped to obtain a reaction mixture. The reaction mixture is crystallized at 80°C for 3h at a stirring speed of 450r / min, and then the crystallization is stopped. After washing with deionized water, it is dried at 50°C for 12h. LiAlZn-LDH with a molar ratio of Zn to Al of 0.1:1 is obtained. According to the above preparation method, LiAlZn-LDH with different molar ratios of Zn and Al are prepared respectively by adjusting the molar ratio of Zn and Al.

[0041] Example 1

[0042] 1g of the binder polysulfone (PSF) was dissolved in 6.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent consisted of 0.21g of PVP-K15, 0.34g of PVP-K30, and 0.28g of PEG-600. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.05:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 300 rpm for 30 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 5 minutes. This mechanical mixing and shear-emulsification process was repeated three times, and the granulated slurry was heated to 40°C.

[0043] The granulation slurry is added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution is 100 mg / L, the temperature is 40°C, and the distance between the granulation slurry and the water is controlled to be 30 cm. The weight of the lithium chloride aqueous solution and the granulation slurry is 5:1. The granulation slurry precipitates solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles are separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L is mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed 3 times, and then dried at 40°C for 5 hours to obtain solid particles, which are lithium adsorbents. The actual picture of the adsorbent is as follows Figure 1 As shown by Figure 1 It can be seen that the lithium adsorbent is a white sphere with uniform particle size distribution.

[0044] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0045] Example 2

[0046] 1 g of binder polystyrene (PS) was dissolved in 16.7 mL of N,N-dimethylacetamide and stirred at 50°C and 300 rpm for 30 minutes to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent consisted of 0.21 g of PVP-K15, 0.27 g of PVP-K30, and 0.18 g of PEG-600. 7 g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.08:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 200 rpm for 30 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 30 minutes. This mechanical mixing and shear-emulsification process was repeated twice, and the mixture was heated to 50°C to obtain a granulated slurry.

[0047] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 2.5 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 50°C. The distance between the granulation slurry and the water was controlled to be 20 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 3:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 2 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 500 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 3:1 and stirred and washed 5 times. Then, it was dried at 40°C for 3 hours to obtain solid particles, which were the lithium adsorbent.

[0048] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0049] Example 3

[0050] 1 g of binder polymethyl methacrylate (PMMA) was dissolved in 5 mL of N,N-dimethylformamide and stirred at 500 rpm for 360 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 120 minutes to obtain a premix solution. The pore-forming agent consisted of 0.38 g of PVP-K15, 0.34 g of PVP-K30, and 0.28 g of PEG-600. 3 g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.1:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 400 rpm for 10 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 1 minute. This mechanical mixing and shear-emulsification process was repeated five times to obtain a granulated slurry at 20°C.

[0051] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 500 mg / L and the temperature was 20°C. The distance between the granulation slurry and the water was controlled to be 40 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 6:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 100 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 10:1 and stirred and washed three times. Then, it was dried at 45°C for 6 hours to obtain solid particles, which were the lithium adsorbent.

[0052] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0053] Example 4

[0054] 1 g of the binder polysulfone (PSF) was dissolved in 6.3 mL of N-methylpyrrolidone and stirred at 20°C and 100 rpm for 30 minutes to completely dissolve the binder; then, a pore-forming agent was added and stirred for 30 minutes to obtain a premixed solution; wherein the pore-forming agent included: 0.21 g of PVP-K15, 0.34 g of PVP-K30, 0.14 g of PEG-600 and 0.14 g of PEG-2000. 6 g of zinc-doped aluminum-based adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH is 0.15:1 and the particle size is <200 mesh) was added to the above-obtained premixed solution, and the obtained mixed slurry was mechanically mixed at a speed of 300 rpm for 30 minutes using a stirring device, and then sheared and emulsified for 5 minutes using a handheld emulsifier; the above-mentioned mechanical mixing operation and shear emulsification operation were alternately performed 3 times, and the granulation slurry was heated to obtain a temperature of 40°C.

[0055] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 200 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 6:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 30°C for 10 hours to obtain solid particles, which were the lithium adsorbent.

[0056] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm at room temperature for 2 hours for adsorption.

[0057] Example 5

[0058] 1g of the binder polysulfone (PSF) was dissolved in 6.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent comprised 0.32g of PVP-K15 and 0.51g of PVP-K30. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.1:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 200 rpm for 30 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 5 minutes. This mechanical mixing and shear-emulsification process was repeated three times, and the granulated slurry was heated to 40°C.

[0059] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 500 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 40 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 5:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 30°C for 12 hours to obtain solid particles, which were the lithium adsorbent.

[0060] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0061] Example 6

[0062] 1 g of binder polysulfone (PSF) was dissolved in 6.3 mL of N-methylpyrrolidone and stirred at 20°C and 100 rpm for 30 minutes to completely dissolve the binder; then, a pore-forming agent was added thereto and stirred at 40°C for 40 minutes to obtain a premixed solution; wherein the pore-forming agent included: 0.21 g of PVP-K15, 0.34 g of PVP-K30, 0.14 g of PEG-600 and 0.14 g of PEG-6000. 6 g of zinc-doped aluminum-based adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH is 0.05:1 and the particle size is <200 mesh) was added to the above-obtained premixed solution, and the obtained mixed slurry was mechanically mixed at a speed of 300 rpm for 30 minutes using a stirring device, and then sheared and emulsified for 5 minutes using a handheld emulsifier; the above-mentioned mechanical mixing operation and shear emulsification operation were alternately performed 3 times, and the granulation slurry was heated to obtain a temperature of 40°C.

[0063] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 5:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 40°C for 6 hours to obtain solid particles, which were the lithium adsorbent.

[0064] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0065] Example 7

[0066] 1 g of binder polysulfone (PSF) was dissolved in 6.3 mL of N-methylpyrrolidone and stirred at 20°C and 100 rpm for 30 minutes to completely dissolve the binder; then, a pore-forming agent was added thereto and stirred at 40°C for 50 minutes to obtain a premixed solution; wherein the pore-forming agent included: 0.21 g of PVP-K15, 0.34 g of PVP-K30, 0.14 g of PEG-600 and 0.14 g of PEG-10000. 6 g of zinc-doped aluminum-based adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH is 0.05:1 and the particle size is <200 mesh) was added to the above-obtained premixed solution, and the obtained mixed slurry was mechanically mixed at a speed of 300 rpm for 30 minutes using a stirring device, and then sheared and emulsified for 5 minutes using a handheld emulsifier; the above-mentioned mechanical mixing operation and shear emulsification operation were alternately performed 3 times, and the granulation slurry was heated to obtain a temperature of 40°C.

[0067] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 300 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 5:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 50°C for 4 hours to obtain solid particles, which were the lithium adsorbent.

[0068] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0069] Example 8

[0070] 1g of polysulfone (PSF) binder was dissolved in 8.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent comprised 0.32g of PVP-K15 and 0.51g of PVP-K30. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.05:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 200 rpm for 20 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 3 minutes. The mechanical mixing and shear-emulsification operations were repeated three times, and the granulated slurry was heated to 20°C.

[0071] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 1 mL / min. The concentration of the lithium chloride aqueous solution was 300 mg / L and the temperature was 20°C. The distance between the granulation slurry and the water was controlled to be 20 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 5:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 50°C for 3 hours to obtain solid particles, which were the lithium adsorbent.

[0072] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0073] Example 9

[0074] 1g of the binder polysulfone (PSF) was dissolved in 6.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent comprised 0.21g of PVP-K15, 0.34g of PVP-K30, and 0.28g of PEG-600. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.15:1 and the particle size was <200 mesh) was added to the premix solution. The resulting mixed slurry was mechanically mixed at 300 rpm for 30 minutes using a stirring device, then shear-emulsified using a handheld emulsifier for 5 minutes. The mixture was then heated to 40°C to obtain a granulated slurry.

[0075] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 10:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 800 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 40°C for 5 hours to obtain solid particles, which were the lithium adsorbent.

[0076] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0077] Comparative Example 1

[0078] 1g of the binder polysulfone (PSF) was dissolved in 6.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premixed solution. The pore-forming agent comprised 0.21g of PVP-K15, 0.34g of PVP-K30, and 0.28g of PEG-600. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.15:1 and the particle size was <200 mesh) was added to the premixed solution. The resulting mixed slurry was mechanically mixed at 300 rpm for 30 minutes using a stirring device to obtain a granulated slurry at 40°C.

[0079] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 6:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. A lithium chloride aqueous solution with a concentration of 300 mg / L was mixed with the lithium adsorbent precursor in a weight ratio of 5:1 and stirred and washed three times. Then, it was dried at 50°C for 10 hours to obtain solid particles, which were the lithium adsorbent.

[0080] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0081] Comparative Example 2

[0082] 1 g of polysulfone (PSF), a binder, was dissolved in 6.3 mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premix solution. The pore-forming agent consisted of 0.21 g of PVP-K15, 0.34 g of PVP-K30, and 0.28 g of PEG-600. 6 g of zinc-doped aluminum adsorbent powder, LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.15:1 and the particle size was <200 mesh), was added to the premix solution. The resulting mixed slurry was mechanically mixed at 300 rpm for 30 minutes using a stirring device and then shear-emulsified using a handheld emulsifier for 5 minutes. This mechanical mixing and shear-emulsification process was repeated three times, and the mixture was heated to 40°C to obtain a granulated slurry.

[0083] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 6:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. Deionized water and the lithium adsorbent precursor were mixed in a weight ratio of 5:1 and stirred and washed three times. The lithium adsorbent precursor was then dried at 50°C for 3 hours to obtain solid particles, which were the lithium adsorbent.

[0084] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0085] Comparative Example 3

[0086] 1g of the binder polysulfone (PSF) was dissolved in 6.3mL of N-methylpyrrolidone and stirred at 100 rpm for 30 minutes at 20°C to completely dissolve the binder. A pore-forming agent was then added and stirred for 20 minutes to obtain a premixed solution. The pore-forming agent comprised 0.21g of PVP-K15, 0.34g of PVP-K30, and 0.28g of PEG-600. 6g of zinc-doped aluminum adsorbent powder LiAlZn-LDH (wherein the molar ratio of Zn to Al in LiAlZn-LDH was 0.15:1 and the particle size was <200 mesh) was added to the premixed solution. The resulting mixed slurry was mechanically mixed at 300 rpm for 30 minutes using a stirring device to obtain a granulated slurry at 40°C.

[0087] The granulation slurry was added to 30 mL of lithium chloride aqueous solution at a rate of 0.8 mL / min. The concentration of the lithium chloride aqueous solution was 100 mg / L and the temperature was 40°C. The distance between the granulation slurry and the water was controlled to be 30 cm. The weight ratio of the lithium chloride aqueous solution to the granulation slurry was 6:1. The granulation slurry precipitated solid particles in the lithium chloride aqueous solution. After standing for 12 hours, the solid particles were separated to obtain a lithium adsorbent precursor. Deionized water and the lithium adsorbent precursor were mixed in a weight ratio of 5:1 and stirred and washed three times. The lithium adsorbent precursor was then dried at 50°C for 3 hours to obtain solid particles, which were the lithium adsorbent.

[0088] The lithium adsorbent obtained above was first mixed with water at a solid-liquid ratio of 15 g / L at 40°C for 2 hours for activation. The activated lithium adsorbent was placed in salt lake brine and stirred at 200 rpm for 3 hours at room temperature for adsorption.

[0089] The lithium adsorbents prepared in the examples and comparative examples were tested for relevant properties, and the results are shown in Table 1. The testing methods for the data in the table are further explained as follows.

[0090] Contact angle measurement: This test uses a contact angle measurement system, specifically comprising applying the granulated slurry prepared in the Examples and Comparative Examples to a solid surface, drying it to form a thin film, and then dripping liquid onto the film using a dropper. A high-definition camera records the image of the water droplet contacting the sample, and the angle between the water droplet and the sample is measured using the tangent method. This parameter reflects the wettability of the lithium adsorbent; a small contact angle indicates good wettability, which is conducive to adsorption.

[0091] Test of specific surface area of ​​lithium adsorbent: using specific surface area and porosity adsorption instrument test, specifically including: weighing 0.2-0.4g of lithium adsorbent sample to be tested into a sample tube, and testing the specific surface area, pore volume and pore size distribution of the lithium adsorbent sample by N2 adsorption method;

[0092] The mechanical compressive strength test of the lithium adsorbent is conducted using a particle strength measuring instrument. Specifically, the test includes: using a speed-controlled motor drive system to uniformly load the load and apply pressure to the particle adsorbent until the particle adsorbent cracks. Each particle adsorbent sample is measured three times, and the average value is taken to obtain the mechanical compressive strength of the lithium adsorbent particles.

[0093] Lithium adsorbent wear rate test: The obtained lithium adsorbent was quantitatively placed in a ball mill and ball-milled at a speed of 500 rpm / min for 30 minutes to obtain the ball-milled lithium adsorbent. The difference between the initial mass of the adsorbent (before ball milling) and the mass of the lithium adsorbent after ball milling / initial mass of the adsorbent × 100% was used to obtain the lithium adsorbent wear rate;

[0094] The test method for the gram adsorption capacity of lithium adsorbent is as follows: the activated lithium adsorbent is placed in salt lake brine, stirred and adsorbed at room temperature at a stirring speed of 200 rpm for 3 hours. The gram adsorption capacity of lithium adsorbent is calculated as (the mass of lithium in salt lake brine before adsorption - the mass of lithium in salt lake brine after adsorption) / the mass of lithium adsorbent.

[0095] Table 1

[0096]

[0097] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0098] Examples 1 to 9 are lithium adsorbents prepared by the lithium adsorbent molding method provided in this application. During the preparation of the adsorbent, the granulation slurry was subjected to multiple alternating mixing operations and shear emulsification operations, and the lithium adsorbent precursor was washed with an aqueous solution of chloride salt and / or lithium salt. According to the data in Table 1, the lithium adsorbents prepared in Examples 1 to 9 not only have good wettability and mechanical compressive strength, but also have a larger specific surface area; they are used to adsorb lithium in salt lake brine, and the gram adsorption capacity is above 4 mg, and can even reach 5.90 mg. In particular, in Examples 1 to 8, the parameters in the preparation process of the lithium adsorbent are controlled within the preferred range, and the prepared lithium adsorbent has better performance.

[0099] In contrast, in Comparative Examples 1 to 3, the lithium adsorbents were prepared without either high-speed shear emulsification or the use of aqueous chloride and / or lithium salt solutions during washing of the lithium adsorbent precursor. The resulting lithium adsorbents exhibited significantly lower wettability, mechanical compressive strength, and specific surface area than the lithium adsorbents in the Examples. When used to adsorb lithium from salt lake brine, the gram adsorption capacity was only approximately 3 mg, significantly lower than that achieved in the Examples of this application.

[0100] In summary, the lithium adsorbent molding method provided by the present invention can improve the pore size distribution structure of the lithium adsorbent, increase the exposure of the active sites of the lithium adsorbent, and increase the specific surface area of ​​the lithium adsorbent, which is beneficial to effectively improve the Li + The adsorption capacity and adsorption rate can be improved, and the mechanical compressive strength and adsorption performance of the lithium adsorbent can be further improved. In addition, the preparation method is simple to operate and suitable for large-scale production.

[0101] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for forming a lithium adsorbent, characterized in that: The molding method comprises the following steps: dissolving a binder and a pore former in an organic solvent to obtain a premixed solution; adding lithium adsorbent powder to the premixed solution, and performing multiple alternating mixing operations and shear emulsification operations on the obtained mixed slurry to obtain a granulation slurry; adding the granulation slurry into an anti-solvent to precipitate solid particles in the anti-solvent; separating the solid particles after standing to obtain a lithium adsorbent precursor; The lithium adsorbent precursor is washed and dried in sequence to obtain the lithium adsorbent; wherein the washing solvent used in the washing process is an aqueous solution of chloride salt and / or lithium salt.

2. The method for forming a lithium adsorbent according to claim 1, wherein: The mixing operation and the shearing emulsification operation are alternately performed 2 to 5 times; Preferably, the mixing operation includes: mechanically mixing the mixed slurry using a stirring device at a stirring speed of 200 to 400 rpm; the shear emulsification operation includes: performing shear emulsification using a handheld emulsifier or a fixed emulsifier; Preferably, the mixing operation lasts for 10 to 30 minutes each time; and the shearing and emulsification operation lasts for 1 to 30 minutes each time.

3. The method for forming a lithium adsorbent according to claim 1, wherein: The weight ratio of the binder to the pore-forming agent is (1-1.5):1; Preferably, the weight ratio of the binder to the lithium adsorbent powder is 1:(3-7).

4. The method for forming a lithium adsorbent according to any one of claims 1 to 3, characterized in that: The washing solvent is a lithium chloride aqueous solution and / or a sodium chloride aqueous solution; Preferably, the concentration of the washing solvent is 100 to 500 mg / L; Preferably, the weight ratio of the washing solvent to the lithium adsorbent precursor is (3-10):1; Preferably, the washing times are 3 to 5 times.

5. The method for forming a lithium adsorbent according to any one of claims 1 to 3, characterized in that: The granulation slurry is added to the anti-solvent at a rate of 0.8 to 2.5 mL / min; Preferably, when the granulation slurry is added, the distance between the granulation slurry and the anti-solvent is controlled to be 20 to 40 cm; Preferably, the temperature of the anti-solvent is 20 to 50°C; Preferably, the weight ratio of the anti-solvent to the granulation slurry is (3-6):1; Preferably, the standing time is 2 to 12 hours; Preferably, the temperature of the granulation slurry is 20-50°C.

6. The method for forming a lithium adsorbent according to any one of claims 1 to 3, characterized in that: The step of dissolving the binder and the pore-forming agent in the organic solvent comprises: first dissolving the binder in the organic solvent, performing a first mixing, and then adding the pore-forming agent therein and performing a second mixing to obtain the premixed solution; Preferably, the temperature of the first mixing and the second mixing is 20 to 50°C; Preferably, the first mixing time is 30 to 360 minutes, and the second mixing time is 20 to 120 minutes; Preferably, in the premixed solution, the mass concentration of the binder is 0.06 to 0.2 g / mL.

7. The method for forming a lithium adsorbent according to any one of claims 1 to 6, characterized in that: The binder is one or more of polyvinyl chloride, polysulfone, polystyrene and polymethyl methacrylate; preferably, the binder is polysulfone; Preferably, the pore-forming agent is a water-soluble polymer or an inorganic salt aqueous solution; preferably, the mass concentration of the inorganic salt aqueous solution is 1 to 5%; Preferably, the water-soluble polymer is one or more of PVP-K15, PVP-K30, PEG-600, PEG-2000, PEG-6000 and PEG-10000; More preferably, the pore-forming agent is one or more of PVP-K15, PVP-K30 and PEG-600; Preferably, the inorganic salt aqueous solution is a sodium chloride aqueous solution; Preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dichloromethane; More preferably, the organic solvent is N-methylpyrrolidone.

8. The method for forming a lithium adsorbent according to any one of claims 1 to 6, characterized in that: The lithium adsorbent powder is at least one of aluminum-based lithium adsorption powder and doped aluminum-based lithium adsorption powder; preferably, the lithium adsorbent powder is the doped aluminum-based lithium adsorption powder; Preferably, the aluminum-based lithium adsorption powder is xLiCl·2Al(OH)3·nH2O, wherein x is 0.2 to 0.9 and n is 0.3 to 2; Preferably, the doped aluminum-based lithium adsorption powder is LiAlZn-LDH and / or LiAlMg-LDH; Preferably, the molar ratio of Zn to Al in the LiAlZn-LDH is (0.05-0.15):1; Preferably, the molar ratio of the Mg to the Al in the LiAlMg-LDH is (0.05-0.15):1; Preferably, the particle size of the lithium adsorbent powder is less than 200 mesh.

9. The method for forming a lithium adsorbent according to any one of claims 1 to 6, characterized in that: The anti-solvent is one or more of a sodium chloride aqueous solution, a lithium chloride aqueous solution, an ethanol solution of sodium chloride, an ethanol solution of lithium chloride, a mixed solution of sodium chloride, ethanol and water, and a mixed solution of lithium chloride, ethanol and water; Preferably, the anti-solvent is a lithium chloride aqueous solution; Preferably, the concentration of the anti-solvent is 100 to 500 mg / L; Preferably, the molding process further comprises activating the lithium adsorbent, wherein the activation operation comprises: mixing the washed and dried lithium adsorbent precursor with water at a solid-liquid ratio of 10 to 20 g / L; Preferably, the activation time is 1 to 3 hours, and the activation temperature is 20 to 50°C; Further preferably, in the activation process, the solid-liquid ratio is 15 g / L, the activation time is 2 h, and the activation temperature is 40° C. Preferably, the drying temperature is 15 to 50° C., and the drying time is 3 to 12 hours.

10. A lithium adsorbent, characterized in that The lithium adsorbent is prepared by the lithium adsorbent molding method according to any one of claims 1 to 9; preferably, the particle size of the lithium adsorbent is 1.5 to 2.5 mm, the water contact angle of the lithium adsorbent is less than 76°, and the mechanical compressive strength of the lithium adsorbent is ≥5.8 MPa.

Images