A spherical lithium-extracting adsorbent and a preparation method thereof

Abstract

The application discloses a spherical lithium-adsorbing agent and a preparation method thereof. The preparation method comprises the following steps: adding a stabilizer into a dispersion medium, mixing and stirring uniformly under heating, and preparing an oil phase; then mixing and preparing a water phase by mixing monomers, a cross-linking agent, an inert solvent, an alkaline catalyst and a lithium-adsorbing agent, and performing pre-polymerization; finally, mixing the water phase with the oil phase, and further performing polymerization and aging through reverse suspension to prepare the spherical lithium-adsorbing agent; and the stabilizer comprises inorganic stabilizers and organic stabilizers. + The spherical lithium-adsorbing agent has good hydrophilicity, high adsorption active sites and Li contacting speed, adsorption rate and adsorption capacity are high; the spherical degree is high, the mechanical strength is good, the bed pressure is low, the plugging problem of the resin column is solved, and the service life of the adsorbing agent is prolonged; the adsorbing agent has a more stable three-dimensional network space structure and is not prone to loss; the adsorbing agent can be directly applied to industrial large-scale production, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of lithium adsorbents, specifically to a spherical lithium extraction adsorbent and its preparation method. Background Technology

[0002] Lithium, the third element in the periodic table, is the lightest metallic element found in nature. Due to its unique physical and chemical properties, lithium and its compounds are widely used in medicine, chemicals, energy, aerospace, and other fields. In recent years, with the continuous rise of the green new energy industry chain, the demand for lithium has also increased dramatically. Therefore, the rational development and utilization of lithium resources and the recycling and reuse of existing lithium-containing resources have become urgent.

[0003] Currently, commonly used lithium extraction methods include chemical precipitation, extraction, calcination, membrane methods, and adsorption methods, each with its own advantages and disadvantages. Chemical precipitation involves using solar energy or reagents to precipitate carbonates and aluminates; this method is simple and practical, but limited to salt lakes with low magnesium-to-lithium ratios. Extraction utilizes Li... + Separation and extraction are achieved by exploiting the solubility difference between organic and inorganic solvents. This method boasts high separation and recovery rates and can be carried out at ambient temperature and pressure. However, it requires corrosion-resistant equipment, and organic solvents cause significant environmental pollution. Calcination involves calcining the evaporated and dried brine powder at temperatures above 550°C, followed by a series of complex processes to obtain lithium carbonate. This method is energy-intensive, generates large amounts of hydrogen chloride gas during calcination, causing severe equipment corrosion and pollution, resulting in low lithium yield and high costs; it is now largely obsolete. Membrane separation uses nanofiltration or electrodialysis to extract lithium. Its advantages include environmental friendliness and low energy consumption, but disadvantages include membrane clogging, significant pollution, and low recovery rates. Adsorption, with its high selectivity, low operating costs, low energy consumption, simple and efficient operation, recyclable adsorbents, and green and pollution-free nature, has become an important means of obtaining lithium resources.

[0004] Lithium adsorbents used in adsorption methods mainly include organic and inorganic adsorbents. Common inorganic lithium adsorbents include manganese-based, titanium-based, antimony-based, and aluminum-based adsorbents. Currently, these adsorbents are all in powder form with a particle size not exceeding 200 μm. Direct use results in high solubility, difficulty in filtration, and poor flowability and permeability, making them unsuitable for large-scale industrial applications and promotion. To enable the industrial application of powdered adsorbents, there are currently two main granulation methods. One method involves uniformly mixing the adsorbent powder with an organic polymer binder, and then using different granulation processes to produce adsorbents of a specific shape, as illustrated in Chinese patent documents CN 110743516 A, CN 112313006 A, and CN 108722372A. Another method involves polymer polymerization to attach powdered adsorbents to materials with a certain three-dimensional network structure, resulting in spherical or irregularly shaped granular adsorbents, as seen in patent documents US4221767, CN 108854996 A, CN 116237026 A, and CN 115739045A. Although various granulation methods have solved the problems of solid-liquid separation, improved fluidity, and reduced solubility and osmotic pressure, some binders have poor hydrophilicity, leading to a decrease in adsorption active sites; or the granulated particles are large with a small specific surface area, resulting in a slow adsorption rate; or the amount of powder loaded in the polymerization is insufficient, leading to poor adsorption effects; or the adhesion and loading are not strong enough, causing powder detachment. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is the problem existing in the granulation of existing lithium adsorbents, thereby providing a spherical lithium extraction adsorbent and its preparation method.

[0006] Therefore, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing a spherical lithium extraction adsorbent, comprising the following steps:

[0008] S1: Add the stabilizer to the dispersion medium, heat and stir to mix evenly, and prepare an oil phase;

[0009] S2: Mix monomers, crosslinking agents, inert solvents, alkaline catalysts, and lithium adsorbents to form an aqueous phase for prepolymerization;

[0010] S3: The aqueous phase and oil phase are mixed and then further polymerized and aged by reverse suspension to obtain the spherical lithium extraction adsorbent.

[0011] Furthermore, the organic stabilizer includes at least one of the following: sorbitan fatty acid ester (span), polysorbate (tween), hexadecyl phosphate monoester, octadecyl phosphate monoester, sodium dodecyl sulfonate, and oleyl alcohol;

[0012] The inorganic stabilizer includes at least one of magnesium carbonate, barium carbonate, calcium carbonate, calcium sulfate, calcium phosphate, and talc.

[0013] The mass ratio of the organic stabilizer to the inorganic stabilizer is (1-2):(1-5);

[0014] Preferably, the stabilizer is a mixture of oleyl alcohol, hexadecyl phosphate monoester and calcium carbonate in a mass ratio of (2-4):(0.5-2):(5-30).

[0015] The dispersion medium has a boiling point >75°C and includes at least one of alkanes, cycloalkanes, aromatic hydrocarbons, gasoline, edible oil, silicone oil, turbine oil, and liquid wax.

[0016] Preferably, the dispersion medium is turbine oil.

[0017] The monomer is at least one of monophenol, monomethyl-substituted phenol, dimethyl-substituted phenol, catechol, resorcinol, hydroquinone, substituted diphenol, and naphthol;

[0018] Preferably, the monomer is a mixture of catechol, hydroquinone and resorcinol in a mass ratio of (18-12):(9-4):(3-1).

[0019] The crosslinking agent is at least one of paraformaldehyde, aliphatic aldehydes with no more than 5 carbon atoms, furfural, benzaldehyde, terephthalaldehyde, o-phthalaldehyde, iso-phthalaldehyde, and salicylaldehyde.

[0020] Preferably, the crosslinking agent is terephthalaldehyde;

[0021] The inert solvent is at least one of water, 1,4-butanediol, glycerol, propylene glycol, and ethylene glycol; the alkaline catalyst is at least one of sodium hydroxide, barium hydroxide, ammonia, calcium hydroxide, ethylamine, triethylamine, and hexamethylenetetramine.

[0022] Preferably, the inert solvent is a mixture of water and 1,4-butanediol in a mass ratio of 1:(3-9);

[0023] The alkaline catalyst is triethylamine.

[0024] The lithium adsorbent is a manganese-based, aluminum-based, titanium-based, or crown ether-based powder adsorbent with a particle size ≤20μm;

[0025] Furthermore, the mass ratio of stabilizer to monomer is (1-12):40, and the mass ratio of dispersion medium to monomer and lithium adsorbent is (10-15):1:4, preferably (12-14):1:4;

[0026] The mass ratio of monomer to crosslinking agent is (2-15):5, and the mass ratio of monomer to alkaline catalyst is 50:(1-5).

[0027] The mass ratio of monomer to inert solvent is 1:(2-8).

[0028] Furthermore, the heating temperature in step S1 is 45℃-75℃;

[0029] The prepolymerization temperature in step S2 is 45℃-75℃, and the time is 2-4h.

[0030] The polymerization temperature in step S3 is 65℃-85℃, the time is 2-6h, and the aging temperature is 85℃-130℃, the time is 2h-4h.

[0031] The present invention also provides a spherical lithium extraction adsorbent, which is prepared by the above preparation method.

[0032] The technical solution of this invention has the following advantages:

[0033] (1) The spherical lithium extraction adsorbent after granulation of the present invention has good hydrophilicity, and the adsorption active sites are compatible with Li. + This invention features rapid contact and adsorption rate (dynamic column adsorption can reach adsorption equilibrium within 4 Bv), and high adsorption capacity (up to 12 mg / g). The spherical lithium adsorbent prepared by this invention exhibits high sphericity (sphericity ≥ 0.98), good mechanical strength (sphericity after grinding > 93%), is not easily broken, has low bed pressure, solves the clogging problem of resin columns, and extends the service life of the adsorbent. Compared with existing adsorbent particles, the spherical adsorbent of this invention has a smaller particle size (≤ 1 mm), a more stable three-dimensional network structure, and is less prone to loss as a powdered adsorbent; it can be directly applied to large-scale industrial production and has broad prospects for industrial application.

[0034] (2) This invention uses specific raw materials to prepare spherical lithium extraction adsorbents and adopts a process of preparing oil and aqueous phases separately, and then mixing them using reverse suspension polymerization. This successfully prepares hydrogen-bonded phenolic resin-based spherical lithium extraction adsorbents with numerous phenolic hydroxyl groups, which is more conducive to improving the polarity of hydrogen-bonded adsorbents. Moreover, this invention also uses a method of mixing organic and inorganic stabilizers, which results in high sphericity, good sphericity, and no sphericity sticking.

[0035] (3) In the preparation of the spherical lithium extraction adsorbent, this invention eliminates the need for the addition of toxic curing agents and pore-forming agents, reducing environmental pollution during preparation and use, and also lowering costs. The spherical lithium extraction adsorbent prepared using the technical solution of this invention possesses highly developed cross-linked structures (phenolic resin) in its molecular structure, giving it excellent mechanical properties, thermal stability, and chemical corrosion resistance. Therefore, it will not exhibit compression deformation or agglomeration during use. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is the result of the cyclic stability test in Embodiment 7 of the present invention. Detailed Implementation

[0038] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0039] The powdered lithium adsorbent precursor used in this embodiment is an aluminum-based lithium adsorbent precursor, prepared as follows: 1. Weigh a certain mass of aluminum trichloride hexahydrate and lithium chloride according to a molar ratio of aluminum ions to lithium ions of 1.5:1 and dissolve them together. 2. Under stirring, add the above mixed solution dropwise to a 5M sodium hydroxide solution at 75℃ at a rate of 9 ml / min. After controlling the pH at the reaction endpoint to 6-8, stop the dropwise addition and continue the reaction at this temperature for 2 hours until the reaction is complete. 3. Filter to separate the solid and liquid. Wash the solid with a mixture of water and ethanol in a 1:1 ratio and dry it to obtain the aluminum-based adsorbent. 4. Grind the dried adsorbent using a ball mill until the particle size is ≤20 μm.

[0040] The following specific embodiments further illustrate the present invention. The examples given do not represent all embodiments of the present invention; only some embodiments are described as examples. Specific embodiments are as follows:

[0041] Example 1

[0042] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0043] (1) Weigh 1.0g span-80, 0.5g sodium octadecylbenzenesulfonate and 2.0g talc powder and add them to 500.0g n-octane. Stir and mix this solution at 75℃ to prepare an oil phase for later use.

[0044] (2) In a 500ml three-necked flask, add 50.0g phenol, 20g deionized water, 200g ethylene glycol, and 1.5g sodium hydroxide. Turn on the stirrer and heat the reaction system to 75℃. Then add 23.8g paraformaldehyde, 200g lithium adsorbent powder, and 2.0g HMTA (hexamethylenetetramine) to the reaction system to form an aqueous phase. Continue to keep the temperature and react for 2 hours for prepolymerization.

[0045] (3) Quickly pour the aqueous phase into the oil phase, let it stand for 4 minutes, then start stirring and heat to 85°C for 2 hours. Continue heating to 95°C for 2 hours to finish the reaction. Allow it to cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate separates into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water, each time using 2-5 times the volume of the spheres. After washing, boil the polymer spheres in water until they are odorless to obtain the spherical lithium adsorbent.

[0046] Example 2

[0047] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0048] (1) Weigh 1.0g of hexadecyl phosphate monoester and 0.5g of magnesium carbonate and add them to 750g of edible oil. Stir and mix the solution at 55℃ to prepare an oil phase for later use.

[0049] (2) In a 500ml three-necked flask, add 50.0g of 3,5-xylenol, 20g of deionized water, 150g of ethylene glycol, and 1.5g of sodium hydroxide. Turn on the stirrer and heat the reaction system to 55℃. Then add 200g of lithium adsorbent powder and 38.4g of butyraldehyde to the reaction system to form an aqueous phase. Continue to keep the reaction at the temperature for 2 hours for prepolymerization.

[0050] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 5 minutes, then start stirring and heat to 75℃ and keep it at that temperature for 2 hours. Continue heating to 85℃ and age for 3 hours to complete the reaction. Allow it to cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, using 2-5 times the volume of water each time. Then wash them twice more with tap water. After washing, boil the polymer spheres in water until they are odorless to obtain the spherical lithium adsorbent.

[0051] Example 3

[0052] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0053] (1) Weigh 1.5g of Tween-60 and 0.5g of calcium carbonate and add them to 700.0g of silicone oil. Stir and mix the solution at 65°C until it is homogeneous and prepare an oil phase for later use.

[0054] (2) In a 500ml three-necked flask, add 50.0g of o-diphenol, 30g of deionized water, 170g of glycerol and 1.5g of sodium hydroxide. Turn on the stirrer and heat the reaction system to 65℃. Then add 200g of lithium adsorbent powder and 72.3g of benzaldehyde to the reaction system to form an aqueous phase. Continue to keep the temperature and react for 2h for prepolymerization.

[0055] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 6 minutes, then start stirring and heat to 75℃ and keep it at that temperature for 2 hours. Then heat it to 105℃ and continue the reaction for 4 hours. Let it cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent (each time the amount of water should be 2-5 times the volume of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash them with 2-5 times the volume of industrial ethanol. Finally, boil them in water until they are odorless to obtain the spherical lithium extraction adsorbent.

[0056] Example 4

[0057] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0058] (1) Weigh 1.0g of hexadecyl phosphate monoester and 0.5g of magnesium carbonate and add them to 500.0g of gasoline. Stir and mix the solution at 45°C until homogeneous to prepare an oil phase for later use.

[0059] (2) In a 500ml three-necked flask, add 50.0g of m-diphenol, 30g of deionized water, 170g of glycerol, and 5.2g of concentrated ammonia. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 36.5g of terephthalaldehyde to the reaction system to form an aqueous phase. Heat the system to 65℃ and continue to keep it at the temperature for 2 hours for prepolymerization.

[0060] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 2 minutes, then start stirring and heat to 85℃ and keep it at that temperature for 2 hours. Then heat it to 110℃ and continue the reaction for aging for 4 hours. Let it cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has stood and separated into layers, the oil phase can be added with a stabilizer for continued use. Wash the polymer spheres twice with tap water and detergent, and wash them twice with tap water (each time the amount of water should be 2-5 times the volume of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash them with 2-5 times the volume of industrial ethanol. Finally, boil them in water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0061] Example 5

[0062] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0063] (1) Weigh 1.0g of hexadecyl phosphate monoester and 0.5g of calcium sulfate and add them to 500.0g of gasoline. Stir and mix the solution at 45°C until homogeneous to prepare an oil phase for later use.

[0064] (2) In a 500ml three-necked flask, add 35.0g of m-diphenol, 15.0g of 3,5-dimethylphenol, 20g of deionized water, 230g of propylene glycol, and 1.5g of barium hydroxide. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 55.1g of furfural to the reaction system to form an aqueous phase. Continue to heat the system to 65℃ and keep it at the temperature for 2 hours to carry out prepolymerization.

[0065] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 7 minutes, then start stirring and heat to 85℃ for 2 hours. Then heat to 120℃ and continue the aging reaction for 2 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate separates into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, and wash them twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash them with 2-5 times the volume of industrial ethanol. Finally, boil them in water until they are odorless to obtain the spherical lithium extraction adsorbent.

[0066] Example 6

[0067] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0068] (1) Weigh 1.5g oleyl alcohol, 0.5g hexadecyl phosphate monoester and 5g calcium sulfate and add them to 700.0g liquid wax. Stir and mix the solution at 75℃ to prepare the oil phase for later use.

[0069] (2) In a 500ml three-necked flask, add 35.0g of catechol, 15.0g of hydroquinone, 40g of deionized water, 200g of 1,4-butanediol, and 2.5g of calcium hydroxide. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 56.7g of furfural to the reaction system to form an aqueous phase. Continue to heat the system to 75℃ and keep it at that temperature for 2 hours to carry out prepolymerization.

[0070] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 7 minutes, then start stirring, raise the temperature to 95℃ and continue the reaction for 2 hours, then raise the temperature to 130℃ and continue aging for 4 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, the oil phase can be added with a stabilizer for continued use. Wash the polymer spheres twice with tap water and detergent, and wash them twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash them with 2-5 times the volume of industrial ethanol. Finally, boil them in water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0071] Example 7

[0072] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0073] (1) Weigh 1.5g oleyl alcohol, 0.5g hexadecyl phosphate monoester and 10g calcium carbonate and add them to 700.0g turbine oil. Stir and mix the solution at 75℃ to prepare the oil phase for later use.

[0074] (2) In a 500ml three-necked flask, add 30.0g of catechol, 15.0g of hydroquinone, 5.0g of resorcinol, 40g of deionized water, 200g of 1,4-butanediol, and 1.5g of triethylamine. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 36.5g of terephthalaldehyde to the reaction system to form an aqueous phase. Continue to heat the system to 75℃ and keep it at that temperature for 2 hours to carry out prepolymerization.

[0075] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 5 minutes, then start stirring and heat to 95℃ to continue the reaction for 2 hours, then continue to heat to 130℃ for aging for 4 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, and wash twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash with 2-5 times the volume of industrial ethanol. Finally, boil with water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0076] Example 8

[0077] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0078] (1) Weigh 2.0g of hexadecyl phosphate monoester and 8g of calcium carbonate and add them to 600.0g of turbine oil. Stir and mix the solution at 75°C until it is homogeneous and prepare an oil phase for later use.

[0079] (2) In a 500ml three-necked flask, add 20.0g of 3,5-dimethylphenol, 30.0g of p-diphenol, 20g of deionized water, 300g of propylene glycol, and 1.5g of sodium hydroxide. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder, 1.3g of paraformaldehyde, and 117g of salicylaldehyde to the reaction system to form an aqueous phase. Continue to heat the system to 75℃ and keep it at the temperature for 2 hours to carry out prepolymerization.

[0080] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 2-10 minutes, then start stirring and heat to 100℃ to continue the reaction for 2 hours, then heat to 120℃ to continue aging for 4 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, and wash twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash with 2-5 times the volume of industrial ethanol. Finally, boil with water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0081] Example 9

[0082] This embodiment provides a spherical lithium extraction adsorbent, the specific preparation method of which is as follows:

[0083] (1) Weigh 1.0g oleyl alcohol, 0.5g hexadecyl phosphate monoester and 10g calcium carbonate and add them to 700.0g turbine oil. Stir and mix this solution at 75℃ to prepare an oil phase for later use.

[0084] (2) In a 500ml three-necked flask, add 30.0g of catechol, 15.0g of hydroquinone, 5.0g of resorcinol, 40g of deionized water, 320g of 1,4-butanediol, and 5g of triethylamine. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 36.5g of terephthalaldehyde to the reaction system. Continue to heat the system to 75℃ and keep it at that temperature for 2 hours to carry out prepolymerization.

[0085] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 5 minutes, then start stirring and heat to 95℃ to continue the reaction for 2 hours, then heat to 130℃ to continue aging for 4 hours. Cool naturally to room temperature, filter, and after the filtrate has separated into layers, the oil phase can still be used. Wash the polymer spheres twice with tap water and detergent, and wash them twice with tap water (each time the amount of water is 2-5 times the volume of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash them with 2-5 times the volume of industrial ethanol. Finally, boil them in water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0086] Comparative Example 1

[0087] This comparative example provides a spherical lithium extraction adsorbent. The only difference from Example 7 is that only an organic stabilizer is used. The specific preparation method is as follows:

[0088] (1) Weigh 1.5g of oleyl alcohol and 0.5g of hexadecyl phosphate and add them to 700.0g of turbine oil. Stir and mix the solution at 75°C to prepare an oil phase for later use.

[0089] (2) In a 500ml three-necked flask, add 30.0g of catechol, 15.0g of hydroquinone, 5.0g of resorcinol, 40g of deionized water, 200g of 1,4-butanediol, and 1.5g of triethylamine. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 36.5g of terephthalaldehyde to the reaction system to form an aqueous phase. Continue to heat the system to 75℃ and keep it at that temperature for 2 hours to carry out prepolymerization.

[0090] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 5 minutes, then start stirring and heat to 95℃ to continue the reaction for 2 hours, then continue to heat to 130℃ for aging for 4 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, and wash twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash with 2-5 times the volume of industrial ethanol. Finally, boil with water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0091] Comparative Example 2

[0092] This comparative example provides a spherical lithium extraction adsorbent. The only difference from Example 7 is that only an inorganic stabilizer is used. The specific preparation method is as follows:

[0093] (1) Weigh 10g of calcium carbonate and add it to 700.0g of turbine oil. Stir and mix the solution at 75℃ to prepare an oil phase for later use.

[0094] (2) In a 500ml three-necked flask, add 30.0g of catechol, 15.0g of hydroquinone, 5.0g of resorcinol, 40g of deionized water, 200g of 1,4-butanediol, and 1.5g of triethylamine. Turn on the stirrer and heat the reaction system to 45℃. Then add 200g of lithium adsorbent powder and 36.5g of terephthalaldehyde to the reaction system to form an aqueous phase. Continue to heat the system to 75℃ and keep it at that temperature for 2 hours to carry out prepolymerization.

[0095] (3) Quickly pour the above aqueous phase into the oil phase, let it stand for 5 minutes, then start stirring and heat to 95℃ to continue the reaction for 2 hours, then continue to heat to 130℃ for aging for 4 hours. Cool naturally to room temperature, filter to obtain polymer spheres and filtrate. After the filtrate has separated into layers, a stabilizer can be added to the oil phase for continued use. Wash the polymer spheres twice with tap water and detergent, and wash twice with tap water (each time the water volume is 2-5 times that of the spheres). After washing, transfer the polymer spheres to a glass exchange column and wash with 2-5 times the volume of industrial ethanol. Finally, boil with water until the polymer spheres are odorless to obtain the spherical lithium extraction adsorbent.

[0096] Experimental Example 1

[0097] The adsorbents obtained in the examples and comparative examples were subjected to performance tests. The specific test methods were as follows: wet apparent density was determined according to GB / T 8331-2008; moisture content was determined according to GB / T 5757-2008; particle size was determined according to GB / T 5758-2001; sphericity after grinding was determined according to GB / T 12598-2001; and sphericity was tested using the sphericity formula: The calculation yields V. p S is the volume of the spherical particle. p The surface area of ​​the spherical particles is shown in Table 1 below.

[0098] Table 1. Performance results of the adsorbents obtained in the examples and comparative examples.

[0099]

[0100]

[0101] As shown in the table above, the lithium adsorbent prepared by this invention has a moisture content of 55%-60% and contains numerous hydrophilic functional groups (hydroxyl groups), exhibiting good hydrophilicity, which is beneficial for rapid contact of the active sites of the adsorbent. The particle size distribution ranges from 0.1mm to 1.0mm; relatively speaking, the smaller the particle size, the larger the specific surface area, which is more conducive to rapid adsorption. The sphericity after grinding is above 93%, and its mechanical strength is superior to that of conventional resins. Its pressure resistance and deformation resistance are far superior to existing polymer-bonded granulation methods. In contrast, the spherical lithium adsorbents obtained in the comparative examples showed significantly worse sphericity, a lower sphericity after grinding, a wider particle size range, and a significant increase in moisture content and a decrease in wet apparent density.

[0102] Experimental Example 2

[0103] 1.0 g of the spherical lithium adsorbent obtained in the examples and comparative examples was accurately weighed and placed in a 150 ml stoppered conical flask. Then, 50 ml of brine from a salt lake (provided by a salt lake company) was accurately added. The flask was placed in a 30°C constant temperature water bath shaker (130 r / min) for adsorption for 2 hours. After filtration, the supernatant was collected and then diluted 50 times. The lithium ion content was detected using an ICP inductively coupled plasma atomic emission spectrometer. The adsorption capacity (mg / g) was calculated as (lithium concentration in the brine - lithium concentration after adsorption) * 0.05 / 1.0. For example, the adsorption capacity (mg / g) in Example 1 was (479.02 - 387.05) * 0.05 / 1.0 = 4.6. Specific results are shown in Table 2.

[0104] Table 2 Adsorption performance of the adsorbents obtained in the examples and comparative examples

[0105]

[0106]

[0107] As shown in the table above, the adsorbent does not adsorb calcium or potassium in any of the embodiments. Since sodium is included in the formation of the adsorbent precursor, only the brine composition and the completeness of the test are presented here. Regarding lithium, it can be seen that all embodiments exhibit excellent adsorption performance for lithium, with Example 7, which uses the preferred embodiment of this application, showing the best adsorption capacity of 12.49 mg / g for lithium. It can also be seen that each embodiment shows trace adsorption of boron and magnesium. The adsorption of boron and magnesium in Example 7 did not affect its adsorption of lithium, indicating that it has good selective adsorption for lithium. However, the comparative columns show that when the technical solution of this application is not used, both the adsorption capacity and the adsorption selectivity of the obtained lithium adsorbent decrease simultaneously.

[0108] Experimental Example 3

[0109] Example 7, exhibiting the best adsorption performance, was selected. 80 ml of spherical lithium adsorbent was placed in a 2.0 cm * 30 cm glass exchange column for adsorption-desorption experiments. The adsorption-desorption experiment was cycled 20 times to examine the cyclic stability of the adsorbent. The conditions for the adsorption-desorption process were: brine flowed through the adsorption column, the adsorbed brine reached saturation at approximately 4 Bv, and 3 Bv was desorbed using the desorption solution. Figure 1 It can be seen that the adsorption rate and desorption rate fluctuate significantly in the first five cycles. This is because, after the adsorbent is formed, the lithium that can be intercalated or deintercalated is not fully extracted. As adsorption and desorption proceed, the active sites gradually leak out until equilibrium is reached. From the sixth cycle onwards, the adsorption rate and desorption rate are basically stable between 87%-88% and 95%-98%, respectively, indicating that the overall spherical lithium adsorbent has good cyclic adsorption performance. This problem is a common issue faced by current lithium adsorbent powder granulation. Compared with other current granulation methods, after granulation using the method described in this application, due to the numerous hydrophilic groups—hydroxyl groups—of the phenolic resin, lithium ions can reach the active sites more quickly and be adsorbed during lithium extraction. At the same time, the strong hydrophilicity also allows the unexposed active sites to be desorbed faster compared to other granulation methods.

[0110] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a spherical lithium extraction adsorbent, characterized in that, Includes the following steps: S1: Add the stabilizer to the dispersion medium, heat and stir to mix evenly, and prepare an oil phase; S2: Mix monomers, crosslinking agents, inert solvents, alkaline catalysts, and lithium adsorbents to form an aqueous phase for prepolymerization; S3: The aqueous phase and oil phase are mixed and then further polymerized and aged by reverse suspension to obtain the spherical lithium extraction adsorbent; The stabilizers include inorganic stabilizers and organic stabilizers; The organic stabilizer is selected from at least one of sorbitan fatty acid ester, polysorbate, hexadecyl phosphate monoester, octadecyl phosphate monoester, and oleyl alcohol; The inorganic stabilizer is selected from at least one of magnesium carbonate, calcium carbonate, calcium sulfate, and talc. The mass ratio of the organic stabilizer to the inorganic stabilizer is (1-2):(1-5); The monomer is at least one of monomethyl substituted phenol, dimethyl substituted phenol, catechol, resorcinol, hydroquinone, substituted diphenol, and naphthol; The crosslinking agent is at least one of paraformaldehyde, aliphatic aldehydes with no more than 5 carbon atoms, furfural, benzaldehyde, terephthalaldehyde, o-phthalaldehyde, iso-phthalaldehyde, and salicylaldehyde. The mass ratio of monomer to crosslinking agent is (2-15):

5.

2. The preparation method according to claim 1, characterized in that, The stabilizer is a mixture of oleyl alcohol, hexadecyl phosphate monoester and calcium carbonate in a mass ratio of (2-4):(0.5-2):(5-30).

3. The preparation method according to claim 1 or 2, characterized in that, The dispersion medium has a boiling point >75°C, and the dispersion medium includes at least one of alkanes, cycloalkanes, aromatic hydrocarbons, gasoline, edible oil, silicone oil, turbine oil, and liquid wax.

4. The preparation method according to claim 3, characterized in that, The dispersion medium is turbine oil.

5. The preparation method according to claim 1, characterized in that, The monomer is a mixture of catechol, hydroquinone and resorcinol in a mass ratio of (18-12):(9-4):(3-1).

6. The preparation method according to claim 1, characterized in that, The crosslinking agent is terephthalaldehyde.

7. The preparation method according to claim 1, characterized in that, The inert solvent is at least one of water, 1,4-butanediol, glycerol, propylene glycol, and ethylene glycol. The alkaline catalyst is at least one of sodium hydroxide, barium hydroxide, ammonia, calcium hydroxide, ethylamine, triethylamine, and hexamethylenetetramine.

8. The preparation method according to claim 7, characterized in that, The inert solvent is a mixture of water and 1,4-butanediol in a mass ratio of 1:(3-9); The alkaline catalyst is triethylamine.

9. The preparation method according to claim 1, characterized in that, The lithium adsorbent is a manganese-based, aluminum-based, titanium-based, or crown ether-based powder adsorbent with a particle size ≤20μm.

10. The preparation method according to claim 1, characterized in that, The mass ratio of stabilizer to monomer is (1-12):40, and the mass ratio of dispersion medium to monomer and lithium adsorbent is (10-15):1:

4. The mass ratio of monomer to alkaline catalyst is 50:(1-5); The mass ratio of monomer to inert solvent is 1:(2-8).

11. The preparation method according to claim 10, characterized in that, The mass ratio of dispersion medium to monomer and lithium adsorbent is (12-14):1:

4.

12. The preparation method according to claim 1, characterized in that, The heating temperature in step S1 is 45℃-75℃; The prepolymerization temperature in step S2 is 45℃-75℃, and the time is 2-4h. The polymerization temperature in step S3 is 65℃-85℃, and the time is 2-6h; the aging temperature is 85℃-130℃, and the time is 2-4h.

13. A spherical lithium extraction adsorbent, characterized in that, It is prepared by any one of claims 1-12.

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