A lithium adsorbent, a preparation method and application thereof

Abstract

The application relates to a lithium adsorbent and a preparation method and application thereof, and belongs to the technical field of lithium extraction from salt lakes, and overcomes the shortcomings of low adsorption efficiency and short cycle service life of the lithium adsorbent in the prior art. The raw material of the lithium adsorbent comprises a lithium adsorbent precursor, a binder and a block polyether polymer; the block polyether polymer is a triblock copolymer of polyethylene glycol and polypropylene glycol; the average molecular weight of the block polyether polymer is 8000-100000; and the molar ratio of the repeating units -OCH2CH2- and -OCH(CH3)CH2- in the block polyether polymer is 7:3-3:7. The lithium adsorbent has high lithium extraction rate and wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from salt lakes, specifically relating to a lithium adsorbent, its preparation method, and its application. Background Technology

[0002] The adsorption method for lithium extraction from salt lakes utilizes lithium adsorbents to extract lithium from Li. + "Its unique adsorption properties, through a continuous process of 'adsorption' and 'desorption,' enable Li..." + Lithium can be concentrated and enriched from a variety of alkali metal ions, and the performance of the lithium adsorbent determines the enrichment of Li. + Key factors.

[0003] Currently, the most widely used method for granulating lithium adsorbents is wet extrusion, which involves blending and granulating the adsorbent precursor powder, polymer binder, and solvent. To accommodate this granulation process, hydrophobic polymers are typically used as binders. This results in low overall hydrophilicity of the granulated adsorbent, leading to a slow wetting rate in brine and consequently low overall adsorption efficiency. Furthermore, the polymer binder itself has poor compatibility with the precursor powder, resulting in weak adhesion between the binder and the precursor powder during granulation. This leads to low strength and poor wear resistance in the adsorbent, ultimately resulting in a short cycle life. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of low adsorption efficiency and short cycle life of lithium adsorbents in the prior art, thereby providing a lithium adsorbent, its preparation method and application.

[0005] To this end, the present invention provides the following technical solution.

[0006] In a first aspect, the present invention provides a lithium adsorbent, the raw materials of which include a lithium adsorbent precursor, a binder and a block polyether polymer.

[0007] The block polyether polymer is a triblock copolymer of polyethylene glycol and polypropylene glycol;

[0008] The average molecular weight Mw of the block polyether polymer is 8,000 to 100,000; the molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- in the block polyether polymer is 7:3 to 3:7.

[0009] For example, the average molecular weight of the block polyether polymer can be 8400, 10000, 13000, 14600, 15000, 15800, 17000, 19000, 25000, 28700, 32000, 35000, 39500, 42000, 48000, 54000, 55000, 60000, 63700, 68000, 72000, 75000, 79200, 84000, 88000, 91300, 94000, or 98000.

[0010] In one possible implementation, the block polyether polymer is 0.5 to 5 wt% of the lithium adsorbent precursor.

[0011] In one possible implementation, the adhesive is a polymeric adhesive;

[0012] Optionally, the Mw of the polymeric adhesive is 1*10 5 ~15*10 5 ;

[0013] Optionally, the adhesive includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, chlorinated polyvinyl chloride, cellulose acetate, carboxymethyl cellulose, chitosan, polymethyl methacrylate, polyacrylonitrile, polyurethane, and polystyrene.

[0014] Optionally, the amount of binder used is 10 to 50 wt% of the lithium adsorbent precursor.

[0015] In one possible implementation, the lithium adsorbent precursor satisfies at least one of the following conditions:

[0016] (1) Selected from aluminum-based lithium adsorbent precursors, titanium-based lithium adsorbent precursors or manganese-based lithium adsorbent precursors;

[0017] Optionally, the aluminum-based lithium adsorbent precursor is xLiCl·2Al(OH)3·nH2O, where x = 0.4–1.0 and n = 0–10;

[0018] Optionally, the precursor of the manganese-based lithium adsorbent is Li(H)Mn2O4 or Li(H). 1.6 Mn 1.6 O4 or Li(H) 1.33 Mn 1.67 O4;

[0019] Optionally, the precursor of the titanium-based lithium adsorbent is Li(H)₂TiO₃ or Li(H)₄Ti₅O₃. 12 ;

[0020] (2) The particle size of the lithium adsorbent precursor is 0.5 to 100 μm, and can be selected as 1 to 10 μm.

[0021] Secondly, the present invention provides a method for preparing a lithium adsorbent, comprising:

[0022] An organic solvent, a binder, a lithium adsorbent precursor, and a block polyether polymer are mixed and granulated to obtain granules. After the granules are hardened, the organic solvent is removed to obtain the lithium adsorbent.

[0023] In one possible implementation, the step of mixing the organic solvent, binder, lithium adsorbent precursor and block polyether polymer further includes adding additives.

[0024] Optionally, the amount of the additive is 0.1 to 5 wt% of the mass of the lithium adsorbent precursor;

[0025] Optionally, the additive includes one or more of the following: polyvinyl alcohol, PVP K30, PVP K60, PVP K90, PEG-200, PEG-400, PEG-1000, PEG-2000, PEG-6000, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, Tween 80, Span 40, γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, vinyltrimethoxysilane, and bis-(3-(triethoxysilane)-propyl)-tetrasulfide. The additive can act as a pore-forming agent and / or improve surface activity, further enhancing the adsorption performance for lithium.

[0026] In one possible implementation, an organic solvent, a binder, a lithium adsorbent precursor, and a block polyether polymer are mixed under heating conditions.

[0027] Optionally, the heating temperature is 25℃~150℃, and optionally 60℃~100℃.

[0028] In one possible embodiment, granule hardening involves immersing the granules in a coagulation bath for hardening. In some embodiments, the coagulation bath is water or an aqueous or ethanolic solution of an organic solvent; the organic solvent in the aqueous or ethanolic solution is one or a mixture of several of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, chloroform, dichloroethane, and ethyl acetate; the concentration of the aqueous or ethanolic solution of the organic solvent is 0–50%, preferably 0–20%.

[0029] In one possible embodiment, the organic solvent includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, chloroform, dichloroethane, and ethyl acetate;

[0030] Optionally, the amount of organic solvent used is 40wt% to 100wt% of the total weight of the binder and lithium adsorbent precursor.

[0031] Thirdly, the present invention provides an application of a lithium adsorbent or a lithium adsorbent prepared according to the above method in the adsorption and extraction of lithium ions in salt lake brine.

[0032] In some implementations, the mixing equipment used to mix the organic solvent, binder, lithium adsorbent precursor, and block polyether polymer is selected from one of the following: kneader, internal mixer, and agitator.

[0033] In some implementations, the extruder used for granulation is selected from any one of a single-screw extruder, a twin-screw extruder, and a reciprocating extruder.

[0034] The technical solution of this invention has the following advantages:

[0035] 1. The lithium adsorbent raw materials of the present invention include a lithium adsorbent precursor, a binder, and a block polyether polymer; the block polyether polymer is a triblock copolymer of polyethylene glycol and polypropylene glycol; the average molecular weight of the block polyether polymer is 8,000 to 100,000; the molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- in the block polyether polymer is 7:3 to 3:7.

[0036] The lithium adsorbent of this invention contains an amphiphilic block polyether polymer, giving it hydrophilicity and good wettability. This allows the adsorbent to wet a large number of pores in a short time, thereby shortening the lithium-ion mass transfer time and increasing the lithium extraction rate. Simultaneously, the introduction of the amphiphilic polymer strengthens the binder's adhesion, making the lithium adsorbent precursor powder less prone to falling off, increasing its wear resistance and strength, and thus extending its cycle life. Furthermore, the block polyether polymer specified in this invention is insoluble in water, preventing it from being dissolved and removed by water during the preparation of the lithium adsorbent or during lithium extraction from salt lake brine, ensuring the performance of the lithium adsorbent during long-term cyclic use.

[0037] 2. The block polyether polymer is 0.5–5 wt% of the lithium adsorbent precursor. Limiting the dosage within this range allows the lithium adsorbent to simultaneously possess good hydrophilicity and wear resistance. Attached Figure Description

[0038] 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.

[0039] Figure 1 This is a graph showing the relationship between adsorption amount and adsorption time. Detailed Implementation

[0040] 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.

[0041] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0042] Example 1

[0043] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0044] (1) Preparation of lithium adsorbent precursor:

[0045] AlCl3·6H2O, LiCl·H2O, and deionized water were ultrasonically mixed at 75℃ for 60 min to obtain a mixed solution with a Li / Al molar ratio of 1.5 / 2, a lithium ion concentration of 0.075 mol / L, and an aluminum ion concentration of 0.1 mol / L. The mixed solution and ammonia (6 mol / L) were simultaneously added dropwise to a reaction vessel at a rate of 7.5 ml / min, with a stirring speed of 150 rpm. The entire reaction was carried out in a circulating water bath at 90℃, with the final pH value controlled at 7. After the reaction, the mixture was allowed to stand at 90℃ for 24 h. The solid was then filtered, washed with water, dried, and pulverized to obtain a lithium adsorbent precursor powder, LiCl·2Al(OH)3·H2O, with an average particle size of 5 μm.

[0046] (2) Weigh 10 kg of (1) lithium adsorbent precursor powder, 2 kg of polyacrylonitrile (Mw = 500000, Maclean), 9 kg of N,N-dimethylformamide and 0.4 kg of triblock copolymer of polyethylene glycol and polypropylene glycol (Aladdin Technology Co., Ltd., average molecular weight of 15800, molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- is 3:7), and 0.2 kg of PVP K90, 0.05 kg of Tween 80 and 0.1 kg of γ-glycidyl etheroxypropyltrimethoxysilane. Mix them in a mixer at 70°C until uniform. Then granulate them using a piston extruder to obtain lithium adsorbent semi-finished product. Soak the lithium adsorbent semi-finished product in water to harden it and remove the solvent contained inside. Then, granules with a particle size of 0.8-2.0 mm can be obtained.

[0047] Example 2

[0048] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0049] (1) Preparation of lithium adsorbent precursor:

[0050] AlCl3·6H2O, LiCl·H2O, and deionized water were ultrasonically mixed at 75℃ for 60 min to obtain a mixed solution with a Li / Al molar ratio of 1.5 / 2, a lithium ion concentration of 0.075 mol / L, and an aluminum ion concentration of 0.1 mol / L. The mixed solution and ammonia (6 mol / L) were simultaneously added dropwise to a reaction vessel at a rate of 7.5 ml / min, with a stirring speed of 150 rpm. The entire reaction was carried out in a circulating water bath at 90℃, with the final pH value controlled at 7. After the reaction, the mixture was allowed to stand at 90℃ for 24 h. The solid was then filtered, washed with water, dried, and pulverized to obtain a lithium adsorbent precursor powder, LiCl·2Al(OH)3·H2O, with an average particle size of 5 μm.

[0051] (2) Weigh 10 kg of (1) lithium adsorbent precursor powder, 2 kg of polyacrylonitrile (Mw = 500000, Maclean), 9 kg of N-methylpyrrolidone and 0.05 kg of triblock copolymer of polyethylene glycol and polypropylene glycol (Aladdin Technology Co., Ltd., average molecular weight 39500, molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- is 7:3), and 0.05 kg of PEG-6000. Mix them with a stirrer at 70°C until uniform. Then extrude and granulate them using a piston extruder to obtain lithium adsorbent semi-finished product. Soak the lithium adsorbent semi-finished product in an aqueous solution of 20 wt% N-methylpyrrolidone to harden it. Then wash it with water to remove the solvent contained inside, and you can get lithium adsorbent in granular form with a particle size of 0.8-2.0 mm.

[0052] Example 3

[0053] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0054] (1) Preparation of lithium adsorbent precursor:

[0055] AlCl3·6H2O, LiCl·H2O, and deionized water were ultrasonically mixed at 75℃ for 60 min to obtain a mixed solution with a Li / Al molar ratio of 1.5 / 2, a lithium ion concentration of 0.075 mol / L, and an aluminum ion concentration of 0.1 mol / L. The mixed solution and ammonia (6 mol / L) were simultaneously added dropwise to a reaction vessel at a rate of 7.5 ml / min, with a stirring speed of 150 rpm. The entire reaction was carried out in a circulating water bath at 90℃, with the final pH value controlled at 7. After the reaction, the mixture was allowed to stand at 90℃ for 24 h. The solid was then filtered, washed with water, dried, and pulverized to obtain a lithium adsorbent precursor powder, LiCl·2Al(OH)3·H2O, with an average particle size of 5 μm.

[0056] (2) Weigh 10 kg of (1) lithium adsorbent precursor powder, 1 kg of polymethyl methacrylate (Mw = 350000 Aladdin Technology Co., Ltd.), 11 kg of N,N-dimethylacetamide and 0.5 kg of triblock copolymer of polyethylene glycol and polypropylene glycol (Aladdin Technology Co., Ltd., average molecular weight of 68000, molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- is 3:7), and 0.5 kg of PVP K60. Mix them with a kneader at 80°C until uniform, and then extrude and granulate them using a single screw extruder to obtain lithium adsorbent semi-finished product. Finally, soak the lithium adsorbent semi-finished product in a 5% concentration of N,N-dimethylformamide aqueous solution to harden it, and then wash it with water to remove the solvent contained inside, and granular lithium adsorbent can be obtained.

[0057] Example 4

[0058] This embodiment provides a method for preparing a lithium adsorbent, which is basically the same as that in Example 1, except that the amount of the triblock copolymer of polyethylene glycol and polypropylene glycol added is 0.2 kg.

[0059] Example 5

[0060] This embodiment provides a method for preparing a lithium adsorbent, which is basically the same as that in Example 1, except that the molar ratio of the repeating units -OCH2CH2- and -OCH(CH3)CH2- is 7:3.

[0061] Comparative Example 1

[0062] This comparative example provides a method for preparing a lithium adsorbent, which is basically the same as that in Example 1, except that a triblock copolymer of polyethylene glycol and polypropylene glycol is not added.

[0063] Comparative Example 2

[0064] This comparative example provides a method for preparing a lithium adsorbent, which is basically the same as that in Example 1, except that the same mass of a triblock copolymer of polyethylene glycol and polypropylene glycol (Aladdin Technology Co., Ltd., with an average molecular weight of 1900 and a molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- of 9:1) is used instead of the triblock copolymer of polyethylene glycol and polypropylene glycol in Example 1. In this comparative example, the triblock copolymer of polyethylene glycol and polypropylene glycol is used as a pore-forming agent in the aqueous system. Although the triblock copolymer of polyethylene glycol and polypropylene glycol is added to the raw materials, it is removed during the washing process because it is soluble in water.

[0065] Test case

[0066] (1) Adsorption efficiency detection method:

[0067] 500g (dry weight) of lithium adsorbent particles prepared in the examples and comparative examples were desorbed using deionized water at 50°C until the precursor powder was 0.4LiCl·2Al(OH)3·H2O (i.e., the lithium adsorbent was activated before adsorption). The desorbed lithium adsorbent was then placed in high magnesium-to-lithium ratio brine from a salt lake for adsorption. The adsorption capacity of the lithium adsorbent at different times (1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h) was calculated based on the lithium ion concentration difference in the water sample. A graph showing the relationship between adsorption capacity and adsorption time for each example and comparative example was plotted. The test results are as follows: Figure 1 As shown.

[0068] Depend on Figure 1 Comparing Examples 1-5 with Comparative Examples 1 and 2, it can be seen that after adding the block polyether polymer specified in this invention, the adsorbent requires a shorter time to reach saturation adsorption, and the adsorption efficiency is higher.

[0069] A comparison of Examples 1 and 4 shows that increasing the amount of block polyether polymer added can further shorten the adsorption time required to achieve the same adsorption capacity and improve the adsorption efficiency.

[0070] A comparison of Examples 1 and 5 shows that the more hydrophilic segments in the block polyether polymer, the shorter the adsorption time required to achieve the same adsorption capacity, and the higher the adsorption efficiency. This demonstrates that the addition of amphiphilic block polyether polymers can improve the overall hydrophilicity of the adsorbent, thereby enabling the adsorbent to wet the brine more quickly, and thus improving the lithium extraction rate and adsorption efficiency.

[0071] (2) Method for evaluating wear rate after repeated use:

[0072] 500g (dry weight) of lithium adsorbent particles prepared in the examples and comparative examples were respectively loaded into chromatography columns and adsorbed using brine from a high magnesium-to-lithium ratio salt lake for 1 hour. The adsorption was then resolved with deionized water at room temperature for 1 hour. This simulated 1000 cycles of continuous dynamic industrial operation. The wear rate of the lithium adsorbent after 1000 cycles was calculated based on the mass difference of the adsorbent. Specific test results are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Wear rate = (mass of lithium adsorbent before operation - mass of lithium adsorbent after 1000 operation cycles) / mass of lithium adsorbent before operation * 100%

[0077] As shown in the table above, the addition of block polyether polymers reduces wear and extends the lifespan of the lithium adsorbent after recycling, and the more hydrophilic segments there are, the lower the wear rate. This also verifies that the addition of block polyether polymers strengthens the adhesion between the lithium adsorbent precursor powder and the binder, resulting in a more robust bond between the lithium adsorbent precursor powder and the binder.

[0078] 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 lithium adsorbent, characterized in that, The raw materials include lithium adsorbent precursors, binders, and block polyether polymers; The block polyether polymer is a triblock copolymer of polyethylene glycol and polypropylene glycol; The block polyether polymer has an average molecular weight of 8,000 to 100,000; the molar ratio of repeating units -OCH2CH2- and -OCH(CH3)CH2- in the block polyether polymer is 7:3 to 3:

7. The block polyether polymer is 0.5~5 wt% of the lithium adsorbent precursor. The binder is a polymeric binder, and the amount of binder used is 10-50 wt% of the mass of the lithium adsorbent precursor. The lithium adsorbent precursor is selected from aluminum-based lithium adsorbent precursors, titanium-based lithium adsorbent precursors, or manganese-based lithium adsorbent precursors.

2. The lithium adsorbent according to claim 1, characterized in that, The adhesive includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl chloride, chlorinated polyvinyl chloride, cellulose acetate, carboxymethyl cellulose, chitosan, polymethyl methacrylate, polyacrylonitrile, polyurethane, and polystyrene.

3. The lithium adsorbent according to claim 1, characterized in that, The aluminum-based lithium adsorbent precursor is xLiCl·2Al(OH)3·nH2O, where x = 0.4~1.0 and n = 0~10.

4. The lithium adsorbent according to claim 1, characterized in that, The precursors for the manganese-based lithium adsorbent are Li(H)Mn2O4 and Li(H). 1.6 Mn 1.6 O4 or Li(H) 1.33 Mn 1.67 O4.

5. The lithium adsorbent according to claim 1, characterized in that, The precursor of the titanium-based lithium adsorbent is Li(H)₂TiO₃ or Li(H)₄Ti₅O₃. 12 .

6. The lithium adsorbent according to claim 1, characterized in that, The particle size of the lithium adsorbent precursor is 0.5~100μm.

7. The lithium adsorbent according to claim 6, characterized in that, The particle size of the lithium adsorbent precursor is 1~10μm.

8. A method for preparing the lithium adsorbent according to any one of claims 1-7, characterized in that, include: Organic solvent, binder, lithium adsorbent precursor and block polyether polymer are mixed and granulated to obtain granules; After the granules are hardened, the organic solvent is removed to obtain the lithium adsorbent.

9. The method for preparing the lithium adsorbent according to claim 8, characterized in that, The step of mixing organic solvents, binders, lithium adsorbent precursors, and block polyether polymers also includes adding additives.

10. The method for preparing the lithium adsorbent according to claim 9, characterized in that, The amount of the additive is 0.1 to 5 wt% of the lithium adsorbent precursor.

11. The method for preparing the lithium adsorbent according to claim 9, characterized in that, The additives include one or more of the following: polyvinyl alcohol, PVP K30, PVP K60, PVP K90, PEG-200, PEG-400, PEG-1000, PEG-2000, PEG-6000, sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, Tween 80, Span 40, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, and bis-(3-(triethoxysilane)-propyl)-tetrasulfide.

12. The method for preparing the lithium adsorbent according to claim 8, characterized in that, Organic solvent, binder, lithium adsorbent precursor, and block polyether polymer are mixed under heating conditions.

13. The method for preparing the lithium adsorbent according to claim 12, characterized in that, The heating temperature is 25℃~150℃.

14. The method for preparing the lithium adsorbent according to claim 13, characterized in that, The heating temperature is 60℃~100℃.

15. The method for preparing the lithium adsorbent according to claim 8, characterized in that, Granular hardening involves immersing the granules in a coagulation bath for hardening.

16. The method for preparing the lithium adsorbent according to claim 8, characterized in that, The organic solvents include one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, chloroform, dichloroethane, and ethyl acetate.

17. The method for preparing the lithium adsorbent according to claim 16, characterized in that, The amount of organic solvent used is 40 wt% to 100 wt% of the total weight of the binder and lithium adsorbent precursor.

18. The use of the lithium adsorbent according to any one of claims 1-7 or the lithium adsorbent prepared by any one of claims 8-17 in the adsorption and extraction of lithium ions in salt lake brine.

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