Preparation method of high-strength lithium adsorbent

Abstract

The invention relates to a preparation method of a high-strength lithium adsorbent, and belongs to the field of chemical preparation. Dissolving a polymer binder and a pore-foaming agent in a heated organic solvent; the high-molecular binder is composed of a polymer containing an aromatic ring structure and a polymer containing a long-chain branched structure; after dissolving, adding a powder adsorbent, and mixing to obtain a granulation emulsion; putting the granulation emulsion into an autoclave for defoaming treatment, and then carrying out spinning extrusion to obtain initial rising fibers; and soaking the primary rising fiber in a hot water bath, granulating, screening and washing to obtain the lithium adsorbent. According to the present invention, the lithium adsorbent granulation uses the high polymer material containing the aromatic ring and the long-chain branched structure, such that the excellent high cycle service life is provided, the operation cost is low, and the method is suitable for the industrial-scale lithium extraction process.

Description

Technical Field

[0001] The invention relates to a method for preparing a high-strength lithium adsorbent, and belongs to the field of chemical preparation. Background Art

[0002] The main technical problems solved by high mechanical strength granulated lithium adsorbents are how to give the adsorbents sufficient physical strength to adapt to the harsh conditions in industrial applications while maintaining or improving the lithium ion adsorption performance. Specifically, these technical problems include: (1) Improving mechanical strength: The granulated lithium adsorbent needs to have sufficient mechanical strength to prevent crushing and pulverization caused by friction and pressure during transportation, loading and unloading, and use. This is crucial to maintain the effective surface area and pore structure of the adsorbent, thereby ensuring long-term stable lithium adsorption performance. (2) Enhancing pressure resistance and wear resistance: For lithium adsorbents used in fixed bed reactors, they must be able to withstand high working pressures without significant deformation or rupture; at the same time, they should have good wear resistance under dynamic conditions to avoid the generation of fine particles due to wear, which in turn affects the separation effect and equipment maintenance. (3) Optimizing regeneration performance: High mechanical strength granulated lithium adsorbents are easy to regenerate, that is, they can still maintain good physical integrity and adsorption efficiency after multiple adsorption-desorption cycles, reducing operating costs and extending service life.

[0003] In summary, the high-strength granulated lithium adsorbent involved in the present invention aims to overcome the defects of traditional powdered or loose structure adsorbents and provide a new material that is more durable, has excellent performance and is suitable for large-scale applications.

[0004] With the rapid growth of global demand for lithium batteries, the efficient extraction and recovery of lithium resources has become crucial. Traditional lithium extraction methods such as precipitation and solvent extraction have problems such as high cost and environmental unfriendliness. Therefore, the development of new and efficient lithium adsorption materials has become a research hotspot. Among them, granulated lithium adsorbents have shown significant advantages in fixed bed adsorption devices due to their good fluidity and easy operability. However, lithium adsorbents prepared by traditional granulation technology often have insufficient mechanical strength and are easily broken or worn during use, resulting in decreased adsorption performance. Therefore, the development of granulated lithium adsorbents with high mechanical strength is of great significance for improving lithium adsorption efficiency and extending the service life of adsorbents.

[0005] The most similar implementations are:

[0006] (1) Material selection: Use high-strength inorganic materials or organic-inorganic hybrid materials as the matrix to improve mechanical strength and stability. (2) Granulation process optimization: Control the particle size and shape through methods such as spray drying, extrusion granulation or spheronization granulation, while enhancing the bonding force between particles. (3) Application of binders: Use environmentally friendly or functional binders to increase the adhesion between particles while maintaining or improving adsorption performance. (4) Surface modification and post-treatment: Surface modification or heat treatment of particles to improve structural stability and durability. (5) Composite structure design: Construct a core-shell structure or layered composite material to ensure mechanical strength without affecting the adsorption performance of lithium ions.

[0007] Granulated adsorbents in the prior art generally have the following disadvantages: (1) Fragility: Due to insufficient mechanical strength, these adsorbent particles are easily broken during handling, transportation or use. This not only increases losses, but may also lead to an increase in fine powder, affecting the operating environment and adsorption performance. (2) Short service life: Lower mechanical strength means that the adsorbent is more easily damaged, resulting in an increase in the frequency of its replacement, thereby increasing operating costs and maintenance workload. (3) Large fluid resistance: When the adsorbent particles are broken into smaller particles, the fluid resistance of the bed will increase, affecting the air flow or liquid flow rate through the adsorbent bed and reducing the treatment efficiency. (4) Difficult regeneration: The structural integrity of some adsorbents may be affected after multiple adsorption-desorption cycles, especially if they have poor mechanical strength, which may hinder the effectiveness of their regeneration process.

[0008] Chinese invention patent CN 115845825 B provides a method for preparing a lithium adsorbent, wherein the binder is composed of polyvinyl chloride, polyurethane and chlorinated polyvinyl chloride in a weight ratio of 60-80:10-20:10-20.

[0009] Chinese invention patent application CN 109225124 A provides a method for preparing a granular lithium adsorbent, wherein the multiple polymers are at least one of polyvinylidene fluoride, polyethylene, polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, polystyrene, polyvinylidene fluoride, polyvinylidene chloride, ABS resin, polyamide, polyformaldehyde, polycarbonate, polyether ketone, polyether sulfone, polyphenylene ether, polyurethane, polyvinyl butyral, polyvinyl pyrrolidone, polyacrylic acid, polymethyl methacrylate, polyethylene glycol, polyvinyl alcohol, and polyethylene terephthalate.

[0010] Chinese invention patent application CN 119215870 A discloses a lithium adsorbent particle and a preparation method and application thereof. The polymer binder is selected from one or more of polysulfone, polyvinylidene fluoride, polyvinyl chloride, chlorinated polyvinyl chloride, cellulose acetate, carboxymethyl cellulose and chitosan.

[0011] The products of the above three are not strong in comprehensive performance in terms of compression and wear resistance. Summary of the invention

[0012] In view of the above shortcomings, the objectives of the present invention include: (1) Improving mechanical strength: improving the granulation process or material composition to enhance the mechanical strength of the adsorbent particles so that they can better withstand the physical stress during handling and use. (2) Prolonging the service life: by improving the durability of the adsorbent, reducing the need for frequent replacement and reducing long-term operating costs. (3) Optimizing fluid mechanics: ensuring that the adsorbent particles maintain a suitable size distribution to maintain low fluid resistance and efficient mass transfer performance. (4) Promoting regeneration ability: designing or selecting adsorbent materials that can withstand repeated adsorption-desorption cycles without significant loss of structural integrity. (5) Stable performance: ensuring that the adsorbent provides consistent selectivity and adsorption capacity throughout its service life.

[0013] In order to solve the above problems and achieve the purpose of the invention, the present invention provides a method for preparing a high-strength lithium adsorbent, the steps of which include:

[0014] Dissolving a polymer binder and a porogen in a heated organic solvent; the polymer binder is composed of a polymer containing an aromatic ring structure and a polymer containing a long-chain branched structure;

[0015] After the mixture is dissolved, a powdered adsorbent is added and mixed to obtain a granulation emulsion;

[0016] The granulated emulsion is placed in a pressure autoclave for defoaming treatment, and then subjected to spinning extrusion to obtain initial fiber;

[0017] The initial fibers are placed in a hot water bath for soaking, and then granulated, sieved and washed to obtain the lithium adsorbent.

[0018] Furthermore, the mass ratio of the polymer containing an aromatic ring structure to the polymer containing a long-chain branched structure is 4:1 to 6:1.

[0019] Furthermore, the polymer containing an aromatic ring structure is one or more of polyethylene terephthalate, polycarbonate, polyimide, polyetheretherketone, polyarylate, polystyrene, polyurethane, polyphenylene sulfide, and polysulfone.

[0020] Furthermore, the polymer containing a long-chain branched structure is one or more of branched polyethylene, branched polypropylene, branched polybutene-1, branched polyester, and branched polycarbonate.

[0021] Furthermore, the mass of the porogen is 30% to 32% of the mass of the polymer binder; the mass of the powder adsorbent is 186% to 900% of the mass of the polymer binder; and the mass of the organic solvent is 600% to 800% of the mass of the polymer binder.

[0022] Furthermore, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the porogen is one or more of water-soluble inorganic salts such as urea, polyvinylpyrrolidone, sodium chloride, potassium chloride, magnesium chloride, etc.

[0023] Furthermore, the heating temperature is 45° C. to 80° C.; and the defoaming treatment time is 20 to 30 minutes.

[0024] Furthermore, the granulation method is wet spinning granulation, pellet granulation or extrusion granulation.

[0025] Furthermore, the temperature of the hot water bath is 30° C. to 50° C.; and the soaking time is 1 to 2 hours.

[0026] The invention also provides a high-strength lithium adsorbent having a large number of micropores and prepared by the above method.

[0027] The beneficial effects of the present invention are as follows:

[0028] The binder used in the lithium adsorbent of the present invention includes a polymer containing an aromatic ring and a polymer containing a long-chain branched structure. The aromatic ring itself has rigidity, and this rigid structure makes the polymer molecular chain arranged more closely and orderly in space. This close arrangement helps to improve the mechanical strength and modulus of the polymer. The π-π stacking effect between the aromatic rings is a strong intermolecular force. This force can enhance the interaction between the polymer molecular chains, thereby improving the mechanical compressive resistance of the polymer. The long-chain branched structure can significantly increase the entanglement points between the molecular chains. These entanglement points can effectively disperse stress and prevent stress concentration when the material is subjected to external force, thereby improving the toughness and impact resistance of the material. The long-chain branched structure can be used as a nucleating agent to accelerate nucleation, but at the same time it will hinder the growth of crystals, and ultimately lead to a reduction in the size of spherulites. Smaller spherulite size can improve the toughness of the material, because small spherulites are more likely to undergo plastic deformation rather than brittle fracture when subjected to external force. This makes the adsorbent have excellent compression and wear resistance. While ensuring high mechanical strength, a large number of micropores are retained by using a porogen, so the adsorption capacity is still high.

[0029] Polymers containing aromatic ring structures have excellent rigidity and thermal stability due to their unique chemical structure. By introducing long-chain branched structures, not only the mechanical strength is improved, but also other properties such as heat resistance, chemical stability and processing performance are improved. Heat treatment in a water bath can slow down the phase inversion rate, thereby improving the internal structure of the polymer and making the polymer chain arrangement more orderly, thereby enhancing rigidity.

[0030] Based on the above description, the present invention can solve the problem that traditional lithium adsorbents are easy to become hardened and lose powder during the adsorption and extraction of lithium, and significantly improve the dissolution and wear problems of traditional granulated lithium adsorbents during operation, so that the product has an excellent high cycle life, stability and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of an embodiment of the present invention.

[0032] Figure 2 This is a SEM image of a finished high-strength lithium adsorbent according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. Figure 1 shown.

[0034] Example 1.

[0035] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat it to 65°C. Weigh 0.6 kg of polycarbonate, 0.12 kg of branched polyethylene, and 0.23 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0036] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0037] (3) Soak the as-spun fibers in a hot water bath at 40°C for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and porogen, and finally a high-strength lithium adsorbent product is obtained, the SEM image of which is shown in FIG. Figure 2 shown.

[0038] Test Item 1. Long-term flushing test of the product obtained in Example 1

[0039] The adsorbent was filled into the chromatographic column, and the pH of the raw brine was adjusted to 4.5. The raw brine was circulated by a peristaltic pump in a top-in and bottom-out manner. The flow rate was 20 BV / h. The experimental results showed that the dissolution loss rate was ≤0.04% / 1,000 cycles, indicating that the adsorbent had good anti-dissolution performance.

[0040] Test Item 2. Mechanical Strength Test of the Product Prepared in Example 1

[0041] The adsorbent was filled into a chromatographic column and immersed in brine, and then a pressure of 0.5 MPa was applied. After running continuously for 30*24 hours, the adsorbent did not deform or become hardened or adhered, indicating that the adsorbent has good pressure resistance.

[0042] Test Item 3. Test on the Abrasion Roundness of the Product Prepared in Example 1

[0043] This test is based on the current national standard GB / T 12598-2023.

[0044] (1) Sample sieving: 100 mL of the adsorbent prepared in Example 1 was sieved. The aperture of the test sieve used was equal to the upper and lower limits of the required particle size range (10-30 mesh).

[0045] (2) Rolling: Measure 40g of the adsorbent obtained in step (1), transfer all the adsorbent in the measuring cylinder to the drum with 50mL of the original halogen / electrodialysis tail liquid, add 10 porcelain balls, and tighten the drum cover. Install the drum on the ball mill and roll for 40min±2s. Remove the drum, open the cover, transfer all the adsorbent to the test sieve cloth, shake off the water, flatten it, and dry it at 60℃ for 2.5 hours so that the particles can roll freely.

[0046] (3) Separation and weighing: Use a 16-mesh standard sieve to separate the adsorbent into intact particles and broken particles. Place the intact particles and broken particles in weighing bottles and weigh them on an analytical balance. Record the mass of the intact particles and broken particles.

[0047] (4) The experimental results show that the ball rate of the adsorbent prepared in Example 1 is ≥95%. This means that after the abrasion test, at least 95% of the resin particles of the adsorbent can maintain their original shape. Such characteristics enable it to operate stably in practical applications.

[0048] Example 2.

[0049] (1) Weigh 4.5 kg of N-methylpyrrolidone and heat it to 45°C. Weigh 0.6 kg of polyethylene terephthalate, 0.15 kg of branched polypropylene, and 0.225 kg of polyvinylpyrrolidone K30 and dissolve them in N-methylpyrrolidone. After they are completely dissolved, add 1.39 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0050] (2) The granulated emulsion is transferred to an autoclave and subjected to a defoaming treatment for 20 minutes, followed by a spinning extrusion operation to obtain spun fibers.

[0051] (3) Soaking the as-spun fibers in a hot water bath at 30° C. for 1 hour. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0052] Example 3.

[0053] (1) Weigh 4.2 kg of dimethyl sulfoxide and heat it to 80°C. Weigh 0.6 kg of polyetheretherketone, 0.1 kg of branched polycarbonate, and 0.245 kg of sodium chloride and dissolve them in dimethyl sulfoxide. After they are completely dissolved, add 5.4 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0054] (2) The granulated emulsion was transferred to an autoclave for defoaming for 30 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0055] (3) Soaking the as-spun fibers in a hot water bath at 50° C. for 2 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0056] Example 4.

[0057] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat it to 65°C. Weigh 0.6 kg of polycarbonate, 0.12 kg of polysulfone, and 0.23 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0058] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0059] (3) Soaking the as-spun fibers in a hot water bath at 40° C. for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0060] Example 5.

[0061] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat it to 65°C. Weigh 0.6 kg of branched polyethylene, 0.12 kg of branched polycarbonate, and 0.23 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0062] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0063] (3) Soaking the as-spun fibers in a hot water bath at 40° C. for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0064] Comparative Example 1.

[0065] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat it to 65°C. Weigh 0.6 kg of polypyrrole, 0.12 kg of branched polyethylene, and 0.23 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0066] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0067] (3) Soaking the as-spun fibers in a hot water bath at 40° C. for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0068] Comparative Example 2.

[0069] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat it to 65°C. Weigh 0.6 kg of polycarbonate, 0.12 kg of branched polyethylene, and 0.365 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0070] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0071] (3) Soaking the as-spun fibers in a hot water bath at 40° C. for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0072] Comparative Example 3.

[0073] (1) Weigh 5.04 kg of N,N-dimethylacetamide and heat to 65°C. Weigh 0.6 kg of polycarbonate, 0.12 kg of branched polyethylene, and 0.23 kg of polyethylene glycol and dissolve them in N,N-dimethylacetamide. After the mixture is completely dissolved, add 2.88 kg of powdered adsorbent and mix thoroughly to obtain a granulation emulsion.

[0074] (2) The granulated emulsion was transferred to an autoclave for defoaming for 25 minutes, and then subjected to spinning extrusion operation to obtain primary fibers.

[0075] (3) Soaking the as-spun fibers in a hot water bath at 80° C. for 1.5 hours. Then, the soaked as-spun fibers are pelletized, sieved, and washed in sequence to remove the solvent and the porogen, and finally a high-strength lithium adsorbent product is obtained.

[0076] The thousand-cycle dissolution loss rate and lithium adsorption capacity of the samples of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0077] Table 1

[0078]

Claims

1. A method for preparing a high-strength lithium adsorbent, comprising the steps of: Dissolving a polymer binder and a porogen in a heated organic solvent; the polymer binder is composed of a polymer containing an aromatic ring structure and a polymer containing a long-chain branched structure; After being dissolved, a powdered adsorbent is added and mixed to obtain a granulation emulsion; The granulated emulsion is placed in a pressure autoclave for defoaming treatment, and then subjected to spinning extrusion to obtain initial fibers; The initial fibers are placed in a hot water bath for soaking, and then granulated, sieved and washed to obtain the lithium adsorbent.

2. The method according to claim 1, characterized in that The mass ratio of the polymer containing an aromatic ring structure to the polymer containing a long-chain branched structure is 4:1 to 6:

1.

3. The method according to claim 2, characterized in that The polymer containing an aromatic ring structure is one or more of polyethylene terephthalate, polycarbonate, polyimide, polyetheretherketone, polyarylate, polystyrene, polyurethane, polyphenylene sulfide, and polysulfone.

4. The method according to claim 2, characterized in that: The polymer containing a long-chain branched structure is one or more of branched polyethylene, branched polypropylene, branched polybutene-1, branched polyester, and branched polycarbonate.

5. The method according to claim 1, characterized in that The mass of the porogen is 30% to 32% of the mass of the polymer binder; the mass of the powder adsorbent is 186% to 900% of the mass of the polymer binder; and the mass of the organic solvent is 600% to 800% of the mass of the polymer binder.

6. The method according to claim 1, characterized in that The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide; the porogen is one or more of urea, polyvinylpyrrolidone, sodium chloride, potassium chloride, magnesium chloride and other water-soluble inorganic salts.

7. The method according to claim 1, characterized in that The heating temperature is 45° C. to 80° C.; the defoaming treatment time is 20 to 30 minutes.

8. The method according to claim 1, characterized in that The granulation method is wet spinning granulation, pellet granulation or extrusion granulation.

9. The method according to claim 1, characterized in that: The temperature of the hot water bath is 30° C. to 50° C.; the soaking time is 1 to 2 hours.

10. A high-strength lithium adsorbent having a large number of micropores, prepared by any method of claims 1-9.

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