An electrically driven method for forming lithium extraction adsorbent particles from salt lakes

Abstract

This invention discloses an electrically driven method for forming lithium extraction adsorbent particles from salt lakes, comprising the following steps: (1) preparing raw materials: main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent, and organic solvent; (2) mixing raw materials: mixing the raw materials in sequence to obtain a slurry; (3) extrusion molding: extruding the slurry through a porous mold panel; (4) curing molding: curing the slurry through a non-solvent-induced phase conversion method; (5) cutting into granules. Using the method provided in this invention, a high-strength granular lithium extraction adsorbent from salt lakes can be obtained, and this adsorbent has ideal porosity and adsorption performance, low cost, and good adsorption effect.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology. Specifically, it relates to an electrically driven method for forming lithium extraction adsorbent particles from salt lakes. Background Technology

[0002] Against the backdrop of global dual-carbon policies, new energy materials are developing rapidly, and new energy batteries, as an important member of the new energy family, are increasingly in demand in our lives and production. Lithium, as the lightest metal element in nature with the lowest standard electrode potential and the largest electrochemical equivalent, is an ideal "battery metal." Therefore, it will have long-term rigid demand in power and energy storage applications that require high specific energy, and is known as the "white oil of the future."

[0003] Currently, lithium resources are mainly obtained from salt lakes. Electrolytic deintercalation is one of the main methods for lithium extraction from salt lakes. It usually requires coating the current collector with a lithium extraction adsorbent. After a period of use, the lithium extraction adsorbent on the current collector may fall off or become ineffective. At this time, the entire current collector needs to be recoated, which is quite troublesome. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide an electrically driven method for forming lithium extraction adsorbent particles from salt lakes. Using this method, a high-strength granular lithium extraction adsorbent from salt lakes can be obtained, and the adsorbent has ideal porosity and adsorption performance, low cost, and good adsorption effect.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for electrically driven lithium extraction adsorbent particle forming in salt lakes includes the following steps:

[0007] (1) Prepare raw materials: main material, ultra-high molecular weight adhesive, conductive agent, pore-forming agent, hydrophilic agent and organic solvent;

[0008] (2) Mixing raw materials: Mix the raw materials in sequence to obtain a slurry;

[0009] (3) Extrusion molding: The slurry is extruded through a porous mold panel to form a mold;

[0010] (4) Curing and molding: Curing and molding is carried out by a non-solvent phase inversion method;

[0011] (5) Cut into granules.

[0012] In the above-mentioned electrically driven method for forming lithium extraction adsorbent particles from salt lakes, in step (1), the mass ratio of the main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent, and organic solvent is (30-50):(2.5-10):(2.5-10):(2.5-10):(5-20):(20-60). The mass ratio of the main material in the raw materials directly affects the lithium extraction capacity of the adsorbent, the mass ratio of the conductive agent directly affects the conductivity of the lithium extraction adsorbent, and the proportion of ultra-high molecular weight binder, pore-forming agent, hydrophilic agent, and organic solvent affects the strength and surface properties of the adsorbent, and indirectly affects its adsorption performance. When the above-mentioned raw materials are within this ratio range, the lithium extraction capacity, conductivity, strength, and porosity of the lithium extraction adsorbent can achieve a good balance, effectively exerting its physical and chemical adsorption properties. When the mass ratio of the main material is too high, although the lithium extraction capacity will increase, the mechanical strength of the adsorbent will decrease, making it prone to disintegration in salt lake brine. Increasing the proportion of ultra-high molecular weight binder is beneficial to improving the strength of the lithium extraction adsorbent, but it may cause a decrease in porosity, reducing the specific surface area of ​​the adsorbent. Increasing the amount of pore-forming agent can increase the specific surface area of ​​the adsorbent, but it will cause a decrease in the mechanical strength of the adsorbent, which is not conducive to achieving a balance between mechanical strength and adsorption effect.

[0013] In the above-mentioned electrically driven method for forming lithium extraction adsorbent particles from salt lakes, in step (1), the mass ratio of the main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent, and organic solvent is 50:5:5:5:5:30. When the components in the raw materials are in this mass ratio, the adsorbent has high strength, good conductivity, and high adsorption capacity.

[0014] In the above-mentioned electrically driven method for forming lithium adsorbent particles from salt lakes, in step (1): the main material is lithium iron phosphate; the ultra-high molecular weight binder is sulfonated polyether sulfone, the degree of sulfonation of sulfonated polyether sulfone is 5% to 10%, and the average relative molecular mass is 12,000 to 14,000; the conductive agent is conductive carbon black, the pore-forming agent is lithium chloride, the hydrophilic agent is polyvinyl alcohol, and the organic solvent is N,N-dimethylacetamide.

[0015] In the above-mentioned electrically driven lithium extraction adsorbent particle forming method from salt lakes, the raw materials are mixed in the following order in step (2): a hydrophilic agent, an ultra-high molecular weight binder, a conductive agent, a main material, and a pore-forming agent are added sequentially to the organic solvent. This order of adding raw materials can effectively reduce the viscosity of the slurry, improve the uniformity of the slurry, and facilitate the formation of uniform and continuous strips when the slurry is extruded.

[0016] In the above-mentioned electrically driven method for forming lithium adsorbent granules from salt lakes, in step (3): the equipment used for extrusion granulation includes a porous mold panel, a material cylinder, a sealing cover plate, a drive shaft, and a motor. One end of the drive shaft is driven and connected to the motor, and the other end extends from the first end of the material cylinder into the material cylinder and is connected to the sealing cover plate inside the material cylinder. The porous mold panel is detachably connected to the second end of the material cylinder. The slurry is located in the material cylinder between the sealing cover plate and the porous mold panel. The motor drives the drive shaft to drive the sealing cover plate to reciprocate linearly in the material cylinder, thereby extruding the slurry between the sealing cover plate and the porous mold panel from the holes on the porous mold panel to the outside of the material cylinder.

[0017] In the above-mentioned electrically driven method for forming lithium adsorbent particles from salt lakes, the porous mold panel is a circular plastic plate or a circular stainless steel plate, and the material cylinder is a cylinder; the holes on the porous mold panel are in the form of a dot matrix mesh.

[0018] In the aforementioned electrically driven method for forming lithium-extraction adsorbent particles from salt lakes, the holes on the porous mold panel are round, square, or rectangular; the diameter of the round holes is 1–2 mm; the size of the rectangular holes is 1 mm × 2 mm; the side length of the square holes is 1–2 mm; and the forward speed of the drive shaft is 5 cm / min–50 cm / min. When the diameter of the holes on the porous mold panel 1 is within the above range, the obtained adsorbent is finer, and the internal salt is more easily dissolved to form pores, resulting in higher porosity. The forward speed of the drive shaft is equal to the extrusion rate of the slurry. When the extrusion rate of the slurry is within this range, it is easier to obtain continuous elongated materials, reducing waste. At the same time, the obtained adsorbent particles are more uniform, with higher adsorption capacity and strength.

[0019] In the above-mentioned electrically driven method for forming lithium adsorbent particles from salt lakes, during the extrusion of slurry in step (3), the slurry is controlled to be extruded at a uniform speed through the porous mold panel; in step (4), the long strip material extruded in step (3) is immersed in pure water or a solution with a volume ratio of ethanol to water of 2:8 at a temperature of 20-40℃ until it solidifies and forms a shape, and then the solidified long strip material is soaked in pure water for 12-24 hours to desalinate and form pores, and finally dried at a temperature of 40-90℃ for 8-12 hours, and cut into granules with a length of 0.5-1.5 mm to obtain the adsorbent.

[0020] In the above-mentioned electrically driven method for forming lithium extraction adsorbent particles from salt lakes, in step (4), the elongated material extruded in step (3) is immersed in pure water at a temperature of 20°C until it solidifies and forms a particle. Then, the solidified elongated material is soaked in pure water for 24 hours to desalinate and form pores. After desalination and pore formation, it is first dried at 40°C for 4 hours, and then dried at 90°C for 4 hours. It is then cut into granules with a length of 1.5 mm to obtain the adsorbent. Pure water and N,N-dimethylacetamide, which is used as a solvent, have a large polarization difference. Using pure water for solidification is beneficial to improving the strength of the adsorbent. The heat treatment procedure of first low temperature and then high temperature allows the adsorbent to solidify slowly at a lower temperature, which is less likely to produce large pores. Then, it is completely solidified at a higher temperature, which is beneficial to ensure the uniformity of the size and internal structure of the adsorbent.

[0021] The technical solution of the present invention achieves the following beneficial technical effects:

[0022] 1. This invention provides a lithium extraction adsorbent from salt lakes by precisely proportioning the mass ratio of the main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent, and organic solvent, and by using extrusion molding and a non-solvent-induced phase inversion method for curing at 20–40°C. Compared with traditional adsorbents, the adsorbent prepared by the method of this invention has suitable particle size, porosity, and strength, making it particularly suitable for electrochemical adsorption of lithium, and it does not require coating on a current collector. When using the adsorbent provided by this invention for lithium extraction, there is no need to use large amounts of pure water or acids / alkalis for desorption; the efficiency of lithium ion adsorption is high, effectively saving materials and energy, and making it more environmentally friendly.

[0023] 2. In the preparation of the lithium extraction adsorbent from salt lakes in this invention, polyvinyl alcohol is first added to N,N-dimethylacetamide to prepare a hydrophilic agent solution. The hydrophilic agent accelerates the dissolution of sulfonated polyethersulfone. Then, conductive carbon black, lithium iron phosphate, and lithium chloride are added sequentially, which reduces the viscosity of the slurry, making it easier to stir evenly. This ensures that the slurry viscosity is suitable for an extrusion rate of 20 cm / min and a 1 mm circular hole on the die panel. During extrusion, it forms a thin, elongated cylindrical shape that is less prone to breakage. The salt in the thin, elongated slurry dissolves more easily to form pores, resulting in an adsorbent with appropriate pore structure and surface properties. The adsorbent also has less residual salt content. This increases the lithium adsorption capacity while preventing the adsorbent from dissolving a large amount of salt during the lithium extraction process, which would cause adsorbent disintegration and loss of conductivity and lithium extraction performance. The cylindrical adsorbent has fewer defects and therefore higher strength. In the curing and molding step, pure water with a polarity significantly different from N,N-dimethylacetamide is used as a coagulation bath for the slurry, which accelerates the phase transformation process. This further improves the structural compactness and strength of the adsorbent. The heat treatment procedure of first holding at 40℃ for 4 hours and then at 90℃ for 4 hours allows the adsorbent to solidify slowly first, making it less likely to produce large pores. Then, thorough drying and solidification can ensure the uniformity of adsorbent size and strength, and protect the fine and uniform pore structure formed in the dissolution and pore-forming step, preventing pore agglomeration and bridging. This allows the resistance of the adsorbent to be maintained within the normal range, preventing excessive electron flow resistance in the adsorbent during electro-deintercalation and lithium extraction, which would lead to a decrease in lithium extraction efficiency.

[0024] 3. The adsorbent particle forming method provided in this invention innovatively employs a porous die panel and a motor-driven reciprocating linear motion extrusion forming device, achieving uniform extrusion and continuous production of the slurry. The design of the porous die panel allows the slurry to form uniform and regular particle shapes through its holes, improving the consistency and quality stability of the adsorbent particles. Furthermore, by controlling the forward speed of the drive shaft, the uniformity and continuity of the extruded elongated material can be ensured, thereby optimizing the structure and appearance morphology of the adsorbent particles. This innovative equipment and method not only improves production efficiency but also reduces production costs. Moreover, the adsorbent particle forming method provided in this invention is simple, convenient, has low requirements, and is easy to industrialize, providing new ideas for the preparation of other adsorbents. Attached Figure Description

[0025] Figure 1 A photograph of the adsorbent after molding in this invention;

[0026] Figure 2 A photograph of the finished product after the adsorbent is molded and cut in this invention;

[0027] Figure 3 A schematic diagram of the structure of the porous mold panel in this invention;

[0028] Figure 4 A schematic diagram of the extrusion granulation equipment in this invention.

[0029] The reference numerals in the figure are: 1-perforated mold panel; 2-sealing cover plate; 3-drive shaft; 4-motor. Detailed Implementation

[0030] Example 1

[0031] Polyvinyl alcohol, sulfonated polyethersulfone, conductive carbon black, lithium iron phosphate, and lithium chloride were sequentially added to N,N-dimethylacetamide and mixed thoroughly by mechanical stirring to obtain a slurry. The mass ratio of polyvinyl alcohol, sulfonated polyethersulfone, conductive carbon black, lithium iron phosphate, lithium chloride, and N,N-dimethylacetamide used was 5:5:5:50:5:30. The degree of sulfonation of the sulfonated polyethersulfone used was 9%, and the average relative molecular mass was 13,000.

[0032] The fineness of the slurry, measured by a scraper fineness gauge, is 40 μm, indicating that the raw materials in the slurry are uniformly dispersed. Uniform dispersion of raw materials in the slurry helps prevent the agglomeration of raw material particles during slurry mixing.

[0033] The slurry obtained in this embodiment is filled into, as shown in... Figure 4 In the material cylinder of the extrusion granulation equipment shown, the drive shaft 3 is set to advance at a speed of 20 cm / min, causing the slurry to be uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous mold panel 1. Figure 3 As shown, the porous mold panel 1 has circular holes arranged in a dot matrix pattern. The slurry is extruded through the 1mm diameter circular holes on the porous mold panel 1, forming a long strip shape. The extruded strip is then immersed in pure water at 20℃ until it solidifies and takes its final shape (e.g., ...). Figure 1 (As shown), it was then soaked in pure water for 24 hours for desalination and pore formation, and finally dried at 90°C for 8 hours and cut into 1.5 mm long particles to obtain the adsorbent. The adsorbent prepared in this embodiment is as follows: Figure 2 As shown.

[0034] In the adsorbent preparation process of this embodiment, the slurry is not easily broken during extrusion and can be continuously extruded into cylindrical strips. After measurement and testing, the adsorbent prepared in this embodiment has a diameter range of 1.1-1.2 mm, a tensile strength of 3.25 MPa, a porosity of 48%, an electrical conductivity of 0.15 Ωm, and a lithium adsorption capacity of 20.6 mg / g.

[0035] Comparative Example 1

[0036] Sulfonated polyethersulfone, lithium iron phosphate, conductive carbon black, lithium chloride, and polyvinyl alcohol were sequentially added to N,N-dimethylacetamide and mixed thoroughly by mechanical stirring to obtain a slurry. The mass ratio of sulfonated polyethersulfone, lithium iron phosphate, conductive carbon black, lithium chloride, polyvinyl alcohol, and N,N-dimethylacetamide used was 5:50:5:5:5:30. The slurry fineness measured by a scraper fineness meter was 90 μm, indicating that the slurry was not uniform.

[0037] The slurry obtained in this comparative example was loaded into the material cylinder of an extrusion granulation equipment. The forward speed of the drive shaft 3 was set to 20 cm / min, and the slurry was uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous die panel 1. After being extruded through the 1 mm diameter circular holes on the porous die panel 1, the slurry was shaped into elongated strips. The extruded elongated material was immersed in 20°C pure water until it solidified and formed. Then, it was soaked in pure water for 24 hours to desalinate and form pores. Finally, it was dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0038] In the preparation process of the adsorbent in this comparative example, the slurry extrusion process is prone to breakage and it is difficult to continuously extrude into strips with an average length of 20cm.

[0039] Example 2

[0040] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 5 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with the stainless steel porous mold panel 1. After being extruded through the 1 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0041] The adsorbent prepared in this embodiment has a diameter range of 1.2–1.3 mm, a tensile strength of 2.45 MPa, a porosity of 53%, an electrical conductivity of 0.24 Ωm, and a lithium adsorption capacity of 15.2 mg / g.

[0042] Example 3

[0043] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 50 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous mold panel 1. After being extruded through the 1 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0044] In this embodiment, the slurry extrusion process is relatively fast, and the extruded long strips of material are relatively easy to break. The adsorbent obtained in this embodiment has a diameter range of 1.05-1.1 mm, a tensile strength of 3.10 MPa, a porosity of 40%, an electrical conductivity of 0.14 Ωm, and a lithium adsorption capacity of 19.5 mg / g.

[0045] Example 4

[0046] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with the stainless steel porous mold panel 1. After being extruded through the 2 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into a long strip. The extruded strip is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0047] The adsorbent prepared in this embodiment has a diameter range of 2.15–2.30 mm, a tensile strength of 3.52 MPa, a porosity of 42%, an electrical conductivity of 0.13 Ωm, and a lithium adsorption capacity of 18.2 mg / g.

[0048] Example 5

[0049] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous mold panel 1. After being extruded through the 2 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is immersed in 40°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0050] The adsorbent prepared in this embodiment has a diameter range of 2.10–2.20 mm, a tensile strength of 3.10 MPa, a porosity of 45%, an electrical conductivity of 0.15 Ωm, and a lithium adsorption capacity of 18.8 mg / g.

[0051] Example 6

[0052] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous mold panel 1. After being extruded through the 2 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is placed in a 20°C ethanol aqueous solution (water to ethanol volume ratio 8:2) until it solidifies and forms a shape. Then, it is soaked in pure water for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0053] The adsorbent prepared in this embodiment has a diameter range of 2.10–2.20 mm, a tensile strength of 2.85 MPa, a porosity of 49%, an electrical conductivity of 0.21 Ωm, and a lithium adsorption capacity of 16.2 mg / g.

[0054] Example 7

[0055] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is extruded uniformly from one end of the extrusion granulation equipment equipped with the PVC plastic porous mold panel 1. After being extruded through the 1 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0056] The adsorbent prepared in this embodiment has a diameter range of 1.10–1.20 mm, a tensile breaking strength of 3.10 MPa, a porosity of 50%, an electrical conductivity of 0.14 Ωm, and a lithium adsorption capacity of 20.1 mg / g.

[0057] Example 8

[0058] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with the stainless steel porous mold panel 1. After being extruded through the 1 mm × 2 mm rectangular holes on the porous mold panel 1, the slurry is shaped into a long strip. The extruded long strip is immersed in pure water at 20°C until it solidifies and takes shape. Then it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 1.5 mm long granules to obtain the adsorbent.

[0059] The adsorbent prepared in this embodiment is an elliptical shape with a major diameter of 2.5 mm and a minor diameter of 1.1 mm. It has a tensile strength of 2.15 MPa, a porosity of 53%, an electrical conductivity of 0.19 Ωm, and a lithium adsorption capacity of 18.8 mg / g.

[0060] Example 9

[0061] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with the stainless steel porous mold panel 1. After being extruded through the 1 mm circular holes on the porous mold panel 1, the slurry is shaped into a long strip. The extruded long strip is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried first at 40°C for 4 hours, then at 90°C for 4 hours, and cut into 1.5 mm long granules to obtain the adsorbent.

[0062] The adsorbent prepared in this embodiment has a diameter range of 1.1 to 1.15 mm, a tensile strength of 3.55 MPa, a porosity of 48%, an electrical conductivity of 0.12 Ωm, and a lithium adsorption capacity of 22.3 mg / g.

[0063] Example 10

[0064] The slurry used in this embodiment is the same as in Embodiment 1. The slurry is loaded into the material cylinder of the extrusion granulation equipment. The forward speed of the drive shaft 3 is set to 20 cm / min, and the slurry is uniformly extruded from one end of the extrusion granulation equipment equipped with a stainless steel porous mold panel 1. After being extruded through the 1 mm diameter circular holes on the porous mold panel 1, the slurry is shaped into elongated strips. The extruded elongated material is immersed in 20°C pure water until it solidifies and takes shape. Then, it is soaked for 24 hours for desalination and pore formation. Finally, it is dried at 90°C for 8 hours and cut into 0.5 mm long granules to obtain the adsorbent.

[0065] In this embodiment, the adsorbent has a diameter range of 1.1–1.2 mm, a tensile strength of 3.25 MPa, a porosity of 48%, an electrical conductivity of 0.19 Ωm, and a lithium adsorption capacity of 19.6 mg / g.

[0066] Table 1 shows the various indicators of the adsorbents prepared in the above examples.

[0067] Table 1:

[0068]

[0069] Comparing Example 1 and Comparative Example 1, it can be seen that adding polyvinyl alcohol, sulfonated polyethersulfone, conductive carbon black, lithium iron phosphate and lithium chloride in the order of addition to N,N-dimethylacetamide can effectively reduce the viscosity of the slurry during stirring, thereby improving the uniformity of the slurry.

[0070] Comparing Examples 1, 2, and 3, it can be seen that an extrusion rate of 20 cm / min is more suitable for the extrusion granulation equipment. This rate can ensure the extrusion of continuous long strips of material, and the final adsorbent has a high lithium adsorption capacity and strength.

[0071] Comparing Examples 1 and 4, it can be seen that when the holes on the porous mold panel 1 are 1mm round holes, the obtained adsorbent is finer, and the internal salt is more easily dissolved to form pores, resulting in higher porosity. Comparing Examples 1 and 8, it can be seen that compared with the elliptical adsorbent particles obtained in Example 8, the cylindrical adsorbent obtained in Example 1 has fewer defects and higher strength.

[0072] Comparing Examples 1 and 6, it is evident that using pure water in a coagulation bath accelerates the phase transformation process, resulting in a denser and stronger adsorbent structure. This is because pure water and N,N-dimethylacetamide, the solvent, exhibit significant polarization differences. Although the adsorbent exhibits high porosity in an ethanol-water solution (ethanol to water volume ratio of 2:8) coagulation bath system, its strength is low, potentially leading to relatively poor performance in actual production applications.

[0073] Comparing Examples 1 and 9, it is evident that after soaking, desalting, and pore-forming, a drying process involving first maintaining the temperature at 40°C for 4 hours and then at 90°C for 4 hours is beneficial for obtaining an adsorbent with high strength, high conductivity, and high lithium extraction capacity. This is because the heat treatment process, starting with a low temperature and then increasing the temperature, allows the adsorbent to solidify slowly at a lower temperature, reducing the likelihood of large pores, and then fully solidify at a higher temperature, which helps ensure the uniformity of the adsorbent's size.

[0074] Comparing Example 1 and Example 10, it can be seen that cutting the adsorbent into 1.5 mm long particles is more conducive to improving the lithium adsorption capacity of the adsorbent.

[0075] A comprehensive comparison shows that the method in Example 9 is a relatively ideal method for forming lithium-extraction adsorbent particles.

[0076] 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 the claims of this patent application.

Claims

1. A method for electrically driven lithium extraction adsorbent particle forming in salt lakes, characterized in that, Includes the following steps: (1) Preparation of raw materials: main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent and organic solvent; the mass ratio of main material, ultra-high molecular weight binder, conductive agent, pore-forming agent, hydrophilic agent and organic solvent is (30~50):(2.5~10):(2.5~10):(2.5~10):(5~20):(20~60); the main material is lithium iron phosphate; the ultra-high molecular weight binder is sulfonated polyether sulfone, the degree of sulfonation of sulfonated polyether sulfone is 5%~10%, and the average relative molecular mass is 12000~14000; the conductive agent is conductive carbon black, the pore-forming agent is lithium chloride, the hydrophilic agent is polyvinyl alcohol, and the organic solvent is N,N-dimethylacetamide; (2) Mixing raw materials: Mix the raw materials in sequence to obtain a slurry; the order of mixing the raw materials is as follows: add hydrophilic agent, ultra-high molecular weight binder, conductive agent, main material and pore-forming agent to the organic solvent in sequence; (3) Extrusion molding: The slurry is extruded through the porous mold panel (1) to form a mold; (4) Curing and molding: Curing and molding is carried out by a non-solvent phase inversion method; (5) Cut into granules; In step (3), the slurry is extruded at a uniform speed through the porous mold panel (1). In step (4), the long strip material extruded in step (3) is immersed in pure water or a solution with a volume ratio of ethanol to water of 2:8 at a temperature of 20-40°C until it solidifies and forms a shape. Then, the solidified long strip material is soaked in pure water for 12-24 hours to desalinate and form pores. Finally, it is dried at a temperature of 40-90°C for 8-12 hours and cut into granules with a length of 0.5-1.5 mm to obtain the adsorbent.

2. The electrically driven method for forming lithium extraction adsorbent particles from salt lakes according to claim 1, characterized in that, In step (1): the mass ratio of the main material, ultra-high molecular weight adhesive, conductive agent, pore-forming agent, hydrophilic agent and organic solvent is 50:5:5:5:5:

30.

3. The electrically driven method for forming lithium extraction adsorbent particles from salt lakes according to claim 1, characterized in that, In step (3): the equipment used for extrusion granulation includes a perforated die panel (1), a material cylinder, a sealing cover plate (2), a drive shaft (3) and a motor (4). One end of the drive shaft (3) is driven and connected to the motor (4), and the other end extends from the first end of the material cylinder into the material cylinder and is connected to the sealing cover plate (2) inside the material cylinder. The perforated die panel (1) is detachably connected to the second end of the material cylinder. The slurry is located in the material cylinder between the sealing cover plate (2) and the perforated die panel (1). The motor (4) drives the drive shaft (3) to drive the sealing cover plate (2) to reciprocate linearly in the material cylinder, thereby extruding the slurry between the sealing cover plate and the perforated die panel (1) from the holes on the perforated die panel (1) to the outside of the material cylinder.

4. The electrically driven method for forming lithium extraction adsorbent particles from salt lakes according to claim 3, characterized in that, The porous mold panel (1) is a circular plastic plate or a circular stainless steel plate, and the material cylinder is a cylinder; the holes on the porous mold panel (1) are dot matrix mesh holes.

5. The electrically driven method for forming lithium extraction adsorbent particles from salt lakes according to claim 3, characterized in that, The holes on the multi-hole mold panel (1) are round holes, square holes or rectangular holes; the diameter of the round hole is 1 to 2 mm; the size of the rectangular hole is 1 mm × 2 mm; the side length of the square hole is 1 to 2 mm; the forward speed of the drive shaft is 5 cm / min to 50 cm / min.

6. The electrically driven method for forming lithium extraction adsorbent particles from salt lakes according to claim 1, characterized in that, In step (4), the long strip material extruded in step (3) is immersed in pure water at a temperature of 20°C until it solidifies and forms a shape. Then, the solidified long strip material is soaked in pure water for 24 hours to desalinate and form pores. After desalination and pore formation, it is dried at 40°C for 4 hours and then dried at 90°C for 4 hours. It is then cut into granules with a length of 1.5 mm to obtain the adsorbent.

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