A granular lithium adsorbent, its preparation method and application

Abstract

This invention relates to a particulate lithium adsorbent, its preparation method, and its application. The method includes the following steps: S1, mixing a polymer, a pore-forming agent, and a first solvent to obtain a first mixture; S2, mixing the first mixture with a lithium-ion sieve adsorbent to obtain a second mixture; S3, contacting the second mixture with a second solvent under an atomized droplet atmosphere to obtain a mixture containing the particulate lithium adsorbent. The method of this invention is simple, easy to operate, and can improve the adsorption capacity and adsorption rate of the particulate lithium adsorbent.

Description

Technical Field

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

[0002] Lithium is the least dense metal in nature and is currently widely used in energy, electronics, medical, and aerospace fields, earning it the nickname "industrial MSG".

[0003] Lithium resources in nature are mainly found in seawater, salt lake brines, granite pegmatite deposits, and geothermal water. Therefore, lithium extraction processes are mainly divided into two methods: brine extraction and ore extraction. Since the beginning of the 20th century, ore extraction has been the primary method for extracting lithium resources. However, after years of mining, high-quality ore sources are almost exhausted. Salt lake brines, on the other hand, are rich in lithium resources, and the extraction process is simple and low-cost. Therefore, brine extraction has become the mainstream research process.

[0004] Although my country is a major lithium resource country, it is also a major lithium consumer. Domestic salt lake brines are mostly characterized by low lithium content and high magnesium-to-lithium ratios, posing significant challenges to lithium extraction. Currently, the main methods for lithium extraction from salt lakes in China include adsorption, precipitation, extraction, and membrane separation. Among these, adsorption is simple, energy-efficient, environmentally friendly, and low-cost, making it suitable for separating and extracting lithium ions from salt lake brines with high magnesium-to-lithium ratios, and it has broad application prospects. The key to lithium extraction via adsorption is the preparation of adsorbents with high selectivity and high adsorption capacity, mainly including ion sieve adsorbents and aluminum-based adsorbents. However, since these adsorbents are synthesized in powder form, they cannot be directly applied to conventional equipment such as fixed-bed adsorption-desorption for lithium extraction. Therefore, the development of commercially viable granular porous adsorbents is of great significance for the future development of lithium resources. Summary of the Invention

[0005] In view of the above background, in order to overcome the problems of poor permeability and flowability of powdered lithium-ion adsorbents and low porosity of granular adsorbents in the existing technology, the purpose of this invention is to solve at least one of the shortcomings of the existing technology. For example, one objective of this invention is to provide a method for preparing granular lithium adsorbents, which is simple in process, easy to operate, and can improve the adsorption capacity and adsorption rate of granular lithium adsorbents. Another objective of this invention is to provide a granular lithium adsorbent corresponding to the above preparation method, wherein the granular lithium adsorbent particles have high strength and good toughness, and are not easily broken or pulverized when packed into an adsorption tower.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a particulate lithium adsorbent, comprising the following steps:

[0007] S1. Mix the polymer, pore-forming agent and first solvent to obtain a first mixture;

[0008] S2. Mix the first mixture with the lithium ion sieve adsorbent to obtain a second mixture;

[0009] S3. The second mixture is brought into contact with the second solvent under an atomized droplet atmosphere to obtain a mixture containing the particulate lithium adsorbent.

[0010] In some embodiments of the present invention, the polymer is selected from one or more of polyethylene, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, and polyethersulfone.

[0011] In some embodiments of the present invention, the pore-forming agent is selected from one or more of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and potassium nitrate.

[0012] In some embodiments of the present invention, the first solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and tetrahydrofuran.

[0013] In this invention, the polymer, pore-forming agent, and first solvent are all available from Bailingwei Technology. However, it is understood that raw materials from other sources capable of producing the particulate lithium adsorbent of this invention are also applicable.

[0014] In some embodiments of the present invention, the mass ratio of the polymer to the first solvent is (0.01-5):1, preferably (0.1-1):1.

[0015] In some embodiments of the present invention, the mass ratio of the pore-forming agent to the first solvent is (0.05-0.3):1, preferably (0.1-0.2):1.

[0016] In some embodiments of the present invention, when the lithium-ion sieve adsorbent is added in step S2, the mass ratio of the lithium-ion sieve adsorbent to the first organic solvent is (0.1-1):1, preferably (0.2-0.5):1.

[0017] According to the present invention, the mixing temperature in both step S1 and step S2 can be 10 to 100°C.

[0018] In some embodiments of the present invention, the atomized droplet atmosphere is formed by a poor solvent of the polymer; preferably, the poor solvent is one or both of water and ethanol.

[0019] According to the present invention, the atomized droplet atmosphere can be formed by a cold mist humidifier or an ultrasonic humidifier.

[0020] In some embodiments of the present invention, the second solvent is a poor solvent for the polymer; preferably, the second solvent is one or more of water, ethanol, propanol, ethylene glycol and acetone.

[0021] In some embodiments of the present invention, the mass ratio of the second mixture to the second solvent is (0.01 to 0.3):1, preferably (0.10 to 0.15):1.

[0022] In some embodiments of the present invention, in step S3, the contact is to add the second mixture dropwise to the second solvent; preferably, the dropwise addition rate is 0.1 to 1.0 ml / min, i.e., 3 to 30 drops / min. The dropwise addition rate specified by the present invention enables the second mixture to contact the second solvent in the form of droplets and undergo non-solvent-induced phase separation, and ensures that the second mixture is in contact with the atomized droplets for 2 to 20 seconds during the condensation and dripping process at the end of the tube.

[0023] The above-mentioned non-solvent-induced phase separation of the present invention refers to the following: the second mixture after atomization contains a first solvent, and the first solvent in the formed particulate adsorbent is not removed. At this time, the particulate adsorbent is placed in a reagent that is more miscible with the first solvent and is a poor solvent of the polymer, so that the first solvent is extracted, the residual solvent in the particulate adsorbent is removed, and the particulate adsorbent is solidified.

[0024] According to the present invention, the second mixture can be added dropwise to the second solvent using a peristaltic pump. The flow rate of the peristaltic pump is 0.1–1 ml / min, preferably 0.18–0.25 ml / min; the contact time between the second mixture and the atomized droplets during coagulation and dripping is 2–20 s; the inner diameter of the hose used for the peristaltic pump is 1.6 or 2.4 mm, preferably 1.6 mm; and the time for non-solvent-induced phase separation of the second mixture in the second solvent is 30 min–4 h, preferably 30 min–1 h.

[0025] In this invention, the non-solvent phase separation time is the time after the second mixture droplets come into contact with the atomized droplets, and then the second solvent (which is the undesirable solvent for the polymer) is added to remove the first solvent and solidify the mixture. In other words, the time the atomized pre-treated second mixture is immersed in the second solvent.

[0026] In this invention, the atomization pretreatment time is the time it takes for a droplet of the second mixture to come into contact with the atomized droplet during the process of condensation and dripping from the end of the peristaltic pump hose. In this invention, the consumption rate of the atomized droplets is 20 g / h.

[0027] According to the present invention, a poor solvent for polymers refers to a solvent that has a weak dissolving ability for polymeric solutes and whose interaction parameter with the polymeric solute is close to or greater than 0.5.

[0028] In this invention, after contacting the second mixture with the second solvent in atomized droplet atmosphere in step S3 (e.g., adding the second mixture dropwise to the second solvent), the pores on the surface of the particulate adsorbent can be effectively enlarged, fully exposing the lithium-ion sieve coated by the polymer, increasing the specific surface area of ​​the adsorbent, and ensuring that the particulate adsorbent has a high adsorption capacity and adsorption rate. In atomized droplet atmosphere, the droplets of the second mixture are in full contact with the atomized droplets during the droplet addition process, forming pores on the surface of the adsorbent, further increasing the specific surface area. The particulate material after non-solvent-induced phase separation in the second solvent is removed, dried (e.g., at 20–60°C), and then the particulate lithium adsorbent is obtained.

[0029] According to the present invention, the particle size of the particulate lithium adsorbent obtained by the preparation method of the present invention is uniform, and the average particle size can be about 4 mm. However, it is understood that the particle size of the particulate lithium adsorbent is not limited to this.

[0030] The principle of the preparation method of the present invention is to mix the lithium-ion sieve adsorbent with the first mixture to obtain the second mixture, and then add it dropwise to the second solvent (a poor solvent for the polymer) under an atomizing atmosphere to carry out non-solvent phase separation to remove the first solvent and solidify the particulate adsorbent to obtain particulate lithium adsorbent.

[0031] The preparation method of the present invention adds an atomization pretreatment process to the traditional granulation process. The flow rate can be controlled by a peristaltic pump, thereby controlling the atomization time of the dropping process. This exposes the adsorbent sites on the surface of the obtained granular lithium adsorbent, increases the specific surface area, enhances hydrophilicity, and improves the adsorption capacity and adsorption rate of the obtained granular lithium adsorbent.

[0032] In some embodiments of the present invention, the method for preparing the lithium-ion sieve adsorbent includes the following steps:

[0033] A. The titanium source, lithium source and dispersant are ball-milled to obtain a ball-milled mixture;

[0034] B. The ball-milled mixture is calcined to obtain a lithium-ion sieve adsorbent precursor.

[0035] C. The lithium-ion sieve adsorbent precursor is leached with an inorganic acid solution to obtain the lithium-ion sieve adsorbent.

[0036] In some embodiments of the present invention, the titanium source is selected from one or more of anatase titanium dioxide, rutile titanium dioxide, and plate titanium dioxide.

[0037] According to the present invention, anatase titanium dioxide, rutile titanium dioxide and plate titanium dioxide can be purchased from Bailingwei Technology.

[0038] In some embodiments of the present invention, the lithium source is selected from one or more of lithium nitrate, lithium carbonate, lithium acetate, lithium chloride, and lithium hydroxide.

[0039] According to the present invention, lithium nitrate, lithium carbonate, lithium acetate, lithium chloride, and lithium hydroxide can all be purchased from Bailingwei Technology.

[0040] In some embodiments of the present invention, the dispersant is selected from one or more of ethanol and acetone.

[0041] In some embodiments of the present invention, the molar ratio of titanium in the titanium source to lithium in the lithium source is 1:(2 to 2.5), preferably 1:(2 to 2.125).

[0042] In some embodiments of the present invention, the mass ratio of the dispersant to the total mass of the titanium source and the lithium source is (1-4):1, preferably (1-2):1.

[0043] According to the present invention, the ball milling process in step A can be performed in a ball milling jar containing stainless steel balls. The diameter of the stainless steel balls used is 1 to 5 mm, preferably 3.5 mm. The mass of the stainless steel balls placed in the ball milling jar is 10 to 40 times the total mass of the titanium source and the lithium source, preferably 20 times.

[0044] In some embodiments of the present invention, the conditions for ball milling in step A include: the ball milling speed is 200 to 400 rpm, preferably 300 rpm; and the ball milling time is 1 to 8 hours, preferably 4 to 5 hours.

[0045] In this invention, after completing the ball milling process in step A, the resulting ball-milled mixture can be dried at a temperature of 10–100°C, preferably 40–60°C. The ball-milled mixture is then dried before undergoing the calcination process in step B.

[0046] In some embodiments of the present invention, the conditions for calcination include: a calcination temperature of 600°C to 900°C and a calcination time of 3 to 8 hours.

[0047] According to the present invention, the calcination process is carried out in an air atmosphere, and after calcination, the lithium ion sieve adsorbent precursor Li2TiO3 is obtained.

[0048] In some embodiments of the present invention, the inorganic acid solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution, preferably hydrochloric acid solution; preferably, the molar concentration of the inorganic acid solution is 0.1 to 1 mol / L, more preferably 0.2 to 0.5 mol / L.

[0049] According to the present invention, lithium in the lithium-ion sieve adsorbent precursor is leached with an inorganic acid solution. After the leaching process is completed, the precursor can be filtered, washed, dried and ground to obtain powdered lithium-ion sieve adsorbent H2TiO3.

[0050] There are no particular limitations on the filtration, washing, drying, and grinding processes in this invention; those skilled in the art can determine them according to the actual situation.

[0051] A second aspect of the present invention provides a particulate lithium adsorbent prepared by the method described in the first aspect above.

[0052] According to the present invention, the obtained granular lithium adsorbent uses a polymer as a binder to form and granulate lithium adsorbent powder, resulting in granular lithium adsorbent with uniform particle size and an average particle size that can be controlled at around 4 mm.

[0053] The third aspect of the present invention provides an application of the granular lithium adsorbent prepared by the method described in the first aspect above in lithium extraction, especially in the adsorption of salt lake brine, seawater, geothermal water, and solid waste leachate.

[0054] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0055] (1) The preparation method provided by the present invention adds an atomization pretreatment process to the traditional granulation process, which exposes the surface adsorbent sites of the prepared granular lithium adsorbent, increases the specific surface area, enhances hydrophilicity, and can improve the adsorption capacity and adsorption rate of the prepared granular lithium adsorbent.

[0056] (2) The preparation method provided by the present invention has a simple preparation process, low cost, and little environmental pollution, and is suitable for industrial application.

[0057] (3) The granular lithium adsorbent prepared by the method of the present invention has high particle strength, good toughness, uniform particle size and stable performance. It does not break or pulverize after being loaded into an adsorption column for multiple (e.g., more than 15) adsorption-desorption cycles.

[0058] (4) The granular lithium adsorbent prepared by the method of the present invention is suitable for adsorbing lithium in lithium-containing solutions such as salt lake brine, seawater, geothermal water, and solid waste leachate. It has uniform particle size and stable performance. Attached Figure Description

[0059] The present invention will now be described in further detail with reference to the accompanying drawings.

[0060] Figure 1 The particulate porous lithium adsorbent prepared in Example 1.

[0061] Figure 2The image shows the surface morphology of the particulate porous lithium adsorbent prepared in Example 1.

[0062] Figure 3 The graph shows the change in adsorption capacity of the granular porous lithium adsorbent prepared in Example 1 with the number of cycles. Detailed Implementation

[0063] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments and accompanying drawings. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0064] The granular porous lithium adsorbent prepared in this invention is used for lithium adsorption. Adsorption capacity is an important parameter for evaluating lithium adsorption materials. An important indicator for measuring the adsorption performance of an adsorbent is the adsorption capacity Q, which is the mass of lithium ions adsorbed from the solution by a unit mass of granular porous lithium adsorbent when adsorption reaches equilibrium. Its calculation formula is as follows:

[0065]

[0066] In the formula: Q is the adsorption capacity at a certain temperature, in mg / g; C0 and C are the initial and saturated concentrations of ions in the solution, respectively, in mg / L; V is the volume of the adsorption solution, in L; M is the mass of the particulate adsorbent, in g.

[0067] In this invention, the atomization pretreatment time t can be controlled by adjusting the flow rate of the peristaltic pump, and its calculation formula is as follows:

[0068]

[0069] In the formula: t is the atomization pretreatment time of each mixture droplet, in seconds; v is the flow rate of the peristaltic pump, in ml / min; R is the radius of the second mixture droplet, in cm.

[0070] In the following examples, all chemical reagents used were commercially available products, and no special purification treatment was performed unless otherwise specified. The weight-average molecular weights of the polyethylene, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, and polyethersulfone were 4000-120000 g / mol, and could be obtained from Bailingwei Technology or Innocare. In the following examples, the polyvinyl chloride (product number: 189588; brand: Aldrich), polyvinylidene fluoride (product number: 427144; brand: Aldrich), polyacrylonitrile (product number: 226749; brand: J&K), and polyethylene glycol (product number: 939758; brand: J&K) were all purchased from Bailingwei Technology.

[0071] In the following examples, the simulated brine was prepared by reacting lithium chloride and magnesium chloride, wherein Li + The concentration is 0.15 g / L, Mg 2+ The concentration was 4 g / L, and the pH of the simulated brine was adjusted to 9.5 using ammonia and ammonium chloride.

[0072] Example 1

[0073] Preparation of lithium-ion sieve adsorbent:

[0074] Anatase TiO2 and Li2CO3 were weighed at a molar ratio of 1:1.05 and added to a stainless steel ball mill jar. Then, ethanol equivalent to twice the solid mass and 3.5 mm stainless steel beads equivalent to 20 times the solid mass were added to the ball mill jar. The mixture was ball milled at 200 rpm for 4 hours using a planetary ball mill. After drying at 40°C, the mixture was placed in a muffle furnace and calcined at 800°C in air for 6 hours. After cooling, the mixture was eluted with 0.5 mol / L HCl for 24 hours to obtain a lithium ion sieve.

[0075] Atomization pretreatment yields granular lithium adsorbent:

[0076] Polyvinyl chloride, N-methylpyrrolidone, and sodium chloride were mixed and dissolved in a mass ratio of 2:10:1 to obtain a polymer solution. A lithium ion sieve, equivalent to 30% of the mass percentage of N-methylpyrrolidone, was then added and mixed thoroughly to obtain a homogeneous mixture. Deionized water was added to an ultrasonic humidifier to create an atomizing atmosphere (the consumption of atomized droplets was 20 g / h). The homogeneous mixture was then added dropwise to the deionized water (the mass ratio of deionized water to the homogeneous mixture was 10:1) under the atomized droplet atmosphere using a peristaltic pump equipped with a 1.6 mm inner diameter hose. This non-solvent-induced phase separation formed solid particles. The flow rate of the homogeneous mixture in the hose was 0.2 ml / min, the atomization time of the mixture droplets was approximately 10 seconds, and the non-solvent-induced phase separation time was 30 minutes. After the non-solvent-induced phase separation was completed, the solid particles were removed and dried at 40°C to obtain granular lithium adsorbent A1 with a particle size of approximately 4 mm.

[0077] The obtained granular lithium adsorbent A1 was used to conduct an adsorption experiment of lithium ions in simulated brine, and the results are listed in Table 1.

[0078] Example 2

[0079] Preparation of lithium-ion sieve adsorbent:

[0080] Rutile TiO2 and LiNO3 were weighed in a molar ratio of 1:2 and added to a stainless steel ball mill jar. Then, acetone equivalent to 2.5 times the solid mass and 4mm stainless steel beads equivalent to 20 times the solid mass were added to the ball mill jar. The mixture was ball-milled at 300 rpm for 4 hours using a planetary ball mill. After drying at 40℃, the mixture was placed in a muffle furnace and calcined at 750℃ in air atmosphere for 6 hours. After cooling, the mixture was eluted with 0.5 mol / L HCl for 24 hours to obtain the lithium ion sieve adsorbent.

[0081] Atomization pretreatment yields granular lithium adsorbent:

[0082] Polyvinylidene fluoride, N,N dimethylformamide, and potassium chloride were mixed and dissolved in a mass ratio of 2.5:10:0.5 to obtain a polymer solution. A lithium-ion sieve adsorbent, equivalent to 28% of the mass percentage of N,N dimethylformamide, was then added and mixed thoroughly to obtain a homogeneous mixture. Deionized water was added to an ultrasonic humidifier to create an atomized droplet atmosphere (the consumption of atomized droplets was 20 g / h). The homogeneous mixture was then added dropwise to the deionized water (the mass ratio of deionized water to the homogeneous mixture was 10:1) under the atomized droplet atmosphere using a peristaltic pump equipped with a 1.6 mm inner diameter hose for non-solvent-induced phase separation to form solid particles. The flow rate of the homogeneous mixture in the hose was 0.4 ml / min, the atomization time of the mixture droplets was approximately 5 seconds, and the non-solvent-induced phase separation time was 30 min. After the non-solvent-induced phase separation process was completed, the solid particles were removed and dried at 40°C to obtain granular lithium adsorbent A2 with a particle size of approximately 4 mm.

[0083] The obtained granular lithium adsorbent A2 was used to conduct an adsorption experiment of lithium ions in simulated brine, and the results are listed in Table 1.

[0084] Example 3

[0085] Preparation of lithium-ion sieve adsorbent:

[0086] Weigh out TiO2 and LiCl in a molar ratio of 1:2 and add them to a stainless steel ball mill jar. Then add ethanol equivalent to twice the solid mass and 2.5 mm stainless steel beads equivalent to 25 times the solid mass to the ball mill jar. Use a planetary ball mill to mill at a rate of 300 rpm for 3 hours. After drying at 40℃, place it in a muffle furnace and calcine it at 800℃ in an air atmosphere for 7 hours. After cooling, elute with 0.2 mol / L HCl for 24 hours to obtain the lithium ion sieve adsorbent.

[0087] Atomization pretreatment yields granular lithium adsorbent:

[0088] Polyacrylonitrile, N,N dimethylacetamide, and potassium sulfate were mixed and dissolved in a mass ratio of 2:10:1 to obtain a polymer solution. Then, lithium-ion sieve adsorbent, equivalent to 30% of the mass percentage of N,N dimethylacetamide, was added and mixed thoroughly to obtain a homogeneous mixture. Deionized water was added to an ultrasonic humidifier to create an atomized droplet atmosphere (the consumption of atomized droplets was 20 g / h). The homogeneous mixture was then added dropwise to anhydrous ethanol (the mass ratio of anhydrous ethanol to the homogeneous mixture was 10:1) under the atomized droplet atmosphere using a peristaltic pump equipped with a 2.4 mm inner diameter hose for non-solvent-induced phase separation to form solid particles. The flow rate of the homogeneous mixture in the hose was 0.2 ml / min, the atomization time of the mixture droplets was approximately 10 seconds, and the non-solvent-induced phase separation time was 30 min. After the non-solvent-induced phase separation process was completed, the solid particles were removed and dried at 40°C to obtain granular lithium adsorbent A3 with a particle size of approximately 4 mm.

[0089] The obtained granular lithium adsorbent A3 was used to conduct an adsorption experiment of lithium ions in simulated brine, and the results are listed in Table 1.

[0090] Example 4

[0091] Preparation of lithium-ion sieve adsorbent:

[0092] Weigh rutile TiO2 and LiOH in a molar ratio of 1:2.1 and add them to a stainless steel ball mill jar. Then add acetone equivalent to 1.5 times the solid mass and 4mm grinding steel balls equivalent to 25 times the solid mass to the ball mill jar. Use a planetary ball mill to ball mill at a rate of 400 rpm for 3 hours. After drying at 50℃, place it in a muffle furnace and calcine it at 850℃ in an air atmosphere for 6 hours. After cooling, wash with 0.1mol / L HCl for 24 hours to obtain the lithium ion sieve adsorbent.

[0093] Atomization pretreatment yields granular lithium adsorbent:

[0094] Polyethylene glycol, N,N dimethylacetamide, and potassium nitrate were mixed and dissolved in a mass ratio of 2:10:1 to obtain a polymer solution. Then, lithium-ion sieve adsorbent, equivalent to 28% of the mass percentage of N,N dimethylacetamide, was added and mixed thoroughly to obtain a homogeneous mixture. Deionized water was added to a cold mist humidifier to create an atomized droplet atmosphere (the consumption of atomized droplets was 20 g / h). The homogeneous mixture was then added dropwise to the deionized water (the mass ratio of deionized water to the homogeneous mixture was 10:1) under the atomized droplet atmosphere using a peristaltic pump equipped with a 1.6 mm inner diameter hose for non-solvent-induced phase separation to form solid particles. The flow rate of the homogeneous mixture in the hose was 0.2 ml / min; the atomization time of the mixture droplets was approximately 10 seconds, and the non-solvent-induced phase separation time was 30 min. After the non-solvent-induced phase separation process was completed, the solid particles were removed and dried at 40°C to obtain granular lithium adsorbent A4 with a particle size of approximately 4 mm.

[0095] The obtained granular lithium adsorbent A4 was used to conduct an adsorption experiment of lithium ions in simulated brine, and the results are listed in Table 1.

[0096] Example 5

[0097] Except for setting the flow rate of the uniform mixture in the tubing to 0.4 ml / min and the atomization time of the mixture droplets to approximately 5 seconds, the remaining steps were the same as in Example 1, resulting in lithium-ion sieve adsorbent A5 with a particle size of approximately 4 mm. Adsorption experiments of lithium ions in simulated brine were conducted using the obtained lithium-ion sieve adsorbent, and the results are listed in Table 1.

[0098] Example 6

[0099] Except for setting the flow rate of the uniform mixture in the tubing to 0.7 ml / min and the atomization time of the mixture droplets to approximately 3 seconds, the remaining steps were the same as in Example 1, resulting in lithium-ion sieve adsorbent A6 with a particle size of approximately 4 mm. Adsorption experiments of lithium ions in simulated brine were conducted using the obtained lithium-ion sieve adsorbent, and the results are listed in Table 1.

[0100] Comparative Example 1

[0101] Except for the absence of atomization pretreatment, all other steps were the same as in Example 1, resulting in lithium-ion sieve adsorbent B1 with a particle size of approximately 4 mm. Adsorption experiments of lithium ions in simulated brine were conducted using the obtained lithium-ion sieve adsorbent, and the results are listed in Table 1.

[0102] Comparative Example 2

[0103] Except for the absence of atomization pretreatment, all other steps were the same as in Example 2, resulting in lithium-ion sieve adsorbent B2 with a particle size of approximately 4 mm. Adsorption experiments of lithium ions in simulated brine were conducted using the obtained lithium-ion sieve adsorbent B2, and the results are listed in Table 1.

[0104] The adsorbent products prepared in Examples 1-4 and Comparative Examples 1-2 were placed in simulated brine for adsorption experiments. The adsorption capacity Q was calculated according to the adsorption capacity calculation formula, and the results are shown in Table 1.

[0105]

[0106] According to Table 1, comparing the adsorption performance results of adsorbent product A1 with adsorbent product B1 and adsorbent product A2 with adsorbent product B2, it can be seen that the adsorption effect of the particulate ion adsorbent without atomization pretreatment is poor, while the adsorption effect of lithium is significantly increased after atomization. Comparing adsorbent product A1, adsorbent product A5 and adsorbent product A6, it can be seen that as the flow rate of the homogeneous mixture decreases, i.e. the atomization pretreatment time increases, the adsorption effect of the particulate ion adsorbent gradually increases.

[0107] The specific surface area of ​​the adsorbent products prepared in Examples 1-4 and Comparative Examples 1-2 was tested, and the results are shown in Table 2.

[0108]

[0109] According to Table 2, comparing the specific surface area test results of adsorbent product A1 and adsorbent product B1, and adsorbent product A2 and adsorbent product B2, it can be seen that the specific surface area of ​​the particulate ion adsorbent without atomization pretreatment is smaller, while the specific surface area of ​​the particulate ion adsorbent after atomization is significantly increased. Comparing the specific surface areas of A1, A5, and A6 shows that the lower the flow rate of the homogeneous mixture, i.e., the longer the atomization pretreatment time, the larger the specific surface area.

[0110] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing a particulate lithium adsorbent, comprising the following steps: S1. Mix the polymer, pore-forming agent and first solvent to obtain a first mixture; S2. Mix the first mixture with the lithium ion sieve adsorbent to obtain a second mixture; S3. The second mixture is brought into contact with the second solvent under an atomized droplet atmosphere to obtain a mixture containing the particulate lithium adsorbent. in, The polymer is selected from one or more of polyethylene, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, and polyethersulfone; The atomized droplet atmosphere is formed by a poor solvent of the polymer; the second solvent is a poor solvent of the polymer.

2. The method according to claim 1, characterized in that, The pore-forming agent is selected from one or more of sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and potassium nitrate; and / or The first solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, and tetrahydrofuran.

3. The method according to claim 1, characterized in that, The mass ratio of the polymer to the first solvent is (0.01~5):1; and / or The mass ratio of the pore-forming agent to the first solvent is (0.05~0.3):1; and / or The mass ratio of the lithium-ion sieve adsorbent to the first solvent is (0.1~1):

1.

4. The method according to claim 3, characterized in that, The mass ratio of the polymer to the first solvent is (0.1~1):1; and / or The mass ratio of the pore-forming agent to the first solvent is (0.1~0.2):1; and / or The mass ratio of the lithium-ion sieve adsorbent to the first solvent is (0.2~0.5):

1.

5. The method according to claim 1, characterized in that, The atomized droplet atmosphere is formed by one or both of water and ethanol; and / or The second solvent is one or more of water, ethanol, propanol, ethylene glycol, and acetone.

6. The method according to any one of claims 1-5, characterized in that, The mass ratio of the second mixture to the second solvent is (0.01 to 0.3):

1.

7. The method according to claim 6, characterized in that, The mass ratio of the second mixture to the second solvent is (0.10~0.15):

1.

8. The method according to any one of claims 1-5, characterized in that, The contact is described as adding the second mixture dropwise into the second solvent.

9. The method according to claim 8, characterized in that, The dripping rate is 0.1–1.0 ml / min.

10. The method according to any one of claims 1-5, characterized in that, The method for preparing the lithium-ion sieve adsorbent includes the following steps: A. The titanium source, lithium source and dispersant are ball-milled to obtain a ball-milled mixture; B. The ball-milled mixture is calcined to obtain a lithium-ion sieve adsorbent precursor. C. The lithium-ion sieve adsorbent precursor is leached with an inorganic acid solution to obtain the lithium-ion sieve adsorbent.

11. The method according to claim 10, characterized in that, The titanium source is selected from one or more of anatase titanium dioxide, rutile titanium dioxide, and plate titanium dioxide; and / or The lithium source is selected from one or more of lithium nitrate, lithium carbonate, lithium acetate, lithium chloride, and lithium hydroxide; and / or The dispersant is selected from one or more of ethanol and acetone.

12. The method according to claim 10, characterized in that, The molar ratio of titanium in the titanium source to lithium in the lithium source is 1:(2~2.5); and / or The mass ratio of the dispersant to the total mass of the titanium source and the lithium source is (1~4):

1.

13. The method according to claim 12, characterized in that, The molar ratio of titanium in the titanium source to lithium in the lithium source is 1:(2~2.125); and / or The mass ratio of the dispersant to the total mass of the titanium source and the lithium source is (1~2):

1.

14. The method according to claim 10, characterized in that, The conditions for calcination include: a calcination temperature of 600℃~900℃ and a calcination time of 3~8 hours; and / or The inorganic acid solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution; and / or, the molar concentration of the inorganic acid solution is 0.1~1 mol / L.

15. The method according to claim 14, characterized in that, The inorganic acid solution is a hydrochloric acid solution; and / or, the molar concentration of the inorganic acid solution is 0.2~0.5 mol / L.

16. A particulate lithium adsorbent prepared by any one of claims 1-15.

17. The application of a particulate lithium adsorbent prepared by any one of claims 1-15 in lithium extraction.

18. The application according to claim 17, characterized in that, The application refers to the use of the granular lithium adsorbent in the adsorption of salt lake brine, seawater, geothermal water, and solid waste leachate.

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