Method for preparing lithium-ion sieve particles, and use of lithium-ion sieve particles

Abstract

The present disclosure belongs to the technical field of extraction of lithium from a salt lake. Disclosed are a method for preparing lithium-ion sieve particles, and the use of lithium-ion sieve particles. The method comprises: mixing a lithium-ion sieve powder, a binder and a pore forming agent, and then extruding and granulating same, so as to obtain porous particles; placing carbon fibers in a strong oxidizing solution to undergo a first heat treatment, taking same out, and cleaning and drying same, so as to obtain modified carbon fibers; and placing the modified carbon fibers in a silane coupling agent solution to undergo a second heat treatment, so as to obtain a turbid liquid, adding the porous particles to the turbid liquid, mixing same until uniform, subjecting same to a third heat treatment, and filtering and drying same, so as to obtain lithium-ion sieve particles.

Description

Preparation method and application of lithium ion sieve particles Technical Field

[0001] The present disclosure belongs to the technical field of lithium extraction from salt lakes, and particularly relates to a preparation method of lithium ion sieve particles and applications thereof. Background Art

[0002] Salt lake lithium resources account for over 69% of the world's industrial lithium reserves, primarily distributed in South America, North America, and Asia. Salt lake regions are often sparsely populated, have underdeveloped infrastructure, and suffer from insufficient energy supplies, severely hindering the development and utilization of these resources. Methods for extracting lithium from brine include evaporation and crystallization, precipitation, extraction, adsorption, calcination, and membrane separation.

[0003] Among them, the adsorption method uses lithium selective adsorbents to separate and extract lithium, which is especially suitable for salt lake brine with high Mg / Li. The key to this method lies in the selection of adsorbent materials. Generally, adsorbent materials can be divided into two categories: organic adsorbents and inorganic adsorbents. Organic adsorbents usually use strong acidic cation exchange resins to selectively collect and recover lithium from lithium-containing solutions, mainly relying on Coulomb force to adsorb lithium ions into the resin. However, this type of adsorbent has a low affinity for lithium ions and low selectivity for lithium ions, making it unsuitable for lithium extraction and recovery. The working principle of inorganic lithium adsorbents mainly relies on the affinity of inorganic lithium ion adsorbents to Li + Due to its unique memory effect and selectivity, it has the advantages of low cost, good cycle stability and high selectivity, making it the most promising adsorbent for adsorbing lithium ions from lithium-containing solutions. According to the classification of the main elements in inorganic lithium ion adsorbent materials, they mainly include aluminum salt adsorbents, antimony acid adsorbents, titanium oxide adsorbents and manganese oxide adsorbents.

[0004] Although these lithium ion sieve materials have advantages such as large adsorption capacity, high selectivity, and good cyclic stability, they are usually present in powder form. In industrial applications, they have poor fluidity, low circulation efficiency, and are easily lost. In addition, powdered ion sieve materials can cause a large pressure drop, resulting in high energy consumption in column operations, and cannot be directly used for lithium extraction from salt lake brine. These shortcomings are currently mainly overcome by the granulation molding technology of powder lithium ion sieve. The granulation method is to evenly mix lithium ion sieve powder and a high molecular polymer with adhesive properties, and then form spherical particles through the polymerization reaction of the binder itself. Through granulation, the powder ion sieve can be given good mechanical strength, thereby being able to adapt to industrial column operations, effectively improving the recycling and permeability of the lithium ion sieve powder. Materials with PVC, PVDF, etc. as binders have excellent mechanical properties, acid and alkali resistance, easy molding, and low cost. However, compared with powder adsorbents, the adsorption performance of the ion sieve particles after granulation will be significantly reduced. This is because PVC and PVDF binders are hydrophobic materials, which reduce the diffusion capacity of lithium ions. There are also related reports on the use of binders containing hydrophilic groups such as agar, chitosan, polyacrylonitrile, and polyacrylamide to granulate powders, thereby improving the adsorption performance by increasing the permeability and wettability of adsorbed water. However, hydrophilic binders have low stability in water and poor mechanical properties, which reduces the circulation performance of the adsorbent and is not suitable for long-term use.

[0005] Summary of the Invention

[0006] The present disclosure aims to at least solve the technical problems existing in the above-mentioned prior art. To this end, the present disclosure provides a preparation method of lithium ion sieve particles and its application.

[0007] According to one aspect of the present disclosure, a method for preparing lithium ion sieve particles is proposed, comprising the following steps:

[0008] S1: mixing lithium ion sieve powder, a binder, and a pore-forming agent, and then extruding and granulating the mixture to obtain porous particles;

[0009] S2: placing the carbon fiber filaments in a strong oxidizing solution for a first heating treatment, taking out the carbon fiber filaments and washing and drying them to obtain modified carbon fiber filaments;

[0010] S3: placing the modified carbon fiber filaments in a silane coupling agent solution for a second heating treatment to obtain a suspension, adding the porous particles to the suspension and mixing, performing a third heating treatment, filtering, and drying to obtain the lithium ion sieve particles.

[0011] In some embodiments of the present disclosure, in step S1, the lithium ion sieve powder is a titanium-based lithium ion sieve, a manganese-based lithium ion sieve, or an aluminum-based lithium ion sieve.

[0012] In some embodiments of the present disclosure, in step S1, the binder is at least one of PVDF, PVC or epoxy resin.

[0013] In some embodiments of the present disclosure, in step S1, the pore-forming agent is at least one of ethanol, isopropanol, or n-butanol. The pore-forming agent is a volatile organic compound. The high temperature associated with the extrusion process allows the pore-forming agent to rapidly volatilize and generate gas, resulting in a porous structure in the extruded particles. This porous structure has strong liquid absorption properties.

[0014] In some embodiments of the present disclosure, in step S1, the extrusion granulation is performed using an extruder, and the segmented temperature range of the extruder is 110-250°C.

[0015] In some embodiments of the present disclosure, in step S1, the mass ratio of the lithium ion sieve powder to the pore-forming agent is 1:(0.1-0.2).

[0016] In some embodiments of the present disclosure, in step S1, the mass ratio of the lithium ion sieve powder to the binder is 1:(0.15-0.3).

[0017] In some embodiments of the present disclosure, in step S1, the porous particles have a particle size of 1-5 mm.

[0018] In some embodiments of the present disclosure, in step S2, the strong oxidizing solution is at least one of nitric acid, sodium hypochlorite, hydrogen peroxide, ammonium persulfate, acidic potassium permanganate, acidic potassium dichromate, or potassium persulfate.

[0019] In some embodiments of the present disclosure, in step S2, the temperature of the first heating treatment is 70-90° C., and the time is 3-6 hours.

[0020] In some embodiments of the present disclosure, in step S2, the length of the carbon fiber filaments is 0.1-2 mm.

[0021] In some embodiments of the present disclosure, in step S3, the temperature of the second heating treatment is 60-80° C., and the time is 2-4 hours.

[0022] In some embodiments of the present disclosure, in step S3, the temperature of the third heating treatment is 90-110° C., and the time is 1-3 hours.

[0023] In some embodiments of the present disclosure, in step S3, the silane coupling agent is at least one of 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane.

[0024] In some embodiments of the present disclosure, in step S3, the silane coupling agent solution is prepared by ultrasonic dispersion according to a mass ratio of silane coupling agent to anhydrous ethanol = 1: (4-5).

[0025] In some embodiments of the present disclosure, in step S3, the mass content of the carbon fiber filaments in the lithium ion sieve particles is 1%-10%.

[0026] The present disclosure also provides the use of the lithium ion sieve particles prepared by the preparation method in extracting lithium from salt lakes.

[0027] According to the embodiments of the present disclosure, there are at least the following beneficial effects:

[0028] The present invention utilizes a strong oxidizing solution to perform surface oxidation etching on carbon fiber filaments, and introduces oxygen-active functional groups (such as hydroxyl and carboxyl groups), which can improve the hydrophilicity of carbon fiber filaments, reduce the surface tension of carbon fiber filaments, and make them easy to disperse evenly in the solution without attracting each other and affecting the processing performance. The oxidized carbon fiber is first combined with a silane coupling agent and then grafted to the surface of lithium ion sieve particles. Silane coupling serves as a bridging agent between carbon fiber filaments and lithium ion sieve particles. Its silaneoxy end reacts with the oxygen-active functional groups of carbon fiber filaments, and the organic functional group end combines with the hydrophobic binder in the lithium ion sieve particles, so that there are multiple interfacial bonding effects such as covalent bonds and hydrogen bonds in the interface area, which plays a good bridging role, thereby improving the interface strength between carbon fiber and lithium ion sieve particles. The present invention connects carbon fiber filaments to the surface of lithium ion sieve particles. The carbon fiber filaments can disturb the solution near the lithium ion sieve particles, enhance the convection mass transfer effect near the lithium ion sieve particles, and make the lithium-containing solution near the lithium ion sieve particles enter the pores of the particles more smoothly and quickly, thereby improving the problem of hydrophobic binders reducing the diffusion capacity of lithium ions. The disturbance of the solution by the carbon fiber filaments on the surface of the particles increases the diffusion capacity of lithium ions in the solution, thereby improving the adsorption efficiency of the lithium ion sieve particles. Compared with hydrophilic binders, hydrophobic binders have higher stability in water and better mechanical properties, and are suitable for the recycling of lithium ion sieve particles. In addition, the polar groups introduced into the carbon fibers after surface treatment enhance the hydrophilicity, which can further improve the permeability and wettability of the lithium ion sieve particles in the solution, thereby improving the adsorption efficiency. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the concept and technical effects of the present disclosure in conjunction with embodiments to fully understand the purpose, features and effects of the present disclosure.

[0030] Example 1

[0031] This embodiment prepares a lithium ion sieve particle, and the specific process is as follows:

[0032] (1) Manganese lithium ion sieve powder MnO2·0.5H2O, PVDF, and ethanol were mixed in a mass ratio of 1:0.2:0.1 and extruded into granules using a twin-screw extruder. The first section temperature of the extruder was 130°C, the second section temperature was 170°C, the third section temperature was 190°C, the fourth section temperature was 210°C, and the die head temperature was 230°C. After extrusion, the extruded strips were pelletized using a pelletizer to obtain porous granules with a particle size D50 of 2.3 mm.

[0033] (2) Immerse carbon fiber filaments with a length of about 0.5 mm in a 2 mol / L nitric acid solution and reflux at 85° C. for 4 h to perform surface oxidation treatment on the carbon fiber filaments. Remove the carbon fiber and wash and dry it to obtain improved carbon fiber filaments.

[0034] (3) The improved carbon fiber yarn is placed in a 3-aminopropyltriethoxysilane solution (3-aminopropyltriethoxysilane: anhydrous ethanol solution mass ratio = 1:4), refluxed at 75 ° C for 2.5 hours, cooled to room temperature, and then the porous particles of step (1) are added to the above suspension and mixed. The mixture is refluxed at 100 ° C for 1.5 hours. After the reaction is completed, it is filtered and dried to obtain lithium ion sieve particles with carbon fibers attached to the surface. The mass content of carbon fibers in the product lithium ion sieve particles is 4%.

[0035] Example 2

[0036] This embodiment prepares a lithium ion sieve particle, and the specific process is as follows:

[0037] (1) Manganese lithium ion sieve powder MnO2·0.5H2O, PVDF, and isopropyl alcohol were mixed in a mass ratio of 1:0.15:0.15, and then extruded into granules using a twin-screw extruder. The first section temperature of the extruder was 130°C, the second section temperature was 170°C, the third section temperature was 190°C, the fourth section temperature was 210°C, and the die head temperature was 230°C. After extrusion, the extruded strips were pelletized using a pelletizer to obtain porous granules with a particle size D50 of 4.0 mm.

[0038] (2) Immerse carbon fiber filaments with a length of about 1 mm in a 2 mol / L nitric acid solution and reflux at 90°C for 3 h to perform surface oxidation treatment on the carbon fiber filaments. Remove the carbon fiber and wash and dry it to obtain improved carbon fiber filaments.

[0039] (3) The improved carbon fiber yarn is placed in a 3-aminopropyltrimethoxysilane solution (3-aminopropyltrimethoxysilane: anhydrous ethanol solution mass ratio = 1:5), refluxed at 70 ° C for 5 hours, cooled to room temperature, and then the porous particles of step (1) are added to the above suspension and mixed, and refluxed at 95 ° C for 2 hours. After the reaction is completed, it is filtered and dried to obtain lithium ion sieve particles with carbon fibers attached to the surface. The mass content of carbon fibers in the product lithium ion sieve particles is 3%.

[0040] Example 3

[0041] This embodiment prepares a lithium ion sieve particle, and the specific process is as follows:

[0042] (1) Manganese lithium ion sieve powder MnO2·0.5H2O, PVDF, and ethanol were mixed in a mass ratio of 1:0.3:0.1 and extruded into granules using a twin-screw extruder. The first section temperature of the extruder was 130°C, the second section temperature was 170°C, the third section temperature was 190°C, the fourth section temperature was 210°C, and the die head temperature was 230°C. After extrusion, the extruded strips were pelletized using a pelletizer to obtain porous granules with a particle size D50 of 5 mm.

[0043] (2) Immerse carbon fiber filaments with a length of about 1.2 mm in a 1 mol / L sodium hypochlorite solution and reflux at 90° C. for 3 h to perform surface oxidation treatment on the carbon fiber filaments. Take out the carbon fiber and wash and dry it to obtain improved carbon fiber filaments.

[0044] (3) The improved carbon fiber yarn is placed in a 3-aminopropyltriethoxysilane solution (3-aminopropyltriethoxysilane: anhydrous ethanol solution mass ratio = 1:4), refluxed at 80 ° C for 3 hours, cooled to room temperature, and then the porous particles of step (1) are added to the above suspension and mixed, and refluxed at 110 ° C for 3 hours. After the reaction is completed, it is filtered and dried to obtain lithium ion sieve particles with carbon fibers attached to the surface. The mass content of carbon fibers in the product lithium ion sieve particles is 7%.

[0045] Comparative Example

[0046] This comparative example prepares a lithium ion sieve particle. The difference from Example 1 is that only step (1) of Example 1 is performed, and the obtained porous particle is the lithium ion sieve particle of this comparative example.

[0047] Test example

[0048] The adsorption performance of the lithium ion sieve particles prepared in the above examples and comparative examples was tested. The test method is as follows: 300g of the lithium ion sieve particles from the examples and comparative examples were weighed and placed into an adsorption column. 10kg of brine was then passed through the column at a rate of 5 seconds per drop. The lithium content after passing through the column was measured, and the lithium adsorption capacity was calculated. The results are shown in Table 2.

[0049] The calculation formula of adsorption capacity is as follows: adsorption capacity = (lithium content in brine before adsorption - lithium content in brine after adsorption) * mass of brine passing through the column / mass of lithium ion sieve particles.

[0050] Table 1 Chemical composition of salt lake brine

[0051] Table 2 Lithium adsorption capacity and cyclic adsorption performance of lithium ion sieve particles

[0052] As can be seen from Table 2, the lithium adsorption capacity of the embodiment is higher than that of the comparative example, indicating that the lithium ion sieve particles disclosed in the present invention have higher adsorption efficiency after being grafted with carbon fiber filaments.

Claims

1. A method for preparing lithium ion sieve particles, It is characterized in that The following steps are involved: S1: mixing lithium ion sieve powder, a binder and a pore-forming agent, and then extruding and granulating the mixture to obtain porous particles; S2: placing the carbon fiber filaments in a strong oxidizing solution for a first heating treatment, taking out the carbon fiber filaments and washing and drying them to obtain modified carbon fiber filaments; S3: placing the modified carbon fiber filaments in a silane coupling agent solution for a second heating treatment to obtain a suspension, adding the porous particles to the suspension and mixing, performing a third heating treatment, filtering and drying to obtain the lithium ion sieve particles.

2. The preparation method according to claim 1, It is characterized in that In step S1, the lithium ion sieve powder is a titanium-based lithium ion sieve, a manganese-based lithium ion sieve or an aluminum-based lithium ion sieve.

3. The preparation method according to claim 1, It is characterized in that In step S1, the adhesive is at least one of PVDF, PVC or epoxy resin.

4. The preparation method according to claim 1, It is characterized in that In step S1, the pore-forming agent is at least one of ethanol, isopropanol or n-butanol.

5. The preparation method according to claim 1, It is characterized in that In step S1, the mass ratio of the lithium ion sieve powder to the pore-forming agent is 1:(0.1-0.2).

6. The preparation method according to claim 1, It is characterized in that In step S1, the mass ratio of the lithium ion sieve powder to the binder is 1:(0.15-0.3).

7. The preparation method according to claim 1, It is characterized in that In step S1, the porous particles have a particle size D50 of 1-5 mm.

8. The preparation method according to claim 1, It is characterized in that In step S2, the strong oxidizing solution is at least one of nitric acid, sodium hypochlorite, hydrogen peroxide, ammonium persulfate, acidic potassium permanganate, acidic potassium dichromate or potassium persulfate.

9. The preparation method according to claim 1, It is characterized in that In step S2, the temperature of the first heating treatment is 70-90°C and the time is 3-6 hours.

10. The preparation method according to claim 1, It is characterized in that In step S2, the length of the carbon fiber filaments is 0.1-2 mm.

11. The preparation method according to claim 1, It is characterized in that In step S3, the temperature of the second heating treatment is 60-80°C and the time is 2-4 hours.

12. The preparation method according to claim 1, It is characterized in that In step S3, the temperature of the third heating treatment is 90-110° C. and the time is 1-3 hours.

13. The preparation method according to claim 1, It is characterized in that In step S3, the silane coupling agent is at least one of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

14. The preparation method according to claim 1, It is characterized in that In step S3, the silane coupling agent solution is prepared by ultrasonic dispersion according to the mass ratio of silane coupling agent to anhydrous ethanol = 1: (4-5).

15. The preparation method according to claim 1, It is characterized in that In step S3, the mass content of carbon fiber filaments in the lithium ion sieve particles is 1%-10%.

16. Use of the lithium ion sieve particles obtained by the preparation method according to any one of claims 1 to 15 in extracting lithium from salt lakes.

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