Preparation method and application of low-density composite lithium adsorbent

Abstract

The invention relates to a low-density composite lithium adsorbent as well as a preparation method and application thereof, belongs to the technical field of lithium extraction, and solves the problems that an existing powder composite lithium adsorbent is difficult to recover and high in loss, and a column type large-size particle adsorbent has contradictory requirements on structural strength, looseness and porosity. The composite lithium adsorbent has a core-shell structure, the core is low-density solid bubbles, the shell is a lithium adsorbent, and the mass ratio of the core to the shell is 1: (0.1-2). The surface of the solid bubble with a large specific surface area is coated with the lithium adsorbent, on one hand, the adsorption performance of the lithium adsorbent on lithium in the liquid lithium ore can be improved, on the other hand, due to the low-density characteristic of the solid bubble, the recovery difficulty of the adsorbent can be reduced through efficient solid-liquid separation, and the recovery efficiency is improved. High mechanical strength and stable materials endow the adsorbent with excellent cycle stability, and are beneficial to long-term cycle use in industrial application scenarios; in addition, the preparation method of the composite lithium adsorbent is simple and environment-friendly, and is easy for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium extraction, and particularly relates to a low-density composite lithium adsorbent and a preparation method and application thereof. BACKGROUND

[0002] Lithium resources exist in the form of solid lithium ore resources and liquid lithium ore resources, and the development and extraction technology of lithium resources is crucial to ensure clean and reliable lithium supply. At present, the development and extraction of lithium resources mainly include thermal-chemical extraction of hard rock ore and evaporation extraction of brine; however, the extraction of lithium from solid lithium ore has problems such as high energy consumption and serious environmental pollution; although 87% of liquid lithium ore resources use the salt field evaporation method, this method is time-consuming and has a large evaporation capacity, and is only suitable for processing high-quality brine.

[0003] In view of the advantages of abundant reserves and low development cost of liquid lithium ore resources, developing sustainable technologies for extracting lithium from various liquid lithium ore resources is of great significance to the development of new energy industry, and extracting lithium from liquid lithium ore such as salt lake brine, underground brine and geothermal water has become a research hotspot. At present, the methods for extracting lithium from liquid lithium ore include precipitation method, solvent extraction method, electrochemical method, membrane method and adsorption method. Among them, the adsorption method has attracted widespread attention due to its simple process, good selectivity, high recovery rate and simple operation, and has become the focus of researchers due to its weak environmental footprint and high adsorption performance.

[0004] The powder adsorbent has problems such as difficult recovery and large loss in the application process, and often needs to be prepared into large-size particle adsorbent through granulation technology, and then an adsorption column or an adsorption tower is used for adsorption and lithium extraction; however, the column-type large-size particle adsorbent also has great problems in actual application: in order to maintain a high adsorption rate and adsorption capacity, the adsorbent is often prepared into large particles with porous and loose structure; however, the column operation in the adsorption process also requires that the adsorbent particles have a certain structural strength to prevent crushing, thereby affecting the adsorption effect and recycling performance, that is, the particle structure cannot be too loose, and the loose porous structure and the higher structural strength are contradictory, and it is difficult to balance the two for the existing large-size particle adsorbent.

[0005] Therefore, there is an urgent need for a composite lithium adsorbent that can balance good lithium adsorption performance and good recycling performance, improve the extraction efficiency of lithium in liquid lithium ore, and reduce the cost. SUMMARY

[0006] In view of the above analysis, the embodiments of the present application aim to provide a low-density composite lithium adsorbent and a preparation method and application thereof, to solve at least one of the problems of the existing powder composite lithium adsorbent, such as difficult recovery, large loss, and the contradictory requirements of the column-type large-size particle adsorbent for structural strength and loose porous structure.

[0007] In one aspect, the embodiments of the present application provide a low-density composite lithium adsorbent, the composite lithium adsorbent having a core-shell structure, the core being a solid bubble having a density of 0.1-0.9 g / cm 3 The shell being a lithium adsorbent, wherein the mass ratio of the solid bubble to the lithium adsorbent is 1:0.1-2.

[0008] Further, the solid bubble is one or more of hollow glass beads, hollow glass microspheres, fly ash floating beads, and ceramic bubbles.

[0009] Further, the solid bubble has a particle size of 10-1000 μm and a compressive strength of 1-200 MPa.

[0010] Further, the lithium adsorbent is one of a manganese-based ion sieve, a titanium-based ion sieve, and an aluminum-based adsorbent.

[0011] In a second aspect, the embodiments of the present application provide a preparation method of the low-density composite lithium adsorbent, the method comprising: (1) performing surface etching on a solid bubble to obtain a surface-roughened solid bubble; (2) mixing the surface-roughened solid bubble with a lithium salt and a metal compound in a solution to form a suspension, and performing an in-situ growth reaction to obtain a lithium adsorbent precursor coated on the surface of the solid bubble; (3) eluting the lithium adsorbent precursor coated on the surface of the solid bubble to obtain a low-density composite lithium adsorbent having the solid bubble as a core and the lithium adsorbent as a shell.

[0012] Further, in step (1), the solid bubble is placed in a strong alkali solution for surface etching, the strong alkali solution being a sodium hydroxide or potassium hydroxide aqueous solution having a concentration of 0.5-5 mol / L.

[0013] Further, the surface etching specifically involves placing the solid bubble in the strong alkali solution at a solid-liquid ratio of 10-100 g / L and stirring.

[0014] Further, in step (2), the lithium salt is at least one of lithium chloride, lithium nitrate, lithium hydroxide, and lithium acetate.

[0015] Further, the metal compound is at least one of tetrabutyl titanate, titanium isopropoxide, manganese nitrate, manganese acetate tetrahydrate, aluminum chloride, and aluminum nitrate.

[0016] Further, the molar ratio of lithium ions in the lithium salt to metal ions in the metal compound is 1:(0.5-2).

[0017] Further, in step (2), the mass fraction of the solid bubbles in the suspension is 0.5wt%-30wt%.

[0018] Further, the mass ratio of the lithium salt to the solid bubbles is 1:0.5-30.

[0019] Further, the lithium adsorbent is one of a manganese-based ion sieve, a titanium-based ion sieve, and an aluminum-based adsorbent.

[0020] Further, in step (3), at least one of deionized water, dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid is used to elute the precursor obtained in step (2), and the solid-liquid ratio of the elution is 1-50g / L.

[0021] In a third aspect, the present application also provides a method for extracting lithium from a liquid lithium ore by using the composite lithium adsorbent.

[0022] Compared with the prior art, the present application can achieve at least one of the following beneficial effects: 1. Compared with existing powder adsorbents and large-size particle adsorbents, the present application coats the lithium adsorbent on the surface of solid bubbles with a large specific surface area, which can improve the adsorption performance of the lithium adsorbent on lithium in the liquid lithium ore, and the density (0.1-0.9g / cm 3 ) of the solid bubbles is lower than that of water, so that the solid bubbles can float in the process of extracting lithium from the liquid lithium ore by limiting the mass ratio of the solid bubbles to the lithium adsorbent, thereby realizing efficient solid-liquid separation to reduce the difficulty of recovering the adsorbent, and the high mechanical strength and stable material quality can provide excellent cycle stability for the adsorbent, which is conducive to long-term cyclic use in industrial application scenarios.

[0023] 2. The present application regulates the particle size of the solid bubbles, so that the low-density composite lithium adsorbent has good dispersibility in the use process and prevents agglomeration while providing as large a specific surface area as possible to realize more coating of the lithium adsorbent.

[0024] 3. The present application regulates the concentration of the strong alkali solution and the proportion of the solid bubbles to be etched, which can not only remove oil on the surface but also realize further surface etching treatment to improve the interface roughness, increase the deposition sites of the lithium adsorbent prepared in the subsequent reaction on the solid bubbles, and make the surface of the etched solid bubbles rich in hydroxyl groups, which is conducive to the deposition of the lithium adsorbent prepared after the reaction on the solid bubbles and improves the stability of the coated lithium adsorbent.

[0025] 4. The present application regulates the proportion of the solid bubbles to the lithium salt in the suspension, which can regulate the mass ratio of the solid bubbles to the lithium adsorbent in the composite lithium adsorbent and control the product density to be less than the density (1g / cm 3), to ensure that the lithium can float during the extraction process, thereby realizing efficient solid-liquid separation to reduce the difficulty of recovering the adsorbent.

[0026] 5、The preparation method of the composite lithium adsorbent is simple, environmentally friendly, and easy to scale up, which helps to realize efficient, environmentally friendly, and low-cost application of the lithium adsorbent in the lithium extraction process of salt lakes.

[0027] 6、The composite lithium adsorbent can float on the surface of the liquid phase during the lithium extraction process of the liquid-phase lithium ore, and after 8 cycles of adsorption, the overall recoverability of the material is not less than 90%, and the adsorption capacity retention rate is still maintained at more than 90% relative to the first adsorption, which exhibits excellent recyclability and cycle stability.

[0028] The above technical solutions can be combined with each other in the present application to realize more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated herein and constitute a part of the detailed description. The drawings illustrate embodiments of the present application and, together with the detailed description, serve to explain the principles of the present application. Figure 1 SEM picture of the composite lithium adsorbent prepared for Example 1 of the present application; Figure 2 Comparison chart of the maximum adsorption capacity of the composite lithium adsorbent prepared for Examples 1, 3, and 5 of the present application and the maximum adsorption capacity of the lithium adsorbent prepared for Comparative Examples 1, 2, and 3; Figure 3 Lithium ion adsorption capacity chart of the titanium-based coated composite lithium adsorbent prepared for Example 1 and the powder lithium adsorbent prepared for Comparative Example 1 in a brine solution at different times; Figure 4 Density data column chart of the composite lithium adsorbent prepared for Examples 1-5 and the lithium adsorbent prepared for Comparative Examples 1-4. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present application will be specifically described below in conjunction with the accompanying drawings, wherein the drawings constitute a part of the present application and are used to illustrate the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0031] In view of the advantages of rich reserves and low development cost of liquid lithium ore resources, developing sustainable technologies for extracting lithium from various liquid lithium ores is of great significance for the development of new energy industry. Lithium extraction from liquid lithium ores such as salt lake brine, underground brine and geothermal water has become a research hotspot. Lithium adsorbents have great application potential in the purification of lithium from liquid lithium ores due to their unique ion sieving effect.

[0032] However, there are problems such as recovery difficulty and large loss in the application process of existing powder lithium adsorbents. Large-size particle adsorbents prepared by traditional granulation technology for column adsorption also have great problems in actual application process: in order to maintain high adsorption rate and adsorption capacity, the adsorbent is often prepared into porous and loose large particles; however, the column operation of the adsorption process also requires that the adsorbent particles have a certain structural strength to prevent crushing, which affects the adsorption effect and recycling performance, that is, the particle structure cannot be too loose, and the loose porous structure is in contradiction with the higher structural strength, and it is difficult to balance the two for existing large-size particle adsorbents.

[0033] Therefore, the embodiments of the present application provide a low-density composite lithium adsorbent, as shown in the following formula: Figure 1 The composite lithium adsorbent has a core-shell structure, the core is a solid bubble with a density of 0.1-0.9 g / cm 3 , and the shell is a lithium adsorbent, wherein the mass ratio of the solid bubble to the lithium adsorbent is 1:0.1-2.

[0034] Compared with existing powder adsorbents and large-size particle adsorbents, the lithium adsorbent in the present application is coated on the surface of the solid bubble with a large specific surface area, which can improve the adsorption performance of the lithium adsorbent for lithium in liquid lithium ore on the one hand, and on the other hand, the density (0.1-0.9 g / cm 3 ) of the solid bubble is lower than that of water, and by limiting the mass ratio (1:0.1-2) of the solid bubble to the lithium adsorbent, the lithium can be floated in the process of extracting lithium from liquid lithium ore, thereby realizing efficient solid-liquid separation to reduce the difficulty of adsorbent recovery; the high mechanical strength and stable material quality endow the adsorbent with excellent cycle stability, which is beneficial to long-term cyclic use in industrial application scenarios.

[0035] It should be noted that in order to ensure that the density is less than water and good mechanical strength and chemical stability are ensured, the solid bubble is one or more of hollow glass beads, hollow glass beads, fly ash floating beads and ceramic bubbles.

[0036] According to some preferred embodiments of the present application, the solid bubble is hollow glass beads, hollow glass beads, fly ash floating beads or ceramic bubbles.

[0037] It should be noted that the particle size of the solid bubble in the present application is 10-1000 μm, which can be 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 850 μm, 900 μm, 1000 μm and the like. Preferably, the material with uniform particle size distribution as much as possible is selected, which is beneficial to form a uniform and complete lithium adsorbent coating layer on the surface thereof, and thus the low-density composite lithium adsorbent prepared can have good dispersibility in use, avoiding agglomeration.

[0038] It should be noted that the compressive strength of the solid bubble in the present application is 1 MPa-200 MPa, which can be 1 MPa, 5 MPa, 10 MPa, 20 MPa, 40 MPa, 60 MPa, 70 MPa, 100 MPa, 120 MPa, 150 MPa, 180 MPa, 200 MPa, and the compressive strength of the solid bubble after loading the active substance is unchanged.

[0039] It should be noted that the surface of the solid bubble in the present application is etched to increase the interface roughness and provide more coating sites for the lithium adsorbent.

[0040] More specifically, the surface of the solid bubble in the present application is etched by a strong alkali solution, which not only increases the interface roughness of the surface of the solid bubble, provides more mechanical sites and is beneficial to the subsequent loading of the lithium adsorbent, but also introduces hydroxyl groups on the surface of the solid bubble, enhances the hydrophilicity and reactivity of the surface, and thus significantly improves the uniformity and stability of the coating of the lithium adsorbent on the surface of the solid bubble.

[0041] It should be noted that in order to ensure that the composite adsorbent has high selectivity, excellent adsorption capacity and fast adsorption kinetics for target lithium ions, the type of the lithium adsorbent coated on the surface of the solid bubble needs to be limited in the present application.

[0042] Specifically, the lithium adsorbent is one of manganese-based ion sieve, titanium-based ion sieve and aluminum-based adsorbent, preferably H2TiO3, λ-MnO2 type ion sieve, .

[0043] It should be noted that the lithium adsorbent coated on the surface of the solid bubble in the present application can be selected and matched according to actual needs and specific conditions (such as pH), which is helpful to further optimize the performance of adsorption and make it better adapt to different aqueous solution environments to realize lithium adsorption.

[0044] In the process of extracting lithium from liquid lithium ore by using the lithium adsorbent, after 8 cycles of adsorption, the overall recoverability of the material is not less than 90%, and the adsorption capacity retention rate thereof can still be maintained at more than 90% relative to the first adsorption, thereby exhibiting excellent recoverability, cycle stability and practical value.

[0045] In a second aspect, the present application provides a preparation method of the low-density composite lithium adsorbent, and the method comprises: (1) performing surface etching on the solid bubble to obtain a surface-roughened solid bubble; (2) mixing the surface-roughened solid bubble with a lithium salt and a metal compound in a solution to form a suspension, and performing an in-situ growth reaction to obtain a lithium adsorbent precursor coated on the surface of the solid bubble; (3) eluting the lithium adsorbent precursor coated on the surface of the solid bubble to obtain a low-density composite lithium adsorbent with the solid bubble as a core and the lithium adsorbent as a shell.

[0046] It should be noted that, in order to etch the surface of the solid bubble while removing oil therefrom, the present application needs to use a strong alkali solution to treat the solid bubble, and the concentration of the strong alkali solution for cleaning and etching is limited.

[0047] Specifically, in step (1), the solid bubble is subjected to surface etching in a strong alkali solution, and the strong alkali solution is a sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 0.5-5.0 mol / L, which can be 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2.0 mol / L, 2.5 mol / L, 3.0 mol / L, 3.5 mol / L, 4.0 mol / L, 4.5 mol / L or 5.0 mol / L. If the concentration of the strong alkali solution is too high, the surface etching will be excessive, which not only damages the surface morphology and structural integrity of the solid bubble, but also reduces the mechanical strength and even causes the particle to break. If the concentration of the strong alkali solution is too low, the surface of the solid bubble cannot be cleaned thoroughly, the etching effect is poor, a long time is required, or the solid bubble cannot be etched.

[0048] In order to promote the etching of the solid bubble by the strong alkali solution, the temperature for etching the solid bubble by the strong alkali solution is controlled to be 20-80℃, which can be 20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃. If the temperature is too low, the etching rate is too slow, but it also cannot be too high, otherwise the strong alkali solution will splash.

[0049] In order to ensure the etching effect, the solution needs to be stirred during the etching process, and the time can be 1-8h, which can be 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h; the etching effect is poor if the time is too short, the roughening treatment degree of the solid bubble surface is not enough, and the solution will damage the structure of the solid bubble surface if the time is too long, which will also affect the subsequent loading of the lithium adsorbent.

[0050] It should be noted that in order to improve the etching effect of the strong alkali solution on the solid bubble under the condition of improving cost and efficiency, the ratio of the strong alkali solution to the solid bubble to be etched needs to be limited.

[0051] Specifically, in step (1), the surface etching is specifically placing the solid bubble in the strong alkali solution at a solid-liquid ratio of 10-100g / L, which can be 10g / L, 20g / L, 30g / L, 40g / L, 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, and stirring.

[0052] It should be noted that in order to remove the residual alkali and moisture on the surface of the material after etching, and obtain the solid bubble which is convenient for subsequent functionalization, the solid bubble after etching needs to be treated.

[0053] Specifically, in step (1), the solid-liquid separation is performed on the etched solution, the floating solid product is washed to neutral with deionized water, and then dried at a temperature of 40-100℃ for 4-12h. Higher drying temperature is beneficial to remove residual moisture, but it cannot be too high, otherwise the surface micro-porous structure may be damaged. It also cannot be too low, otherwise the moisture evaporation rate will be too slow, and the drying will not be complete. Sufficient time is beneficial to moisture evaporation, but it also cannot be too long, otherwise it will lead to low energy efficiency.

[0054] In order to make the lithium adsorbent obtained by reaction be able to be coated on the surface of the etching modified solid bubble, the lithium adsorbent is one of manganese-based ion sieve, titanium-based ion sieve and aluminum-based adsorbent, and the raw material of the lithium adsorbent needs to be limited.

[0055] Specifically, in step (2), the lithium salt is at least one of lithium chloride, lithium nitrate, lithium hydroxide and lithium acetate.

[0056] Specifically, in step (2), the metal compound is at least one of tetrabutyl titanate, titanium isopropyl alcohol, manganese nitrate, manganese acetate tetrahydrate, aluminum chloride and aluminum nitrate.

[0057] In order to ensure the full reaction between raw materials, the molar ratio of lithium ions in the lithium salt to metal ions in the metal compound is 1:(0.5-2), and in actual operation, the ratio of the two needs to be adjusted according to the specific raw materials selected, which can be 1:0.5, 1:1, 1:2.

[0058] It should be noted that in order to control the reaction rate and ensure that the lithium ion sieve with the target crystal form can be uniformly and completely coated on the surface of the solid bubble, and finally obtain a composite adsorbent with high adsorption capacity and excellent stability, the content and ratio of the raw materials in the mixed reaction suspension need to be limited.

[0059] Specifically, in step (2), the mass fraction of the solid bubble in the suspension is 0.5wt%-30wt%, which can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%. If the content of solid bubble is too low, it will significantly reduce the final capacity and increase unnecessary economic cost. If the content is too high, the dispersion in the suspension is uneven and easy to agglomerate, which will affect the uniform coating of lithium adsorbent on its surface and affect the adsorption performance of the final composite material.

[0060] Specifically, in step (2), the mass ratio of the lithium salt to the solid bubble is 1:0.5-30, which can be 1:0.5, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30. If the mass ratio is too high, it will lead to an excessive amount of lithium adsorbent precursor, which is easy to form an excessively thick coating layer or even agglomerate itself, thereby blocking the mass transfer channel and further reducing the lithium adsorption performance. If the mass ratio is too low, it may form a too thin or discontinuous coating layer, which will result in insufficient total adsorption capacity of the composite material.

[0061] It should be noted that in order to adjust the appropriate reaction system to optimize the nucleation and growth process of the lithium adsorbent precursor on the surface of the solid bubble, the solution of mixing each raw material is at least one of deionized water, anhydrous ethanol, hydrogen peroxide, acetic acid, citric acid, and ammonia water. For example, deionized water, deionized water and anhydrous ethanol, anhydrous ethanol and acetic acid, deionized water and hydrogen peroxide, deionized water, citric acid and ammonia water.

[0062] It should be noted that, according to the selection of raw materials, the reaction conditions for in-situ growth on the surface of the solid bubble will be different, which can be a hydrothermal reaction at high temperature, an acid-base neutralization reaction at a lower temperature, etc. For example, when lithium chloride and tetrabutyl titanate are used for in-situ growth reaction on the surface of the solid bubble, a hydrothermal reaction at 160°C is needed to obtain an intermediate, and then high-temperature calcination at 700°C is needed to obtain a lithium titanate precursor, and after elution, a composite lithium adsorbent with solid bubbles as the core and titanium H2TiO3 type ion sieve as the shell is obtained; when lithium nitrate and aluminum nitrate are used for in-situ growth reaction on the surface of the solid bubble, only a co-precipitation reaction under alkaline conditions at 45°C is needed, and after elution, a composite lithium adsorbent with solid bubbles as the core and Li / Al-LDH as the shell is obtained. It should be noted that, in the process of preparing manganese-based adsorbents or titanium-based adsorbents, the intermediate product preliminarily loaded on the surface of the solid bubble after the reaction of the raw materials provided by the present application is obtained, such as Li-Ti-O network structure sol, amorphous lithium manganese oxide; further, after solid-liquid separation, it is further subjected to a series of high-temperature treatment to complete crystallization to obtain a precursor material.

[0063] Specifically, in step (3), the intermediate product preliminarily coated on the surface of the solid bubble prepared by using titanium and manganese metal compounds is calcined, specifically: a calcination temperature of 400-900°C is used for calcination treatment for 4-10 h, the calcination temperature and time are adjusted according to different intermediate products, the calcination temperature cannot be too low, otherwise the raw materials cannot be completely decomposed and converted into a specific crystal phase with lithium adsorption performance, and the calcination temperature cannot be too high, otherwise the product crystal grains will grow excessively or the structure will collapse, the time cannot be too long, which will increase the energy consumption, and the time cannot be too short, which will cause incomplete crystallization and affect the subsequent performance.

[0064] It should be noted that, in order to remove the lithium ions embedded in the composite adsorbent precursor, thereby preparing a material that can selectively embed lithium ions, in step (3), at least one of deionized water, dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid is used to elute the precursor obtained in step (2), and the solid-liquid ratio for the elution is controlled to be 1-50 g / L, which can be 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, or 50 g / L.

[0065] It should be noted that, in order to achieve efficient and thorough acid elution of lithium, the present application needs to control the concentration of the eluent to be 0.1-0.5 mol / L, a too high concentration will cause the skeleton elements to be dissolved and lost, affecting the structural stability and cycle life, and a too low concentration will cause the ion sieve to be completely eluted and the elution time to be too long.

[0066] In order to improve the elution efficiency, the conditions of the elution process are regulated, specifically: the elution temperature is 20-80℃, the elution time is 2-24h, and the stirring speed is 100-600r / min.

[0067] After the elution is completed, the floating solid product is washed to neutral with deionized water through solid-liquid separation, and then dried again to obtain the coated self-floating lithium adsorbent. The drying temperature is 50-80℃, and the drying time is 4-12h.

[0068] In a third aspect, the embodiments of the present application also provide a method for applying the composite lithium adsorbent to extract lithium from liquid lithium ore. The liquid lithium ore includes salt lake brine, underground brine, geothermal brine, etc.

[0069] Compared with the existing powder adsorbent and large-size particle adsorbent, the lithium ion adsorbent of the present application is coated on the surface of the solid bubble substrate with a large specific surface area. On the one hand, in the process of extracting lithium from liquid lithium ore, the solid bubble substrate with a large specific surface area helps to better contact with lithium ions in the solution, thereby improving the mass transfer rate and the adsorption capacity of the lithium adsorbent for lithium in the liquid lithium ore. On the other hand, the density of the solid bubble (0.1-0.9g / cm 3 ) is lower than the density of water, and by limiting the mass ratio of the solid bubble to the lithium ion sieve, the density of the composite lithium adsorbent is less than the density of water, which can float in the process of extracting lithium from liquid lithium ore, thereby realizing efficient solid-liquid separation to reduce the difficulty of adsorbent recovery. In addition, the high mechanical strength and stable material of the solid bubble substrate endow the adsorbent with excellent cycle stability, which is beneficial to long-term cyclic use in industrial application scenarios and reduces the cost of lithium adsorption.

[0070] When the composite lithium adsorbent provided by the present application is applied to the process of extracting lithium from liquid lithium ore, the lithium adsorbent can float on the water surface, which is convenient for solid-liquid separation and recovery. After 8 cycles of adsorption, the overall recoverability of the material is not less than 90%, and the adsorption capacity retention rate is still maintained at more than 90% relative to the first adsorption, which exhibits excellent recyclability, cycle stability and practical value.

[0071] According to some preferred embodiments of the present application, the conditions for applying the solid bubble lithium adsorbent to adsorb and extract lithium from salt lake brine include: the concentration of Li + in the salt lake brine is 0.1-1000 ppm, the pH is 5-12.0, the adsorption temperature is 10-60℃, the time is 1-48h, and the usage of the solid bubble lithium adsorbent is 1-5000g / L.

[0072] The technical solutions of the present application are further explained by specific examples and comparative examples below.

[0073] Example 1 The present embodiment provides a preparation method of a coated self-floating composite lithium adsorbent, which specifically comprises the following steps: (1) 20 g of hollow glass microspheres (density of 0.22 g / cm 3 , median particle size of 88 μm, and compressive strength of 50 MPa) were weighed and placed in a 300 mL sodium hydroxide solution with a concentration of 5 mol / L, stirred at a speed of 200 rpm in a 80°C water bath environment for 2 h, then washed with deionized water until neutral, and dried in an 80°C oven for 12 h after solid-liquid separation; (2) 0.746 g of lithium chloride was weighed and added to 20 mL of deionized water until completely dissolved, and then slowly dropped into a suspension of 3 mL of tetrabutyl titanate, 35 mL of anhydrous ethanol, and 0.5 g of S1 product uniformly mixed at a stirring speed of 400 r / min, and stirred for 30 min, then the suspension was transferred to a 100 mL hydrothermal reactor, and hydrothermal reaction was carried out at 160°C for 12 h; after the reaction was completed, solid-liquid separation was carried out, the floating solid product was washed with deionized water and ethanol three times, dried in a 60°C oven for 8 h, and then placed in a muffle furnace, heated to 700°C at a heating rate of 5°C / min, and calcined for 4 h, to obtain a titanium coated self-floating composite lithium adsorbent precursor; (3) the coated self-floating composite lithium adsorbent precursor was weighed according to a solid-liquid ratio of 20 g / L, placed in a dilute HCl solution with a concentration of 0.1 mol / L for elution treatment to remove lithium ions, the treatment temperature was 60°C, the time was 8 h, and the stirring speed was 400 r / min; after the acid elution treatment was completed, the product was washed with deionized water until the washing liquid was neutral, and then placed in a 50°C oven for drying for 12 h to obtain a titanium coated self-floating composite lithium adsorbent.

[0074] The prepared titanium coated composite lithium adsorbent was subjected to adsorption test, the solutions before and after adsorption were filtered by a 0.45 μm inorganic membrane filter, the lithium ion concentration was determined by ICP-OES, and the adsorption equilibrium capacity was calculated. The adsorption experiment conditions were as follows: the solid-liquid ratio of the composite lithium adsorbent to the lithium-containing solution was 10 mg / mL, the initial concentration of the lithium-containing solution was 100 ppm, the adsorption temperature was 25°C, the pH was 12.0, and the adsorption time was 24 h. According to the calculation of the adsorption capacity of the effective adsorbent, the results showed that the adsorption capacity of the titanium coated self-floating composite lithium adsorbent for lithium was 26.81 mg / g; after washing with water until neutral, the adsorption experiment was repeated to determine the cyclic adsorption performance, and after 8 times of repetition, the overall recovery rate of the material was 99.28%, and the adsorption capacity retention rate relative to the first adsorption was 99.06%.

[0075] Example 2 The embodiment provides a preparation method of a coated self-floating composite lithium adsorbent, and specifically comprises the following steps: (1) 40 g of hollow glass beads (density: 0.11 g / cm 3 , medium particle size: 615 μm, and compressive strength: 1 MPa) are weighed and placed in a 500 mL potassium hydroxide solution with a concentration of 0.5 mol / L, and stirring is performed at a speed of 100 rpm in a 40°C water bath environment for 2 h; after the reaction is completed, solid-liquid separation is performed, the floating solid product is washed to neutral with deionized water, and then is placed in a 100°C oven for drying for 4 h; (2) 2.4 g of lithium acetate dihydrate is weighed and added into 20 mL of ethanol with a concentration of 50%, 2 mL of acetic acid and 1.5 g of S1 product are added dropwise, stirring is performed at a speed of 200 r / min in a 60°C water bath environment, after complete dissolution, 4 mL of a mixed solution of tetrabutyl titanate and 20 mL of anhydrous ethanol is slowly dropped, stirring is performed for 30 min until complete gelation, after standing for 12 h, drying is performed in a 60°C oven for 8 h, then the product is placed in a muffle furnace, and heating is performed at a heating rate of 5°C / min until 750°C, and calcination is performed for 4 h; after the calcination is completed, a titanium coated self-floating composite lithium adsorbent precursor is obtained; (3) according to a solid-liquid ratio of 5 g / L, an appropriate amount of the titanium coated self-floating composite lithium adsorbent precursor is weighed and placed in a dilute H2SO4 solution with a concentration of 0.1 mol / L for elution treatment to remove lithium ions, the treatment temperature is 20°C, the treatment time is 12 h, and the stirring speed is 400 r / min; after the acid elution treatment is completed, the product is washed with deionized water until the washing liquid is neutral; and the product is placed in a 50°C oven for drying for 12 h, and a titanium coated self-floating composite lithium adsorbent is obtained.

[0076] The titanium coated composite lithium adsorbent prepared in the same manner as in Embodiment 1 is subjected to an adsorption test, and the result shows that the adsorption capacity of the titanium coated self-floating composite lithium adsorbent for lithium is 25.54 mg / g; after washing with clean water until neutral, the adsorption experiment is performed again to determine the cyclic adsorption performance, and after 8 times of repetition, the overall recoverability of the material is 98.46%, and the adsorption capacity retention rate is reduced to 98.82% relative to the first adsorption.

[0077] Embodiment 3 The embodiment provides a preparation method of a coated self-floating composite lithium adsorbent, and specifically comprises the following steps: (1) 20 g of hollow glass beads (density: 0.85 g / cm 3, the median particle size is 90 μm, and the compressive strength is 200 MPa) is placed in a 1000 mL sodium hydroxide solution with a concentration of 0.6 mol / L, stirred at a speed of 400 rpm in a 60°C water bath environment for 4 h, washed with deionized water until neutral after solid-liquid separation, and then placed in a 40°C oven for drying for 12 h; (2) 0.2 g of lithium hydroxide monohydrate is dissolved in 1.8 mL of a mixed solution of hydrogen peroxide and 25 mL of deionized water until completely dissolved, and then added dropwise to a uniformly mixed suspension of 1 g of S1 product, 1.8 g of manganese nitrate and 25 mL of deionized water under continuous stirring at 300 r / min, and stirred for 20 min, and then poured into a 100 mL hydrothermal reaction kettle, and hydrothermal reaction is carried out at 150°C for 8 h. After the reaction is completed, solid-liquid separation is carried out, the floating solid product is washed with deionized water and ethanol three times, dried in a 70°C oven for 8 h, and then placed in a muffle furnace, and heated to 800°C at a heating rate of 5°C / min and calcined for 5 h, and the manganese-coated self-floating composite lithium adsorbent precursor is obtained after calcination. (3) A certain amount of manganese-coated self-floating composite lithium adsorbent precursor is weighed according to a solid-liquid ratio of 20 g / L and placed in a 0.5 mol / L dilute HCl solution for elution treatment to remove lithium ions, the treatment temperature is 30°C, the treatment time is 4 h, and the stirring speed is 200 r / min. After acid elution treatment, the product is washed with deionized water until the washing liquid is neutral. It is placed in a 80°C oven for drying for 4 h to obtain a manganese-coated self-floating composite lithium adsorbent.

[0078] The manganese-coated self-floating composite lithium adsorbent prepared in the same manner as in Example 1 is subjected to adsorption test, and the results show that the adsorption capacity of the manganese-coated self-floating composite lithium adsorbent for lithium is 21.81 mg / g. After washing with clean water until neutral, the adsorption performance is determined again, and after 8 times of recycling, the overall recovery rate of the material is 98.81%, and the adsorption capacity retention rate is 97.68% relative to the first adsorption.

[0079] Example 4 The embodiment provides a preparation method of a coated self-floating composite lithium adsorbent, which specifically comprises the following steps: (1) 30 g of fly ash floating beads (density 0.49 g / cm 3 , median particle size 758 μm, and compressive strength 60 MPa) are placed in a 400 mL potassium hydroxide solution with a concentration of 2.5 mol / L, stirred at a speed of 200 rpm in a 40°C water bath environment for 6 h, washed with deionized water until neutral after solid-liquid separation, and then placed in an 80°C oven for drying for 6 h. (2) 12 mL of manganese nitrate (50%) and 1.77 g of lithium nitrate were measured and added to 100 mL of deionized water, and stirred at 100 r / min in a water bath environment at 75°C, completely dissolved, then 5 g of S1 product and 11.33 mL of citric acid were added, and concentrated ammonia water with a concentration of 28% was added to adjust the pH to 7, and after the sol was formed after reacting for 2 h, it was placed in an oven at 80°C for drying for 8 h, then it was placed in a muffle furnace, and the temperature was increased to 700°C at a rate of 5°C / min, and calcined for 8 h, after the calcination was completed, the product was washed with deionized water and ethanol for three times, and after the solid-liquid separation, the floating solid product was dried in an oven at 80°C for 8 h, to obtain a manganese-coated self-floating composite lithium adsorbent precursor; (3) The manganese-coated self-floating composite lithium adsorbent precursor was weighed according to a solid-liquid ratio of 10 g / L and placed in a 0.2 mol / L dilute HNO3 solution for elution treatment to remove lithium ions, the treatment temperature was 25°C, the time was 24 h, and the stirring speed was 200 r / min. After the acid elution treatment was completed, the product was washed with deionized water until the washing liquid was neutral. It was placed in a 60°C oven and dried for 6 h to obtain a manganese-coated self-floating composite lithium adsorbent.

[0080] The manganese-coated composite lithium adsorbent prepared was subjected to adsorption test by the same method as in Example 1, except that the adsorption time was 12 h, and the results showed that the adsorption capacity of the manganese-coated self-floating composite lithium adsorbent for lithium was 19.65 mg / g. After washing with water to neutral, the adsorption experiment was repeated for the cycle adsorption performance, and after 8 times, the overall recoverability of the material was 99.07%, and the adsorption capacity retention rate was 97.79% relative to the first adsorption.

[0081] Example 5 (1) 20 g of ceramic bubbles (density 0.75 g / cm 3 , median particle size 1000 μm, compressive strength 5 MPa) were weighed and placed in a 2000 mL sodium hydroxide solution with a concentration of 2.0 mol / L, and stirred at a speed of 50 rpm in a water bath environment at 20°C for 8 h, after the reaction was completed, the solid-liquid separation was carried out, and the floating solid product was washed with deionized water to neutral, and then placed in a 60°C oven for drying for 10 h; (2) Take 1.387 g of lithium nitrate and 4 g of aluminum nitrate nonahydrate and add them to 20 mL of deionized water, stir at 100 r / min in a water bath environment at 45°C, after complete dissolution, add 10 g of S1 product, drop sodium hydroxide solution into the suspension under stirring until the pH rises to 6.0, stir for 1 h, then age the product for 24 h, then wash the product, dry it in an oven at 60°C for 8 h, and the aluminum-coated self-floating composite lithium adsorbent precursor is obtained; (3) Take an appropriate amount of aluminum-coated composite lithium adsorbent precursor according to a solid-liquid ratio of 2 g / L and place it in deionized water for elution treatment to remove lithium ions, the treatment temperature is 40°C, the time is 24 h, and the stirring speed is 600 r / min. The product floating on the surface is taken out and dried in a 60°C oven for 6 h to obtain the aluminum-coated composite lithium adsorbent.

[0082] The prepared manganese-coated composite lithium adsorbent is subjected to adsorption test by the same method as in Example 1, except that the pH is 7.0. The results show that the adsorption capacity of the aluminum-coated self-floating composite lithium adsorbent for lithium is 7.87 mg / g. After washing with water to neutral, the adsorption experiment is carried out again to determine the cyclic adsorption performance. After 8 times of repetition, the overall recovery rate of the material is 98.68%, and the adsorption capacity retention rate relative to the first adsorption is 97.12%.

[0083] Example 6 The present comparative example provides a preparation method of a coated self-floating composite lithium adsorbent, which specifically comprises the following steps: (1) Weigh 20 g of hollow glass beads (density 0.22 g / cm3, median particle size 88 μm, compressive strength 50 MPa) and place them in a 300 mL solution of sodium hydroxide with a concentration of 1.0 mol / L, stir at a speed of 200 rpm in a water bath environment at 80°C for 2 h, separate the solid and liquid, then wash with deionized water until neutral, and dry in an oven at 80°C for 12 h.

[0084] (2) Take 0.746 g of lithium chloride and add it to 20 mL of deionized water until it is completely dissolved, slowly drop it into 3 mL of tetrabutyl titanate, 35 mL of anhydrous ethanol, and 0.5 g of hollow glass beads (density 0.22 g / cm 3, the medium particle size is 88 μm) are uniformly mixed, the suspension is transferred to a 100 mL hydrothermal reactor after stirring for 30 min, and a hydrothermal reaction is carried out at 160℃ for 12 h. After the reaction is completed, solid-liquid separation is carried out, the floating solid product is washed with deionized water and ethanol three times, and is placed in a muffle furnace after being dried in a 60℃ oven for 8 h, and is heated to 600℃ at a heating rate of 5℃ / min and calcined for 4 h. The titanium-based coated self-floating composite lithium adsorbent precursor is obtained after calcination is completed; (3) The coated self-floating composite lithium adsorbent precursor is weighed according to a solid-liquid ratio of 20 g / L and is placed in a 0.1 mol / L dilute HCl solution for elution treatment to remove lithium ions, the treatment temperature is 60℃, the time is 8 h, and the stirring speed is 400 r / min. After acid elution treatment is completed, the product is washed with deionized water until the washing liquid is neutral. The coated self-floating composite lithium adsorbent is obtained after being placed in a 50℃ oven and dried for 12 h.

[0085] The titanium-based coated composite lithium adsorbent prepared is subjected to adsorption test by using the same method as in Example 1. The results show that the adsorption capacity of the titanium-based coated self-floating composite lithium adsorbent for lithium is 20.81 mg / g. After washing with clean water to neutral, the adsorption experiment is carried out again to determine the cyclic adsorption performance. After repeating 8 times, the overall recoverability of the material is 98.73%, and the adsorption capacity retention rate is 96.26% relative to the first adsorption.

[0086] Comparative Example 1 The present comparative example provides a preparation method of a titanium-based composite lithium adsorbent, specifically comprising the following steps: (1) 0.8 g of lithium chloride is weighed and added to 20 mL of deionized water until completely dissolved, and is slowly dropped into 3 mL of tetrabutyl titanate dissolved in 35 mL of anhydrous ethanol at a stirring speed of 400 r / min. After stirring for 30 min, the mixed solution is transferred to a 100 mL hydrothermal reactor, and a hydrothermal reaction is carried out at 160℃ for 12 h. After the reaction is completed, the product is washed with deionized water and ethanol three times, and is placed in a muffle furnace after being dried in a 60℃ oven for 8 h, and is heated to 500℃ at a heating rate of 5℃ / min and calcined for 4 h. The product is washed with deionized water and ethanol three times after calcination is completed, and is dried in a 60℃ oven for 8 h. The titanium-based lithium adsorbent precursor is obtained. (2) The prepared titanium-based composite lithium adsorbent precursor was placed in a 0.2 mol / L dilute HCl solution for elution treatment to remove lithium ions at a solid-liquid ratio of 5 g / L, a treatment temperature of 25°C, a treatment time of 12 h, and a stirring speed of 200 r / min. After the acid elution treatment, the product was washed with deionized water until the washing liquid was neutral. The product was placed in a 60°C oven for drying to obtain the titanium-based lithium adsorbent.

[0087] The prepared titanium-based coated composite lithium adsorbent was subjected to an adsorption test by using the same method as in Example 1. The results showed that the adsorption capacity of the titanium-based lithium adsorbent for lithium was 24.83 mg / g. After washing with clean water until neutral, the lithium adsorbent was subjected to an adsorption test again to determine the cyclic adsorption performance. After 8 repetitions, the overall recoverability of the material was 72.62%, and the adsorption capacity retention rate relative to the first adsorption was reduced to 87.26%.

[0088] Comparative Example 2 The present comparative example provides a preparation method of a manganese-based composite lithium adsorbent, specifically comprising the following steps: (1) 3.52 g of lithium hydroxide monohydrate was dissolved in a mixed solution of 1.2 mL of hydrogen peroxide and 30 mL of deionized water until completely dissolved, and then the solution was added dropwise to a uniformly mixed suspension of 4.30 g of manganese nitrate and 30 mL of deionized water under continuous stirring at 300 r / min. After stirring for 20 min, the mixture was poured into a 100 mL hydrothermal reactor, and hydrothermal reaction was carried out at 120°C for 12 h. After the reaction was completed, solid-liquid separation was performed, and the solid product was washed with deionized water and ethanol three times. After drying in a 70°C oven for 8 h, the product was placed in a muffle furnace and calcined at a temperature increasing rate of 5°C / min to 800°C for 5 h. The manganese-based lithium adsorbent precursor was obtained after calcination. (2) An appropriate amount of the manganese-based lithium adsorbent precursor was placed in a 0.5 mol / L dilute HCl solution for elution treatment to remove lithium ions at a solid-liquid ratio of 20 g / L, a treatment temperature of 30°C, a treatment time of 4 h, and a stirring speed of 200 r / min. After the acid elution treatment, the product was washed with deionized water until the washing liquid was neutral. The product was dried in an 80°C oven for 4 h to obtain the manganese-based composite lithium adsorbent.

[0089] The prepared manganese-based coated composite lithium adsorbent was subjected to an adsorption test by using the same method as in Example 3. The results showed that the adsorption capacity of the manganese-based lithium adsorbent for lithium was 18.78 mg / g. After 8 repetitions, the overall recoverability of the material was 70.83%, and the adsorption capacity retention rate relative to the first adsorption was reduced to 85.18%.

[0090] Comparative Example 3 (1) Take 3.7 g of lithium nitrate and 10 g of aluminum nitrate nonahydrate into 40 mL of deionized water, stir at 100 r / min in a water bath environment at 45°C, and after complete dissolution, add sodium hydroxide solution dropwise to the suspension until the pH rises to 6.0, stir for 1 h, then age the product for 24 h, then wash the product, and dry it in an oven at 60°C for 8 h to obtain an aluminum-based lithium adsorbent precursor.

[0091] (2) Take an appropriate amount of aluminum-based lithium adsorbent precursor according to a solid-liquid ratio of 2 g / L, and place it in deionized water for elution treatment to remove lithium ions, the treatment temperature is 40°C, the time is 24 h, and the stirring speed is 600 r / min. After the reaction is completed, perform solid-liquid separation, place the floating solid product in a 60°C oven for drying for 6 h to obtain an aluminum-based lithium adsorbent.

[0092] The prepared aluminum-based coated composite lithium adsorbent was subjected to adsorption test by the same method as in Example 5. The results showed that the adsorption capacity of the aluminum-based adsorbent for lithium was 6.95 mg / g, and after 8 cycles, the overall recoverability of the material was 68.57%, and the adsorption capacity retention rate relative to the first adsorption was reduced to 85.20%.

[0093] Comparative Example 4 The same method as in Actual Example 1 was used, except that step (1) was not included, and finally a titanium-based composite lithium adsorbent was obtained.

[0094] The prepared titanium-based coated composite lithium adsorbent was subjected to adsorption test by the same method as in Example 1, and the results showed that the adsorption capacity for lithium was 24.81 mg / g. After washing with water to neutral, the adsorption performance was measured again by cyclic adsorption experiment, and after 8 cycles, the overall recoverability of the material was 85.62%, and the adsorption capacity retention rate relative to the first adsorption was reduced to 76.26%.

[0095] Comparative Example 5 The same method as in Actual Example 1 was used, except that in step (1), the amount of lithium chloride added was 1.592 g, and the amount of tetrabutyl titanate used was 6 mL, and finally a titanium-based composite lithium adsorbent was obtained.

[0096] The prepared titanium-based coated composite lithium adsorbent was subjected to adsorption test by the same method as in Example 1, and the results showed that the adsorption capacity for lithium was 18.93 mg / g. After washing with water to neutral, the adsorption performance was measured again by cyclic adsorption experiment, and after 8 cycles, the overall recoverability of the material was 88.32%, and the adsorption capacity retention rate relative to the first adsorption was reduced to 88.34%.

[0097] The prepared coated composite lithium adsorbent takes solid bubbles as a substrate, and the powder composite lithium adsorbent is coated on the substrate by in-situ synthesis. The yield of lithium ion adsorbent precursor is calculated by the amount of lithium salt and metal compound, and the theoretical loading amount of the precursor in the product is calculated according to the percentage, and the lithium adsorption capacity of the loaded composite lithium adsorbent is converted for comparison and analysis. Figure 2 The data of the adsorption capacity of the prepared examples 1, 3, 5 and the adsorption capacity of the comparative examples 1, 2, 3 are compared. Through Figure 2 It can be seen that the adsorption capacity of the coated composite lithium adsorbent is higher than that of the prepared powder composite lithium adsorbent, and the adsorption capacity is increased by 8%. The powder composite lithium adsorbent is uniformly coated on the surface of the hollow bubble by in-situ growth to form a core-shell structure, which not only realizes the uniform distribution of the adsorbent, but also further increases the effective specific surface area. This helps to improve the lithium ion transmission path, reduce the surface adsorption accumulation, weaken the mass transfer resistance between lithium ions and adsorption sites, and further improve the lithium adsorption performance.

[0098] Figure 3 The lithium ion adsorption capacity of the samples prepared in example 1 and comparative example 1 changes with time. As can be seen from the figure, the adsorption capacity of the samples of example 1 and comparative example 1 gradually increases with time. In the initial stage of adsorption, the sample surface has more adsorption sites, which can quickly adsorb free lithium ions in the aqueous phase. The adsorption kinetics of the sample is analyzed by using the pseudo-second-order kinetics equation, and the related parameters are listed in table 1. The rate constant K2: example 1> comparative example 1, the sample of example 1 shows a relatively fast adsorption rate. The sample of example 1 has good dispersibility due to the microspherical morphology of the solid bubble, which helps to realize uniform distribution in the aqueous phase, so as to realize more efficient contact with lithium ions, and therefore shows a relatively fast adsorption rate.

[0099] Table 1 Pseudo-second-order adsorption kinetics fitting parameters

[0100] Comparative example 4 omits the alkali treatment process in step (1), and through comparative analysis, it can be seen that the sample of example 1 obtained after alkali treatment shows higher recoverability and better adsorption performance. Alkali treatment not only can clean the surface, but also can increase the reaction activity by introducing hydroxyl group, so as to help to build a stable active material layer on the surface of the solid bubble, and thus greatly improve the structural integrity and adsorption performance of the final composite adsorbent.

[0101] In Comparative Example 5, the ratio of the key raw materials is changed, and the increase of lithium salt and metal salt should increase the proportion of active material in the composite lithium adsorbent, but the adsorption capacity (18.93 mg / g) does not increase but decreases. This is because the excess adsorbent causes the shell to be too thick, thereby blocking the adsorption sites, causing the adsorption performance to decrease.

[0102] The present application uses a solid bubble as a substrate to combine the preparation of the powder adsorbent, thereby preparing a coated self-floating composite lithium adsorbent, which effectively improves the recyclability of the composite lithium adsorbent, reduces the difficulty of solid-liquid recovery, avoids material loss in subsequent cyclic use, and provides certain mechanical strength, improves the stability and service life of the formed material, and is conducive to long-term cyclic use in industry.

[0103] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A low density composite lithium adsorbent, characterized by, The composite lithium adsorbent has a core-shell structure, the core is a solid bubble substrate with a density of 0.1-0.9 g / cm 3 0.1-0.9 g / cm3, and the shell is a lithium adsorbent, wherein the mass ratio of the solid bubble to the lithium adsorbent is 1:0.1-2.

2. The composite lithium adsorbent of claim 1, wherein, The solid bubbles are one or more of hollow glass beads, hollow glass microspheres, fly ash floating beads, and ceramic bubbles. The particle size of the solid bubbles is 10-1000 μm, and the compressive strength is 1-200 MPa.

3. The composite lithium adsorbent of claim 1, wherein, The lithium adsorbent is one of manganese-based ion sieve, titanium-based ion sieve, and aluminum-based adsorbent.

4. A process for the production of a low density composite lithium adsorbent as claimed in any one of claims 1 to 3, characterised in that, The method comprises: (1) etching the surface of the solid bubbles to obtain surface-roughened solid bubbles; (2) mixing the surface-roughened solid bubbles with lithium salt and metal compound in a solution to form a suspension, and performing in-situ growth reaction to obtain lithium adsorbent precursor coated on the surface of the solid bubbles; (3) eluting the lithium adsorbent precursor coated on the surface of the solid bubbles to obtain low-density composite lithium adsorbent with the solid bubbles as the core and the lithium adsorbent as the shell.

5. The method of claim 4, wherein, In step (1), the surface of the solid bubbles is etched in a strong alkali solution, which is sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 0.5-5 mol / L.

6. The method of claim 5, wherein, The surface etching is specifically placing the solid bubbles in the strong alkali solution at a solid-liquid ratio of 10-100 g / L and stirring.

7. The method of claim 4, wherein, In step (2), the lithium salt is at least one of lithium chloride, lithium nitrate, lithium hydroxide, and lithium acetate; and / or the metal compound is at least one of tetrabutyl titanate, titanium isopropoxide, manganese nitrate, manganese acetate tetrahydrate, aluminum chloride, and aluminum nitrate; and / or the molar ratio of lithium ions in the lithium salt to metal ions in the metal compound is 1:(0.5-2).

8. The method of claim 4, wherein, In step (2), the mass ratio of the lithium salt to the solid bubbles is 1:0.5-30; and / or the mass fraction of the solid bubbles in the suspension is 0.5wt%-30wt%.

9. The method of claim 4, wherein, In step (3), at least one of deionized water, dilute hydrochloric acid, dilute nitric acid, and dilute sulfuric acid is used to elute the precursor obtained in step (2), wherein the solid-liquid ratio of the elution is 1-50 g / L; and / or the lithium adsorbent is one of manganese-based ion sieve, titanium-based ion sieve, and aluminum-based adsorbent.

10. Application of the composite lithium adsorbent of any one of claims 1-3 or the composite lithium adsorbent prepared by the method of any one of claims 4-9 to extraction of lithium from liquid lithium ore.

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