Process for the preparation of lithium adsorbent and process for the extraction of lithium

Abstract

The application provides a preparation method of a lithium adsorbent, comprising the following steps: providing first particles, the first particles comprising magnetic particles and a first inorganic substance loaded on the surface of the magnetic particles, the first inorganic substance being a lithium source or an aluminum source; mixing the first particles with a solution containing a second inorganic substance, the second inorganic substance being a lithium source or an aluminum source, and the first inorganic substance being different from the second inorganic substance, to obtain second particles after reaction; placing the second particles in a solution containing the first inorganic substance and the second inorganic substance, to obtain precursor particles after reaction; and placing the precursor particles in an acidic solution, to obtain the lithium adsorbent after reaction, the lithium adsorbent comprising the magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the material of the lithium adsorption layer comprising LiX·2Al(OH)3·nH2O, X being an acid radical ion in the acidic solution. The preparation method is simple in operation, high in preparation efficiency, and can prepare the lithium adsorbent with good coating effect. The application further provides a method for extracting lithium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium extraction, in particular to a preparation method of lithium adsorbent and a method for extracting lithium. BACKGROUND

[0002] Lithium has important applications in the fields of electronics, metallurgy, chemical industry, medicine, etc. Lithium mainly exists in lithium ore, salt lake brine, geothermal brine and seawater in nature. For liquid lithium resources (salt lake brine, geothermal brine and seawater), adsorbent method can be used to extract lithium. However, the coating effect of the lithium adsorption layer in the current lithium adsorbent is not good, which affects the adsorption effect and service life of the lithium adsorbent, and is not conducive to the extraction of lithium. SUMMARY

[0003] Therefore, the present application provides a preparation method of lithium adsorbent, which is simple in operation, high in preparation efficiency, can prepare lithium adsorbent with good coating effect, and reduces the cost of lithium extraction.

[0004] In a first aspect, the present application provides a preparation method of lithium adsorbent, comprising: providing first particles, the first particles comprising magnetic particles and a first inorganic substance loaded on the surface of the magnetic particles, the first inorganic substance being a lithium source or an aluminum source; mixing the first particles with a solution containing a second inorganic substance, and obtaining second particles after reaction, the second inorganic substance being the lithium source or the aluminum source, and the first inorganic substance and the second inorganic substance being different; placing the second particles in a solution containing the first inorganic substance and the second inorganic substance, and obtaining precursor particles after reaction; placing the precursor particles in an acidic solution, and obtaining lithium adsorbent after reaction, the lithium adsorbent comprising the magnetic particles and a lithium adsorption layer wrapping the magnetic particles, and the material of the lithium adsorption layer comprising LiX·2Al(OH)3·nH2O, X being an acid radical ion in the acidic solution.

[0005] Optionally, the second particles are placed in a solution containing the first inorganic substance and the second inorganic substance to obtain precursor particles after reaction, comprising: placing the second particles in a solution containing the first inorganic substance to form a mixed system; adding a solution containing the second inorganic substance to the mixed system to obtain the precursor particles after reaction.

[0006] Further, the solid-liquid ratio of the second particles and the solution containing the first inorganic substance is 1g:(10-500)mL.

[0007] Further, the concentration of the solution containing the first inorganic substance is 0.5mol / L-5mol / L.

[0008] Further, the reaction time of the second particles and the solution containing the first inorganic substance is 10min-120min.

[0009] Further, the concentration of the solution containing the second inorganic substance is 0.5-5 mol / L.

[0010] Further, the adding speed of the solution containing the second inorganic substance is 20-5000 mL / min.

[0011] Further, the molar ratio of lithium element to aluminum element in the solution containing the first inorganic substance and the solution containing the second inorganic substance is 0.5-0.75.

[0012] Optionally, the providing the first particles comprises mixing the magnetic particles with the solution containing the first inorganic substance, and obtaining the first particles after standing.

[0013] Further, the magnetic particles are placed in the solution containing the first inorganic substance at a solid-liquid ratio of 1 g:(10-500) mL, stirred at a speed of 100-1000 rpm for 10-120 min, and the first particles are separated after standing for 1-24 h, and the concentration of the solution containing the first inorganic substance is 0.5-5 mol / L.

[0014] Further, the solution containing the first inorganic substance is gradually added to the magnetic particles, and the first particles are separated after standing for 1-24 h, and the mass ratio of the magnetic particles to the adding amount of the solution containing the first inorganic substance is 1 g:(10-50) mL.

[0015] Optionally, the magnetic particles and the first inorganic substance are mixed, and the first particles are obtained after grinding.

[0016] Further, the magnetic particles and the first inorganic substance are mixed at a mass ratio of 1:(1-50), and the first particles are separated after grinding at a speed of 50-300 rpm for 30-300 min.

[0017] Optionally, the precursor particles are obtained by further comprising an aging treatment, and the aging treatment comprises standing at 5-30℃ for 1-24 h.

[0018] Optionally, the lithium source comprises at least one of lithium salt and lithium hydroxide.

[0019] Optionally, the aluminum source comprises at least one of aluminum salt and met aluminates.

[0020] Optionally, the lithium adsorbent has an adsorption capacity greater than or equal to 7 mg / g at the 50th cycle.

[0021] Optionally, the lithium adsorbent has a weight loss rate of less than or equal to 0.06% after 50 cycles.

[0022] Optionally, the magnetic particles have a particle size of 20 nm to 100 μm.

[0023] Optionally, the lithium adsorbent has a particle size of 0.2 μm to 0.2 mm.

[0024] In the preparation method of the lithium adsorbent provided in the present application, the first inorganic substance loaded on the surface of the magnetic particles reacts with the second inorganic substance to form a crystal seed, thereby facilitating the preparation of the precursor particles and helping to improve the coating rate of the lithium adsorption layer on the surface of the magnetic particles, and thus improving the adsorption effect and service life of the lithium adsorbent. Meanwhile, the preparation method is simple to operate and has a high preparation efficiency, which is conducive to the use of the lithium adsorbent.

[0025] In a second aspect, the present application provides a method for extracting lithium, which comprises placing the lithium adsorbent prepared by the preparation method of the first aspect in a lithium-containing solution to adsorb lithium, obtaining a lithium-enriched adsorbent; separating the lithium-enriched adsorbent and desorbing lithium ions in the lithium-enriched adsorbent.

[0026] The method for extracting lithium provided in the present application is simple to operate and has a high adsorption efficiency, and has a good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The preparation method of the lithium adsorbent provided in an embodiment of the present application is shown in the flowchart.

[0028] Figure 2 The preparation method of the lithium adsorbent provided in another embodiment of the present application is shown in the flowchart.

[0029] Figure 3 The preparation method of the lithium adsorbent provided in yet another embodiment of the present application is shown in the flowchart.

[0030] Figure 4 The preparation method of the lithium adsorbent provided in yet another embodiment of the present application is shown in the flowchart.

[0031] Figure 5 The preparation method of the lithium adsorbent provided in yet another embodiment of the present application is shown in the flowchart. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present application.

[0033] Referring to Figure 1 A flow chart of a method for preparing a lithium adsorbent according to an embodiment of the present application is shown in FIG. 1, which includes the following steps:

[0034] S101: providing first particles, the first particles including magnetic particles and first inorganic matter loaded on the surface of the magnetic particles, the first inorganic matter being a lithium source or an aluminum source.

[0035] S102: mixing the first particles with a solution containing second inorganic matter, the second inorganic matter being a lithium source or an aluminum source, and the first inorganic matter and the second inorganic matter being different.

[0036] S103: placing the second particles in a solution containing the first inorganic matter and the second inorganic matter, and obtaining precursor particles after reaction.

[0037] S104: placing the precursor particles in an acidic solution, and obtaining lithium adsorbent after reaction, the lithium adsorbent including magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the material of the lithium adsorption layer including LiX·2Al(OH)3·nH2O, X being an acid radical ion in the acidic solution.

[0038] In the present application, the magnetic particles loaded with the first inorganic matter are reacted with the second inorganic matter to obtain second particles with crystal seeds, so that when the second particles are placed in the solution containing the first inorganic matter and the second inorganic matter, the first inorganic matter and the second inorganic matter can react and deposit on the surface of the crystal seeds, thereby improving the coating rate of the coating layer in the precursor and further improving the coating effect of the lithium adsorption layer on the surface of the magnetic particles, which is conducive to the use of the lithium adsorbent. In related technologies, a dispersant needs to be added during the preparation of the lithium adsorbent to ensure the uniform distribution of the magnetic particles and improve the coating effect. In the present application, the crystal seeds are prepared to improve the coating effect of the coating layer in the precursor, thereby avoiding the use of the dispersant and introducing impurities into the lithium adsorption layer, and improving the adsorption effect of the lithium adsorbent.

[0039] In S101, the first particles include magnetic particles and first inorganic matter loaded on the surface of the magnetic particles, the first inorganic matter being a lithium source or an aluminum source.

[0040] In the present application, the magnetic particles have magnetism, thereby facilitating the separation and screening of the particles in the preparation process and the use process. In the embodiments of the present application, the magnetic particles include at least one of elemental iron, iron alloy, iron-containing compound, iron-containing intermetallic compound, elemental cobalt, cobalt alloy, cobalt-containing compound, cobalt-containing intermetallic compound, elemental nickel, nickel alloy, nickel-containing compound, and nickel-containing intermetallic compound. Specifically, the iron-containing compound can include, but is not limited to, ferrite. The magnetic particles can be, but are not limited to, non-porous particles, porous particles, etc., and the size of the magnetic particles is selected as required. In the related art, in order to improve the coating effect, nano-sized magnetic particles need to be selected; in the present application, since the crystal seeds are prepared first and then the coating layer is formed, the coating effect of the coating layer is improved, and thus the size of the magnetic particles is not particularly required, and nano-sized, micro-sized, or even millimeter-sized magnetic particles are all suitable for the preparation of the lithium adsorbent of the present application. In the embodiments of the present application, the particle size of the magnetic particles is 20 nm to 100 μm. The magnetic particles with the above particle size can improve the saturation magnetization of the lithium adsorbent, thereby facilitating the rapid separation of the particles by the magnetic separation method, and the specific surface area of the magnetic particles with the above particle size is appropriate, thereby facilitating the coating of the lithium adsorption layer. Specifically, the particle size of the magnetic particles can be, but is not limited to, 20 nm, 200 nm, 800 nm, 1 μm, 10 μm, 30 μm, 50 μm, 80 μm, or 100 μm, etc. In an embodiment, the particle size of the magnetic particles is less than 1 μm. In another embodiment, the particle size of the magnetic particles is 1 μm to 10 μm. In yet another embodiment, the particle size of the magnetic particles is 10 μm to 50 μm. In yet another embodiment, the particle size of the magnetic particles is 50 μm to 100 μm.

[0041] In the present application, the first inorganic substance is a lithium source or an aluminum source. In an embodiment of the present application, the lithium source includes at least one of lithium salt and lithium hydroxide. In an embodiment, the lithium salt includes at least one of lithium chloride, lithium sulfate, lithium nitrate, and lithium acetate. In an embodiment of the present application, the aluminum source includes at least one of aluminum salt and meta-aluminate. In an embodiment, the aluminum salt includes at least one of aluminum chloride, aluminum sulfate, and aluminum nitrate. In another embodiment, the meta-aluminate includes at least one of sodium meta-aluminate and potassium meta-aluminate. It can be understood that when the solution containing the first inorganic substance is used in the preparation method, the inorganic substance needs to be selected as a soluble lithium source or aluminum salt; in the present application, the solution containing the first inorganic substance can be, but is not limited to, an aqueous solution.

[0042] In S102, the first particles are mixed with a solution containing the second inorganic substance. Since the first inorganic substance and the second inorganic substance are different, the first inorganic substance loaded on the surface of the first particles can react with the second inorganic substance after mixing to generate LiOH·2Al(OH)3·nH2O. That is, the second particles include magnetic particles and LiOH·2Al(OH)3·nH2O loaded on the surface of the magnetic particles; further, the surface of the magnetic particles also loads the second inorganic substance. It can be understood that the first inorganic substance and the second inorganic substance are different, which means that when the first inorganic substance is a lithium source, the second inorganic substance is an aluminum source; when the first inorganic substance is an aluminum source, the second inorganic substance is a lithium source.

[0043] In an embodiment of the present application, the first inorganic substance is a lithium salt, and the second inorganic substance is a meta-aluminate. In another embodiment of the present application, the first inorganic substance is lithium hydroxide, and the second inorganic substance is an aluminum salt. The lithium salt and the aluminum salt need to react with a base to generate a lithium adsorption layer, or the aluminum salt reacts with a base and then reacts with a lithium salt or lithium hydroxide to obtain a precursor or a lithium adsorption layer, or the meta-aluminate reacts with an acid and then reacts with a lithium salt or lithium hydroxide to obtain a precursor or a lithium adsorption layer. The above process introduces other substances or cannot obtain the required precursor or lithium adsorption layer through one-step reaction, and the preparation process is affected by the addition sequence, the addition concentration, the strength of the base, the reaction temperature, the pH, and other conditions. The reaction is difficult to control, the reaction efficiency is low, and the intercalation reaction efficiency of the lithium salt and the aluminum hydroxide is low, resulting in a low adsorption capacity of the prepared lithium adsorbent. The above method provided by the present application can obtain LiOH·2Al(OH)3·nH2O through one-step precipitation, has small influence on the addition sequence and reaction conditions, is controllable, simple to operate, and has high reaction efficiency, which is conducive to the coating of LiOH·2Al(OH)3·nH2O, and is conducive to the preparation of the precursor and the lithium adsorbent, and improves the coating effect and the adsorption capacity of the lithium adsorbent. In an embodiment, the first particles include magnetic particles and a lithium salt loaded on the surface of the magnetic particles, and the second inorganic substance is a meta-aluminate. In another embodiment, the first particles include magnetic particles and lithium hydroxide loaded on the surface of the magnetic particles, and the second inorganic substance is an aluminum salt. In yet another embodiment, the first particles include magnetic particles and a meta-aluminate loaded on the surface of the magnetic particles, and the second inorganic substance is a lithium salt. In yet another embodiment, the first particles include magnetic particles and an aluminum salt loaded on the surface of the magnetic particles, and the second inorganic substance is lithium hydroxide.

[0044] In an embodiment of the present application, the first particles are placed in a solution containing the second inorganic substance, and after stirring and mixing, the second particles are obtained by standing. In an embodiment, the concentration of the solution containing the second inorganic substance is 0.5 mol / L to 5 mol / L. The above concentration is conducive to the reaction of the first inorganic substance and the second inorganic substance on the magnetic surface. Specifically, the concentration of the solution containing the second inorganic substance can be, but is not limited to, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, etc. In an embodiment, the solid-liquid ratio of the first particles and the solution containing the second inorganic substance is 1 g:(10-500) mL. The above solid-liquid ratio is conducive to the reaction of the first inorganic substance and the second inorganic substance. Specifically, the solid-liquid ratio of the first particles and the solution containing the second inorganic substance can be, but is not limited to, 1 g:50 mL, 1 g:100 mL, 1 g:200 mL, 1 g:300 mL, 1 g:400 mL, or 1 g:500 mL, etc. In an embodiment, the stirring includes stirring at a speed of 100 rpm to 1000 rpm for 10 min to 120 min. The above stirring allows the first particles and the second inorganic substance in the solution to be in sufficient contact and react, which is conducive to the generation of the crystal seeds. Specifically, the stirring speed can be, but is not limited to, 100 rpm, 200 rpm, 500 rpm, 700 rpm, 900 rpm, or 1000 rpm, etc., and the stirring time can be, but is not limited to, 10 min, 20 min, 40 min, 50 min, 70 min, 90 min, 100 min, or 110 min, etc. In an embodiment, the standing time is 1 h to 24 h. The standing allows the first inorganic substance and the second inorganic substance to be in sufficient reaction to form the crystal seeds. Specifically, the standing time can be, but is not limited to, 1 h, 3 h, 5 h, 6 h, 10 h, 15 h, 18 h, 21 h, or 24 h, etc. In a specific embodiment, the standing time is 1 h to 10 h. In an embodiment, after standing, the second particles are obtained by separation. Specifically, the second particles can be, but are not limited to, obtained by vacuum filtration, centrifugal drying, centrifugal sedimentation, or magnetic separation; and the solution after separation of the second particles can be recycled.

[0045] In another embodiment of the present application, the solution containing the second inorganic substance is gradually added to the first particles, and the second particles are obtained after standing. The solution containing the second inorganic substance can be added to the first particles by means of dropwise addition, spraying, etc. In an embodiment, the concentration of the solution containing the second inorganic substance is 0.5 mol / L-5 mol / L. The above concentration is conducive to the reaction of the first inorganic substance and the second inorganic substance. Specifically, the concentration of the solution containing the second inorganic substance can be, but is not limited to, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, etc. In an embodiment, the solid-liquid ratio of the first particles and the solution containing the second inorganic substance is 1 g:(1-50) mL. The above solid-liquid ratio is conducive to the reaction of the first inorganic substance and the second inorganic substance. Specifically, the solid-liquid ratio of the first particles and the solution containing the second inorganic substance can be, but is not limited to, 1 g:5 mL, 1 g:10 mL, 1 g:15 mL, 1 g:20 mL, 1 g:30 mL, 1 g:40 mL, or 1 g:50 mL, etc. It can be understood that the above solid-liquid ratio is the solid-liquid ratio of the first particles and the solution containing the second inorganic substance after the solution containing the second inorganic substance is added. In an embodiment, the standing time is 1 h-24 h. The first inorganic substance and the second inorganic substance are allowed to fully react to form a crystal seed by standing. Specifically, the standing time can be, but is not limited to, 1 h, 3 h, 5 h, 6 h, 10 h, 15 h, 18 h, 21 h, or 24 h, etc. In an embodiment, after standing, the second particles are further separated. Specifically, the second particles can be separated by, but are not limited to, vacuum filtration, centrifugal drying, centrifugal sedimentation, or magnetic separation; the solution after the second particles are separated can also be recycled. In a specific embodiment, the first particles can be laid flat on a vessel, the solution containing the second inorganic substance can be uniformly added dropwise or sprayed (for example, a sprayer can be used) on the surface of the first particles, the dry first particles are fully soaked, and the second particles are obtained after standing after the addition is completed.

[0046] In S103, the second particles are placed in a solution containing the first inorganic substance and the second inorganic substance, and the first inorganic substance and the second inorganic substance preferentially react on the surface of the crystal seed, so that the crystal seed grows further, and precursor particles with good coating rate are obtained. When the magnetic particles are directly mixed with the lithium source and the aluminum source for reaction, it is difficult to ensure that the reaction occurs on the surface of the magnetic particles, so that the coating rate of the magnetic particles is low, which affects the coating effect and adsorption effect of the lithium adsorbent; the method provided in the present application allows the reaction to occur on the crystal seed, improves the coating effect, and is conducive to the use of the lithium adsorbent. In the present application, the precursor particles include the magnetic particles and the LiOH·2Al(OH)3·nH2O coating layer wrapped on the surface of the magnetic particles.

[0047] In S104, the precursor particles are placed in an acidic solution to convert the LiOH·2Al(OH)3·nH2O coating layer on the surface of the precursor particles into LiX·2Al(OH)3·nH2O through a reaction. In an embodiment, the concentration of the acidic solution is 2wt%-20wt%. The above concentration is conducive to the generation of LiX·2Al(OH)3·nH2O. Specifically, the concentration of the acidic solution can be, but is not limited to, 2wt%, 5wt%, 7wt%, 10wt%, 13wt%, 15wt%, 17wt% or 20wt%, etc. In the present application, the acidic solution can be, but is not limited to, at least one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid. In the LiX·2Al(OH)3·nH2O, X is an acid radical ion in the acidic solution, such as Cl - , SO4 2- , NO3 - , CH3COO - , etc. In an embodiment, the stirring speed of the precursor particles and the acidic solution when mixed is 100rpm-1000rpm. Specifically, the stirring speed can be, but is not limited to, 100rpm, 200rpm, 500rpm, 700rpm, 900rpm or 1000rpm, etc. In an embodiment, the precursor particles and the acidic solution are stirred for 30min-60min after mixing. Specifically, the stirring time can be, but is not limited to, 30min, 40min, 50min, 60min, etc. In an embodiment, the precursor particles are mixed with water, and then the acidic solution is added, wherein the solid-liquid ratio of the precursor particles and water can be 1g:(1-50)mL. Specifically, the solid-liquid ratio of the precursor particles and water can be, but is not limited to, 1g:5mL, 1g:10mL, 1g:15mL, 1g:20mL, 1g:30mL, 1g:40mL or 1g:50mL, etc. In an embodiment, the precursor particles are mixed with water, and then the acidic solution is added, and the pH is controlled to be 6-7, thereby facilitating the reaction. In a specific embodiment, the precursor particles are mixed with water at a solid-liquid ratio of 1g:(10-50)mL, stirred at a stirring speed of 100rpm-1000rpm, 2wt%-20wt% acidic solution is slowly added, and the pH value is adjusted to 6-7 during the process; after the adjustment is completed, the stirring is continued for 30min-60min. If the pH value exceeds 7, a small amount of acid solution is continuously added to adjust the pH value to 6-7. In the present embodiment, the lithium adsorbent is cleaned. Specifically, the lithium adsorbent can be sprayed and cleaned with water, and the solid-liquid ratio of the lithium adsorbent and water can be 1g:(10-50)mL, and after cleaning, dehydration is performed through vacuum filtration or centrifugal drying. In the present embodiment, after cleaning, drying treatment is also included; the drying treatment includes drying at 60°C-120°C for 1h-3h.

[0048] Please refer to Figure 2A flow chart of a method for preparing a lithium adsorbent according to another embodiment of the present application is shown in FIG. 2, which comprises the following steps:

[0049] S201: mixing the magnetic particles with a solution containing a first inorganic substance to obtain first particles after standing.

[0050] S202: mixing the first particles with a solution containing a second inorganic substance to obtain second particles after reaction, the second inorganic substance being a lithium source or an aluminum source, and the first inorganic substance and the second inorganic substance being different.

[0051] S203: placing the second particles in a solution containing the first inorganic substance and the second inorganic substance to obtain precursor particles after reaction.

[0052] S204: placing the precursor particles in an acidic solution to obtain the lithium adsorbent after reaction, the lithium adsorbent comprising the magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the lithium adsorption layer being made of LiX·2Al(OH)3·nH2O, X being an acid radical in the acidic solution.

[0053] In S202, S203 and S204, the related descriptions can be referred to the above S102, S103 and S104, and will not be repeated here.

[0054] In S201, the magnetic particles are mixed with a solution containing a first inorganic substance to obtain first particles after standing.

[0055] In an embodiment of the present application, the first particles are obtained by placing the magnetic particles in a solution containing the first inorganic substance, stirring and mixing, and then standing. The first inorganic substance can be, but is not limited to, loaded on the surface of the magnetic particles by electrostatic action, wetting action, and capillary action. In an embodiment, the concentration of the solution containing the first inorganic substance is 0.5 mol / L-5 mol / L. The above concentration is conducive to loading an appropriate amount of the first inorganic substance on the magnetic surface. Specifically, the concentration of the solution containing the first inorganic substance can be, but is not limited to, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, etc. In an embodiment, the solid-liquid ratio of the magnetic particles and the solution containing the first inorganic substance is 1 g:(10-500) mL. The above solid-liquid ratio is conducive to loading an appropriate amount of the first inorganic substance on the magnetic surface. Specifically, the solid-liquid ratio of the magnetic particles and the solution containing the first inorganic substance can be, but is not limited to, 1 g:50 mL, 1 g:100 mL, 1 g:200 mL, 1 g:300 mL, 1 g:400 mL, or 1 g:500 mL, etc. In an embodiment, the stirring includes stirring at a speed of 100 rpm-1000 rpm for 10 min-120 min. The above stirring allows the magnetic particles and the first inorganic substance in the solution to be in sufficient contact, which is conducive to the loading of the first inorganic substance. Specifically, the stirring speed can be, but is not limited to, 100 rpm, 200 rpm, 500 rpm, 700 rpm, 900 rpm, or 1000 rpm, etc., and the stirring time can be, but is not limited to, 10 min, 20 min, 40 min, 50 min, 70 min, 90 min, 100 min, or 110 min, etc. In an embodiment, the standing time is 1 h-24 h. The standing allows the first inorganic substance to be loaded on the surface of the magnetic particles. Specifically, the standing time can be, but is not limited to, 1 h, 3 h, 5 h, 6 h, 10 h, 15 h, 18 h, 21 h, or 24 h, etc. In an embodiment, after standing, the first particles are separated. Specifically, the first particles can be separated by, but are not limited to, vacuum filtration, centrifugal drying, centrifugal sedimentation, or magnetic separation; and the solution after the separation of the first particles can be recycled. In a specific embodiment, the magnetic particles are placed in a solution containing the first inorganic substance at a solid-liquid ratio of 1 g:(10-500) mL, stirred at a speed of 100 rpm-1000 rpm for 10 min-120 min, and then separated after standing for 1 h-24 h to obtain the first particles, and the concentration of the solution containing the first inorganic substance is 0.5 mol / L-5 mol / L.

[0056] In another embodiment of the present application, the solution containing the first inorganic substance is gradually added to the magnetic particles, and the first particles are obtained after standing. The solution containing the first inorganic substance can be added to the magnetic particles by means of dropwise addition, spraying, etc. In an embodiment, the concentration of the solution containing the first inorganic substance is 0.5 mol / L-5 mol / L. The above concentration is conducive to loading an appropriate amount of the first inorganic substance on the magnetic surface. Specifically, the concentration of the solution containing the first inorganic substance can be, but is not limited to, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, etc. In an embodiment, the solid-liquid ratio of the magnetic particles and the solution containing the first inorganic substance is 1 g:(10-50) mL. The above solid-liquid ratio is conducive to loading an appropriate amount of the first inorganic substance on the magnetic surface. Specifically, the solid-liquid ratio of the magnetic particles and the solution containing the first inorganic substance can be, but is not limited to, 1 g:10 mL, 1 g:15 mL, 1 g:20 mL, 1 g:30 mL, 1 g:40 mL, or 1 g:50 mL, etc. It can be understood that the above solid-liquid ratio is the solid-liquid ratio of the magnetic particles and the solution containing the first inorganic substance after the solution containing the first inorganic substance is added. In an embodiment, the standing time is 1 h-24 h. The first inorganic substance is loaded on the surface of the magnetic particles by standing. Specifically, the standing time can be, but is not limited to, 1 h, 3 h, 5 h, 6 h, 10 h, 15 h, 18 h, 21 h, or 24 h, etc. In an embodiment, after standing, the first particles are further separated. Specifically, the first particles can be separated by means of vacuum filtration, centrifugal drying, centrifugal sedimentation, or magnetic separation; and the solution after the first particles are separated can be recycled. In a specific embodiment, the solution containing the first inorganic substance is gradually added to the magnetic particles, and the first particles are separated after standing for 1 h-24 h, and the mass ratio of the magnetic particles to the added amount of the solution containing the first inorganic substance is 1 g:(10-50) mL. In another specific embodiment, the magnetic particles can be laid flat on a vessel, the solution containing the first inorganic substance is uniformly added dropwise or sprayed (for example, a sprayer can be used) on the surface of the magnetic particles, the dry magnetic particles are fully soaked, and the first particles are obtained after standing after the addition is completed.

[0057] Please refer to Figure 3 The flow chart of the preparation method of the lithium adsorbent provided in another embodiment of the present application comprises:

[0058] S301: The magnetic particles and the first inorganic substance are mixed, and the first particles are obtained after grinding.

[0059] S302: The first particles are mixed with a solution containing a second inorganic substance, and the second particles are obtained after reaction. The second inorganic substance is a lithium source or an aluminum source, and the first inorganic substance and the second inorganic substance are different.

[0060] S303: placing the second particles into a solution containing the first inorganic substance and the second inorganic substance, to obtain precursor particles after reaction.

[0061] S304: placing the precursor particles into an acidic solution, to obtain lithium adsorbents after reaction, the lithium adsorbents comprising magnetic particles and lithium adsorption layers wrapping the magnetic particles, the lithium adsorption layers comprising LiX·2Al(OH)3·nH2O, X being an acid radical in the acidic solution.

[0062] S302, S303 and S304 can refer to the related descriptions in S102, S103 and S104 above, and will not be described here again.

[0063] In S301, the surface of the magnetic particles is loaded with the first inorganic substance by grinding. In an embodiment, the mass ratio of the magnetic particles and the first inorganic substance is 1:(1-50). The above mass ratio is conducive to loading the first inorganic substance on the surface of the magnetic particles. Specifically, the mass ratio of the magnetic particles and the first inorganic substance can be, but is not limited to, 1, 1:10, 1:20, 1:30, 1:40 or 1:50, etc. In an embodiment, the grinding includes processing at a speed of 50 rpm-300 rpm for 30 min-300 min. Specifically, the speed of the grinding can be, but is not limited to, 50 rpm-100 rpm, 100 rpm-150 rpm, 150 rpm-200 rpm, 200 rpm-250 rpm or 250 rpm-300 rpm, etc., the time of the grinding can be, but is not limited to, 30 min-60 min, 60 min-120 min, 120 min-240 min or 240 min-300 min, etc., and the grinding can be, but is not limited to, performed in a ball mill or a jar mill. In a specific embodiment, the magnetic particles and the first inorganic substance are mixed at a mass ratio of 1:(1-50), and after grinding at a speed of 50 rpm-300 rpm for 30 min-300 min, the first particles are separated.

[0064] In the embodiments of the present application, the magnetic particles are pretreated before the first particles are prepared. In the embodiments of the present application, the magnetic particles can be ground to improve the uniformity of dispersion of the magnetic particles and avoid uneven coating caused by agglomeration. In an embodiment, the grinding treatment includes a treatment at a speed of 50 rpm-300 rpm for 30 min-300 min. Specifically, the speed of the grinding treatment can be, but is not limited to, 50 rpm-100 rpm, 100 rpm-150 rpm, 150 rpm-200 rpm, 200 rpm-250 rpm or 250 rpm-300 rpm, etc., the time of the grinding treatment can be, but is not limited to, 30 min-60 min, 60 min-120 min, 120 min-240 min or 240 min-300 min, etc., and the grinding treatment can be, but is not limited to, performed in a ball mill or a jar mill.

[0065] Referring to Figure 4 A flow chart of a method for preparing a lithium adsorbent according to another embodiment of the present application is shown in FIG. 4, which includes the following steps:

[0066] S401: providing first particles, the first particles including magnetic particles and a first inorganic material loaded on the surface of the magnetic particles, the first inorganic material being a lithium source or an aluminum source.

[0067] S402: mixing the first particles with a solution containing a second inorganic material to obtain second particles after reaction, the second inorganic material being a lithium source or an aluminum source, and the first inorganic material and the second inorganic material being different.

[0068] S403: placing the second particles in a solution containing the first inorganic material to form a mixed system.

[0069] S404: adding a solution containing the second inorganic material to the mixed system to obtain precursor particles after reaction.

[0070] S405: placing the precursor particles in an acidic solution to obtain lithium adsorbent after reaction, the lithium adsorbent including magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the material of the lithium adsorption layer including LiX·2Al(OH)3·nH2O, X being an acid radical in the acidic solution.

[0071] S401, S402 and S405 can refer to the related descriptions in S101, S102 and S104 described above, which will not be repeated here.

[0072] In S403, the second particles are first placed in a solution containing the first inorganic substance, so that the unreacted second inorganic substance on the surface of the second particles reacts with the first inorganic substance, and the reaction only occurs on the surface of the second particles, improving the coating effect; and the areas on the surface of the second particles that have not been loaded can continue to be loaded with the first inorganic substance, so that when the second inorganic substance is added again, the coating effect is further improved by reaction, so that the coating effect of a single magnetic particle can be improved, and the coating effect of the whole magnetic particles can also be improved. In an embodiment, the concentration of the solution containing the first inorganic substance is 0.5 mol / L-5 mol / L. The above concentration is conducive to the preparation of the precursor. Specifically, the concentration of the solution containing the first inorganic substance can be but is not limited to 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc. In an embodiment, the solid-liquid ratio of the second particles and the solution containing the first inorganic substance is 1 g:(10-500) mL. The above solid-liquid ratio is conducive to the preparation of the precursor, and is also helpful for the reaction of the first inorganic substance with the second inorganic substance on the surface of the second particles, and is conducive to the loading of the first inorganic substance on the surface of the magnetic particles that have not been coated. Specifically, the solid-liquid ratio of the second particles and the solution containing the first inorganic substance can be but is not limited to 1 g:50 mL, 1 g:100 mL, 1 g:200 mL, 1 g:300 mL, 1 g:400 mL or 1 g:500 mL, etc. In an embodiment, the reaction time of the second particles and the solution containing the first inorganic substance is 10 min-120 min. Specifically, the reaction time of the second particles and the solution containing the first inorganic substance can be but is not limited to 10 min, 20 min, 40 min, 50 min, 70 min, 90 min, 100 min or 110 min, etc. In an embodiment, the second particles and the solution containing the first inorganic substance are reacted at a rotation speed of 100 rpm-1000 rpm, which is conducive to sufficient reaction. Specifically, the rotation speed can be but is not limited to 100 rpm, 200 rpm, 500 rpm, 700 rpm, 900 rpm or 1000 rpm, etc.

[0073] In S404, a solution containing a second inorganic substance is added to the mixed system, and a precursor particle is obtained by reaction. In an embodiment, the concentration of the solution containing the second inorganic substance is 0.5-5 mol / L. The above concentration is conducive to the preparation of the precursor. Specifically, the concentration of the solution containing the second inorganic substance can be, but is not limited to, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, etc. In an embodiment, the adding speed of the solution containing the second inorganic substance is 20-5000 mL / min. In this way, the crystal seed is conducive to growth, the LiOH·2Al(OH)3·nH2O coating layer is formed, and the coating rate is ensured. Specifically, the adding speed of the solution containing the second inorganic substance can be, but is not limited to, 20-100 mL / min, 100-500 mL / min, 500-1000 mL / min, 1000-2000 mL / min, 2000-3000 mL / min, 3000-4000 mL / min or 4000-5000 mL / min, etc. In the present application, the solution containing the second inorganic substance can be added to the mixed system by, but not limited to, a peristaltic pump, a centrifugal pump or a metering pump, etc. In an embodiment, the molar ratio of lithium element and aluminum element in the solution containing the first inorganic substance and the solution containing the second inorganic substance is 0.5-0.75. Within this range, the first inorganic substance and the second inorganic substance can fully react, avoid waste, and save preparation cost. Specifically, the molar ratio of lithium element and aluminum element in the solution containing the first inorganic substance and the solution containing the second inorganic substance can be, but is not limited to, 0.5, 0.55, 0.6, 0.65, 0.7 or 0.75, etc. In an embodiment, after the solution containing the second inorganic substance is added to the mixed system, the reaction time is 30-120 min, which is conducive to full reaction and improves the coating rate and coating uniformity. Specifically, the reaction time can be, but is not limited to, 30 min, 50 min, 65 min, 80 min, 90 min, 100 min or 120 min, etc. In an embodiment, the reaction temperature for preparing the precursor particle is 20-90°C, which is conducive to full reaction and improves the coating effect of the precursor particle. Specifically, the reaction temperature for preparing the precursor particle can be, but is not limited to, 20°C, 30°C, 50°C, 70°C, 80°C or 90°C, etc. In an embodiment, the stirring speed for adding the solution containing the second inorganic substance to the mixed system is 100-1000 rpm, which is conducive to full reaction. Specifically, the stirring speed can be, but is not limited to, 100 rpm, 200 rpm, 500 rpm, 700 rpm, 900 rpm or 1000 rpm, etc.In one embodiment, the first inorganic substance and the second inorganic substance used in the preparation of the second particles are the same as the first inorganic substance and the second inorganic substance in the solution containing the first inorganic substance and the second inorganic substance in which the second particles are placed. In this way, the unreacted second inorganic substance on the surface of the second particles can be fully reacted, further improving the coating effect and coating uniformity. For example, if lithium salt and aluminate are used in the preparation of the second particles, then the first inorganic substance and the second inorganic substance in the solution containing the first inorganic substance and the second inorganic substance in which the second particles are placed are lithium salt and aluminate. For another example, if lithium hydroxide and aluminum salt are used in the preparation of the second particles, then the first inorganic substance and the second inorganic substance in the solution containing the first inorganic substance and the second inorganic substance in which the second particles are placed are lithium hydroxide and aluminum salt.

[0074] Please refer to Figure 5 The flow chart of the method for preparing the lithium adsorbent according to another embodiment of the present application is shown in FIG. 2, which includes the following steps:

[0075] S501: providing first particles, the first particles including magnetic particles and a first inorganic substance loaded on the surface of the magnetic particles, the first inorganic substance being a lithium source or an aluminum source.

[0076] S502: mixing the first particles with a solution containing a second inorganic substance, the second inorganic substance being a lithium source or an aluminum source, and the first inorganic substance and the second inorganic substance being different, to obtain second particles after reaction.

[0077] S503: placing the second particles in a solution containing the first inorganic substance and the second inorganic substance, to obtain precursor particles after reaction and aging treatment.

[0078] S504: placing the precursor particles in an acidic solution, to obtain lithium adsorbent after reaction, the lithium adsorbent including magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the material of the lithium adsorption layer including LiX·2Al(OH)3·nH2O, X being an acid radical in the acidic solution.

[0079] In the above embodiment, the S501, S502 and S504 can refer to the related descriptions in the S101, S102 and S104, which will not be repeated here.

[0080] In S503, after the reaction of the second particles with the solution containing the first inorganic substance and the second inorganic substance, aging treatment can be further performed to make the unreacted part fully react, improve the coating effect, and make the precursor particles continue to grow, thereby improving the uniformity of the particle size. In one embodiment, the aging treatment includes standing at 5-30°C for 1-24h. Specifically, the temperature of the aging can be but is not limited to 5°C, 10°C, 15°C, 20°C, 25°C or 30°C, etc., and the time of the aging can be but is not limited to 1h, 5h, 8h, 10h, 13h, 15h, 18h, 21h or 24h, etc.

[0081] In the embodiments of the present application, the first particles, the second particles, the precursor particles and the lithium adsorbent can be separated by, but are not limited to, vacuum filtration, centrifugal drying, centrifugal sedimentation or magnetic separation. In an embodiment, the separation can be performed by magnetic separation, which is simpler and more convenient to operate.

[0082] The present application also provides a lithium adsorbent prepared by any of the above embodiments, wherein the lithium adsorbent comprises magnetic particles and a lithium adsorption layer wrapping the magnetic particles, and the lithium adsorption layer is made of LiX·2Al(OH)3·nH2O, wherein X is an acid radical in an acidic solution. The lithium adsorption layer in the lithium adsorbent has high coating rate, good coating effect and good uniformity, and the lithium adsorbent has stable structure and excellent adsorption performance, which is beneficial to the extraction of lithium. In the present application, n is a positive integer.

[0083] In the present application, the thickness of the lithium adsorption layer can be selected as required, and the lithium adsorption layer with nanoscale, microscale or even millimeter scale thickness can be prepared by the preparation method provided by the present application. In the embodiments of the present application, the particle size of the lithium adsorbent is 0.2 μm-0.2 mm. The lithium adsorbent with the above particle size is not easy to lose during use and has high adsorption efficiency. Specifically, the particle size of the lithium adsorbent can be, but is not limited to, 0.2 μm, 0.35 μm, 1 μm, 5 μm, 15 μm, 80 μm, 120 μm, 150 μm or 175 μm. In an embodiment, the particle size of the lithium adsorbent is 0.2 μm-10 μm. In another embodiment, the particle size of the lithium adsorbent is 10 μm-100 μm. In still another embodiment, the particle size of the lithium adsorbent is 100 μm-200 μm.

[0084] In the present application, the lithium adsorption layer does not contain dispersants, binders and the like, thereby improving the adsorption performance of the lithium adsorbent.

[0085] In the embodiments of the present application, the adsorption capacity of the lithium adsorbent at the 50th cycle is greater than or equal to 7 mg / g. That is, the mass of lithium ions adsorbed by 1 g of the lithium adsorbent at the 50th cycle is greater than or equal to 7 mg. The lithium adsorbent has excellent adsorption capacity, and the coating rate of the lithium adsorbent is high, so that the lithium adsorbent can still maintain high adsorption capacity after multiple cycles. Specifically, the adsorption capacity of the lithium adsorbent at the 50th cycle is greater than or equal to 7 mg / g, 7.5 mg / g, 8 mg / g, 8.5 mg / g, 9 mg / g, etc. In an embodiment, the adsorption capacity of the lithium adsorbent at the 50th cycle is 7 mg / g-9 mg / g. In the embodiments of the present application, the weight loss rate of the lithium adsorbent after 50 cycles is less than or equal to 0.06%. The weight loss rate of the lithium adsorbent is low, that is, the coating binding force of the lithium adsorbent is high, which is beneficial to the long-term stable use of the lithium adsorbent.

[0086] The application also provides a method for extracting lithium, comprising: placing the lithium adsorbent in any of the above embodiments into a lithium-containing solution to adsorb lithium, to obtain a lithium-enriched adsorbent; separating the lithium-enriched adsorbent and desorbing lithium ions in the lithium-enriched adsorbent. In the application, the lithium-containing solution can be brine or seawater; since the lithium adsorbent has a certain magnetism, an external magnetic field can be used to separate the lithium adsorbent from the mixed system, that is, the lithium-enriched adsorbent is efficiently separated from the lithium-containing solution by a magnetic separation method. This method is beneficial to reduce production cost, and the lithium adsorbent has good coating effect, high binding force, can still maintain high adsorption capacity and low weight loss rate after long-term use, and has a long service life.

[0087] The effects of the technical solutions of the application are further illustrated below through specific examples.

[0088] Example 1

[0089] A preparation method of a lithium adsorbent, comprising:

[0090] The nickel powder (particle size in the range of 10 μm) is placed in a jar mill and ground at a speed of 200 rpm for 60 min. The ground nickel powder is immersed in a 4 mol / L LiCl solution at a solid-liquid ratio of 1 g:20 mL, stirred at a speed of 500 rpm for 60 min, and after standing for 3 h, vacuum filtration is used to separate the first particles.

[0091] The first particles are immersed in a 2 mol / L sodium metaaluminate solution at a solid-liquid ratio of 1 g:50 mL, stirred at a speed of 500 rpm for 60 min, and after standing for 3 h, vacuum filtration is used to separate the second particles.

[0092] The second particles are placed in a 2 mol / L sodium metaaluminate solution at a solid-liquid ratio of 1 g:50 mL, and stirred at a speed of 500 rpm for 30 min to mix the solid and liquid sufficiently; at a stirring speed of 300 rpm, a 4 mol / L LiCl solution is added through a peristaltic pump at a flow rate of 50 mL / min at room temperature according to a Li / Al molar ratio of 1.1:2, and after the addition is completed, the reaction is continued for 60 min. After the reaction is completed, the system is continuously stood at room temperature for 12 h. After standing, vacuum filtration is used for solid-liquid separation to obtain the precursor particles.

[0093] The precursor particles were added to deionized water at a solid-liquid ratio of 1 g:30 mL, and a 5 wt% hydrochloric acid solution was slowly added for reaction at a stirring rate of 500 rpm until the pH value was adjusted to 6.0. After the adjustment was completed, stirring was continued for 30 min, and then solid-liquid separation was performed by vacuum filtration. After the separation, spray washing was performed with deionized water at a solid-liquid ratio of 1 g:30 mL, and then dehydration was performed by vacuum filtration. After the dehydration, the lithium adsorbent was obtained by drying at 80°C for 3 h.

[0094] Example 2

[0095] A method for preparing a lithium adsorbent includes:

[0096] Nickel powder (having a particle size in the range of 10 μm) was placed in a jar mill and ground at a rotation speed of 200 rpm for 60 min. The ground nickel powder was immersed in a 4 mol / L LiCl solution at a solid-liquid ratio of 1 g:20 mL, and stirred at a rotation speed of 500 rpm for 60 min. After standing for 3 h, first particles were obtained by vacuum filtration.

[0097] The first particles were immersed in a 2 mol / L sodium metaaluminate solution at a solid-liquid ratio of 1 g:50 mL, and stirred at a rotation speed of 500 rpm for 60 min. After the solid and liquid were thoroughly mixed and reacted, the mixture was allowed to stand for 3 h. After the standing, second particles were obtained by vacuum filtration.

[0098] The second particles were placed in a 4 mol / L LiCl solution at a solid-liquid ratio of 1 g:50 mL, and thoroughly mixed at a stirring rate of 500 rpm for 30 min. While maintaining a stirring rate of 300 rpm, a 2 mol / L sodium metaaluminate solution was added at a flow rate of 50 mL / min by a peristaltic pump under room temperature conditions, according to a Li / Al molar ratio of 1.1:2. After the addition was completed, the reaction was continued for 60 min. After the reaction was completed, the mixture was allowed to stand for 12 h under room temperature conditions. After the standing, precursor particles were obtained by vacuum filtration.

[0099] The precursor particles were added to deionized water at a solid-liquid ratio of 1 g:30 mL, and a 5 wt% hydrochloric acid solution was slowly added for reaction at a stirring rate of 500 rpm until the pH value was adjusted to 6.0. After the adjustment was completed, stirring was continued for 30 min, and then solid-liquid separation was performed by vacuum filtration. After the separation, spray washing was performed with deionized water at a solid-liquid ratio of 1 g:30 mL, and then dehydration was performed by vacuum filtration. After the dehydration, the lithium adsorbent was obtained by drying at 80°C for 3 h.

[0100] Example 3

[0101] A method for preparing a lithium adsorbent includes:

[0102] The same as Example 2, except that the method of solid-liquid separation is changed to magnetic separation.

[0103] Comparative Example 1

[0104] A preparation method of a lithium adsorbent, comprising:

[0105] 100 g of ferroferric oxide powder with a median particle size of 70 nm is added to 1 L of deionized water, 0.3 g of sodium hexametaphosphate is added as a dispersant, and auxiliary ultrasonic is used for strong stirring at 1000 rpm. 100 g of AlCl3 powder is added to the ferroferric oxide dispersion, and is dispersed and stirred for 30 min to fully dissolve the AlCl3. 30 g of sodium hydroxide powder is added to the system within 30 min, so that aluminum hydroxide is gradually deposited on the interface of the ferroferric oxide, and a magnetic core @ Al(OH)3·nH2O is prepared. Then, 42 g of LiCl powder is added to the above system, and is dispersed and reacted for 10 min to prepare a magnetic core @ adsorbent. The above mixture is subjected to solid-liquid separation by using a magnetic separator, a filter press or a centrifuge, and a dehydrated magnetic core @ LiX·2Al(OH)3·nH2O is obtained. 1 L of deionized water is added to the above material for washing, and the lithium adsorbent is prepared after washing three times.

[0106] Comparative Example 2

[0107] A preparation method of a lithium adsorbent, comprising:

[0108] Nickel powder (particle size in the range of 10 μm) is placed in a jar mill and ground at a speed of 200 rpm for 60 min. The ground nickel powder is immersed in a 2 mol / L sodium metaaluminate solution at a solid-liquid ratio of 1 g:50 mL, and is stirred at a speed of 500 rpm for 30 min to fully mix the solid and liquid. The stirring speed is maintained at 300 rpm, and a 4 mol / L LiCl solution is added at a flow rate of 50 mL / min at a Li / Al molar ratio of 1.1:2 under room temperature conditions. After the addition is completed, the reaction is continued for 60 min. After the reaction is completed, the precursor particles are obtained by vacuum filtration under room temperature conditions.

[0109] The precursor particles are added to deionized water at a solid-liquid ratio of 1 g:30 mL, and a 5 wt% hydrochloric acid solution is slowly added for reaction at a stirring speed of 500 rpm until the pH value is adjusted to 6.0. After the adjustment is completed, the stirring is continued for 30 min, and then the solid-liquid separation is performed by vacuum filtration. After the separation, the lithium adsorbent is obtained by spray washing with deionized water at a solid-liquid ratio of 1 g:30 mL, followed by dehydration by vacuum filtration, and drying at 80°C for 3 h.

[0110] Performance detection

[0111] The lithium adsorbent of each embodiment and comparative example was subjected to adsorption performance test, and the test conditions were as follows: a certain amount of lithium-containing brine was subjected to adsorption and desorption test, the mass concentration of Li + in the brine was 0.0209%, and the mass concentration of Mg 2+ was 8.2860%. 10 g of lithium adsorbent was weighed, added into 500 mL of brine for adsorption, the stirring rate was 500 rpm, and the adsorption time was 90 min. After the adsorption was completed, the lithium adsorbent was separated from the solution by magnetic separation to obtain lithium-rich adsorbent and adsorption tail liquid. After the separation, the lithium-rich adsorbent was washed with 500 mL of deionized water to remove the residual brine on the surface of the lithium-rich adsorbent. The lithium-rich adsorbent was added into 500 mL of deionized water for desorption, the reaction temperature was controlled at 40°C, the stirring rate was 500 rpm, the desorption time was 120 min, and the desorption filtrate was obtained by magnetic separation. The above adsorption, washing and desorption process was one adsorption cycle. The content of lithium ions in the adsorption tail liquid was measured by ICP instrument. 50 cycles were continuously tested, and the adsorption capacity of the 50th cycle was calculated. After 50 cycles, solid-liquid separation was performed by suction filtration with a 0.45 μm microporous filter membrane. Before the suction filtration, the microporous filter membrane was dried at 130°C to constant weight. After the suction filtration, the microporous filter membrane and the separated lithium-rich adsorbent were dried at 130°C to constant weight. The weight of the lithium-rich adsorbent after 50 cycles was calculated. The weight loss of the lithium adsorbent was the difference between the initial weight of the lithium adsorbent and the weight of the lithium adsorbent after 50 cycles. The weight loss rate was the percentage of the weight loss of the lithium adsorbent relative to the original weight of the lithium adsorbent. The results are shown in Table 1.

[0112] Table 1 Performance test results

[0113]

[0114] As can be seen from Table 1, the adsorbent prepared in Comparative Example 1 has low adsorption capacity and high weight loss rate, and the coating effect is poor. In Comparative Example 2, no seed crystal is prepared, but direct reaction is performed, so that the lithium adsorbent has low adsorption capacity, high weight loss rate and poor coating effect. The lithium adsorbent prepared in the embodiments of the present application can still maintain high adsorption capacity after 50 cycles, and has low weight loss rate, indicating that the lithium adsorbent has good coating performance and high coating binding force. Compared with Example 1, the method of Example 2 further improves the coating rate. Compared with Example 2, the method of Example 3 can reduce the loss of lithium adsorbent.

[0115] The above describes the preferred embodiments of the present application, but cannot be construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which are also considered within the protection scope of the present application.

Claims

1. A method for producing a lithium adsorbent, characterized by, The application relates to a lithium adsorbent and a preparation method thereof. Providing first particles, the first particles comprising magnetic particles and a first inorganic substance loaded on the surface of the magnetic particles, the first inorganic substance being a lithium source or an aluminum source; Mixing the first particles with a solution containing a second inorganic substance, the second inorganic substance being the lithium source or the aluminum source and being different from the first inorganic substance, to obtain second particles after reaction, the second particles comprising the magnetic particles and LiOH.2Al(OH)3.nH2O loaded on the surface of the magnetic particles; Placing the second particles in a solution containing the first inorganic substance and the second inorganic substance to obtain precursor particles after reaction; Placing the precursor particles in an acidic solution to obtain the lithium adsorbent after reaction, the lithium adsorbent comprising the magnetic particles and a lithium adsorption layer wrapping the magnetic particles, the material of the lithium adsorption layer comprising LiX.2Al(OH)3.nH2O, X being an acid radical in the acidic solution.

2. The production method according to claim 1, wherein The second particles are placed in a solution containing the first inorganic substance and the second inorganic substance to obtain the precursor particles after reaction, comprising: The second particles are placed in a solution containing the first inorganic substance to form a mixed system; The solution containing the second inorganic substance is added to the mixed system to obtain the precursor particles after reaction.

3. The production method according to claim 2, wherein The solid-liquid ratio of the second particles and the solution containing the first inorganic substance is 1g:(10-500)mL; The concentration of the solution containing the first inorganic substance is 0.5mol / L-5mol / L; The reaction time of the second particles and the solution containing the first inorganic substance is 10min-120min; The concentration of the solution containing the second inorganic substance is 0.5mol / L-5mol / L; The adding speed of the solution containing the second inorganic substance is 20mL / min-5000mL / min; The molar ratio of lithium element and aluminum element in the solution containing the first inorganic substance and the solution containing the second inorganic substance is 0.5-0.

75.

4. The production method according to claim 1, wherein The first particles are obtained by mixing the magnetic particles with the solution containing the first inorganic substance and standing, or by mixing the magnetic particles and the first inorganic substance and grinding. The magnetic particles are placed in the solution containing the first inorganic substance at a solid-liquid ratio of 1g:(10-500)mL, stirred at a rotating speed of 100rpm-1000rpm for 10min-120min, and separated after standing for 1h-24h to obtain the first particles, the concentration of the solution containing the first inorganic substance being 0.5mol / L-5mol / L; or The solution containing the first inorganic substance is gradually added to the magnetic particles, and the first particles are separated after standing for 1h-24h, the mass ratio of the magnetic particles to the adding amount of the solution containing the first inorganic substance being 1g:(10-50)mL; or 5. The production method according to claim 4, wherein ​ ​ The magnetic particles and the first inorganic substance are mixed in a mass ratio of 1:(1-50), and the first particles are obtained after grinding at a rotation speed of 50 rpm-300 rpm for 30 min-300 min.

6. The production method according to claim 1, wherein The obtained precursor particles further comprise an aging treatment, wherein the aging treatment comprises standing at 5℃-30℃ for 1h-24h.

7. The production method according to claim 1, wherein The lithium source comprises at least one of a lithium salt and lithium hydroxide; and the aluminum source comprises at least one of an aluminum salt and a meta-aluminate.

8. The production method according to claim 1, wherein The lithium adsorbent has an adsorption capacity of greater than or equal to 7 mg / g at the 50th cycle. The lithium adsorbent has a weight loss rate of less than or equal to 0.06% after 50 cycles.

9. The production method according to claim 1, wherein The magnetic particles have a particle size of 20 nm-100 μm. The lithium adsorbent has a particle size of 0.2 μm-0.2 mm.

10. A method of extracting lithium, characterized by, The method comprises placing the lithium adsorbent obtained by the preparation method of any one of claims 1-9 in a lithium-containing solution to adsorb lithium, thereby obtaining a lithium-enriched adsorbent. The lithium-enriched adsorbent is separated, and lithium ions in the lithium-enriched adsorbent are desorbed.

Images