Manganese-dioxide-coated manganese-based lithium adsorbent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of salt lake lithium extraction, and particularly relates to a manganese dioxide coated manganese-based lithium adsorbent and a preparation method and application thereof. The manganese-based lithium adsorbent precursor is prepared from spherical manganese carbonate, manganese dioxide coating modification is further achieved through a low-temperature oxidation reduction technology, the manganese-dioxide-coated manganese-based lithium adsorbent is obtained, and the obtained manganese-dioxide-coated manganese-based lithium adsorbent can achieve efficient lithium extraction of salt lake brine with the high magnesium-lithium ratio. And meanwhile, the method has the advantages of low manganese loss rate (less than 1.5%), high recyclability, low preparation cost and the like, and has a wide application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium extraction from salt lakes, and more specifically, relates to a manganese-based lithium adsorbent coated with manganese dioxide, and a preparation method and application thereof. Background Art

[0002] Lithium is an important element in the development of modern energy. This lightest alkali metal is widely used in various fields such as new energy. It is an indispensable raw material for high-energy-density lithium batteries, and lithium batteries are an important source of power for new energy vehicles, grid energy storage, portable electronic devices, and power tools. In recent years, with the rapid development of the new energy industry, the demand for lithium batteries has exploded, triggering a continuous increase in the global market demand for lithium resources. There are two main forms of global lithium resources: one is lithium-containing ores, such as lithium mica, spodumene, and lithium saponite; the other is lithium-containing water resources, such as salt lake brine and seawater. Surveys have shown that more than 60% of the total lithium exists in salt lakes and seawater. Therefore, salt lake lithium resources have become an important source for the development of the lithium battery industry. The methods for extracting lithium from salt lakes include adsorption, electrodialysis, electrochemical deintercalation, and solvent extraction. However, except for the high-quality salt lakes with low magnesium-to-lithium ratios in South America, which have been mined on a large scale, the mining of most salt lake lithium resources with high magnesium-to-lithium ratios has encountered difficulties. Due to Mg 2+ and Li + They have almost the same properties. For salt lake brine with a magnesium-lithium molar ratio of more than 6, the application of conventional solar evaporation precipitation is very limited, and the adsorption method provides a possibility to solve this problem.

[0003] The widespread application of power and energy storage lithium batteries in the field of new energy has led to a continuous increase in the global demand for lithium resources. Among the proven lithium resources on the earth, the lithium reserves in salt lake brines are the largest. The high total salt content, complex composition, and low lithium concentration of salt lake brines increase the technical difficulty of separating and extracting lithium from them. Therefore, methods for highly selective separation of lithium ions have attracted much attention, especially the use of inorganic materials such as manganese oxide, titanium oxide, and iron phosphate to separate and extract lithium has become a hot topic. Manganese oxide adsorbents include LiMn2O4, Li 1.33 Mn l.67 O4 and Li 1.6 Mn 1.6 O4. They react with Li + It has high selectivity and exhibits high adsorption capacity. 1.6 Mn 1.6O4 is the most representative of all spinel materials of manganese oxide adsorbents because of its good stability and high theoretical adsorption capacity after multiple cycles of adsorption. However, during the lithium insertion and extraction process, especially during the extraction process, about 3.7% of manganese dissolution occurs in manganese oxide ion sieve adsorbents. The dissolution of manganese will not only cause the attenuation of the adsorption amount, but also cause water pollution of raw water and desorption liquid in practical applications.

[0004] Therefore, it is very necessary to develop a new lithium ion adsorbent with lower manganese loss. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing manganese oxide-based ion sieve adsorbents during the lithium insertion and extraction process, especially the high manganese dissolution loss (>1.5%) during the extraction process, and to provide a method for preparing a manganese dioxide-coated manganese-based lithium adsorbent.

[0006] The object of the present invention is to provide a manganese-based lithium adsorbent coated with manganese dioxide, wherein the manganese dissolution loss of the obtained manganese-based lithium adsorbent coated with manganese dioxide is less than 1.5%.

[0007] Another object of the present invention is to provide application of the manganese-based lithium adsorbent coated with manganese dioxide.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a method for preparing a manganese dioxide-coated manganese-based lithium adsorbent, comprising the following steps:

[0010] S1. The bicarbonate-containing solution is mixed with an ethanol aqueous solution containing a divalent manganese salt to react completely, filtered, and the precipitate is dried to obtain spherical manganese carbonate;

[0011] S2. The spherical manganese carbonate obtained in step S1 and the lithium salt are fully ground, calcined at 240 to 270 ° C for 150 to 180 min, then heated to 350 to 380 ° C and fully calcined, and cooled to obtain a manganese-based lithium adsorbent precursor;

[0012] S3. The dispersion containing the manganese-based lithium adsorbent precursor obtained in step S2, the divalent manganese salt solution, and the potassium permanganate solution are fully mixed and reacted until the reaction is complete, and then post-treated to obtain a manganese-based lithium adsorbent precursor coated with manganese dioxide;

[0013] S4. The manganese dioxide-coated manganese-based lithium adsorbent precursor obtained in step S3 is subjected to acid elution to remove lithium, and then dried to obtain the manganese dioxide-coated manganese-based lithium adsorbent.

[0014] In view of the problem that the existing manganese oxide-based ion sieve adsorbents have a high manganese dissolution loss (>1.5%) during the lithium insertion and extraction process, especially during the extraction process, the manganese-based lithium adsorbent coated with manganese dioxide prepared by the above-mentioned preparation method of the present invention does not significantly reduce the amount of lithium adsorption (generally speaking, after the adsorbent is coated, the adsorption performance of the obtained adsorbent will also be significantly reduced), while effectively reducing the manganese loss rate (<1.5%), and has good recyclability.

[0015] Preferably, the molar ratio of manganese to lithium of the spherical manganese carbonate and the lithium salt is 1:(0.8-1.2).

[0016] Preferably, the mass ratio of manganese dioxide in the manganese-based lithium adsorbent precursor and the manganese dioxide-coated manganese-based lithium adsorbent is (12-15):1.

[0017] Preferably, the divalent manganese salt is selected from manganese sulfate, manganese chloride, manganese nitrate or a hydrate of any of the above divalent manganese salts.

[0018] Preferably, the bicarbonate is selected from sodium bicarbonate or potassium bicarbonate.

[0019] Preferably, the lithium salt is selected from lithium nitrate, lithium chloride, lithium sulfate or lithium acetate, more preferably lithium nitrate.

[0020] Further, the reaction principle in step S1: 2HCO3 - +Mn 2+ =MnCO3↓+CO2↑+H2O.

[0021] Further, the reaction principle in step S2: 1.6LiMnO2+0.402→Li 1.6 Mn 1.6 O4.

[0022] Further, the reaction principle in step S3: 3Mn 2+ +2MnO4 - +2H2O=5MnO2+2H + .

[0023] Preferably, the molar ratio of the divalent manganese in the divalent manganese salt to the bicarbonate in the bicarbonate-containing solution is 1:(2-2.5). A slight excess of bicarbonate is beneficial to the reaction.

[0024] Preferably, the mixing ratio of the divalent manganese salt, water and ethanol in the ethanol solution containing the divalent manganese salt is 1 mol: (50-80) L: (4-10) L.

[0025] Furthermore, in step S1, the bicarbonate-containing solution is an aqueous solution containing bicarbonate, which is obtained by dissolving a bicarbonate-containing reagent in water.

[0026] Preferably, the concentration of the bicarbonate-containing solution is 0.09 to 0.15 mol / L. In actual calculations, due to different digits retained, the calculated results may be slightly different. For example, the calculated concentration is 0.092 mol / L, and the result after rounding is 0.09 mol / L or 0.1 mol / L, both of which fall within the scope of protection of the present invention.

[0027] Furthermore, in step S1, the method for preparing the ethanol aqueous solution of divalent manganese salt comprises the following steps: dissolving the divalent manganese salt in water and then adding ethanol, and mixing well.

[0028] Preferably, in step S1, the concentration of the ethanol aqueous solution containing the divalent manganese salt is 0.02-0.024 mol / L.

[0029] Furthermore, in step S1, the time required for the reaction to be complete is ≥ 10 h.

[0030] Furthermore, in step S1, the drying temperature is 60-80° C. and the drying time is 8-12 hours.

[0031] Preferably, in step S2, the heating rate of the calcination is 5-10°C / min.

[0032] Preferably, in step S2, the sufficient calcination time is 540 to 720 minutes.

[0033] Furthermore, in step S3, the manganese-based lithium adsorbent is obtained by dispersing a manganese-based lithium adsorbent precursor in water, and the mixing ratio of the manganese-based lithium adsorbent precursor to water is preferably 1 g: (80-100) mL.

[0034] Furthermore, in step S3, the divalent manganese salt-containing solution is a divalent manganese salt-containing aqueous solution, which is obtained by dissolving a divalent manganese salt in water, and the concentration of the divalent manganese salt is preferably 0.006 to 0.0084 mol / L.

[0035] Furthermore, in step S3, the potassium permanganate solution is a potassium permanganate aqueous solution obtained by dissolving potassium permanganate in water, and the concentration of the potassium permanganate solution is preferably 0.0037 to 0.005 mol / L.

[0036] Furthermore, in step S3, the volume ratio of the dispersion of the manganese-based lithium adsorbent precursor, the manganese-based lithium adsorbent divalent manganese salt-containing solution and the potassium permanganate solution is preferably 1:1:1.

[0037] Furthermore, in step S3, the post-processing includes centrifugation and drying.

[0038] Furthermore, the drying temperature is 60-80° C. and the drying time is 8-12 hours.

[0039] Furthermore, in step S3, the sufficient mixing time is ≥ 2h.

[0040] Specifically, in step S4, the acid elution of lithium is to use an acid solution to fully leach the lithium element and then filter, and take the precipitate and dry it to obtain a manganese-based lithium adsorbent coated with manganese dioxide. Furthermore, the drying temperature is 60-80° C. and the time is 8-12 hours.

[0041] Furthermore, in step S4, the acid for eluting lithium is selected from hydrochloric acid, and the concentration of the hydrochloric acid solution is 0.3-0.8 mol / L, more preferably 0.5 mol / L.

[0042] Furthermore, in step S4, the time for acid elution of lithium is 100 to 150 minutes.

[0043] The present invention also protects the manganese-based lithium adsorbent coated with manganese dioxide prepared by the preparation method.

[0044] The invention discloses an application of the manganese dioxide-coated manganese-based lithium adsorbent in extracting lithium.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention utilizes spherical manganese carbonate to prepare a manganese-based lithium adsorbent precursor, and further realizes manganese dioxide coating modification through low-temperature redox technology to obtain a manganese-based lithium adsorbent coated with manganese dioxide. The obtained manganese-based lithium adsorbent coated with manganese dioxide can realize efficient lithium extraction from salt lake brine with a high magnesium-to-lithium ratio, and has the advantages of low manganese loss rate (<1.5%), strong recyclability, low preparation cost, etc., and has broad application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a SEM image of the spherical manganese carbonate prepared in the present invention.

[0048] Figure 2 The figure is a schematic diagram of the process flow of the manganese-based lithium adsorbent coated with manganese dioxide of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0050] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0051] Example 1 Lithium extraction effect of manganese-based lithium adsorbents with different manganese-lithium ratios

[0052] A method for preparing a manganese-based lithium adsorbent comprises the following steps:

[0053] (1) Preparation of manganese carbonate: 1.69 g manganese sulfate (0.01 mol) was dissolved in 500 ml water and 40 mL anhydrous ethanol was added under stirring to obtain solution A. 1.68 g sodium bicarbonate (0.02 mol) was dissolved in 210 ml water to obtain solution B. Solution B was slowly added to solution A under stirring, mixed, allowed to stand, and allowed to settle for 10 h. The supernatant was taken out and the white precipitate was dried at 70 ° C for 8 h to obtain white spherical manganese carbonate with the following morphology and structure: Figure 1 As shown, it has a nearly spherical structure.

[0054] (2) Preparation of manganese-based lithium adsorbent precursor: The white spherical manganese carbonate and lithium nitrate obtained in step (1) were fully ground in a mortar at a molar ratio of 1:0.4, 1:0.6, 1:0.8, 1:1, and 1:1.2, respectively, and placed in a tube furnace and set the following program: first, the temperature was raised to 270°C at 10°C / min for 180 min, then the temperature was raised to 350°C at 5°C / min for 720 min, and finally the temperature was naturally lowered to obtain manganese-based lithium adsorbent precursor materials with different manganese-lithium molar ratios.

[0055] (3) Preparation of manganese-based lithium adsorbent: The manganese-based lithium adsorbent precursor material prepared with different manganese-lithium ratios obtained in step (2) was fully stirred in 0.5M hydrochloric acid for 120 minutes to leach the lithium element in the lithium-containing manganese-based lithium adsorbent precursor, and then filtered and dried (70°C, 10h) to obtain a manganese-based lithium adsorbent with specific lithium adsorption. The schematic diagram of the preparation process of the obtained manganese-based lithium adsorbent is as follows: Figure 2 shown.

[0056] (4) Lithium extraction from simulated salt lake brine: 0.1 g of the manganese-based lithium adsorbent prepared with different manganese-lithium ratios obtained in step (3) was placed in simulated brine with a magnesium-lithium ratio of 100:1 (100 mL) for lithium extraction experiments. The results are shown in Table 1.

[0057] Table 1 Lithium extraction effect of manganese-based lithium adsorbents with different manganese-lithium ratios

[0058]

[0059] It can be seen from Table 1 that the lithium adsorption amounts of manganese-to-lithium ratios of 1:0.4, 1:0.6, 1:0.8, 1:1, and 1:1.2 are 6.5 mg / g, 8.4 mg / g, 14.1 mg / g, 12.3 mg / g, and 11.4 mg / g, respectively. It can be concluded that the manganese-based lithium adsorbent with a manganese-to-lithium ratio of 1:(0.8-1.2) has a better lithium extraction effect, among which the manganese-based lithium adsorbent with a manganese-to-lithium ratio of 1:0.8 has the best lithium extraction effect.

[0060] Example 2 Lithium extraction effect of manganese-based lithium adsorbent at different solid-liquid ratios

[0061] (1) Preparation of manganese carbonate: 1.69 g of manganese sulfate (0.01 mol) was dissolved in 500 ml of water and 40 ml of anhydrous ethanol was added under stirring to obtain solution A. 1.68 g of sodium bicarbonate (0.02 mol) was dissolved in 210 ml of water to obtain solution B. Solution B was slowly added to solution A under stirring, mixed, allowed to stand, and allowed to settle for 10 h. The supernatant was taken out and the white precipitate was dried at 70° C. for 8 h to obtain white spherical manganese carbonate.

[0062] (2) Preparation of manganese-based lithium adsorbent precursor: The white spherical manganese carbonate and lithium nitrate obtained in step (1) were fully ground in a mortar at a molar ratio of 1:0.8, and placed in a tube furnace and set up the following program: first, the temperature was raised to 270°C at 10°C / min for 180 min, then the temperature was raised to 350°C at 5°C / min for 720 min, and finally the temperature was naturally lowered to obtain a manganese-based lithium adsorbent precursor.

[0063] (3) Preparation of manganese-based lithium adsorbent: The manganese-based lithium adsorbent obtained in step (2) was fully stirred in 0.5M hydrochloric acid for 120 minutes to leach the lithium element in the lithium-containing manganese-based lithium adsorbent precursor, and then filtered. The precipitate was dried (70°C, 10 hours) to obtain a manganese-based lithium adsorbent that can specifically adsorb lithium.

[0064] (4) Lithium extraction from simulated salt lake brine: 0.1 g of the manganese-based lithium adsorbent obtained in step (3) was placed in 100 mL, 150 mL, 200 mL, and 250 mL of simulated brine with a magnesium-to-lithium ratio of 100:1 for lithium extraction experiments. The results are shown in Table 2.

[0065] Table 2 Lithium extraction effect of manganese-based lithium adsorbent at different solid-liquid ratios

[0066]

[0067] It can be seen from Table 2 that the lithium extraction amounts of solid-liquid ratios (g / L) of 1:1, 1:1.5, 1:2, and 1:2.5 are 14.1 mg / g, 16.75 mg / g, 22.1 mg / g, and 25.75 mg / g, respectively. It can be seen that the adsorption effect increases with the increase of the solid-liquid ratio, indicating that it has strong industrial application prospects.

[0068] Example 3 Lithium extraction effect of manganese-based lithium adsorbent coated with manganese dioxide at different coating ratios

[0069] (1) Preparation of manganese carbonate: 1.69 g of manganese sulfate (0.01 mol) was dissolved in 500 ml of water and 40 ml of anhydrous ethanol was added under stirring to obtain solution A. 1.68 g of sodium bicarbonate (0.02 mol) was dissolved in 210 ml of water to obtain solution B. Solution B was slowly added to solution A under stirring, mixed, allowed to stand, and allowed to settle for 10 h. The supernatant was taken out and the white precipitate was dried at 70° C. for 8 h to obtain white spherical manganese carbonate.

[0070] (2) Preparation of manganese-based lithium adsorbent precursor: The white spherical manganese carbonate and lithium nitrate obtained in step (1) were fully ground in a mortar at a molar ratio of 1:0.8, and placed in a tube furnace and set up the following program: first, the temperature was raised to 270°C at 10°C / min for 180 min, then the temperature was raised to 350°C at 5°C / min for 720 min, and finally the temperature was naturally lowered to obtain a manganese-based lithium adsorbent precursor.

[0071] (3) Using low-temperature redox technology to achieve manganese dioxide coating modification: First, take 5 portions of 0.25 g of the manganese-based lithium adsorbent precursor obtained in step (2) and disperse them in 20 mL of water, which are recorded as solutions A1, A2, A3, A4, and A5. Secondly, according to the chemical equation: 3Mn 2+ +2MnO4 - +2H2O=5MnO2+2H + , 0.036g, 0.023g, 0.018g, 0.015g, and 0.012g of potassium permanganate were dispersed in 20mL of water and recorded as B1, B2, B3, B4, and B5 solutions, 0.058g, 0.036g, 0.029g, 0.025g, and 0.019g of manganese sulfate were dispersed in 20mL of water and recorded as C1, C2, C3, C4, and C5 solutions, and the three solutions of the same sequence number of ABC were mixed respectively, shaken for 2h, centrifuged, and dried (70°C, 10h) to prepare manganese dioxide-coated modified manganese-based lithium adsorbent precursors with coating ratios (mass ratio of manganese-based lithium adsorbent precursor: manganese dioxide) of 5:1, 8:1, 10:1, 12:1, and 15:1.

[0072] (4) Preparation of manganese dioxide-coated manganese-based lithium adsorbent: The manganese dioxide-coated manganese-based lithium adsorbent precursor obtained in step (3) is fully stirred in 0.5M hydrochloric acid for 120 minutes, the lithium element in the manganese dioxide-coated manganese-based lithium adsorbent precursor is leached out and filtered, and the precipitate is dried (70°C, 10 hours) to obtain the manganese dioxide-coated manganese-based lithium adsorbent. The schematic diagram of the preparation process of the obtained manganese dioxide-coated manganese-based lithium adsorbent (also known as modified manganese-based lithium adsorbent) is as follows Figure 2 shown.

[0073] (5) Lithium extraction from simulated salt lake brine: 0.1 g of the manganese-based lithium adsorbent coated with manganese dioxide obtained in step (4) was placed in simulated brine with a magnesium-to-lithium ratio of 100:1 (100 mL) for lithium extraction experiments. The results are shown in Table 3.

[0074] Table 3 Lithium extraction effect of manganese-based lithium adsorbents coated with manganese dioxide at different coating ratios

[0075]

[0076] It can be seen from Table 3 that the lithium extraction amounts of manganese-based lithium adsorbents with mass ratios (manganese-based lithium adsorbent precursor: manganese dioxide) of 5:1, 8:1, 10:1, 12:1, and 15:1 are 6.1 mg / g, 8.2 mg / g, 9.1 mg / g, 12.6 mg / g, and 12.1 mg / g, respectively. It can be seen from the experimental data that the coating ratio (manganese-based lithium adsorbent precursor: manganese dioxide) has a better adsorption effect when it is (12-15):1, among which the coating ratio (manganese-based lithium adsorbent precursor: manganese dioxide) has the best adsorption effect (12.6 mg / g) and the lowest manganese loss value (1.31%) when it is 12:1. Compared with the uncoated manganese-based lithium adsorbent, the manganese loss value (2.48%) decreased by 1.17%, while the amount of lithium extracted was only reduced by 1.5 mg / g after coating (12.6 mg / g) compared with the uncoated amount of lithium extracted (14.1 mg / g). The coating modification of manganese dioxide can effectively reduce the manganese loss rate without significantly reducing the adsorption amount.

[0077] Example 4 Lithium extraction effect of manganese dioxide-coated manganese-based lithium adsorbent at different solid-liquid ratios

[0078] (1) Preparation of manganese carbonate: 1.69 g of manganese sulfate (0.01 mol) was dissolved in 500 ml of water and 40 ml of anhydrous ethanol was added under stirring to obtain solution A. 1.68 g of sodium bicarbonate (0.02 mol) was dissolved in 210 ml of water to obtain solution B. Solution B was slowly added to solution A under stirring, mixed, allowed to stand, and allowed to settle for 10 h. The supernatant was taken out and the white precipitate was dried at 70° C. for 8 h to obtain white spherical manganese carbonate.

[0079] (2) Preparation of manganese-based lithium adsorbent precursor: The white spherical manganese carbonate and lithium nitrate obtained in step (1) were fully ground in a mortar at a molar ratio of 1:0.8, and placed in a tube furnace and set up the following program: first, the temperature was raised to 270°C at 10°C / min for 180 min, then the temperature was raised to 350°C at 5°C / min for 720 min, and finally the temperature was naturally lowered to obtain a manganese-based lithium adsorbent precursor.

[0080] (3) Using low-temperature redox technology to achieve manganese dioxide coating modification: First, 0.25 g of the manganese-based lithium adsorbent precursor obtained in (2) was dispersed in 20 mL of water and recorded as solution A. Secondly, according to the chemical equation: 3Mn 2+ +2MnO4 - +2H2O=5MnO2+2H + 0.015 g potassium permanganate was dispersed in 20 mL of water and recorded as solution B, 0.025 g manganese sulfate was dispersed in 20 mL of water and recorded as solution C, the three solutions ABC were mixed, shaken for 2 h, centrifuged, and dried (70 ° C, 10 h) to prepare a manganese dioxide-coated modified manganese-based lithium adsorbent precursor with a coating ratio (manganese-based lithium adsorbent precursor: manganese dioxide) of 12:1.

[0081] (4) Preparation of manganese dioxide-coated manganese-based lithium adsorbent: The manganese dioxide-coated manganese-based lithium adsorbent precursor obtained in (3) was fully stirred in 0.5 M hydrochloric acid for 120 min, the lithium element in the manganese dioxide-coated manganese-based lithium adsorbent precursor was leached out and filtered, and the precipitate was dried (90° C., 10 h) to obtain the manganese dioxide-coated manganese-based lithium adsorbent.

[0082] (5) Lithium extraction from simulated salt lake brine: 0.1 g of the manganese-based lithium adsorbent coated with manganese dioxide obtained in (4) was placed in 100 mL, 150 mL, 200 mL, and 250 mL of simulated brine with a magnesium-to-lithium ratio of 100:1 for lithium extraction experiments.

[0083] Table 4 Lithium extraction effect of manganese dioxide coated manganese-based lithium adsorbent at different solid-liquid ratios

[0084]

[0085] As shown in Table 4, the lithium extraction amounts of the solid-liquid ratios (g / L) of 1:1, 1:1.5, 1:2, and 1:2.5 are 12.6 mg / g, 18.3 mg / g, 21.8 mg / g, and 24.75 mg / g, respectively, and the best lithium extraction effect (24.75 mg / g) is achieved when the solid-liquid ratio is 1:2.5. It can be seen that the adsorption effect increases with the increase of the solid-liquid ratio, indicating that it has strong industrial application prospects.

[0086] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a manganese-based lithium adsorbent coated with manganese dioxide, It is characterized in that The steps include: S1. The bicarbonate-containing solution is mixed with an ethanol aqueous solution containing a divalent manganese salt to react completely, filtered, and the precipitate is dried to obtain spherical manganese carbonate; S2. The spherical manganese carbonate obtained in step S1 and the lithium salt are fully ground, calcined at 240 to 270 ° C for 150 to 180 min, then heated to 350 to 380 ° C and fully calcined, and cooled to obtain a manganese-based lithium adsorbent precursor; S3. The dispersion containing the manganese-based lithium adsorbent precursor obtained in step S2, the divalent manganese salt solution, and the potassium permanganate solution are fully mixed and reacted until the reaction is complete, and then post-treated to obtain a manganese-based lithium adsorbent precursor coated with manganese dioxide; S4. The manganese dioxide-coated manganese-based lithium adsorbent precursor obtained in step S3 is subjected to acid elution to remove lithium, and then dried to obtain the manganese dioxide-coated manganese-based lithium adsorbent.

2. The preparation method according to claim 1, It is characterized in that In step S2, the molar ratio of manganese to lithium of the spherical manganese carbonate and the lithium salt is 1:(0.8-1.2).

3. The preparation method according to claim 1, It is characterized in that The mass ratio of manganese dioxide in the manganese-based lithium adsorbent precursor and the manganese dioxide-coated manganese-based lithium adsorbent is (12-15):

1.

4. The preparation method according to claim 1, It is characterized in that The divalent manganese salt is selected from manganese sulfate, manganese chloride, manganese nitrate or a hydrate of any of the above divalent manganese salts.

5. The preparation method according to claim 1, It is characterized in that The bicarbonate is selected from sodium bicarbonate or potassium bicarbonate.

6. The preparation method according to claim 1, It is characterized in that The lithium salt is selected from lithium nitrate, lithium chloride, lithium sulfate or lithium acetate.

7. The preparation method according to claim 1, It is characterized in that The molar ratio of the divalent manganese in the divalent manganese salt to the bicarbonate in the bicarbonate-containing solution is 1:(2-2.5).

8. The preparation method according to claim 1, It is characterized in that The mixing ratio of the divalent manganese salt, water and ethanol in the ethanol solution containing the divalent manganese salt is 1 mol: (50-80) L: (4-10) L.

9. A manganese-based lithium adsorbent coated with manganese dioxide prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the manganese dioxide-coated manganese-based lithium adsorbent according to claim 9 in extracting lithium.

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