A method for preparing lithium-free lithium ion sieve

Abstract

The present invention belongs to the technical field of lithium extraction from salt lakes, and specifically relates to a method for preparing a lithium-free lithium ion sieve. The method for preparing a lithium-free lithium ion sieve provided by the present invention can remove the lithium from the lithium-containing lithium ion sieve by using an acid, and protect it with a protective liquid of a specific composition, so that the lithium element in the lithium ion sieve can be removed without destroying the structure of the lithium ion sieve, thereby ensuring the normal use of the lithium ion sieve. According to this method, more than 80% of the lithium ions in the lithium-containing lithium ion sieve product can be reused in the subsequent production of lithium-containing lithium ion sieve products, which not only saves a lot of lithium salt costs, but also does not affect the normal use of the lithium ion sieve product.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium extraction from salt lakes, and in particular relates to a method for preparing a lithium-free lithium ion sieve. Background Art

[0002] Lithium and lithium salts can be widely used in energy, metallurgy, chemical industry and other fields. Lithium is an indispensable raw material to support the development of new energy vehicle industry. Lithium resources will become a bottleneck in the development of new energy vehicles.

[0003] Lithium ion sieve is a process of introducing template Li into inorganic compounds. + First, a lithium ion sieve precursor is formed, and then part of the Li + After extraction, lithium ion sieve adsorbent is formed. According to the molecular memory effect, size effect and sieving effect, lithium ion sieve adsorbent has a strong affinity for Li in the presence of multiple ions. + ions have high adsorption selectivity, and thus Li + It can separate ions from other ions, and is particularly suitable for lithium ions from lithium-containing dilute solutions such as waste lithium battery material leaching solutions, lithium salt production waste liquid, and salt lake brine. + Selective adsorption separation.

[0004] In the process of preparing lithium ion sieves, lithium salt is one of the indispensable raw materials. Due to the increasing demand for lithium salt and the shortage of supply, the prices of lithium carbonate and lithium hydroxide have reached 500,000 yuan / ton. The cost of lithium salt has occupied a lot of operating capital pressure for lithium ion sieve manufacturers.

[0005] Therefore, if a lithium-free lithium-ion sieve can be prepared and the lithium salt used in the production process of the lithium-ion sieve can be recycled, the financial pressure on lithium-ion sieve manufacturers will be greatly reduced. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art in the production process of lithium ion sieves, such as large demand for lithium salts and high costs, thereby providing a method for preparing a lithium-free lithium ion sieve. In particular, the lithium salts used in the production process of the lithium ion sieve can be almost completely recycled.

[0007] To this end, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a lithium-free lithium ion sieve, comprising the following steps:

[0009] S1, removing lithium from the lithium-containing lithium ion sieve with sulfuric acid to obtain a lithium-free lithium ion sieve and a desorption liquid;

[0010] S2, protecting the lithium-free lithium ion sieve with a protective solution, wherein the sodium ion concentration in the protective solution is 40-200 g / L, the potassium ion concentration is 10-100 g / L, the magnesium ion concentration is 10-100 g / L, the anions are chloride ions and / or carbonate ions, and the pH is 7.0-9.0.

[0011] Optionally, step S2 includes: cyclically adsorbing the lithium-free lithium ion sieve with a protective solution, and then storing the lithium-free lithium ion sieve after the cyclic adsorption in the protective solution;

[0012] Optionally, the cycle adsorption time is 1-4h;

[0013] Optionally, during the cyclic adsorption process, the flow rate of the protective solution is 3-8 times the volume of the lithium-containing lithium ion sieve per hour.

[0014] Optionally, the method further includes step S3, separating lithium from the desorption liquid and recycling the lithium to the step of preparing the lithium-containing lithium ion sieve.

[0015] Optionally, in step S1, the concentration of sulfuric acid is 0.1-1 moL / L.

[0016] Optionally, step S1 includes contacting the lithium-containing lithium ion sieve with sulfuric acid for cyclic desorption;

[0017] Optionally, the cycle desorption time is 0.5-4h, and the flow rate of sulfuric acid is 5-30 times the volume of the lithium-containing lithium ion sieve per hour.

[0018] Optionally, calculated as monobasic acid, the amount of sulfuric acid used is 130-150% of the total molar amount of lithium element in the lithium-containing lithium ion sieve.

[0019] Optionally, in step S3, separating lithium from the desorption solution comprises the following steps:

[0020] S31, removing manganese ions in the desorption solution by using a manganese removal resin to obtain a manganese removal solution;

[0021] S32, concentrating the obtained manganese removal solution to a lithium ion concentration of 25-30 g / L;

[0022] S33, adjusting the pH of the concentrated liquid to 11.5-13 with alkali;

[0023] S34, cooling the obtained liquid for crystallization, and separating the solid from the liquid to obtain sodium sulfate decahydrate and a clear liquid;

[0024] S35, evaporating and crystallizing the obtained clear solution to obtain crude lithium hydroxide monohydrate;

[0025] S36, dissolving crude lithium hydroxide monohydrate in water, removing sulfate ions with barium hydroxide, and obtaining a pure lithium hydroxide solution.

[0026] Optionally, the alkali used in step S33 is sodium hydroxide;

[0027] and / or, the temperature of the cooling crystallization in step S34 is -7°C to -15°C;

[0028] And / or, in step S36, the mass ratio of crude lithium hydroxide monohydrate to water is 1:(3-5).

[0029] Optionally, the lithium-free lithium ion sieve further comprises the steps of removing and activating the protective liquid before use;

[0030] Optionally, the activation step is: contacting the lithium-free lithium ion sieve with an acid and washing with water.

[0031] The activation step is a conventional operation in the art, typically and non-limitingly, and specifically comprises: flowing 0.05 mol / L-1 mol / L sulfuric acid or hydrochloric acid through the adsorbent (lithium-free lithium ion sieve) at a flow rate of 10-20 times the volume of the lithium ion sieve containing lithium per hour for 1-6 hours, and then washing with deionized water at a flow rate of 5-30 times the volume of the lithium ion sieve containing lithium per hour for 20-60 minutes. After washing, activation is completed.

[0032] Optionally, the lithium-containing lithium ion sieve is prepared by a high-temperature solid phase method, a precipitation method, a hydrothermal method or a sol-gel method.

[0033] Specifically, a complete and detailed description of the technical solution provided by this application is made in combination with specific operations, including the following steps:

[0034] 1. Safely remove lithium ions from lithium-containing lithium ion sieves

[0035] (1) A certain amount of lithium-containing lithium ion sieve is loaded into the adsorption device.

[0036] (2) Calculate the amount of desorption acid based on the lithium content in the lithium-containing lithium ion sieve. Sulfuric acid is generally used as the desorption acid. The total molar amount of the acid used for desorption (calculated as monobasic acid) should be 130%-150% of the total molar amount of lithium contained in the lithium ion sieve, and the concentration of the desorption acid (calculated as monobasic acid) can be 0.2mol / L-2mol / L. The above acid solution is circulated in the adsorption device for desorption at a flow rate of 5-30 times the volume of the lithium-containing lithium ion sieve / hour for 0.5-4 hours. After desorption is completed, the adsorption column is emptied and all the desorption liquid is collected.

[0037] (3) Rinse the lithium ion sieve with deionized water of 1.5-4 times the volume of the lithium ion sieve containing lithium at a flow rate of 5-30 times the volume of the lithium ion sieve containing lithium per hour for 30 minutes. After the rinsing is completed, empty the adsorption column, collect all the rinsing water, and add it to the above desorption solution.

[0038] (4) Prepare a protective solution with a volume of 1.5-2 times the volume of the lithium-containing lithium ion sieve, whose components are: sodium ion concentration 40-200g / L, potassium ion concentration 10-100g / L, magnesium ion concentration 10-100g / L, anions are chloride ions and carbonate ions, and pH value is 7.0-9.0. After the water washing in step (3) is completed, the protective solution should be immediately connected and circulated for adsorption at a flow rate of 3-8 times the volume of the lithium-containing lithium ion sieve / hour for 1-4 hours. Subsequently, an appropriate amount of protective solution is injected into the container A containing the adsorbent, and then the adsorbed lithium ion sieve is taken out from the adsorption device and stored in the aforementioned container A containing the adsorbent.

[0039] At this point, all lithium ions in the lithium ion sieve have been removed. When the lithium-free lithium ion sieve is ready for use, it only needs to be completely extracted from the protective liquid and activated according to the conventional process before it can be used normally.

[0040] 2. Recycling of lithium ions released from lithium-containing lithium ion sieves

[0041] In order to better recycle the lithium ions released from the lithium ion sieve, sulfuric acid is preferably used for desorption, so that there is no need to use sulfuric acid replacement step for the silver ions in the desorption solution.

[0042] (1) The desorption solution obtained in steps (2) and (3) in the above-mentioned first part is a pure lithium sulfate solution with a small amount of manganese ions.

[0043] (2) Passing the above solution through a manganese removal resin to remove manganese ions; typically, but not limiting, the manganese removal resin is DuPont AmberLite TM IRC120 Na or manganese sand.

[0044] (3) Evaporate the above solution to make the lithium ion concentration reach 25-30 g / L.

[0045] (4) Add sodium hydroxide to adjust the pH value of the above solution to 11.5-13.0.

[0046] (5) The above solution was cooled to -7°C to -15°C, and a large amount of sodium sulfate decahydrate crystals appeared. After centrifugation, a clear liquid B and a solid C were obtained.

[0047] (6) The clear solution B is heated to evaporate and crystallize, and the resulting crystals are crude lithium hydroxide monohydrate.

[0048] (7) The above crystals are dissolved in deionized water at a ratio of 1:(3-5), and after testing the sulfate concentration, barium hydroxide is added at a molar ratio of 1:1 to sulfate, and the clear solution is obtained after filtration. The clear solution is the pure lithium hydroxide concentrated solution C.

[0049] 3. Preparation of lithium-containing lithium ion sieve

[0050] The preparation of lithium-containing lithium ion sieve is a conventional method in the art, which can be a high temperature solid phase method, a precipitation method, a hydrothermal method or a sol-gel method. The hydrothermal method is described in detail below:

[0051] (1) According to the amount of lithium in the lithium hydroxide concentrated solution C described in step (6) of Part 2, a manganese source is added and mixed thoroughly to obtain a mixed solution D

[0052] (2) The mixed solution D is loaded into a hydrothermal reactor equipped with an automatic pressure relief device, the automatic pressure relief pressure is set to 0.15 MPa-0.5 MPa, the hydrothermal temperature is 110-180° C., and the reaction is carried out for 24-96 hours to obtain powder E.

[0053] (3) Sintering the powder E at 350° C.-450° C. for 1-24 hours in an air atmosphere to obtain a lithium-containing lithium ion sieve powder F.

[0054] (4) After the lithium-containing lithium ion sieve powder F is granulated, the lithium-containing lithium ion sieve adsorbent product is obtained.

[0055] The technical solution of the present invention has the following advantages:

[0056] The preparation method of the lithium-free lithium ion sieve provided by the present invention can remove the lithium in the lithium-containing lithium ion sieve by using acid, and protect it with a protective liquid of a specific composition, so that the lithium element in the lithium ion sieve can be removed without destroying the structure of the lithium ion sieve, thereby ensuring the normal use of the lithium ion sieve. According to this method, more than 80% of the lithium ions in the lithium-containing lithium ion sieve product can be reused in the subsequent production of lithium-containing lithium ion sieve products, which not only saves a lot of lithium salt costs, but also does not affect the normal use of the lithium ion sieve product.

[0057] The method for preparing the lithium-free lithium ion sieve provided by the present invention can further improve the structural stability of the lithium-free lithium ion sieve by limiting step S2, thereby improving the adsorption performance. DETAILED DESCRIPTION

[0058] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0059] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0060] In order to facilitate the comparison between data, the lithium-containing lithium ion sieves used in the following examples are all homemade products, Lisi lithium ion sieve adsorbent S-01, and its specific preparation method is as follows:

[0061] Lithium hydroxide monohydrate was dissolved in deionized water at a mass ratio of 1:4, and 6.03kg of manganese dioxide, 21.15kg of manganese tetraoxide, and 423.8g of metal oxide additives (aluminum oxide, magnesium oxide, and lithium oxide were added at a mass ratio of 4:9:1) were added to the above solution. After simple mixing, it was placed in a reactor with an automatic pressure relief device, with a reaction temperature of 160°C, a pressure relief pressure of 0.35MPa, and a reaction time of 72 hours. After the reaction was completed, 36.17kg of lithium ion sieve powder (unsintered) was obtained. In an air atmosphere, it was sintered at 400°C for 12 hours to obtain lithium-containing lithium ion sieve powder, and the finished product Lisi lithium ion sieve adsorbent S-01 was obtained after granulation.

[0062] Example 1

[0063] This embodiment provides a method for preparing a lithium-free lithium ion sieve, and the specific steps are as follows:

[0064] 1. Take 200L of Lisi lithium ion sieve adsorbent S-01, and circulate desorption for 3 hours with 650L of 0.5mol / L sulfuric acid (corresponding to 150% of the lithium amount) and a flow rate of 25 times the volume of lithium ion sieve containing lithium / hour to obtain 650L of lithium sulfate solution with a lithium ion concentration of 4.19g / L and a manganese ion concentration of 198ppm.

[0065] 2. Circulate and clean the solution with deionized water twice the volume of the lithium-containing lithium ion sieve and 20 times the volume of the lithium-containing lithium ion sieve per hour for 30 minutes to obtain 400 L of water washing liquid, which is concentrated to 100 L by evaporation, membrane, etc., and mixed with the lithium sulfate solution obtained in step 1 to obtain 750 L of lithium sulfate solution with a lithium ion concentration of 3.81 g / L.

[0066] 3. Prepare 200L of solution (i.e., protective solution) with a sodium ion concentration of 60g / L, a magnesium ion concentration of 90g / L, a potassium ion concentration of 20g / L, and anions all being chloride ions, with a pH of 8.15. Slowly pass 120L of protective solution through the circulation adsorption at a flow rate of 5 times the volume of lithium-containing lithium ion sieve / hour for 2 hours, then take out the adsorbent (lithium-free lithium ion sieve) from the adsorption device and store it in a container filled with the remaining protective solution, so that the protective solution submerges the adsorbent.

[0067] 4. After the lithium sulfate solution obtained in step 2 is passed through manganese sand, the resulting solution is 748 L of lithium sulfate solution with a lithium ion concentration of 3.75 g / L and a manganese ion concentration of less than 1 ppm.

[0068] 5. Evaporate the lithium sulfate solution in step 4 to 100 L to obtain a lithium sulfate solution with a lithium ion concentration of 28.0 g / L.

[0069] 6. Add 15 kg of sodium hydroxide and adjust the pH value of the solution in 5 to 12.45.

[0070] 7. The solution in step 6 was cooled to -10°C and immediately centrifuged to obtain 70L of clear liquid and 55.8kg of solid (mainly sodium sulfate decahydrate crystals). The lithium loss in this step was 0.98%.

[0071] 8. Evaporate the clear liquid obtained in step 7 to 10 L, centrifuge at 50°C and dry the obtained wet material to obtain 15.2 kg of crude lithium hydroxide monohydrate.

[0072] 9. The above lithium hydroxide monohydrate was dissolved in deionized water at a mass ratio of 1:4. It was found that sulfate was not detected in the solution, so the step of adding barium to remove sulfate was omitted. 6.03 kg of manganese dioxide, 21.15 kg of manganese tetraoxide, and 423.8 g of metal oxide additives (aluminum oxide, magnesium oxide, and lithium oxide were added in a mass ratio of 4:9:1) were added to the above solution. After simple mixing, they were placed in a reactor with an automatic pressure relief device. The reaction temperature was 160°C, the pressure relief pressure was 0.35 MPa, and the reaction time was 72 hours. After the reaction was completed, 36.17 kg of lithium ion sieve powder (unsintered) was obtained. In an air atmosphere, it was sintered at 400°C for 12 hours to obtain lithium-containing lithium ion sieve powder. After granulation, 164.8 L of the finished product Lisi lithium ion sieve adsorbent S-01 (circulation) was obtained.

[0073] Example 2

[0074] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that the composition of the protective solution is: sodium ion concentration 40g / L, magnesium ion concentration 100g / L, potassium ion concentration 10g / L, and all anions are chloride ions.

[0075] Example 3

[0076] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that the composition of the protective solution is: sodium ion concentration 200g / L, magnesium ion concentration 10g / L, potassium ion concentration 100g / L, and all anions are chloride ions.

[0077] Example 4

[0078] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Embodiment 1 in that all anions in the protective solution are carbonate ions.

[0079] Example 5

[0080] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Embodiment 1 in that the amount of sulfuric acid used is 281.67 L, 1 mol / L sulfuric acid (corresponding to 130% of the amount of lithium).

[0081] Example 6

[0082] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Embodiment 1 in that in step 1, cyclic desorption is performed for 4 hours at a flow rate of 8 times the volume of the lithium-containing lithium ion sieve per hour.

[0083] Example 7

[0084] This embodiment provides a method for preparing a lithium-free lithium ion sieve, which is different from Embodiment 1 in that in step 3, the adsorption is circulated for 1 hour at a flow rate of 8 times the volume of the lithium-containing lithium ion sieve per hour.

[0085] Comparative Example 1

[0086] This comparative example provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that potassium ions are used instead of sodium ions in the protective solution in step 3.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that sodium ions are used instead of potassium ions in the protective solution in step 3.

[0089] Comparative Example 3

[0090] This comparative example provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that potassium ions are used instead of magnesium ions in the protective solution in step 3.

[0091] Comparative Example 4

[0092] This comparative example provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that the sodium ion concentration in the protective solution in step 3 is 20 g / L, the potassium ion concentration is 120 g / L, and the magnesium ion concentration is 8 g / L.

[0093] Comparative Example 5

[0094] This comparative example provides a method for preparing a lithium-free lithium ion sieve, which is different from Example 1 in that the anions in the protective solution in step 3 are sulfate ions.

[0095] Test Case

[0096] Take the Lisi S-01 lithium ion sieve adsorbent produced by the conventional process in step 1 of Example 1, the lithium-free lithium ion sieve stored in the protective solution for 60 days in step 3 of each embodiment, and the lithium ion sieve adsorbent produced by recycled lithium ions in step 9 of each embodiment, and activate it with 0.5 mol sulfuric acid and 10 times the volume of lithium ion sieve containing lithium / hour flow rate for 3 hours, and then wash it with deionized water at 20 times the volume of lithium ion sieve containing lithium / hour flow rate for 30 minutes. After activation, carry out 1000 cycles of adsorption experiment on Tibet LMC salt lake brine at room temperature at the same time, and the adsorption flow rate is 10BV / h. The average adsorption efficiency and average data of the adsorbed lithium amount of the corresponding number of cycles (wherein, the first column represents the average data of cycles 1-100, the second column represents the average data of the 101st-200th, and so on. The failure involved in the comparative example is the average data of the cycle before failure) as follows:

[0097] (1) Lisi S-01 (Example 1) lithium ion sieve adsorbent produced by conventional process

[0098] Table 1

[0099]

[0100] (2) Lithium-free lithium ion sieve adsorbent stored in protective solution for 60 days

[0101] Table 2

[0102]

[0103]

[0104] Note: The unit of the amount of adsorbed lithium in the table is mg. “ / ” indicates that the adsorbent has failed and there is no relevant cycle data. Among them, the adsorption efficiency of Comparative Example 3 is 0 at the 189th cycle, and the adsorption efficiency of the following 10 cycles is 0, and the adsorbent is judged to be failed. The corresponding data is. The adsorption efficiency of Comparative Example 4 is 0 at the 338th cycle, and the adsorption efficiency of the following 10 cycles is 0, and the adsorbent is judged to be failed. The adsorption efficiency of Comparative Example 5 is 0 at the 562nd cycle, and the adsorption efficiency of the following 10 cycles is 0, and the adsorbent is judged to be failed.

[0105] (3) Lithium ion sieve adsorbent produced from recycled lithium ions

[0106] Table 3

[0107]

[0108] My plan number

[0109]

[0110] Note: The unit of adsorbed lithium in the table is mg.

[0111] Among them, the difference between Example 2, Example 3, Example 4 and Example 7 and Example 1 only affects the performance of the adsorbent after being placed for 60 days, and has no effect on the performance of the lithium ion sieve produced by the recycled lithium ions.

[0112] According to the above data, it can be seen that there is no significant difference in adsorption cycle performance between the lithium-free lithium ion sieve adsorbent stored in the protective solution, the lithium ion sieve adsorbent produced with recycled lithium ions and the Lisi S-01 lithium ion sieve adsorbent produced by conventional process, indicating that the method for preparing lithium ion sieve using recycled raw materials described in the present invention is feasible.

[0113] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for preparing a lithium-free lithium ion sieve, characterized in that: The steps include: S1, removing lithium from the lithium-containing manganese-based lithium ion sieve with sulfuric acid to obtain a lithium-free manganese-based lithium ion sieve and a desorption liquid; S2, protecting the lithium-free manganese-based lithium ion sieve with a protective solution, wherein the protective solution has a sodium ion concentration of 40-200 g / L, a potassium ion concentration of 10-100 g / L, a magnesium ion concentration of 10-100 g / L, an anion of chloride ion, and a pH of 7.0-9.0; Step S2 comprises: cyclically adsorbing the manganese-based lithium ion sieve containing no lithium and the protective solution, and then storing the manganese-based lithium ion sieve containing no lithium after the cyclic adsorption in the protective solution; S3, separating lithium from the desorption liquid and recycling it to the preparation step of the lithium-containing lithium ion sieve; Before using the lithium-free manganese-based lithium ion sieve, the protective liquid is first removed and then activated; The activation step is: contacting the manganese-based lithium ion sieve without lithium with acid and washing with water.

2. The method for preparing a lithium-free lithium ion sieve according to claim 1, characterized in that: The cycle adsorption time is 1-4h.

3. The method for preparing a lithium-free lithium ion sieve according to claim 1, characterized in that: During the cyclic adsorption process, the flow rate of the protective solution is 3-8 times the volume of the lithium-containing manganese-based lithium ion sieve per hour.

4. The method for preparing a lithium-free lithium ion sieve according to any one of claims 1 to 3, characterized in that: In step S1, the concentration of sulfuric acid is 0.1-1 mol / L.

5. The method for preparing a lithium-free lithium ion sieve according to claim 4, characterized in that: Step S1 includes contacting the lithium-containing manganese-based lithium ion sieve with sulfuric acid for cyclic desorption; The cycle desorption time is 0.5-4h, and the flow rate of sulfuric acid is 5-30 times the volume of the lithium-containing manganese-based lithium ion sieve per hour.

6. The method for preparing a lithium-free lithium ion sieve according to claim 5, characterized in that: Calculated as monobasic acid, the amount of sulfuric acid used is 130-150% of the total molar amount of lithium element in the lithium-containing manganese-based lithium ion sieve.

7. The method for preparing a lithium-free lithium ion sieve according to claim 1, characterized in that: In step S3, separating lithium from the desorption solution comprises the following steps: S31, removing manganese ions in the desorption solution by using a manganese removal resin to obtain a manganese removal solution; S32, concentrating the obtained manganese removal solution to a lithium ion concentration of 25-30 g / L; S33, adjusting the pH of the concentrated liquid to 11.5-13 with sodium hydroxide; S34, cooling the obtained liquid for crystallization, and separating the solid from the liquid to obtain sodium sulfate decahydrate and a clear liquid; S35, evaporating and crystallizing the obtained clear solution to obtain crude lithium hydroxide monohydrate; S36, dissolving crude lithium hydroxide monohydrate in water, removing sulfate ions with barium hydroxide, and obtaining a pure lithium hydroxide solution.

8. The method for preparing a lithium-free lithium ion sieve according to claim 7, characterized in that: The temperature of cooling crystallization in step S34 is -7°C to -15°C; And / or, in step S36, the mass ratio of crude lithium hydroxide monohydrate to water is 1:(3-5).

9. The method for preparing a lithium-free lithium ion sieve according to any one of claims 1-3 or 5-8, characterized in that: The lithium-containing manganese-based lithium ion sieve is prepared by a high-temperature solid phase method, a precipitation method, a hydrothermal method or a sol-gel method.

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