Method for removing calcium and magnesium ions in preparation of battery-grade manganese sulfate

Abstract

The present application relates to the technical field of industrial-grade manganese sulfate treatment, in particular to a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate. The method involves a manganese sulfate leaching solution with a pH value of 4.5-5.5, a calcium concentration of 0.3-1.0 g / L, and a magnesium concentration of 0.8-2.0 g / L. The specific process is as follows: using the filter layer prepared from battery-grade manganese dioxide to pretreat the calcium and magnesium in the manganese sulfate solution; the complexing agent is a composite complexing agent mainly composed of nitrogen triacetic acid and ethylenediaminetetraacetic acid at a mass ratio of 1:1; after adding the precipitant manganese hydroxide, the pH value of the solution is adjusted to above 7.0, and after centrifugal precipitation, dilute sulfuric acid is used to adjust the pH value to 4.5-5.5. After the treatment, the content of calcium and magnesium ions is less than 0.05 g / L. The present application has the advantages of simple process, high calcium and magnesium removal efficiency, low energy consumption, and high economic feasibility.

Description

Technical Field

[0001] This invention relates to the field of industrial-grade manganese sulfate treatment technology, specifically to a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate. Background Technology

[0002] Battery-grade manganese sulfate is an important material in the synthesis of lithium manganese oxide for new energy batteries. The preparation of battery-grade manganese sulfate uses industrial-grade manganese sulfate as raw material, which undergoes oxidation and neutralization to remove Fe. 3+ K + Na + Sulfide treatment to remove heavy metal ions, recrystallization to remove Ca 2+ Mg 2+ Continuous impurity removal is performed to achieve the requirements for battery-grade manganese sulfate. This includes the removal of Ca... 2+ and Mg 2+ This is a problem that currently exists.

[0003] As major by-products in manganese leaching solutions, the removal of calcium and magnesium ions directly affects product quality. Deep purification methods include recrystallization, chemical precipitation, and solvent extraction. Recrystallization requires five repetitions to meet battery-grade requirements, but its drawbacks include high energy consumption and low economic efficiency. Chemical precipitation primarily involves fluoride precipitation. However, this method is time-consuming because CaF2 and MgF2 are ultrafine crystals, difficult to filter, and introduces new impurities like fluoride ions. Fluoride ions are corrosive in acidic manganese sulfate solutions, easily corroding equipment and reducing product quality when used as battery raw materials.

[0004] In summary, existing methods for removing calcium and magnesium during the preparation of battery-grade manganese sulfate suffer from drawbacks such as complex processes, low impurity removal efficiency, high energy consumption, and low economic feasibility. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate. This invention first treats the manganese sulfate solution, filtering out finely separated calcium and magnesium substances. Then, a composite complexing agent is used to complex the calcium and magnesium ions in the manganese sulfate solution. The composite complexing agent reacts with Ca... 2+ Mg 2+ The reaction produces a calcium-magnesium complex that remains in the mother liquor, without introducing new impurities. The mother liquor does not affect subsequent evaporation and crystallization. Finally, a precipitant is used to remove impurities by precipitating calcium and magnesium ions, without introducing new impurities, so that the calcium and magnesium ions precipitate in the form of a double salt. This solves the problems of existing technologies, such as complex processes, low impurity removal efficiency, high energy consumption, and low economic feasibility.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The purpose of this invention is to provide a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate, comprising the following steps: S1. Filter the manganese sulfate solution to obtain the filtered manganese sulfate solution.

[0007] S2. Add a complexing agent to the filtered manganese sulfate solution to perform the first complexation, and obtain crystals.

[0008] S3. The crystals are reconstituted into a manganese sulfate solution for precipitation and impurity removal. The pH is then adjusted to obtain the purified solution.

[0009] S4. Add a composite complexing agent to the purified solution for a second complexation, thereby removing calcium and magnesium ions from the preparation of battery-grade manganese sulfate.

[0010] In a preferred embodiment of the present invention, the manganese sulfate solution is a manganese sulfate leaching solution or an industrial-grade manganese sulfate solution; the volume of the manganese sulfate solution is 200 mL to 4000 mL, and the pH value of the manganese sulfate solution is 4.5 to 5.5.

[0011] In a preferred embodiment of the present invention, the manganese sulfate solution has a manganese sulfate concentration of 530 g / L, a calcium ion content of 0.3 g / L to 1 g / L, and a magnesium ion content of 1.0 g / L to 2.0 g / L.

[0012] In a preferred embodiment of the present invention, the filter layer material is battery-grade manganese dioxide during filtration.

[0013] In a preferred embodiment of the present invention, the composite complexing agent is composed of triacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1, and the amount of composite complexing agent added is 0.5 g / L.

[0014] In a preferred embodiment of the present invention, the first complexation time is 0.5h to 1h and the temperature is 80℃ to 120℃; the second complexation time is 0.5h to 1h and the temperature is 80℃ to 120℃.

[0015] In a preferred embodiment of the present invention, the precipitant during the precipitation process is manganese hydroxide.

[0016] In a preferred embodiment of the present invention, the specific process of adjusting the pH after precipitation is as follows: first, adjust the pH of the solution to 7.0-7.3; then, after centrifugation and filtration, adjust the pH of the solution to 4.5-5.5 with sulfuric acid, wherein the sulfuric acid is a 10wt% sulfuric acid solution.

[0017] In a preferred embodiment of the present invention, the calcium ion concentration in the treated manganese sulfate solution is 0.031 g / L to 0.038 g / L, and the magnesium ion concentration is 0.042 g / L to 0.047 g / L.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate. The method involves filtering a manganese sulfate solution, then adding a composite complexing agent to obtain crystals. The crystals are then reconstituted into a manganese sulfate solution for precipitation, followed by the addition of the composite complexing agent, thereby removing calcium and magnesium ions from the preparation of battery-grade manganese sulfate. Filtration removes finely shaped calcium and magnesium substances, and the composite complexing agent reacts with calcium and magnesium ions in the manganese sulfate solution. 2+ Mg 2+ The reaction produces a calcium-magnesium complex that remains in the mother liquor without introducing new impurities. The mother liquor does not affect subsequent evaporation and crystallization. The precipitant removes impurities by precipitating calcium and magnesium ions without introducing new impurities, causing the calcium and magnesium ions to precipitate in the form of a double salt. This solves the problems of existing technologies, such as complex processes, low impurity removal efficiency, high energy consumption, and low economic feasibility.

[0019] 2. This invention uses battery-grade manganese dioxide to prepare a filter cake for layering, and employs a composite complexing agent, namely nitrilotriacetic acid and ethylenediaminetetraacetic acid, to complex calcium and magnesium ions. Subsequently, manganese hydroxide is used as a precipitant to precipitate and remove impurities from the calcium and magnesium ions. Specifically, the filter cake is used to pretreat the manganese sulfate solution, filtering out finely shaped calcium and magnesium substances. The nitrilotriacetic acid and ethylenediaminetetraacetic acid in the composite complexing agent can react with calcium in the manganese sulfate solution. 2+ Mg 2+ The reaction produces a calcium-magnesium complex that remains in the mother liquor; and no new impurities are introduced, nor does the mother liquor affect subsequent evaporation and crystallization. The addition of manganese hydroxide as a precipitant does not introduce new impurities, causing calcium and magnesium ions to precipitate as double salts. This invention features low energy consumption, high economic feasibility, no introduction of new impurities, no impact on subsequent impurity removal processes, and mild reaction conditions. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0022] This invention provides a method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate, comprising the following steps: S1. Prepare a filter layer using battery-grade manganese dioxide and filter manganese sulfate leachate or industrial-grade manganese sulfate solution.

[0023] The manganese sulfate solution has a pH of 4.5 to 5.5, a volume of 200 mL to 4000 mL, a manganese sulfate concentration of 530 g / L, a calcium ion content of 0.3 g / L to 1 g / L, and a magnesium ion content of 1.0 g / L to 2.0 g / L.

[0024] S2. Add a composite complexing agent to an industrial-grade manganese sulfate solution, stir for 0.5 h to 1 h, evaporate and crystallize at 80 ℃ to 120 ℃, filter when 1 / 3 of the solution has evaporated, and take the crystals.

[0025] The complexing agent is composed of a mixture of triacetic acid and ethylenediaminetetraacetic acid, with a ratio of 1:1 and an addition amount of 0.5 g / L.

[0026] S3. Take the crystals obtained in step S2, prepare a 530 g / L manganese sulfate solution, add manganese hydroxide as a precipitant and stir, adjust the pH of the solution to 7.0-7.3, centrifuge, stir and filter, then add dilute sulfuric acid to adjust the pH of the solution to 4.5-5.5.

[0027] S4. Take the composite complexing agent added in step S3, stir for 0.5h~1h, evaporate and crystallize at 80℃~120℃, filter when 1 / 3 of the solution has evaporated, and take the crystals to remove calcium and magnesium ions in the preparation of battery-grade manganese sulfate, thus obtaining battery-grade manganese sulfate.

[0028] The composite complexing agent is composed of a mixture of triacetic acid and ethylenediaminetetraacetic acid, with a mass ratio of triacetic acid to ethylenediaminetetraacetic acid of 1:1, and the amount of composite complexing agent added is 0.5 g / L.

[0029] It should be noted that this invention pretreats the manganese sulfate solution by filtering out finely granulated calcium and magnesium substances. The triacetic acid and ethylenediaminetetraacetic acid components in the composite complexing agent used can react with calcium in the manganese sulfate solution. 2+ Mg 2+ The reaction produces a calcium-magnesium complex that remains in the mother liquor; and no new impurities are introduced, nor does the mother liquor affect subsequent evaporation and crystallization. The addition of manganese hydroxide as a precipitant does not introduce new impurities, causing calcium and magnesium ions to precipitate as double salts. This invention features low energy consumption, high economic feasibility, no introduction of new impurities, no impact on subsequent impurity removal processes, and mild reaction conditions.

[0030] The following specific examples will provide further explanation.

[0031] Example 1 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using battery-grade manganese dioxide. 1000 mL of industrial-grade manganese sulfate solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.5, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.41 g / L, and the magnesium ion content is 0.92 g / L.

[0032] S2. Add 0.1g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5h, and evaporate to crystallize at 100℃. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0033] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.0. After centrifugation, stirring and filtration, add 10% dilute sulfuric acid to adjust the pH of the solution to 5.2 to obtain the precipitated solution.

[0034] S4. Add 0.05g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0035] In this embodiment, the calcium ion concentration in the manganese sulfate solution after purification in S4 is 0.035 g / L, and the magnesium ion concentration is 0.042 g / L.

[0036] Example 2 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using high-purity battery-grade manganese dioxide. 1000 mL of industrial-grade manganese sulfate solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.2, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.46 g / L, and the magnesium ion content is 0.98 g / L.

[0037] S2. Add 0.25 g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5 h, and evaporate to crystallize at 100 °C. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0038] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.1. After centrifugation, stirring, and filtration, add dilute sulfuric acid to adjust the pH of the solution to 5.6 to obtain the precipitated solution.

[0039] S4. Add 0.12g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0040] In this embodiment, the calcium ion concentration in the purified manganese sulfate solution is 0.033 g / L, and the magnesium ion concentration is 0.045 g / L.

[0041] Example 3 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using high-purity battery-grade manganese dioxide. 1500 mL of manganese sulfate leaching solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.7, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.78 g / L, and the magnesium ion content is 1.38 g / L.

[0042] S2. Add 0.5g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5h, and evaporate to crystallize at 100℃. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0043] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.3. After centrifugation, stirring and filtration, add dilute sulfuric acid to adjust the pH of the solution to 5.8 to obtain the precipitated solution.

[0044] S4. Add 0.25g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0045] In this embodiment, the calcium ion concentration in the purified manganese sulfate solution is 0.038 g / L, and the magnesium ion concentration is 0.047 g / L.

[0046] Example 4 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using high-purity battery-grade manganese dioxide. 2000 mL of manganese sulfate leaching solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.6, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.81 g / L, and the magnesium ion content is 1.47 g / L.

[0047] S2. Add 1g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5h, and evaporate to crystallize at 100℃. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0048] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.2. After centrifugation, stirring, and filtration, add dilute sulfuric acid to adjust the pH of the solution to 5.7 to obtain the precipitated solution.

[0049] S4. Add 0.5g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0050] In this embodiment, the calcium ion concentration in the purified manganese sulfate solution is 0.031 g / L, and the magnesium ion concentration is 0.042 g / L.

[0051] Example 5 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using high-purity battery-grade manganese dioxide. 3000 mL of manganese sulfate leaching solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.7, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.78 g / L, and the magnesium ion content is 1.38 g / L.

[0052] S2. Add 1.5g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5h, and evaporate to crystallize at 100℃. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0053] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.3. After centrifugation, stirring and filtration, add dilute sulfuric acid to adjust the pH of the solution to 5.8 to obtain the precipitated solution.

[0054] S4. Add 0.8g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0055] In this embodiment, the calcium ion concentration in the purified manganese sulfate solution is 0.033 g / L, and the magnesium ion concentration is 0.045 g / L.

[0056] Example 6 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. A filter layer is prepared using high-purity battery-grade manganese dioxide. 4000 mL of manganese sulfate leaching solution is filtered through the filter layer to obtain a filtered manganese sulfate solution. The pH value of the manganese sulfate solution is 4.8, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.81 g / L, and the magnesium ion content is 1.48 g / L.

[0057] S2. Add 2g of the composite complexing agent to the filtered manganese sulfate solution, stir for 0.5h, and evaporate to crystallize at 100℃. Filter after evaporating 1 / 3 of the solution to obtain the crystals. The composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a 1:1 mass ratio.

[0058] S3. Take the crystals from step S2 and reconstitute them into 1000 mL of a 530 g / L manganese sulfate solution. Add manganese hydroxide as a precipitant and stir. Adjust the pH of the solution to 7.3. After centrifugation, stirring and filtration, add dilute sulfuric acid to adjust the pH of the solution to 5.4 to obtain the precipitated solution.

[0059] S4. Add 1g of the composite complexing agent to the precipitated solution, stir for 0.5h, evaporate and crystallize at 100℃, filter when 1 / 3 of the solution has evaporated, collect the crystals, and obtain battery-grade manganese sulfate; the composite complexing agent is a mixture of nitrilotriacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1.

[0060] In this embodiment, the calcium ion concentration in the purified manganese sulfate solution is 0.034 g / L (MS-ICP), and the magnesium ion concentration is 0.046 g / L.

[0061] Comparative Example 1 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. Prepare a filter layer using ordinary filter paper, and filter 1000 mL of industrial-grade manganese sulfate leaching solution through the filter layer to obtain a filtered manganese sulfate solution; the pH value of the manganese sulfate solution is 4.7, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 1.23 g / L, and the magnesium ion content is 2.46 g / L.

[0062] S2. Add 2g of precipitant MnF to the filtered manganese sulfate solution, stir at 40℃ for 0.5h, and then filter to obtain the filtrate.

[0063] S3. Take the filtered material from step S2 and reconstitute it into 1000 mL of a 530 g / L manganese sulfate solution. Measure the calcium ion content as 0.51 g / L and the magnesium ion content as 1.04 g / L. Repeat step S2.

[0064] Repeat step S2 four times until the concentration of calcium and magnesium ions in the manganese sulfate solution is below 0.05 g / L.

[0065] The manganese sulfate in this method contains fluoride ions, which are corrosive to the subsequent production of battery materials from manganese sulfate.

[0066] Comparative Example 2 A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate includes the following steps: S1. Prepare a filter layer using ordinary filter paper, and filter 1000 mL of industrial-grade manganese sulfate leaching solution through the filter layer to obtain a filtered manganese sulfate solution; the pH value of the manganese sulfate solution is 4.7, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 1.02 g / L, and the magnesium ion content is 2.34 g / L.

[0067] S2. The filtered manganese sulfate solution is stirred and evaporated at 100°C. After filtration, the filtrate is obtained.

[0068] S3. Take the filtered material from step S2 and reconstitute it into 1000 mL of a 530 g / L manganese sulfate solution. Measure the calcium ion content as 0.51 g / L and the magnesium ion content as 1.04 g / L. Repeat step S2.

[0069] Repeat step S2 5 times until the concentration of calcium and magnesium ions in the manganese sulfate solution is less than 0.05 g / L.

[0070] This method involves too many evaporation and crystallization cycles, resulting in excessive energy consumption.

[0071] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0072] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate, characterized in that, Includes the following steps: The manganese sulfate solution was filtered to obtain the filtered manganese sulfate solution. A complexing agent was added to the filtered manganese sulfate solution to perform the first complexation, resulting in crystals. The crystals were reconstituted into a manganese sulfate solution for precipitation and impurity removal. The pH was then adjusted to obtain the purified solution. A composite complexing agent is added to the purified solution to perform a second complexation, thereby removing calcium and magnesium ions from the preparation of battery-grade manganese sulfate.

2. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, The manganese sulfate solution is either a manganese sulfate leachate or an industrial-grade manganese sulfate solution; the volume of the manganese sulfate solution is 200 mL to 4000 mL, and the pH value of the manganese sulfate solution is 4.5 to 5.

5.

3. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, In the manganese sulfate solution, the concentration of manganese sulfate is 530 g / L, the calcium ion content is 0.3 g / L to 1 g / L, and the magnesium ion content is 1.0 g / L to 2.0 g / L.

4. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, During filtration, the filter layer material is battery-grade manganese dioxide.

5. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, The complexing agent is composed of triacetic acid and ethylenediaminetetraacetic acid in a mass ratio of 1:1, and the amount of complexing agent added is 0.5 g / L.

6. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, The first complexation time was 0.5h to 1h, and the temperature was 80℃ to 120℃; the second complexation time was 0.5h to 1h, and the temperature was 80℃ to 120℃.

7. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, During the precipitation process, the precipitant is manganese hydroxide.

8. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, The specific process for adjusting the pH after precipitation is as follows: first, adjust the pH of the solution to 7.0-7.3, then centrifuge and filter, and finally adjust the pH of the solution to 4.5-5.5 with sulfuric acid (10wt% sulfuric acid solution).

9. The method for removing calcium and magnesium ions in the preparation of battery-grade manganese sulfate according to claim 1, characterized in that, After treatment, the calcium ion concentration in the manganese sulfate solution was 0.031 g / L to 0.038 g / L, and the magnesium ion concentration was 0.042 g / L to 0.047 g / L.