Method for extracting high-purity manganese carbonate by using electrolytic manganese anolyte

Abstract

The invention relates to the field of manufacturing of high-purity manganese-based materials, in particular to a method for extracting high-purity manganese carbonate by using electrolytic manganese anolyte. Comprising the following steps: S1, adding ammonium fluoride into the electrolytic manganese anolyte, heating and stirring, then adding modified activated carbon, heating and stirring, carrying out filter pressing, and collecting filtrate 1; s2, mixing the eutectic solvent with n-hexane, stirring to obtain an organic phase, mixing the organic phase with the filtrate 1, stirring, and centrifugally layering to obtain an extraction phase and raffinate; s3, the extraction phase obtained in the step S2 is washed with sulfuric acid, reverse extraction is conducted with a sulfuric acid solution according to the flow ratio of the organic phase to the water phase being (6-10): 1, and a manganese-rich solution is obtained; and S4, adding the manganese-rich solution into the ammonium bicarbonate solution, adjusting the pH value, heating and stirring, standing, carrying out filter pressing to obtain a filter cake a and a filtrate 2, and drying the filter cake a to obtain manganese carbonate. The manganese carbonate product prepared by the method is high in purity, and has the advantages of convenience in operation, harmlessness to the environment, high efficiency, good selectivity and the like.

Description

Technical Field

[0001] The invention relates to the field of high-purity manganese-based material manufacturing, and in particular to a method for extracting high-purity manganese carbonate by utilizing electrolytic manganese anolyte. Background Art

[0002] In the production process of electrolytic manganese industry, a large amount of anolyte is produced, which contains a large amount of manganese ion resources, but also mixed with various impurities such as magnesium ions, calcium ions and sulfate ions. If these anolyte are directly discharged, it will not only cause the manganese resources to be lost without reason, resulting in a huge waste of resources; but also these improperly treated anolyte are discharged into the environment, and the various impurities in them will cause serious pollution hazards to ecological environment elements such as soil and water bodies, destroying the ecological balance.

[0003] From the existing treatment methods, the traditional methods have obvious limitations in the purification of manganese ions in the anolyte, and it is difficult to efficiently convert them into high-value-added high-purity manganese carbonate products, which cannot meet the current market demand for high-purity manganese carbonate. It can be seen that the development of a preparation method that is both efficient and environmentally friendly, which can accurately extract high-purity manganese carbonate from electrolytic manganese anolyte, will help to fully tap the potential value of manganese resources and avoid their unwarranted abandonment. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for extracting high-purity manganese carbonate using electrolytic manganese anolyte. The manganese carbonate prepared by the method has high purity, and has the advantages of convenient operation, high efficiency, good selectivity, etc.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A method for extracting high-purity manganese carbonate using electrolytic manganese anolyte, comprising the following steps: S1, take the electrolytic manganese anolyte to be treated, adjust the pH to 6-6.5, add ammonium fluoride to the electrolytic manganese anolyte after adjusting the pH, heat and stir for 2-3h, then add modified activated carbon, heat and stir for 2-3h, filter press, and collect filtrate 1; S2, mixing a low eutectic solvent with n-hexane in a mass ratio of 1-2:5-7, stirring for 8-12 minutes to obtain an organic phase, mixing the organic phase with filtrate 1, heating and stirring for 1-2 hours, centrifuging and stratifying to obtain an extract phase and a raffinate; S3, washing the extract phase obtained in step S2 with sulfuric acid, and stripping with a 4-6 mol / L sulfuric acid solution at a flow ratio of the organic phase to the aqueous phase of 6-10:1 to obtain a manganese-rich solution; S4. Add the manganese-rich solution to the ammonium bicarbonate solution while stirring, adjust the pH to 6-7, heat and stir for 8-12 hours, then let stand for 1-2 hours, filter by pressure to obtain filter cake a and filtrate 2, wash the filter cake a with pure water for 3-5 times, and dry to obtain manganese carbonate.

[0006] Preferably, the mass ratio of ammonium fluoride, modified activated carbon and electrolytic manganese anolyte in step S1 is 4-6:1-2:40-60.

[0007] Preferably, the modified activated carbon is prepared by the following method: A1. Add activated carbon and ferric nitrate nonahydrate into a high-pressure reactor, then add deionized water and ascorbic acid, stir for 10-15 minutes, heat to react for 10-15 hours, cool to room temperature, filter, wash, dry, and calcine to obtain composite activated carbon; A2. Disperse the composite activated carbon in N,N-dimethylformamide, add oxalic acid, heat and stir for 20-30 minutes, then add sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine, heat and stir for 3-5 hours, filter, wash and dry to obtain modified activated carbon.

[0008] Preferably, in step A1, the following components are included by mass: 15-25 parts of activated carbon, 3-5 parts of ferric nitrate nonahydrate, 0.05-0.1 parts of ascorbic acid, and 60-80 parts of deionized water.

[0009] Preferably, in step A2, the mass ratio of modified activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide is 8-12: 1-2: 0.8-1.2: 0.05-0.1: 50-60.

[0010] Preferably, the low eutectic solvent in step S2 is prepared by stirring benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol in a molar ratio of 2-4:1-3:1.2-1.8 at 70-90° C. for 3-5 hours.

[0011] Preferably, the modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir for 10-15 minutes, add trifluoromethanesulfonic acid, heat and stir for 4-6 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid, trifluoromethanesulfonic acid and deionized water is 8-12:2-4:0.2-0.3:60-70.

[0012] Preferably, in step S2, the mass ratio of the organic phase to the filtrate 1 is 3-5:5-8.

[0013] Preferably, the mass ratio of the manganese-rich solution to the ammonium bicarbonate solution in step S4 is 5-8:9-12.

[0014] Preferably, the filtrate 2 in step S4 is further treated with a defluorinating agent.

[0015] The present invention has the following beneficial effects: The present invention not only improves the roughness and specific surface area of ​​the activated carbon by loading ferrosoferric oxide on the surface of the activated carbon, thereby creating more adsorption sites, but also significantly enhances its adsorption efficiency for metal ions. Furthermore, the present invention chemically bonds oxalic acid and sodium 3-chloro-2-hydroxypropane sulfonate to the surface of the composite activated carbon, and the obtained modified activated carbon introduces highly active halogen atoms, hydroxyl functional groups and sulfonate groups, making its molecular chain structure more complex and changeable, thereby strengthening the adsorption and bridging ability of the modified activated carbon for metal ions, and finally achieving a significant improvement in flocculation efficiency.

[0016] The invention mixes citric acid and iminooxalic acid, then adds trifluoromethanesulfonic acid, and heats and stirs to obtain modified citric acid. The introduction of iminooxalic acid allows its imino group and carboxyl group to interact with citric acid molecules, thereby increasing the complexity and diversity of the entire molecular structure, and also introduces more active sites, thereby constructing a more complex complex structure. The introduction of trifluoromethanesulfonic acid allows the carboxyl group and iminooxalic acid molecules to be more easily ionized, thereby increasing the activity of reactants and promoting the reaction, and can reduce the activation energy of the reaction, thereby changing the structure of the reactant molecules and being more conducive to the reaction. Benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol are heated and mixed to obtain a low eutectic solvent. The functional group and molecular structure of the modified citric acid can form a stable complex with manganese ions, thereby achieving selective extraction of manganese ions. In addition, the benzyltrimethylammonium chloride can be used as a solvent for the production of low eutectic solvents. The presence of ammonium chloride can further enhance the selective extraction of manganese ions, and reduce the interference of other impurity ions through electrostatic effect, so that the whole extraction process can achieve a higher extraction efficiency; the introduction of dipentaerythritol can enhance the stability and solubility of the low eutectic solvent. At the same time, the spatial structure of dipentaerythritol is relatively large, which can increase the intermolecular force of the low eutectic solvent, further reduce its melting point and viscosity, and improve its physical properties; the synergistic effect of the three makes the volatilization loss of the low eutectic solvent less, and the stability of the system can be maintained during the extraction process to ensure the smooth progress of the extraction process. In addition, it has good solubility for manganese ions, which is conducive to further improving the extraction efficiency. The prepared low eutectic solvent also has environmentally friendly characteristics, and its synthesis process is relatively simple, without complex processes and cumbersome operating steps. At the same time, the cost of raw materials is low, and it also has good economic feasibility in large-scale applications.

[0017] The present invention constructs an extraction process for a high-purity manganese carbonate product, wherein the modified activated carbon introduced can effectively adsorb precipitations such as calcium fluoride, effectively remove impurities such as calcium ions in the electrolytic manganese anolyte, and also introduces an environmentally friendly low eutectic solvent, the preparation process of which is simple and convenient; the low eutectic solvent can efficiently separate manganese, effectively promote the smooth progress of the entire extraction process; and the final filtrate is defluorinated to ensure that the entire production process is harmless to the environment. The significant advantage of the extraction method proposed by the present invention is that the processing flow is simplified, and the effective separation and removal of impurities can be achieved by relying on an efficient operation mode, which greatly improves the production efficiency of high-purity manganese carbonate products, and also effectively guarantees the quality level of the product, making it more advantageous in market competition. DETAILED DESCRIPTION

[0018] Unless otherwise specified, the materials, reagents, etc. used in the present invention can be obtained from commercial sources.

[0019] Ammonium fluoride, purchased from Langfang Pengcai Fine Chemical Co., Ltd., analytical grade AR, content ≥96%; activated carbon, purchased from Ningxia Shengmei Huarui Activated Carbon Manufacturing Co., Ltd., mesh size: 100 mesh; citric acid, purchased from Wujiang Xinmao Fine Chemical Co., Ltd., industrial grade; benzyltrimethylammonium chloride, purchased from Shandong Xinghai Chemical Co., Ltd.; iminodiacetic acid, purchased from Shandong Yinglang Chemical Co., Ltd., density: 1.436 g / cm 3 ; Trifluoromethanesulfonic acid, purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; dipentaerythritol, purchased from Shandong Suihua Biotechnology Co., Ltd., content: 99%; HPF3500 resin, purchased from Jiangsu Haipu Functional Materials Co., Ltd.; pentaerythritol, purchased from Anhui Jinyueguan New Materials Technology Co., Ltd.

[0020] Example 1 A method for extracting high-purity manganese carbonate using electrolytic manganese anolyte, comprising the following steps: S1. Take the electrolytic manganese anolyte to be treated, adjust the pH to 6, add ammonium fluoride to the electrolytic manganese anolyte after adjusting the pH, stir at 50°C and 100rpm for 3h, then add modified activated carbon, stir at 50°C and 100rpm for 3h, filter press, and collect filtrate 1; wherein the filter press conditions are: filtration pressure of 0.2MPa, filtration time of 5min; the mass ratio of ammonium fluoride, modified activated carbon and electrolytic manganese anolyte is 4:1:40; S2, mixing a low eutectic solvent with n-hexane in a mass ratio of 1:5, stirring at 80 rpm for 8 min to obtain an organic phase, mixing the organic phase with filtrate 1, stirring at 60°C and 100 rpm for 2 h, and centrifuging at 8000 rpm for 6 min to obtain an extract phase and a raffinate; wherein the mass ratio of the organic phase to the filtrate 1 is 3:5; S3, washing the extract phase obtained in step S2 with 1.5 mol / L sulfuric acid for 15 min, and stripping with 4 mol / L sulfuric acid solution at a flow ratio of 6:1 between the organic phase and the aqueous phase to obtain a manganese-rich solution; S4. Add the manganese-rich solution to the ammonium bicarbonate solution while stirring, adjust the pH to 6, stir at 50°C and 100 rpm for 8 hours, then let stand for 1 hour, filter press to obtain filter cake a and filtrate 2, wash the filter cake a with pure water for 3 times, and dry at 80°C for 3 hours to obtain manganese carbonate; wherein the mass ratio of the manganese-rich solution to the ammonium bicarbonate solution is 5:9, and the mass fraction of the ammonium bicarbonate solution is 25%.

[0021] Among them, the modified activated carbon is prepared by the following method: A1. Add activated carbon and ferric nitrate nonahydrate into an autoclave, add deionized water and ascorbic acid, stir at 150 rpm for 10 min, then stir at 60 ° C and 100 rpm for 10 h, cool to room temperature, filter, wash with deionized water 3 times, dry at 70 ° C for 3 h, heat to 600 ° C under a nitrogen atmosphere, and heat for 8 h to obtain composite activated carbon; wherein, by mass: 15 parts of activated carbon, 3 parts of ferric nitrate nonahydrate, 0.05 parts of ascorbic acid, and 60 parts of deionized water; A2. Disperse the composite activated carbon in N,N-dimethylformamide, add oxalic acid, stir at 60°C and 100rpm for 20min, then add sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine, stir at 60°C and 100rpm for 3h, filter, wash with deionized water 3 times, and dry at 70°C for 3h to obtain modified activated carbon; wherein the mass ratio of the composite activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide is 8:1:0.8:0.05:50.

[0022] The low eutectic solvent is prepared by stirring benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol in a molar ratio of 2:1:1.2 at 70°C for 3 hours.

[0023] Modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir for 10 minutes, add trifluoromethanesulfonic acid, stir at 60°C and 100 rpm for 4 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid, trifluoromethanesulfonic acid and deionized water is 8:2:0.2:60.

[0024] Among them, the filtrate 2 also needs to be treated by a defluorination process, which specifically includes: A1. Add the defluorinating agent to the filtrate 2, stir for 15 minutes, adjust the pH to 6.5, and stir for another 10 minutes to obtain a mixed solution; wherein, when the fluorine atom concentration in the filtrate 2 is less than 5ppm, the ratio of the defluorinating agent to the filtrate 2 is 1L:0.9m 3 ; When the fluorine atom concentration in filtrate 2 is 5ppm<20ppm, the ratio of defluorination agent to filtrate 2 is 1.5L:0.9m 3 , the defluorination agent is HPF3500 type resin; A2. Add anionic polyacrylamide to the mixed solution, stir for 20 minutes, let stand for 1 hour, obtain supernatant and sediment, filter the sediment to obtain filter cake b and filtrate 3; wherein the mass ratio of anionic polyacrylamide to the mixed solution is 5:12.

[0025] Example 2 A method for extracting high-purity manganese carbonate using electrolytic manganese anolyte, comprising the following steps: S1. Take the electrolytic manganese anolyte to be treated, adjust the pH to 6.5, add ammonium fluoride to the electrolytic manganese anolyte after adjusting the pH, stir at 70°C and 200rpm for 2h, then add modified activated carbon, stir at 70°C and 200rpm for 2h, filter press, and collect filtrate 1; wherein the filter press conditions are: filtration pressure of 0.25MPa, filtration time of 8min; the mass ratio of ammonium fluoride, modified activated carbon and electrolytic manganese anolyte is 6:2:60; S2, mixing a low eutectic solvent with n-hexane in a mass ratio of 2:7, stirring at 120 rpm for 12 min to obtain an organic phase, mixing the organic phase with filtrate 1, stirring at 70°C and 200 rpm for 1 h, and centrifuging at 10000 rpm for 4 min to obtain an extract phase and a raffinate; wherein the mass ratio of the organic phase to the filtrate 1 is 5:8; S3, washing the extract phase obtained in step S2 with 3 mol / L sulfuric acid for 25 min, and stripping with 6 mol / L sulfuric acid solution at a flow ratio of 10:1 between the organic phase and the aqueous phase to obtain a manganese-rich solution; S4. Add the manganese-rich solution to the ammonium bicarbonate solution while stirring, adjust the pH to 7, stir at 60°C and 200 rpm for 12 hours, then let stand for 2 hours, filter press to obtain filter cake a and filtrate 2, wash the filter cake a with pure water 5 times, and dry at 90°C for 5 hours to obtain manganese carbonate; wherein the mass ratio of the manganese-rich solution to the ammonium bicarbonate solution is 8:12, and the mass fraction of the ammonium bicarbonate solution is 40%.

[0026] Among them, the modified activated carbon is prepared by the following method: A1. Add activated carbon and ferric nitrate nonahydrate to an autoclave, add deionized water and ascorbic acid, stir at 200 rpm for 15 min, then stir at 70 ° C and 200 rpm for 15 h, cool to room temperature, filter, wash with deionized water 5 times, dry at 80 ° C for 5 h, heat to 800 ° C under a nitrogen atmosphere, and heat for 5 h to obtain composite activated carbon; wherein, by mass: 25 parts of activated carbon, 5 parts of ferric nitrate nonahydrate, 0.1 parts of ascorbic acid, and 80 parts of deionized water; A2. Disperse the composite activated carbon in N,N-dimethylformamide, add oxalic acid, stir at 70°C and 200rpm for 30min, then add sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine, stir at 70°C and 200rpm for 5h, filter, wash with deionized water 5 times, and dry at 80°C for 5h to obtain modified activated carbon; wherein the mass ratio of the composite activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide is 12:2:1.2:0.1:60.

[0027] The low eutectic solvent is prepared by stirring benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol in a molar ratio of 4:3:1.8 at 90°C for 5 hours.

[0028] Modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir for 15 minutes, add trifluoromethanesulfonic acid, stir at 70°C and 200 rpm for 6 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid, trifluoromethanesulfonic acid and deionized water is 12:4:0.3:70.

[0029] Among them, the filtrate 2 also needs to be treated by a defluorination process, specifically including: A1. Add the defluorinating agent to the filtrate 2, stir for 35 minutes, adjust the pH to 7.0, and stir for another 15 minutes to obtain a mixed solution; wherein, when the fluorine atom concentration in the filtrate 2 is less than 5ppm, the ratio of the defluorinating agent to the filtrate 2 is 1L:1.1m 3 ; When the fluorine atom concentration in filtrate 2 is 5ppm<20ppm, the ratio of defluorination agent to filtrate 2 is 1.5L:1.1m 3 , the defluorination agent is HPF3500 type resin; A2. Add anionic polyacrylamide to the mixed solution, stir for 30 minutes, let stand for 2 hours, obtain supernatant and sediment, filter the sediment to obtain filter cake b and filtrate 3; wherein the mass ratio of anionic polyacrylamide to the mixed solution is 8:15.

[0030] Example 3 A method for extracting high-purity manganese carbonate using electrolytic manganese anolyte, comprising the following steps: S1. Take the electrolytic manganese anolyte to be treated, adjust the pH to 6.5, add ammonium fluoride to the electrolytic manganese anolyte after adjusting the pH, stir at 60°C and 150rpm for 2.5h, then add modified activated carbon, stir at 60°C and 150rpm for 2.5h, filter press, and collect filtrate 1; wherein the filter press conditions are: filtration pressure of 0.25MPa, filtration time of 6min; the mass ratio of ammonium fluoride, modified activated carbon and electrolytic manganese anolyte is 5:1.5:50; S2, mixing a low eutectic solvent with n-hexane in a mass ratio of 1.5:6, stirring at 100 rpm for 10 min to obtain an organic phase, mixing the organic phase with filtrate 1, stirring at 65° C. and 150 rpm for 1.5 h, and centrifuging at 9000 rpm for 5 min to obtain an extract phase and a raffinate; wherein the mass ratio of the organic phase to the filtrate 1 is 4:7; S3, washing the extract phase obtained in step S2 with 2 mol / L sulfuric acid for 20 min, and stripping with 5 mol / L sulfuric acid solution at a flow ratio of 8:1 between the organic phase and the aqueous phase to obtain a manganese-rich solution; S4. Add the manganese-rich solution to the ammonium bicarbonate solution while stirring, adjust the pH to 6.5, stir at 55°C and 150rpm for 10 hours, then let it stand for 1.5 hours, filter press to obtain filter cake a and filtrate 2, wash the filter cake a with pure water for 4 times, and dry at 85°C for 4 hours to obtain manganese carbonate; wherein the mass ratio of the manganese-rich solution to the ammonium bicarbonate solution is 6:10, and the mass fraction of the ammonium bicarbonate solution is 30%.

[0031] Among them, the modified activated carbon is prepared by the following method: A1. Add activated carbon and ferric nitrate nonahydrate to an autoclave, add deionized water and ascorbic acid, stir at 180 rpm for 13 min, then stir at 65 ° C and 150 rpm for 13 h, cool to room temperature, filter, wash 4 times with deionized water, dry at 75 ° C for 4 h, heat to 700 ° C under a nitrogen atmosphere, and heat for 6 h to obtain composite activated carbon; wherein, by mass: 20 parts of activated carbon, 4 parts of ferric nitrate nonahydrate, 0.08 parts of ascorbic acid, and 70 parts of deionized water; A2. Disperse the composite activated carbon in N,N-dimethylformamide, add oxalic acid, stir at 65°C and 150rpm for 25min, then add sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine, stir at 65°C and 150rpm for 4h, filter, wash with deionized water 4 times, and dry at 75°C for 4h to obtain modified activated carbon; wherein the mass ratio of the composite activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide is 10:1.5:1:0.08:55.

[0032] The low eutectic solvent is prepared by stirring benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol in a molar ratio of 3:2:1.5 at 80°C for 4 hours.

[0033] Wherein, the modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir for 12 minutes, add trifluoromethanesulfonic acid, stir at 65°C and 150 rpm for 5 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid, trifluoromethanesulfonic acid and deionized water is 10:3:0.25:65.

[0034] Among them, the filtrate 2 also needs to be treated by a defluorination process, which specifically includes: A1. Add the defluorinating agent to the filtrate 2, stir for 25 minutes, adjust the pH to 7.0, and stir for another 12 minutes to obtain a mixed solution; wherein, when the fluorine atom concentration in the filtrate 2 is less than 5ppm, the ratio of the defluorinating agent to the filtrate 2 is 1L:1.0m 3 ; When the fluorine atom concentration in filtrate 2 is 5ppm<20ppm, the ratio of defluorination agent to filtrate 2 is 1.5L:1.0m 3 , the defluorination agent is HPF3500 type resin; A2. Add anionic polyacrylamide to the mixed solution, stir for 25 minutes, let stand for 1.5 hours, obtain supernatant and sediment, filter the sediment to obtain filter cake b and filtrate 3; wherein the mass ratio of anionic polyacrylamide to the mixed solution is 7:14.

[0035] Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the preparation method of the deep eutectic solvent is different, as follows: The low eutectic solvent was prepared by stirring benzyltrimethylammonium chloride and modified citric acid in a molar ratio of 2:1 at 70°C for 3 h.

[0036] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the preparation method of the deep eutectic solvent is different, as follows: The low eutectic solvent was prepared by stirring benzyltrimethylammonium chloride and dipentaerythritol in a molar ratio of 2:1.2 at 70°C for 3 hours.

[0037] Comparative Example 3 Comparative Example 3 is the same as Example 1, except that the preparation method of the modified citric acid is different, specifically comprising: Modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir at 60° C. and 100 rpm for 4 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid and deionized water is 8:2:60.

[0038] Comparative Example 4 Comparative Example 4 is the same as Example 1, except that the preparation method of the deep eutectic solvent is different, as follows: The low eutectic solvent was prepared by stirring benzyltrimethylammonium chloride, citric acid and dipentaerythritol in a molar ratio of 2:1:1.2 at 70°C for 3 hours.

[0039] Comparative Example 5 Comparative Example 5 is the same as Example 1, except that the preparation method of the deep eutectic solvent is different, specifically comprising: The low eutectic solvent was prepared by stirring choline chloride, modified citric acid and dipentaerythritol in a molar ratio of 2:1:1.2 at 70°C for 3 hours.

[0040] Comparative Example 6 Comparative Example 6 is the same as Example 1, except that the preparation method of the deep eutectic solvent is different, specifically comprising: The low eutectic solvent was prepared by stirring benzyltrimethylammonium chloride, modified citric acid and pentaerythritol in a molar ratio of 2:1:1.2 at 70°C for 3 hours.

[0041] Comparative Example 7 Comparative Example 7 is the same as Example 1, except that the preparation method of the modified activated carbon is different, specifically comprising: Modified activated carbon is prepared by the following method: Add activated carbon and ferric nitrate nonahydrate into a high-pressure reactor, then add deionized water and ascorbic acid, stir at 150 rpm for 10 min, then stir at 60° C. and 100 rpm for 10 h, cool to room temperature, filter, wash with deionized water 3 times, dry at 70° C. for 3 h, heat to 600° C. under a nitrogen atmosphere for 8 h, and obtain modified activated carbon; wherein, by mass: 15 parts of activated carbon, 3 parts of ferric nitrate nonahydrate, 0.05 parts of ascorbic acid, and 60 parts of deionized water; Comparative Example 8 Comparative Example 8 is the same as Example 1, except that the preparation method of the modified activated carbon is different, specifically comprising: Modified activated carbon is prepared by the following method: The activated carbon was dispersed in N,N-dimethylformamide, oxalic acid was added, and the mixture was stirred at 60°C and 100 rpm for 20 min. Then, sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine were added, and the mixture was stirred at 60°C and 100 rpm for 3 h. The mixture was filtered, washed with deionized water for 3 times, and dried at 70°C for 3 h to obtain modified activated carbon. The mass ratio of activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide was 8:1:0.8:0.05:50.

[0042] Performance Testing The manganese carbonates obtained in Examples 1-3 and Comparative Examples 1-8 were subjected to the following performance tests: The sulfate content of manganese carbonate was tested gravimetrically; The manganese ion content in manganese carbonate is tested according to the potassium permanganate titration method. The manganese carbonate precipitate is dissolved in a hydrochloric acid solution. Under heating conditions, it is titrated with a potassium permanganate solution with a concentration of 0.05 mol / L until the pink color persists for 30 seconds without fading. The manganese content is calculated based on the volume of potassium permanganate consumed.

[0043] The test results are shown in Table 1: Table 1 Test results of Examples 1-3 and Comparative Examples 1-5

[0044] It can be seen from the test results in Table 1 that the present invention uses benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol to prepare a low eutectic solvent, which can efficiently extract manganese in the electrolytic manganese anolyte, and the manganese carbonate product obtained by the subsequent process has high purity, has significant advantages in technology, is simple in process, is easy to operate, has low investment cost, is harmless to the environment, and has broad application prospects and important economic value.

[0045] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A method for extracting high-purity manganese carbonate using electrolytic manganese anolyte, characterized in that: The following steps are involved: S1, take the electrolytic manganese anolyte to be treated, adjust the pH to 6-6.5, add ammonium fluoride to the electrolytic manganese anolyte after adjusting the pH, heat and stir for 2-3h, then add modified activated carbon, heat and stir for 2-3h, filter press, and collect filtrate 1; S2, mixing a low eutectic solvent with n-hexane in a mass ratio of 1-2:5-7, stirring for 8-12 minutes to obtain an organic phase, mixing the organic phase with filtrate 1, stirring for 1-2 hours, centrifuging and stratifying to obtain an extract phase and a raffinate; S3, washing the extract phase obtained in step S2 with sulfuric acid, and stripping with a 4-6 mol / L sulfuric acid solution at a flow ratio of the organic phase to the aqueous phase of 6-10:1 to obtain a manganese-rich solution; S4. Add the manganese-rich solution to the ammonium bicarbonate solution while stirring, adjust the pH to 6-7, heat and stir for 8-12 hours, then let stand for 1-2 hours, filter by pressure to obtain filter cake a and filtrate 2, wash and dry the filter cake a to obtain manganese carbonate.

2. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The mass ratio of ammonium fluoride, modified activated carbon and electrolytic manganese anolyte in step S1 is 4-6:1-2:40-60.

3. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The modified activated carbon is prepared by the following method: A1. Add activated carbon and ferric nitrate nonahydrate into a high-pressure reactor, then add deionized water and ascorbic acid, stir for 10-15 minutes, heat to react for 10-15 hours, cool to room temperature, filter, wash, dry, and calcine to obtain composite activated carbon; A2. Disperse the composite activated carbon in N,N-dimethylformamide, add oxalic acid, heat and stir for 20-30 minutes, then add sodium 3-chloro-2-hydroxypropane sulfonate and triethylamine, heat and stir for 3-5 hours, filter, wash and dry to obtain modified activated carbon.

4. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 3, characterized in that: The weight parts of the raw materials in step A1 are as follows: 15-25 parts of activated carbon, 3-5 parts of ferric nitrate nonahydrate, 0.05-0.1 parts of ascorbic acid, and 60-80 parts of deionized water.

5. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 3, characterized in that: In the step A2, the mass ratio of modified activated carbon, oxalic acid, sodium 3-chloro-2-hydroxypropane sulfonate, triethylamine and N,N-dimethylformamide is 8-12: 1-2: 0.8-1.2: 0.05-0.1: 50-60.

6. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The low eutectic solvent in step S2 is prepared by stirring benzyltrimethylammonium chloride, modified citric acid and dipentaerythritol in a molar ratio of 2-4:1-3:1.2-1.8 at 70-90° C. for 3-5 hours.

7. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 3, characterized in that: The modified citric acid is prepared by the following method: Mix citric acid, iminooxalic acid and deionized water, stir for 10-15 minutes, add trifluoromethanesulfonic acid, heat and stir for 4-6 hours, evaporate and remove the solvent to obtain modified citric acid; wherein the mass ratio of citric acid, iminooxalic acid, trifluoromethanesulfonic acid and deionized water is 8-12:2-4:0.2-0.3:60-70.

8. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The mass ratio of the organic phase to the filtrate 1 in step S2 is 3-5:5-8.

9. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The mass ratio of the manganese-rich solution to the ammonium bicarbonate solution in step S4 is 5-8:9-12.

10. The method for extracting high-purity manganese carbonate using electrolytic manganese anolyte according to claim 1, characterized in that: The filtrate 2 in step S4 needs to be treated with a defluorinating agent.

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