A process for recovering high-purity manganese sulfate from manganese zinc mother liquor
By combining multifunctional modified materials with hydrogen peroxide aqueous solution, the problems of manganese-zinc co-precipitation and organic residue were solved, and the recovery of high-purity manganese sulfate was achieved, thus solving the purity and yield problems in the existing technology.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN MODERN PESTICIDE
- Filing Date
- 2026-04-22
- Publication Date
- 2026-05-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical waste purification and resource recycling, specifically a process for recovering high-purity manganese sulfate from manganese zinc mother liquor. Background Technology
[0002] Mancozeb, as a broad-spectrum protective bactericide, generates a large amount of manganese-rich mother liquor during its synthesis. This mother liquor is extremely complex, presenting the following technical challenges: It contains high concentrations of free zinc ions with similar properties, which can easily lead to manganese-zinc co-precipitation using traditional physical precipitation methods, resulting in a significant decrease in manganese yield; traditional extractants are prone to severe emulsification when processing such complex mother liquors, and it is difficult to achieve deep removal of zinc; the mother liquor contains residual dithiocarbamates and their degradation intermediates; these organic impurities not only result in low purity and poor color of the recovered manganese sulfate, accompanied by volatile organic byproducts, but also act as crystal growth inhibitors, interfering with subsequent crystallization processes, causing the final product to fail to meet battery-grade or high-purity reagent-grade standards. Existing alkaline precipitation-acid dissolution or simple advanced oxidation processes cannot solve the two problems mentioned above at the same time, and are prone to introducing new impurity ions such as sodium and chloride. Therefore, there is an urgent need to develop a new recovery process that can simultaneously achieve highly selective zinc removal and organic mineralization under mild conditions. Summary of the Invention
[0003] The purpose of this invention is to provide a process for recovering high-purity manganese sulfate from manganese zinc mother liquor, aiming to solve the technical problems in the prior art that easily lead to manganese and zinc co-precipitation, low manganese yield, and difficulty in removing complex organic residues when processing complex mother liquors; specifically, the technical solution of this invention is as follows: A process for recovering high-purity manganese sulfate from mancozeb mother liquor includes the following steps: S1: The mancozeb mother liquor is filtered to remove mechanical impurities, and the pH is adjusted to 3.5-4.5 using sulfuric acid to obtain the pretreated mother liquor; S2: Add hydrogen peroxide aqueous solution and multifunctional modified material to the pretreatment mother liquor obtained in step S1, and stir the mixture at a constant temperature of 55-65℃ for 2-3 hours to obtain a mixed solution. S3: The mixture obtained in step S2 is allowed to settle and then separated into solid and liquid phases by pressure filtration to obtain a high-purity manganese sulfate purified solution. S4: The high-purity manganese sulfate purified solution obtained in step S3 is evaporated and concentrated, cooled to 20-25℃ for crystallization, separated by centrifugation, washed with saturated manganese sulfate solution, and dried at a temperature of 100-120℃ to obtain high-purity manganese sulfate crystals.
[0004] Preferably, the multifunctional modified material described in step S2 is obtained through the following preparation steps: (1) Place the chloromethylated crosslinked polystyrene resin in a sulfonating agent and carry out a partial sulfonation reaction at a temperature of 50-70℃ for 2-4 hours. Wash with water until neutral to obtain a partially sulfonated resin with a sulfonation degree of 30%-60%. (2) The partially sulfonated resin obtained in S201 is dispersed in an organic solvent, and aminothiourea and acid-binding agent are added in a mass ratio of 1:(0.5-1.5):(0.5-1.0). The nucleophilic substitution reaction is carried out at a temperature of 80-90℃ for 6-10 hours to obtain an intermediate. (3) Under nitrogen protection, using the intermediate obtained from S202 as the matrix, add appropriate amounts of deionized water, initiator and acrylamide monomer at a mass ratio of 1:(0.5-2.0):(0.05-0.1) of the intermediate, acrylamide monomer and initiator, and carry out surface graft copolymerization reaction at a temperature of 60-75℃ for 4-8 hours. After filtration, washing and vacuum drying, the multifunctional modified material is obtained.
[0005] Preferably, in step S2, the mass fraction of the hydrogen peroxide aqueous solution is 30%, and the amount of hydrogen peroxide aqueous solution added is 1%-3% of the mass of the pretreatment mother liquor; the amount of the multifunctional modified material added is 2%-5% of the mass of the pretreatment mother liquor.
[0006] Preferably, in S201, the sulfonating agent is a mixture of concentrated sulfuric acid and chlorosulfonic acid.
[0007] Preferably, in S202, the organic solvent is N,N-dimethylformamide, and the acid-binding agent is potassium carbonate.
[0008] Preferably, in S203, the initiator is potassium persulfate.
[0009] Preferably, the solid material separated in step S3 is eluted and desorbed by adding a sulfuric acid solution with a concentration of 0.5-1.0 mol / L at a liquid-solid ratio of 2:1 to 5:1, and then recycled back to step S2 for use as the multifunctional modified material.
[0010] Preferably, in step S4, the high-purity manganese sulfate purified solution is fed into a mechanical vapor recompression evaporator for evaporation and concentration.
[0011] Preferably, in step S1, the sulfuric acid is a dilute sulfuric acid with a mass fraction of 10%-20%.
[0012] Preferably, in step S4, the zinc ion content in the obtained high-purity manganese sulfate crystals is less than 5 ppm.
[0013] The beneficial effects of this invention are as follows: This invention achieves highly selective separation of manganese and zinc ions through the chemical bonding between the aminothiourea groups in the multifunctional modified material and zinc ions; this process significantly reduces zinc impurities in the product, resulting in a zinc ion content of less than 5 ppm in the final high-purity manganese sulfate crystals; the partial sulfonation resin in the multifunctional modified material, in conjunction with hydrogen peroxide aqueous solution, removes residual impurities in the mother liquor, effectively preventing interference from residual impurities in subsequent purification steps; and the polyacrylamide grafted onto the surface of the multifunctional modified material promotes impurity aggregation and solid-liquid separation, ultimately yielding high-purity manganese sulfate crystals. Detailed Implementation
[0014] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. In the embodiments and comparative examples of this invention, the content of zinc ions and other metal impurities was determined using inductively coupled plasma atomic emission spectrometry; the total organic carbon was determined using a total organic carbon analyzer; the purity of the manganese sulfate product was determined by titration according to relevant chemical industry standards; the degree of sulfonation of some sulfonated resins was determined by acid-base titration, with test conditions for example: 1g of dry resin was placed in an Erlenmeyer flask, excess 0.1mol / L sodium hydroxide standard solution was added, and after shaking at room temperature for 24h, the remaining NaOH was titrated with 0.1mol / L hydrochloric acid standard solution; In this invention, in order to ensure that the multifunctional modified material has good mass transfer channels and grafting sites, the degree of crosslinking of the chloromethylated crosslinked polystyrene resin is preferably 5%-12%, the chlorine content is preferably 12%-20%, and the average pore size is preferably 15-40 nm.
[0015] Example 1: This embodiment provides a process for recovering high-purity manganese sulfate from mancozeb mother liquor, which specifically includes the following steps; S1. Preparation of pretreatment mother liquor 1000 kg of mancozeb mother liquor was replaced. The manganese ion concentration in the mother liquor was 86.4 g / L, the zinc ion concentration was 1.42 g / L, and the total organic carbon was 3820 mg / L. The mancozeb mother liquor was filtered through a plate and frame filter press with a filter cloth pore size of 10 μm to remove mechanical impurities. Then, the pH was adjusted to 3.5 using 15% dilute sulfuric acid to obtain the pretreated mother liquor. S2, Preparation of multifunctional modified materials and reaction of mixed liquids 100g of chloromethylated crosslinked polystyrene resin with a crosslinking degree of 8%, a chlorine content of 17%, and an average pore size of 25nm was taken, and 500g of a mixed sulfonating agent of concentrated sulfuric acid and chlorosulfonic acid in a mass ratio of 4:1 was added. The mixture was partially sulfonated at 50℃ for 2h. The resin was washed with water until the pH of the filtrate was 7, and then dried to obtain a partially sulfonated resin with a sulfonation degree of 30%. 100g of this partially sulfonated resin was dispersed in 600g of N,N-dimethylformamide, and 50g of aminothiourea and potassium carbonate were added. The mixture was reacted at 80℃ for 6h, and then washed to obtain an intermediate. 100g of the intermediate was placed in a four-necked reaction flask, and nitrogen gas was introduced for 30min. 500g of deionized water, 50g of acrylamide, and 5g of potassium persulfate were added. The mixture was reacted at 60℃ for 4h, filtered, washed, and vacuum dried at 60℃ for 10h to obtain a multifunctional modified material. The pretreatment mother liquor, the above-mentioned multifunctional modified material added at 2% of the mass of the pretreatment mother liquor, and the 30% hydrogen peroxide aqueous solution added at 1% of the mass of the pretreatment mother liquor were added into an enamel-lined reactor and stirred at 280 r / min for 2 h at 55 °C. The sulfonic acid group is used to promote the oxidative decomposition of sulfur-containing organic residues by the hydrogen peroxide aqueous solution, the aminothiourea group is used to fix zinc ions on the solid phase surface, and the polyacrylamide brush is used to promote the aggregation and sedimentation of zinc-containing solid phase and organic particles. S3. Solid-liquid separation to obtain purified liquid After the above mixture was allowed to stand for 20 minutes, it was filtered by pressure. The filtrate was a clear and transparent high-purity manganese sulfate purified solution. The separated solid material was eluted with 0.5 mol / L sulfuric acid solution for 2 hours. After elution, it was washed with water until neutral and returned to the reaction system for reuse. S4. Preparation of high-purity manganese sulfate crystals The purified high-purity manganese sulfate solution was fed into a mechanical vapor recompression evaporator and concentrated to a density of 1.52 g / cm³ under a vacuum of 0.08 MPa. After cooling to 25°C for 6 hours, the solution was separated by centrifugation, washed with a saturated manganese sulfate solution, and dried at 100°C for 4 hours to obtain high-purity manganese sulfate crystals.
[0016] Example 2: This embodiment provides a process for recovering high-purity manganese sulfate from mancozeb mother liquor, which specifically includes the following steps; S1. Preparation of pretreatment mother liquor The operation process is basically the same as in Example 1, except that the pH of the pretreatment mother liquor is adjusted to 4.0; S2, Preparation of multifunctional modified materials and reaction of mixed liquids The preparation process of the multifunctional modified material is basically the same as that in Example 1, except that: in the sulfonation stage, 550g of mixed sulfonating reagent is added and reacted at 60℃ for 3h to obtain a partially sulfonated resin with a sulfonation degree of 45%; in the substitution stage, 100g of aminothiourea and 75g of potassium carbonate are added and reacted at 85℃ for 8h; in the grafting stage, 600g of deionized water, 120g of acrylamide and 8g of potassium persulfate are added and reacted at 68℃ for 6h. During the reaction stage, the amount of multifunctional modified material added was 3.5% of the mass of the pretreatment mother liquor, and the amount of 30% hydrogen peroxide aqueous solution added was 2% of the mass of the pretreatment mother liquor. The mixture was stirred at 60℃ for 2.5 hours. S3. Solid-liquid separation to obtain purified liquid The operation process is the same as in Example 1; S4. Preparation of high-purity manganese sulfate crystals The high-purity manganese sulfate purified solution obtained after pressure filtration is concentrated in a mechanical steam recompression evaporator, cooled and crystallized, and then dried at 110°C to obtain high-purity manganese sulfate crystals.
[0017] Example 3: This embodiment provides a process for recovering high-purity manganese sulfate from mancozeb mother liquor, which specifically includes the following steps; S1. Preparation of pretreatment mother liquor The operation process is basically the same as in Example 1, except that the pH of the pretreatment mother liquor is adjusted to 4.5; S2, Preparation of multifunctional modified materials and reaction of mixed liquids The structure and preparation of the multifunctional modified material are the same as in the previous embodiments; reaction stage: the amount of 30% hydrogen peroxide aqueous solution added is 3% of the mass of the pretreatment mother liquor, the amount of multifunctional modified material added is 5% of the mass of the pretreatment mother liquor, the reaction temperature is 65℃, and the reaction time is 3h; S3. Solid-liquid separation to obtain purified liquid The solid material obtained by pressure filtration was eluted with 1.0 mol / L sulfuric acid solution for 3 h. The zinc ion concentration in the eluent increased and was recovered. The eluted material was washed with water until neutral and then recycled. S4. Preparation of high-purity manganese sulfate crystals The purified high-purity manganese sulfate solution was fed into a mechanical vapor recompression evaporator and concentrated to a density of 1.58 g / cm³ under a vacuum of 0.09 MPa. After cooling to 20°C for 8 hours, the solution was separated by centrifugation and dried at 120°C for 3 hours to obtain high-purity manganese sulfate crystals with large particle size and good flowability.
[0018] Comparative Example 1: The difference between this comparative example and Example 2 is that the step of adding the multifunctional modified material in S2 is omitted, and only 20 kg of hydrogen peroxide aqueous solution is added and stirred at 60°C for 2.5 h. After the reaction is completed, the subsequent pressure filtration and crystallization steps are carried out directly. Other operating steps and process parameters are exactly the same as those in Example 2.
[0019] Comparative Example 2: The difference between this comparative example and Example 2 is that in S2, a type of ungrafted aminothiourea and ungrafted polyacrylamide brush, and 35 kg of partially sulfonated resin with only sulfonic acid groups are used to replace the multifunctional modified material; other operating steps and process parameters are exactly the same as in Example 2.
[0020] Performance testing and characterization methods The testing methods for relevant performance indicators in the embodiments and comparative examples of this invention are as follows: Metal impurity detection: The content of manganese, zinc and other metal impurities was determined using inductively coupled plasma atomic emission spectrometry. Organic residue detection: Total organic carbon was determined using a total organic carbon analyzer; Product purity testing: The purity of manganese sulfate products is determined by titration method in accordance with relevant chemical industry standards; Color and appearance evaluation: The color of the filtrate was tested according to the platinum-cobalt colorimetric method in accordance with GB / T3143 standard, and the transparency of the filtrate was observed by the naked eye. Material and crystal characterization: The degree of sulfonation of some sulfonated resins was determined by acid-base titration; the microstructure and structure of the obtained crystals were analyzed by X-ray diffraction.
[0021] Table 1 Performance test results of each embodiment and comparative example The supplementary observation results are as follows: In Example 2, after the solid material was continuously recycled 10 times, the zinc removal rate remained above 96%, and the performance was stable; Comparative Examples 1 and 2 did not involve the effective recycling of the solid material. As can be seen from the comparison of the test results of Example 2 and Comparative Example 1 in the table, omitting the introduction of the multifunctional modified material will result in a significant decrease in the Zn removal rate from 99.81% to 18.24%, and a significant decrease in the total organic carbon removal rate, with the filtrate appearing slightly yellow and turbid. The underlying mechanism is that relying solely on hydrogen peroxide aqueous solution can only oxidize part of the organic matter, making it difficult to simultaneously achieve deep crystallization purification and zinc removal functions. Zinc ions are still mainly retained in the liquid phase, resulting in high impurity content and low purity in the obtained manganese sulfate crystals, as well as irregular crystals and a large amount of fine powder. The comparison of the test results of Example 2 and Comparative Example 2 in the table shows that when the resin material used only has sulfonic acid groups and lacks aminothiourea groups and polyacrylamide brushes, the Zn removal rate is only 41.57%, the product purity decreases, and the filtrate appears yellow-green and turbid. The underlying mechanism is that the oxidation function of a single sulfonic acid group is insufficient to achieve selective zinc separation and good solid-liquid separation; the lack of aminothiourea groups means that the system loses the chelation sites for selectively fixing zinc ions; and the lack of polyacrylamide brushes makes it difficult for fine zinc-containing solid phases and organic particles to aggregate and settle, resulting in a significant decrease in the clarity of the filtrate, which in turn leads to a large number of impurities adhering to the surface of the final crystallized product. Based on the data from Examples 1 to 3 in the table, it can be seen that, within the process limitations, by reasonably adjusting the amount of hydrogen peroxide aqueous solution and multifunctional modified material, the multifunctional modified material can simultaneously and stably provide oxidation sites, selective chelation sites, and flocculation sites. The synergistic effect of aminothiourea groups, sulfonic acid groups, and polyacrylamide brushes can efficiently achieve the simultaneous removal of zinc ions and organic residues in complex manganese zinc mother liquor, thereby stably recovering high-purity, low-zinc manganese sulfate crystals.
[0022] The above are preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any conventional modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.
Claims
1. A process for recovering high-purity manganese sulfate from mancozeb mother liquor, characterized in that, Includes the following steps: S1: The mancozeb mother liquor is filtered to remove mechanical impurities, and the pH is adjusted to 3.5-4.5 using sulfuric acid to obtain the pretreated mother liquor; S2: Add hydrogen peroxide aqueous solution and multifunctional modified material to the pretreatment mother liquor obtained in step S1, and stir the mixture at a constant temperature of 55-65℃ for 2-3 hours to obtain a mixed solution. S3: The mixture obtained in step S2 is allowed to settle and then separated into solid and liquid phases by pressure filtration to obtain a high-purity manganese sulfate purified solution. S4: The high-purity manganese sulfate purified solution obtained in step S3 is evaporated and concentrated, cooled to 20-25℃ for crystallization, separated by centrifugation, washed with saturated manganese sulfate solution, and dried at a temperature of 100-120℃ to obtain high-purity manganese sulfate crystals.
2. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 1, characterized in that, The multifunctional modified material described in step S2 is obtained through the following preparation steps: S201: Chloromethylated crosslinked polystyrene resin is placed in a sulfonating agent and partially sulfonated at a temperature of 50-70℃ for 2-4 hours. The resin is then washed with water until neutral to obtain a partially sulfonated resin with a degree of sulfonation of 30%-60%. S202: The partially sulfonated resin obtained in S201 is dispersed in an organic solvent, and aminothiourea and acid-binding agent are added at a mass ratio of 1:(0.5-1.5):(0.5-1.0). Nucleophilic substitution reaction is carried out at a temperature of 80-90℃ for 6-10 hours to obtain an intermediate. S203: Under nitrogen protection, using the intermediate obtained in S202 as the matrix, add appropriate amounts of deionized water, initiator and acrylamide monomer at a mass ratio of 1:(0.5-2.0):(0.05-0.1). Perform surface graft copolymerization reaction at a temperature of 60-75℃ for 4-8 hours. After filtration, washing and vacuum drying, obtain the multifunctional modified material.
3. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 2, characterized in that, In step S2, the mass fraction of the hydrogen peroxide aqueous solution is 30%, and the amount of hydrogen peroxide aqueous solution added is 1%-3% of the mass of the pretreatment mother liquor; the amount of the multifunctional modified material added is 2%-5% of the mass of the pretreatment mother liquor.
4. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 2, characterized in that, In S201, the sulfonating agent is a mixture of concentrated sulfuric acid and chlorosulfonic acid.
5. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 2, characterized in that, In S202, the organic solvent is N,N-dimethylformamide, and the acid-binding agent is potassium carbonate.
6. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 2, characterized in that, In S203, the initiator is potassium persulfate.
7. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 1, characterized in that, The solid material separated in step S3 is eluted and desorbed by adding a sulfuric acid solution with a concentration of 0.5-1.0 mol / L at a liquid-solid ratio of 2:1 to 5:1, and then recycled back to step S2 for use as the multifunctional modified material.
8. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 1, characterized in that, In step S4, the high-purity manganese sulfate purified solution is sent to a mechanical vapor recompression evaporator for evaporation and concentration.
9. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 1, characterized in that, In step S1, the sulfuric acid is a dilute sulfuric acid with a mass fraction of 10%-20%.
10. The process for recovering high-purity manganese sulfate from mancozeb mother liquor according to claim 1, characterized in that, In step S4, the zinc ion content in the obtained high-purity manganese sulfate crystals is less than 5 ppm.