A method for producing recycled manganese sulfate

Abstract

The application discloses a production method of recycled manganese sulfate, and relates to the technical fields of hydrometallurgy and battery material recycling. The method comprises the following steps: obtaining a manganese-containing acid leaching solution by acid leaching of MHP materials or battery recycling black powder materials; removing copper by iron powder replacement, adjusting the pH to 4.0-5.0 to remove iron and aluminum, and then adopting a P204 extraction system for extraction, washing and reverse extraction, so as to control the pH of the reverse extraction solution to be 1.5-3.0 and obtain a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L; subsequently, a mixed extraction agent composed of a selective calcium extraction agent DY-SS-02 and P204 or P507 is adopted to perform extraction treatment on the low-zinc manganese sulfate solution, so that calcium and residual zinc in the low-zinc manganese sulfate solution enter the organic phase, and a battery-grade manganese sulfate solution is obtained after phase separation. The application does not need to perform manganese re-extraction in the later stage, can simultaneously reduce the calcium and residual zinc contents in the low-zinc manganese sulfate solution in a relatively simplified process, and is suitable for the purification process of battery-grade manganese sulfate solution prepared from nickel-cobalt-manganese intermediate products or battery recycling black powder materials.

Description

Technical Field

[0001] This invention relates to the fields of hydrometallurgy and battery material recycling technology, specifically to a method for recovering manganese sulfate. Background Technology

[0002] Battery-grade manganese sulfate is one of the commonly used manganese sources for lithium-ion battery cathode materials. With the development of products such as nickel-cobalt-manganese ternary materials and lithium iron phosphate materials, subsequent production processes have placed higher demands on the content of impurities such as calcium, zinc, copper, iron, and aluminum in the manganese sulfate solution. Therefore, when preparing battery-grade manganese sulfate from manganese-containing raw materials, it is usually necessary to remove impurities and purify the leachate.

[0003] Currently, intermediate products from hydrometallurgical processes containing nickel, cobalt, and manganese, as well as black powder from recycled waste lithium-ion batteries, can all be used as raw materials for preparing manganese sulfate solution. After leaching with sulfuric acid, the leachate typically contains impurities such as copper, iron, aluminum, zinc, calcium, and magnesium, in addition to manganese. Existing processes generally involve first removing copper through iron powder replacement, then removing iron and aluminum by adjusting the pH, and finally further treating impurities such as zinc and calcium.

[0004] In the purification of manganese-containing solutions, the P204 extraction system is commonly used for the separation of metal ions such as manganese and zinc. Through P204 extraction, washing, and back-extraction, a manganese sulfate back-extraction solution can be obtained, reducing some of the zinc impurity content. However, the P204 system has limited ability to remove calcium, and a certain amount of calcium may still remain in the back-extracted manganese sulfate solution. For cases requiring further reduction of calcium content, a subsequent calcium removal step is usually necessary.

[0005] Existing technologies already employ synergistic extraction systems to separate manganese from calcium and magnesium. For example, document CN109097599A describes a method for synergistic extraction to separate manganese from calcium and magnesium. While this method can be used to separate manganese from calcium and magnesium, its processing path still revolves around manganese extraction and back-extraction. For low-zinc manganese sulfate solutions obtained through P204 extraction, washing, and back-extraction, this type of method does not offer a simplified solution for the simultaneous post-treatment of residual calcium and zinc. If the manganese extraction route is continued, the subsequent operations remain cumbersome.

[0006] Existing technologies also include methods for preparing battery-grade manganese sulfate using the P204 system or other manganese extraction systems. For example, document CN111187907B relates to a method for purifying manganese sulfate solution, which involves extracting and back-extracting the manganese sulfate solution using a P204 saponified organic phase, followed by further extraction for purification; document CN112079391A relates to a method for preparing battery-grade manganese sulfate from waste lithium battery materials, which involves treating impurities such as calcium, zinc, and copper through P204 pre-removal, P204 manganese extraction, and chemical removal steps using scavenging agents, sulfides, and sodium fluoride; document CN115893498A relates to a method for preparing battery-grade manganese sulfate, which involves pH adjustment, sulfide precipitation, and then extracting manganese into the organic phase using a saponified bis(2,4,4-trimethylpentyl)phosphonic acid extractant, followed by washing, acid washing, and back-extraction to obtain manganese sulfate. The methods described above can improve the purity of manganese sulfate products to some extent, but they mostly involve a process route of first extracting manganese, followed by washing or back-extraction, or require the use of multiple chemical impurity removal agents. This results in a large number of operational units, increasing the types of reagents, acid and alkali consumption, organic phase circulation volume, and the burden of sludge and wastewater treatment. For the low-zinc manganese sulfate solution already obtained after P204 back-extraction, the above methods do not directly solve the problem of simultaneously reducing calcium and residual zinc without re-extracting all manganese; there is still room for further simplification in the subsequent purification process.

[0007] In summary, while existing processes can prepare battery-grade manganese sulfate through extraction and precipitation, the treatment of low-zinc manganese sulfate solutions obtained from P204 back-extraction still suffers from numerous subsequent steps for calcium and residual zinc removal, high reagent consumption, or lengthy processes. Therefore, it is necessary to provide a downstream purification method suitable for low-zinc manganese sulfate solutions to further reduce calcium and residual zinc content in a simplified process. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome the problems of numerous steps in the later stage of calcium and residual zinc removal, large reagent consumption, and relatively complex process in the preparation of battery-grade manganese sulfate solution from nickel-cobalt-manganese raw materials in the prior art. This invention provides a method for preparing recovered manganese sulfate. After obtaining a low-zinc manganese sulfate solution by extraction, washing, and back-extraction with P204, a mixed extractant composed of DY-SS-02 and P204 or P507 is used to simultaneously remove calcium and residual zinc, thereby obtaining a manganese sulfate solution suitable for battery material production. This method can effectively solve the problems in the prior art.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for recovering manganese sulfate, comprising the following steps:

[0010] MHP material or battery recycled black powder is added to sulfuric acid solution for acid leaching, and a reducing agent is added during the acid leaching process to obtain a manganese-containing acid leaching solution;

[0011] Iron powder is added to the manganese-containing acid leaching solution to displace and remove copper ions. After solid-liquid separation, the copper-removed solution is obtained.

[0012] Adjust the pH of the copper-removed solution to 4.0–5.0 to allow iron and aluminum impurities to precipitate and separate, thus obtaining the iron- and aluminum-removed solution.

[0013] The iron and aluminum removed solution was extracted, washed, and back-extracted using the P204 extraction system. During the back-extraction process, the pH of the back-extraction solution was controlled at 1.5–3.0 to obtain a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L.

[0014] A mixed extractant consisting of selective calcium extraction agents DY-SS-02, P204 or P507 and a diluent is used to extract a low-zinc manganese sulfate solution, allowing calcium and residual zinc in the low-zinc manganese sulfate solution to enter the organic phase. After phase separation, a battery-grade manganese sulfate solution is obtained.

[0015] Furthermore, MHP material is a hydrometallurgical intermediate product containing nickel, cobalt, and manganese, while battery recycling black powder material is a nickel, cobalt, and manganese-containing material obtained by crushing and sorting waste lithium-ion battery cathode materials.

[0016] Furthermore, the final pH of the acid leaching is 0.5–2.5, and the reducing agent is hydrogen peroxide or sodium metabisulfite.

[0017] Furthermore, the amount of iron powder added is 1.0 to 1.5 times the amount required to replace copper in the manganese-containing acid leaching solution.

[0018] Further, after adjusting the pH of the copper-removed liquid to 4.0–5.0, solid-liquid separation is performed. The contents of copper, iron, and aluminum in the resulting liquid phase are reduced. The resulting liquid phase is then used as the iron and aluminum-removed liquid for the subsequent P204 extraction step. The P204 extraction system includes P204 and a diluent. The volume fraction of P204 in the P204 extraction system is 10%–30%, and the diluent is sulfonated kerosene.

[0019] Furthermore, when using the P204 extraction system to treat the liquid after iron and aluminum removal, manganese is first introduced into the supported organic phase, then the supported organic phase is washed, and then back-extracted using sulfuric acid solution. By controlling the pH of the back-extraction solution to 1.5–3.0, the resulting back-extraction solution is a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L.

[0020] Furthermore, the mixed extractant includes selective calcium extraction agents DY-SS-02 and P204 and a diluent, wherein the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P204 is 0.5% to 5%, and the remainder is a diluent.

[0021] Furthermore, the mixed extractant includes selective calcium extraction agents DY-SS-02 and P507 and a diluent, wherein the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P507 is 0.5% to 5%, and the remainder is a diluent.

[0022] Furthermore, the diluent is sulfonated kerosene; in the mixed extractant, the volume fraction of DY-SS-02 is 8% to 12%, and the volume fraction of P204 or P507 is 0.8% to 2%.

[0023] Furthermore, when using the aforementioned mixed extractant to extract the low-zinc manganese sulfate solution, the volume ratio of the organic phase to the aqueous phase is 1:1 to 5:1, the number of extraction stages is 1 to 5, the mixing and contact time for each stage is 3 to 10 minutes, and the mixture is allowed to stand and separate after mixing; the calcium content in the battery-grade manganese sulfate solution is not higher than 5 mg / L, and the zinc content is not higher than 1 mg / L.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention addresses the problem of residual calcium and trace amounts of zinc in the low-zinc manganese sulfate solution obtained after P204 extraction, washing, and back-extraction. It employs a mixed extractant consisting of the selective calcium extractant DY-SS-02 and either P204 or P507 for downstream purification. In this mixed extractant, DY-SS-02 primarily enhances calcium removal, while P204 or P507 further reduces residual zinc content, allowing the same extraction step to simultaneously remove both calcium and residual zinc. Compared to using P204, P507, or a single selective calcium extractant, the compound system of this invention is more suitable for downstream purification of low-zinc manganese sulfate solutions, overcoming the limitations of single extractants in controlling calcium and zinc impurities.

[0026] 2. This invention does not employ a complete re-extraction of manganese to purify manganese sulfate. Instead, it directly extracts and removes residual calcium and zinc from the low-zinc manganese sulfate solution already obtained in the P204 system. This avoids setting up a complete process for manganese extraction, washing, and back-extraction in the subsequent stages, reducing the number of operating units and making the process route more compatible with existing wet recycling processes. For systems that prepare manganese sulfate from MHP materials or battery recycled black powder, this treatment method helps reduce the complexity of subsequent purification and reduces acid and alkali consumption and organic phase circulation load caused by multi-stage manganese extraction and back-extraction.

[0027] 3. The front-end process of this invention gradually reduces impurities such as copper, iron, aluminum, and most zinc through sulfuric acid leaching, iron powder replacement to remove copper, pH adjustment to remove iron and aluminum, and P204 extraction and back-extraction. Then, the back-end process further reduces calcium and residual zinc through mixed extractant. The division of labor between each treatment step is clear. The front-end is to obtain a low-zinc manganese sulfate solution suitable for further purification, while the back-end focuses on solving the problems of high calcium content and residual zinc in the low-zinc manganese sulfate solution. This process connection method can improve the impurity control level of the manganese sulfate solution and reduce the pressure of sludge and wastewater treatment caused by using multiple agents such as sulfides, fluorides, and scavenging agents to remove impurities separately.

[0028] 4. In the specific implementation process, after the low-zinc manganese sulfate solution is treated with a mixed extractant composed of DY-SS-02 and P204, the calcium content can be reduced from about 650 mg / L to about 1.5 mg / L, and the zinc content can be reduced from about 15 mg / L to about 0.1 mg / L. This indicates that the compound extraction system can effectively remove calcium and residual zinc from the low-zinc manganese sulfate solution. Therefore, the main effect of this invention is that, without changing the previous P204 process for preparing the low-zinc manganese sulfate solution or without re-extracting all manganese, a manganese sulfate solution suitable for battery material production can be obtained by simultaneously removing calcium and residual zinc in the later stage through a specific compound extractant. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1 The present invention will be further described below with reference to specific embodiments. The following embodiments are used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Based on the disclosure of the present invention, those skilled in the art can make appropriate adjustments to the acid leaching time, reducing agent addition amount, extractant concentration, phase ratio, extraction stage, mixing time, and phase separation time according to the raw material composition, impurity content, equipment conditions, and continuous production requirements.

[0031] As attached Figure 1As shown, the method of the present invention includes: adding nickel-cobalt-manganese raw materials to a sulfuric acid solution for acid leaching, and adding a reducing agent during the acid leaching process to allow manganese in the raw materials to enter the liquid phase, thereby obtaining a manganese-containing acid leaching solution; adding iron powder to the manganese-containing acid leaching solution to displace and remove copper ions, and obtaining a copper-removed solution after solid-liquid separation; adjusting the pH of the copper-removed solution to 4.0-5.0 to allow iron and aluminum impurities to precipitate and separate, thereby obtaining an iron-aluminum-removed solution; using a P204 extraction system to extract, wash, and back-extract the iron-aluminum-removed solution, controlling the pH of the back-extraction solution to 1.5-3.0, thereby obtaining a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L; and then using a mixed extractant including selective calcium extraction agent DY-SS-02, P204 or P507, and a diluent to extract the low-zinc manganese sulfate solution, allowing calcium and residual zinc in the low-zinc manganese sulfate solution to enter the organic phase, and obtaining a battery-grade manganese sulfate solution after phase separation.

[0032] In this invention, the nickel-cobalt-manganese raw material can be MHP material or recycled black powder from waste lithium-ion batteries; MHP material refers to intermediate products containing nickel, cobalt, and manganese produced during hydrometallurgical processes; recycled black powder from batteries refers to materials containing nickel, cobalt, and manganese obtained after waste lithium-ion batteries have undergone crushing, sorting, and other treatments; P204, P507, and sulfonated kerosene can all be commonly used industrial products in the field of hydrometallurgy; the selective calcium extraction agent DY-SS-02 is a selective calcium extraction extractant produced or sold by Deyuan Company, which can preferentially extract calcium ions in the manganese sulfate solution system, but has a weak ability to extract and remove zinc ions; P204 and P507 have good extraction and removal capabilities for zinc ions, but have a weak ability to deeply remove calcium ions; therefore, when DY-SS-02 is compounded with P204 or P507, calcium and residual zinc in the low-zinc manganese sulfate solution can be removed simultaneously in the same subsequent extraction step.

[0033] Unless otherwise specified, the volume fraction of the extractant in this article is calculated based on the total volume of the organic phase; the ratio of O / A refers to the ratio of the volume of the organic phase to the volume of the aqueous phase; the unit of metal element content in each table is mg / L; the metal element content in the solution can be determined by ICP-OES, inductively coupled plasma atomic emission spectrometry, atomic absorption spectrometry or equivalent detection methods commonly used in this field; pH is measured using a calibrated pH meter.

[0034] Example 1

[0035] In this embodiment, nickel-cobalt-manganese hydroxide (MHP) material is used as raw material. A mixed extractant composed of DY-SS-02 and P204 is used to perform post-processing calcium removal and residual zinc removal on the low-zinc manganese sulfate solution obtained by back-extraction of P204.

[0036] MHP material was added to a sulfuric acid solution for acid leaching. During the acid leaching process, hydrogen peroxide was added as a reducing agent to allow manganese in the raw material to enter the liquid phase. Stirring was maintained during the acid leaching process, the acid leaching temperature was controlled at 70-90℃, the acid leaching time was 2-5 hours, and the liquid-solid ratio was controlled at 4:1-8:1 mL / g. The pH at the end of the acid leaching was controlled at 0.5-2.5. In this example, the pH at the end of the acid leaching was 2.3. After the acid leaching was completed, solid-liquid separation was performed to obtain a manganese-containing acid leaching solution. The content of the main impurities in the obtained acid leaching solution is shown in Table 1.

[0037] Table 1. Content of main impurities in acid leaching solution

[0038]

[0039] As shown in Table 1, in addition to manganese, the acid leaching solution also contains impurities such as copper, iron, aluminum, zinc, calcium, and magnesium, which require subsequent impurity removal treatment.

[0040] Iron powder was added to the above-mentioned manganese-containing acid leaching solution to remove copper by displacement. The amount of iron powder added was calculated based on the copper content in the acid leaching solution and was 1.0 to 1.5 times the theoretical amount of copper to be replaced. In this embodiment, the amount of iron powder added was 1.2 times the theoretical amount of copper to be replaced. The displacement temperature was controlled at 40 to 70°C, and the reaction was stirred for 30 to 90 minutes. After the displacement reaction was completed, solid-liquid separation was performed to remove the copper slag produced by the displacement and obtain the copper-removed liquid.

[0041] Subsequently, hydrogen peroxide was added to the copper-removed solution to oxidize ferrous iron, and the pH of the solution was adjusted to 4.0–5.0 using sodium hydroxide solution, manganese carbonate slurry, ammonia, or a pH adjuster commonly used in the art; in this embodiment, the pH was adjusted to 4.8 so that iron and aluminum could be separated from the liquid phase in the form of precipitates; after reacting for 30–120 min, solid-liquid separation was performed to obtain the iron and aluminum-removed solution, which can also be called the pre-extraction solution before entering P204 extraction; the content of the main impurities in the obtained pre-extraction solution is shown in Table 2.

[0042] Table 2. Content of main impurities in the pre-extraction solution after copper and iron / aluminum removal.

[0043]

[0044] As shown in Table 2, after iron powder replacement and pH adjustment, copper was basically removed, and the contents of iron and aluminum were significantly reduced, but the solution still contained high levels of impurities such as zinc, calcium and magnesium.

[0045] The above pre-extraction liquid was extracted, washed, and back-extracted using a P204 extraction system. The P204 extraction system included P204 and a diluent, which was sulfonated kerosene. The volume fraction of P204 in the P204 extraction system was 10% to 30%. To improve the extraction stability, the P204 organic phase could be partially saponified using sodium hydroxide solution or ammonia water, with the saponification rate controlled at 40% to 70%.

[0046] In this embodiment, the P204 extraction system consists of 20% P204 and 80% sulfonated kerosene, with a P204 organic phase saponification rate of 60%. During extraction, the volume ratio of organic phase to aqueous phase (O / A) is controlled at 2:1, with 4 extraction stages. The mixing and contact time for each stage is 5 min, and the settling and phase separation time is 10 min, allowing manganese to enter the loaded organic phase. After washing, the loaded organic phase is back-extracted using sulfuric acid solution. During back-extraction, the pH of the back-extraction solution outlet is controlled at 2.5–3.0 to obtain a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L. The contents of the main impurities in the obtained low-zinc manganese sulfate solution are shown in Table 3.

[0047] Table 3. Content of main impurities in the low-zinc manganese sulfate solution obtained from P204 back-extraction.

[0048]

[0049] As shown in Table 3, after extraction, washing and back-extraction with P204, the zinc content in the obtained manganese sulfate solution has been reduced to 15 mg / L, which is lower than 50 mg / L, and is classified as a low-zinc manganese sulfate solution. However, the calcium content in this low-zinc manganese sulfate solution is still 650 mg / L, and it still contains a small amount of residual zinc, so further downstream calcium removal and residual zinc removal treatment is required.

[0050] Prepare a downstream mixed extractant; take selective calcium extraction agent DY-SS-02, P204 and sulfonated kerosene and mix them evenly to obtain a DY-SS-02 / P204 mixed extractant; in the mixed extractant, the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P204 is 0.5% to 5%, and the remainder is sulfonated kerosene; preferably, the volume fraction of DY-SS-02 is 8% to 12% and the volume fraction of P204 is 0.8% to 2%.

[0051] In this embodiment, a mixed extractant containing 10% DY-SS-02 and 1% P204 is prepared; specifically, 1000 mL of DY-SS-02, 100 mL of P204 and 8900 mL of sulfonated kerosene are taken and thoroughly mixed to obtain a mixed extractant with a total volume of 10000 mL; the volume fraction of DY-SS-02 in the mixed extractant is 10%, the volume fraction of P204 is 1%, and the remainder is sulfonated kerosene.

[0052] The low-zinc manganese sulfate solution shown in Table 3 was contact-extracted with the above-mentioned DY-SS-02 / P204 mixed extractant to allow calcium and residual zinc in the solution to enter the organic phase. Before the subsequent extraction, the pH of the low-zinc manganese sulfate solution was adjusted to 4.0-5.0, and in this embodiment, it was adjusted to pH 4.5. The extraction conditions were: organic phase to aqueous phase volume ratio O / A = 2:1, 3 extraction stages, 5 min of mixing and contact time per stage, 10 min of standing and phase separation time, and extraction temperature of 20-30℃. The aqueous phase obtained after phase separation is the further purified manganese sulfate solution. The content of the main impurities in the obtained manganese sulfate solution is shown in Table 4.

[0053] Table 4. Content of main impurities in manganese sulfate solution after treatment with mixed extractant.

[0054]

[0055] As can be seen from the comparison of Tables 3 and 4, after treatment with the mixed extractant composed of DY-SS-02 and P204, the calcium content in the low-zinc manganese sulfate solution decreased from 650 mg / L to 1.5 mg / L, and the zinc content decreased from 15 mg / L to 0.1 mg / L. This result indicates that the DY-SS-02 / P204 mixed extractant can simultaneously reduce the calcium and residual zinc content in the low-zinc manganese sulfate solution in the same subsequent extraction process. The calcium content in the treated manganese sulfate solution is no higher than 5 mg / L, and the zinc content is no higher than 1 mg / L, making it suitable as a manganese sulfate solution for battery material production.

[0056] The organic phase loaded with calcium and zinc can be back-extracted and regenerated using sulfuric acid solution. During regeneration, a 0.5–2.0 mol / L sulfuric acid solution can be used to contact the loaded organic phase, allowing calcium and zinc to enter the back-extraction solution. After phase separation, the organic phase is returned to the subsequent mixing and extraction step for recycling.

[0057] Example 2

[0058] This embodiment illustrates the use of a mixed extractant consisting of DY-SS-02 and P507 to perform post-treatment of low-zinc manganese sulfate solution for calcium and residual zinc removal.

[0059] Following the method of Example 1, a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L was first prepared; the calcium content of the low-zinc manganese sulfate solution was 640 mg / L and the zinc content was 18 mg / L.

[0060] A DY-SS-02 / P507 mixed extractant is prepared; the mixed extractant includes selective calcium extraction agent DY-SS-02, P507 and sulfonated kerosene, wherein the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P507 is 0.5% to 5%, and the remainder is sulfonated kerosene; preferably, the volume fraction of DY-SS-02 is 8% to 12%, and the volume fraction of P507 is 0.8% to 2%.

[0061] In this embodiment, 1000 mL of DY-SS-02, 100 mL of P507 and 8900 mL of sulfonated kerosene were taken and thoroughly mixed to obtain a total volume of 10000 mL of DY-SS-02 / P507 mixed extractant; the volume fraction of DY-SS-02 in the mixed extractant was 10%, the volume fraction of P507 was 1%, and the remainder was sulfonated kerosene.

[0062] After adjusting the pH of the above low-zinc manganese sulfate solution to 4.5, it was contacted with the DY-SS-02 / P507 mixed extractant for extraction. The extraction conditions were: organic phase to aqueous phase volume ratio O / A = 2:1, three extraction stages, 5 min of mixing and contact time per stage, 10 min of standing and phase separation time, and extraction temperature of 20-30℃. After phase separation, calcium and residual zinc entered the organic phase, and the resulting aqueous phase was the further purified manganese sulfate solution. The contents of the main impurities in the obtained manganese sulfate solution are shown in Table 5.

[0063] Table 5. Content of main impurities in manganese sulfate solution after treatment with DY-SS-02 / P507 mixed extractant.

[0064]

[0065] As shown in Table 5, after treatment with the DY-SS-02 / P507 mixed extractant, the calcium content in the low-zinc manganese sulfate solution decreased from 640 mg / L to 2.3 mg / L, and the zinc content decreased from 18 mg / L to 0.2 mg / L. This result indicates that P507 can replace P204 as the component in the mixed extractant for removing residual zinc, and when combined with DY-SS-02, it can also achieve simultaneous removal of calcium and residual zinc in the later stage of the low-zinc manganese sulfate solution.

[0066] Example 3

[0067] This embodiment uses recycled black powder from waste lithium-ion batteries as raw material to illustrate that the method of the present invention is also applicable to the purification process of preparing battery-grade manganese sulfate solution from recycled black powder from batteries.

[0068] Waste lithium-ion battery recycled black powder is used as raw material. This black powder contains nickel, cobalt, and manganese, as well as impurities such as copper, iron, aluminum, zinc, calcium, and magnesium. The black powder is added to a sulfuric acid solution for acid leaching, with the liquid-to-solid ratio controlled at 4:1 to 10:1 mL / g, the leaching temperature at 60 to 90°C, and the leaching time at 2 to 6 hours. During the acid leaching process, a reducing agent is added according to the valence state of metals such as manganese and cobalt in the black powder. The reducing agent is hydrogen peroxide or sodium metabisulfite. In this embodiment, sodium metabisulfite is used as the reducing agent, and the pH at the end of the acid leaching is controlled at 1.8. After the acid leaching is completed, solid-liquid separation is performed to obtain a manganese-containing acid leaching solution.

[0069] The obtained manganese-containing acid leaching solution was subjected to iron powder replacement to remove copper, pH adjustment to remove iron and aluminum, P2O4 extraction, washing, and back-extraction in sequence. The amount of iron powder added was 1.3 times the theoretical amount required to replace copper in the manganese-containing acid leaching solution. After the replacement reaction was completed, solid and liquid were separated to obtain the copper-removed liquid. Then, the pH of the copper-removed liquid was adjusted to 4.6 to remove iron and aluminum precipitates. After solid and liquid separation, the iron and aluminum-removed liquid was obtained.

[0070] The liquid after iron and aluminum removal was treated with a P204 extraction system. The P204 extraction system consisted of 20% P204 and 80% sulfonated kerosene, with a P204 organic phase saponification rate of 60%. The extraction conditions were O / A = 2:1, with 4 extraction stages and a mixing contact time of 5 min per stage. After washing, the loaded organic phase was back-extracted with sulfuric acid solution, and the pH of the back-extraction solution was controlled at 2.5–3.0 to obtain a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L. The calcium content in the obtained low-zinc manganese sulfate solution was 520 mg / L, and the zinc content was 22 mg / L.

[0071] Subsequently, the obtained low-zinc manganese sulfate solution was treated with a mixed extractant consisting of DY-SS-02 and P204. The mixed extractant consisted of 10% DY-SS-02, 1% P204, and 89% sulfonated kerosene. Before the subsequent extraction, the pH of the low-zinc manganese sulfate solution was adjusted to 4.5. The subsequent extraction conditions were O / A = 2:1, with 3 extraction stages, a mixing contact time of 5 min per stage, and a settling and phase separation time of 10 min. The aqueous phase obtained after phase separation was the further purified manganese sulfate solution. The contents of the main impurities in the obtained manganese sulfate solution are shown in Table 6.

[0072] Table 6. Main impurity content of manganese sulfate solution obtained from battery recycling black powder route.

[0073]

[0074] As shown in Table 6, when using recycled black powder from waste lithium-ion batteries as raw material, after sulfuric acid leaching, iron powder replacement to remove copper, pH adjustment to remove iron and aluminum, P204 extraction, washing and back-extraction, and subsequent DY-SS-02 / P204 mixed extraction, the resulting manganese sulfate solution has a calcium content of 2.5 mg / L and a zinc content of 0.3 mg / L, both of which meet the requirements that the calcium content is not higher than 5 mg / L and the zinc content is not higher than 1 mg / L.

[0075] This embodiment illustrates that the processing target of the present invention is not limited to MHP material, but is also applicable to the recycling of black powder material from waste lithium-ion batteries; as long as the front-end P204 extraction, washing and back-extraction can obtain a low zinc manganese sulfate solution with a zinc content of less than 50 mg / L, the calcium and residual zinc in the back-end can be removed simultaneously by a mixed extractant composed of DY-SS-02 and P204 or P507.

[0076] Example 4

[0077] This embodiment illustrates how to select the composition of the downstream mixed extractant and the extraction conditions.

[0078] When treating low-zinc manganese sulfate solutions, the composition of the mixed extractant and extraction conditions can be adjusted according to the calcium and residual zinc content in the solution to be treated. When the calcium content is high, the volume fraction of DY-SS-02 can be appropriately increased, or the number of extraction stages can be increased. When the residual zinc content is high, the volume fraction of P204 or P507 can be appropriately increased, or the number of extraction stages can be increased. In actual operation, the volume fraction of DY-SS-02 can be controlled at 5% to 20%, the volume fraction of P204 or P507 can be controlled at 0.5% to 5%, and the remainder is sulfonated kerosene.

[0079] During the subsequent extraction, the volume ratio of organic phase to aqueous phase (O / A) can be controlled at 1:1 to 5:1, the number of extraction stages can be controlled at 1 to 5, and the mixing contact time for each stage can be controlled at 3 to 10 minutes. After mixing, the mixture is allowed to stand and separate into organic and aqueous phases. The organic phase is loaded with calcium and zinc, while the aqueous phase is used as a purified manganese sulfate solution.

[0080] To further illustrate the treatment effects of different mixed extractant compositions and extraction conditions, a low-zinc manganese sulfate solution obtained from P204 back-extraction was used for condition investigation. The calcium content of this low-zinc manganese sulfate solution was 650 mg / L, and the zinc content was 15 mg / L. All experiments were conducted at 20–30 °C. Before extraction, the pH of the low-zinc manganese sulfate solution was adjusted to 4.5. The results are shown in Table 7.

[0081] Table 7 Results of the investigation of post-stage mixed extraction conditions

[0082]

[0083] As shown in Table 7, within the range of DY-SS-02 volume fraction of 5%–20%, P204 or P507 volume fraction of 0.5%–5%, O / A ratio of 1:1–5:1, extraction stages of 1–5, and mixing contact time of 3–10 min per stage, by reasonably matching the composition, ratio, extraction stages, and mixing time of the mixed extractant, the calcium content in the low-zinc manganese sulfate solution can be reduced to no more than 5 mg / L, and the zinc content can be reduced to no more than 1 mg / L. More preferably, the volume fraction of DY-SS-02 in the downstream mixed extractant is 8%–12%, the volume fraction of P204 or P507 is 0.8%–2%, the organic phase to aqueous phase volume ratio O / A is 2:1–3:1, the extraction stages are 2–3, and the mixing contact time of each stage is 5–8 min. The above preferred conditions can balance the effects of calcium removal, residual zinc removal, and organic phase usage, and are suitable for continuous or semi-continuous production.

[0084] In this invention, DY-SS-02 is mainly used to improve the removal capacity of calcium, while P204 or P507 is mainly used to further reduce the residual zinc content in the low-zinc manganese sulfate solution. Relying solely on the P204 or P507 system is usually insufficient for deep removal of calcium from the low-zinc manganese sulfate solution. Relying solely on the selective calcium extractant DY-SS-02 limits the ability to further control residual zinc. Therefore, this invention uses a mixed extractant of DY-SS-02 and P204 or P507 for the subsequent purification of the low-zinc manganese sulfate solution obtained from P204 back-extraction, thereby reducing calcium and residual zinc in the same extraction process. This method eliminates the need for subsequent full extraction and back-extraction of manganese, reducing the complexity of the subsequent purification process.

[0085] As can be seen from the above embodiments, the present invention first obtains a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L by sulfuric acid leaching, iron powder replacement to remove copper, pH adjustment to remove iron and aluminum, and P204 extraction, washing, and back-extraction; then, a mixed extractant composed of DY-SS-02 and P204 or P507 is used to perform a post-extraction treatment on the low-zinc manganese sulfate solution, so that the calcium and residual zinc in it enter the organic phase, thereby obtaining a manganese sulfate solution with low calcium and zinc content; after treatment according to the method of the present invention, the calcium content in the obtained manganese sulfate solution can be no higher than 5 mg / L and the zinc content can be no higher than 1 mg / L, which can be used as a manganese sulfate solution for battery material production.

[0086] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, those skilled in the art can adjust the raw material composition, acid leaching conditions, extractant concentration, phase ratio, number of stages and mixing time, etc., and all such changes and improvements fall within the scope of the present invention as claimed.

Claims

1. A method for producing manganese sulfate for recycling, characterized in that, Includes the following steps: MHP material or battery recycled black powder is added to sulfuric acid solution for acid leaching, and a reducing agent is added during the acid leaching process to obtain a manganese-containing acid leaching solution; Iron powder is added to the manganese-containing acid leaching solution to displace and remove copper ions. After solid-liquid separation, the copper-removed solution is obtained. Adjust the pH of the copper-removed solution to 4.0–5.0 to allow iron and aluminum impurities to precipitate and separate, thus obtaining the iron- and aluminum-removed solution. The iron and aluminum removed solution was extracted, washed, and back-extracted using the P204 extraction system. During the back-extraction process, the pH of the back-extraction solution was controlled at 1.5–3.0 to obtain a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L. A mixed extractant consisting of selective calcium extraction agents DY-SS-02, P204 or P507 and a diluent is used to extract a low-zinc manganese sulfate solution, allowing calcium and residual zinc in the low-zinc manganese sulfate solution to enter the organic phase. After phase separation, a battery-grade manganese sulfate solution is obtained.

2. The method for producing manganese sulfate recovery according to claim 1, characterized in that: MHP material is a hydrometallurgical intermediate product containing nickel, cobalt, and manganese, while battery recycling black powder is a material containing nickel, cobalt, and manganese obtained by crushing and sorting waste lithium-ion battery cathode materials.

3. The method for producing manganese sulfate recovery according to claim 1, characterized in that: During the acid leaching process, the final pH of the acid leaching is 0.5 to 2.5, and the reducing agent is hydrogen peroxide or sodium metabisulfite.

4. The method for producing manganese sulfate recovery according to claim 1, characterized in that: The amount of iron powder added is 1.0 to 1.5 times the amount required to replace copper in the manganese-containing acid leaching solution.

5. The method for producing manganese sulfate recovery according to claim 1, characterized in that: After adjusting the pH of the copper-removed liquid to 4.0–5.0, solid-liquid separation was performed. The contents of copper, iron, and aluminum in the resulting liquid phase were reduced. The resulting liquid phase was then used as the iron and aluminum-removed liquid for the subsequent P204 extraction step. The P204 extraction system includes P204 and a diluent. The volume fraction of P204 in the P204 extraction system is 10%–30%, and the diluent is sulfonated kerosene.

6. The method for producing manganese sulfate recovery according to claim 1, characterized in that: When using the P204 extraction system to treat the liquid after iron and aluminum removal, manganese is first introduced into the loaded organic phase, then the loaded organic phase is washed, and then back-extracted with sulfuric acid solution. By controlling the pH of the back-extraction solution to 1.5-3.0, the resulting back-extraction solution is a low-zinc manganese sulfate solution with a zinc content of less than 50 mg / L.

7. The method for producing manganese sulfate recovery according to claim 1, characterized in that: The mixed extractant includes selective calcium extraction agents DY-SS-02 and P204, and a diluent, wherein the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P204 is 0.5% to 5%, and the remainder is a diluent.

8. The method for producing manganese sulfate recovery according to claim 1, characterized in that: The mixed extractant includes selective calcium extraction agents DY-SS-02 and P507 and a diluent, wherein the volume fraction of DY-SS-02 is 5% to 20%, the volume fraction of P507 is 0.5% to 5%, and the remainder is a diluent.

9. A method for producing recovered manganese sulfate according to claim 7 or 8, characterized in that: The diluent is sulfonated kerosene; in the mixed extractant, the volume fraction of DY-SS-02 is 8% to 12%, and the volume fraction of P204 or P507 is 0.8% to 2%.

10. The method for producing a recovered manganese sulfate according to claim 1, characterized in that: When using the aforementioned mixed extractant to extract a low-zinc manganese sulfate solution, the volume ratio of the organic phase to the aqueous phase is 1:1 to 5:1, the number of extraction stages is 1 to 5, the mixing and contact time for each stage is 5 to 10 minutes, and the mixture is allowed to stand and separate after mixing; the calcium content in the battery-grade manganese sulfate solution is not higher than 5 mg / L, and the zinc content is not higher than 1 mg / L.

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