Method for preparing high-purity manganese sulfate from waste liquid containing manganese in waste and old battery recovery

Abstract

The application provides a method for preparing high-purity manganese sulfate from waste liquid containing manganese in waste battery recycling, which comprises the following steps: adjusting the pH of the waste liquid containing manganese in waste battery recycling, adding manganese fluoride as a precipitant, adding a flocculating agent for continuous reaction after the completion of the precipitation reaction, and then separating the precipitate to obtain a calcium-magnesium-removed liquid; adding aluminum sulfate octadecahydrate as a precipitant, adding a precipitant-promoting agent to prepare a fluorine-removing agent, adding the calcium-magnesium-removed liquid, adjusting the pH, and continuously stirring, flocculating and precipitating, and then separating the precipitate to obtain a manganese sulfate purification liquid; and finally adjusting the pH of the manganese sulfate purification liquid, evaporating and concentrating it under heating, controlling the evaporation amount of the crystallization, filtering and separating the crystallization product, and obtaining a high-purity manganese sulfate product. The method solves the problems of high cost of impurity removal and crystallization and insufficient process stability in the preparation process of high-purity manganese sulfate.

Description

Technical Field

[0001] This invention belongs to the field of high-purity manganese sulfate preparation technology, specifically relating to a method for preparing high-purity manganese sulfate from manganese-containing waste liquid recycled from waste batteries. Background Technology

[0002] New energy technologies have become crucial for human sustainable development, and lithium-ion batteries are expected to be widely used in electric vehicles and for storing clean energy sources such as solar and wind power. The development of lithium-ion batteries has created enormous demand for basic materials such as lithium, nickel, cobalt, and manganese. Battery-grade high-purity manganese sulfate is mainly used in the synthesis of ternary lithium-nickel-cobalt cathode materials, lithium manganese oxide cathode materials, and high-purity manganese tetroxide and other electronic chemicals. It has been a hot research topic in the manganese industry in recent years, and its market prospects are widely viewed favorably.

[0003] Currently, the main processes for preparing high-purity manganese sulfate are electrolytic manganese method and acid leaching reduction method. The electrolytic manganese method involves dissolving 99.7% pure manganese metal flakes in sulfuric acid, followed by impurity removal, separation, and purification to obtain manganese sulfate. The acid leaching reduction method uses manganese ore as raw material, undergoing reduction, impurity removal, and crystallization to obtain high-purity manganese sulfate. The electrolytic manganese method is relatively simple, with less stringent impurity removal and purification requirements. However, when the price of electrolytic manganese reaches a high level of around 15,000 yuan / ton, combined with the costs of sulfuric acid dissolution and purification, and considering the current market price of high-purity manganese sulfate at around 5,000 yuan / ton, a situation often arises where production costs exceed market prices, making the electrolytic manganese method for producing high-purity manganese sulfate uneconomical. In terms of quality, battery-grade manganese sulfate has extremely high requirements for the content of impurities such as calcium, magnesium, fluorine, and heavy metals. Industrial production generally uses processes such as recrystallization, extraction, and fluorination precipitation for impurity removal and purification. Recrystallization is simple to operate and does not introduce new impurities; however, multiple recrystallizations are energy-intensive, inefficient, have low Mn recovery rates, and poor process stability. Extraction is effective at separating impurity ions with good selectivity, but it is costly, polluting, and requires regeneration of the extractant. Fluorination precipitation is effective at removing impurities, with controllable quality and low process cost, but it results in high fluorine residue in the solution, increasing the difficulty of removal and making waste residue difficult to handle.

[0004] Among existing high-purity manganese sulfate preparation technologies, fluorination precipitation is relatively mature, but it remains difficult to achieve deep purification and impurity removal at low cost for high fluoride residue levels. Currently, fluoride removal is mainly achieved through extraction or flocculation precipitation. Extraction is cumbersome and costly. Flocculation precipitants mainly include polyferric sulfate or aluminum sulfate. Using polyferric sulfate introduces additional iron ions, so most processes use aluminum sulfate as a defluorinating agent. However, this often requires large amounts of aluminum sulfate to reduce the fluoride ion residue in the solution to below the high-purity manganese sulfate standard, resulting in high reagent consumption, large amounts of waste residue, and lack of economic efficiency for enterprises. Given the current problems of high impurity removal and crystallization costs and insufficient process stability in high-purity manganese sulfate preparation processes, how to achieve efficient and low-consumption impurity removal and crystallization technologies is an urgent problem to be solved. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for preparing high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries, solving the problems of high impurity removal and crystallization costs and insufficient process stability in the preparation process of high-purity manganese sulfate.

[0006] The first aspect of the present invention provides a method for preparing high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries, comprising the following steps:

[0007] S1: Adjust the pH of the manganese-containing waste liquid from the recycling of waste batteries, add manganese fluoride as a precipitant, after the precipitation reaction is complete, add flocculant to continue the reaction, let it stand after the reaction is complete, and separate the precipitate to obtain calcium and magnesium removal solution;

[0008] S2: Using aluminum sulfate octadecylhydrate as a precipitant, a precipitating agent is added to prepare a defluorinating agent, which is then added to the calcium and magnesium removal solution. The pH is adjusted, and the mixture is continuously stirred to flocculate and precipitate. After standing, the precipitate is separated to obtain a manganese sulfate purified solution.

[0009] S3: Adjust the pH of the manganese sulfate purification solution, heat and evaporate to concentrate and crystallize, control the amount of crystallization evaporation, filter and separate the crystallization product to obtain high-purity manganese sulfate product.

[0010] One technical solution of the present invention regarding a method for preparing high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries has at least the following beneficial effects:

[0011] Li, Ni, and Co have high added value in waste battery recycling solutions, and most companies recover and reuse them through extraction. However, Mn has low value, and more than half of these companies generate large amounts of manganese-containing wastewater that urgently needs treatment. Waste battery manganese-containing wastewater itself contains high levels of calcium, aluminum, and fluorine, necessitating a precipitation reaction under specific conditions to synergistically remove these elements. Therefore, this invention proposes a high-purity manganese sulfate removal technology for recovering manganese-containing wastewater from waste batteries, achieving manganese recycling. This technology features low chemical consumption, low energy consumption, and minimal waste residue.

[0012] The method of this invention, on the one hand, is an ion-controlled synergistic calcium and magnesium removal technology. Through chemical precipitation, it precisely controls the ion balance in the solution to synergistically remove calcium and magnesium ions, achieving low fluoride consumption and in-situ fluoride utilization. It produces less precipitated filter residue and allows for rapid separation, significantly reducing raw material and waste residue treatment costs. On the other hand, it is a highly efficient, low-consumption, and low-residue fluoride removal technology. It uses a precipitant-promoting agent to assist in precipitation and flocculation for fluoride removal, while simultaneously causing other impurity ions to undergo secondary flocculation, stabilizing the precipitation process and reducing and recyclable precipitated waste residue.

[0013] The manganese-containing wastewater of this invention is derived from the leachate of recycled waste batteries and mainly includes impurity elements such as Ca, Mg, Al, F, Fe, and Na, with Ca, Al, and F being present in higher concentrations. This invention fully utilizes the Ca, F, and Al salts in the manganese-containing wastewater. Only a small amount of precipitant is added to promote the in-situ precipitation reaction of Ca and F. Further addition of a precipitating agent initiates the flocculation and precipitation of aluminum salts to remove fluoride, while simultaneously removing other impurity ions, thus achieving the product meeting the standards for battery-grade high-purity manganese sulfate.

[0014] The embodiments of the present invention have mild reaction conditions and simple operation. The aluminum salt is fully reacted by the precipitant to achieve deep defluorination, while other impurity ions are simultaneously flocculated, thereby stabilizing the precipitation process. Furthermore, the amount of aluminum sulfate used as the precipitant is greatly reduced, and the generation of precipitation waste is reduced, thus achieving the goal of saving costs.

[0015] In step S1, manganese fluoride is used as a precipitant. The manganese-containing waste liquid is adjusted to a certain temperature and pH, and manganese fluoride is added. After the precipitation reaction is completed, a flocculant is added to continue the reaction. After the reaction is completed, the mixture is allowed to stand for a certain period of time, and the precipitate is separated to obtain the calcium and magnesium removal solution. This method achieves deep removal of calcium and magnesium while minimizing the amount of precipitant used and reducing subsequent fluoride residue. It has the advantages of simple operation, low chemical consumption, and low cost.

[0016] According to some embodiments of the present invention, in step S1:

[0017] pH ranges from 3.0 to 6.0.

[0018] pH can be 4.0, 5.0, 5.5, or a range of any two of these values.

[0019] The amount of manganese fluoride added is 2.5g to 12.5g per liter of manganese-containing waste liquid.

[0020] The amount of manganese fluoride added is 2.5g, 3.0g, 6.0g, or any two of these values ​​per liter of manganese-containing waste liquid.

[0021] The reaction temperature is 20℃~90℃.

[0022] The reaction temperature can be 40℃~60℃.

[0023] The precipitation reaction time is 1 to 4 hours.

[0024] The precipitation reaction time can be 2 to 4 hours.

[0025] pH-adjusting neutralizing agents include at least one of ammonia, manganese carbonate, manganese monoxide, and manganese powder.

[0026] All precipitation reactions were carried out under stirring. This stirring state increases the probability of collisions between calcium and magnesium impurity ions and fluoride ions in the manganese-containing wastewater, accelerates the precipitation reaction rate, and improves the removal rate of calcium and magnesium ions.

[0027] According to some embodiments of the present invention, in step S2:

[0028] The flocculant includes at least one of aluminum sulfate octadechydrate and polyacrylamide.

[0029] The concentration of polyacrylamide in the flocculant can be 0.1%.

[0030] Flocculants facilitate the settling of fluorinated products, improve filtration performance, and enable rapid separation of filter residue.

[0031] According to some embodiments of the present invention, the precipitant includes at least one of aluminum isopropoxide, aluminum acetate, and aluminum benzoate.

[0032] Using aluminum sulfate octadecahydrate as a precipitant and adding a precipitating agent to prepare a defluorination agent, this agent is added to the calcium and magnesium removal solution obtained in the first step. The reaction temperature and pH are controlled, and the mixture is stirred continuously for a certain period of time to allow fluoride ions and aluminum salts in the calcium and magnesium removal solution to precipitate and flocculate. After standing for a certain period of time, the precipitate is separated to obtain manganese sulfate purified solution. This is a highly efficient, low-consumption, and low-residue defluorination technology.

[0033] The pH ranges from 4.0 to 6.0.

[0034] pH can be 4.5, 5.0, 5.5, or a range of any two of these values.

[0035] The defluorination reaction time is 1 to 4 hours, specifically 2 hours, 4 hours, or a range thereof.

[0036] pH neutralizing agents include at least one of sodium hydroxide, ammonia, manganese carbonate, manganese monoxide, and manganese powder.

[0037] The mass percentage of sodium hydroxide can be 0.1% or 10%. In existing technologies, using sodium hydroxide or ammonia as a pH adjuster can easily cause localized over-alkalinity, leading to manganese loss. To reduce manganese loss and avoid introducing other impurities, manganese powder can be preferentially used for pH adjustment.

[0038] The precipitant accounts for 1% to 10% of the mass of the aluminum sulfate octadechydrate.

[0039] The precipitant comprises 1.0%, 2.0%, 5.0% of the mass of the aluminum sulfate octadechydrate, or a range formed by any two of these values.

[0040] The mass ratio of aluminum in the defluorinating agent to fluorine in the calcium and magnesium removal solution is 0.5 to 1.5.

[0041] The defluorination reaction temperature is 40℃~80℃, specifically 50℃, 60℃, or any two of these values.

[0042] The settling time can be from 1 to 48 hours, specifically 3 hours, 12 hours, 18 hours, 24 hours, 48 ​​hours, or any range of two of these values.

[0043] The solid-liquid separation method includes at least one of centrifugation and filtration.

[0044] According to some embodiments of the present invention, in step S3:

[0045] The pH is 2.5–3.5.

[0046] pH can be 2.5, 2.9, 3.0, 3.5, or a range of any two of these values.

[0047] According to some embodiments of the present invention, in step S3, the evaporation rate of the concentrated crystallization of manganese sulfate purification solution is 60% to 80%, specifically 65%, 70%, 80%, or any two of these values ​​forming a range.

[0048] Manganese sulfate purification solution is purified by adjusting the pH, heating to 200℃ for evaporation and crystallization, controlling the amount of crystallization and evaporation, and separating the solid and liquid to obtain wet manganese sulfate semi-finished product. After high-temperature drying, high-purity manganese sulfate product is obtained.

[0049] The drying temperature for semi-finished manganese sulfate can be 120℃.

[0050] The drying time for wet manganese sulfate semi-finished product is 4 to 12 hours, specifically 4 hours or 8 hours.

[0051] The remaining mother liquor from the concentrated crystallization of manganese sulfate purification solution can be recycled back into the system to participate in the crystallization process.

[0052] The method of this invention uses manganese fluoride as a precipitant to remove calcium and magnesium, making full use of the calcium, magnesium and fluoride ions originally present in the manganese-containing waste liquid, controlling the ion balance precipitation conditions, and can quickly and efficiently remove calcium and magnesium ions from the solution. The process is simple and easy to realize industrial continuous production, which greatly reduces the amount of precipitant and the amount of precipitated filter residue, reduces the residue of fluoride ions, and reduces the cost of raw materials and subsequent impurity removal.

[0053] Furthermore, this invention employs a precipitant to assist aluminum sulfate in flocculation and precipitation for fluoride removal. Through precise control of conditions such as pH and temperature, fluoride ions and other impurity ions in the solution are efficiently removed, with a fluoride ion removal rate of over 98%. This significantly reduces the amount of aluminum sulfate added as a precipitant. At the same time, the amount of fluoride removal waste is reduced, and the fluoride removal agent can be regenerated through further acid dissolution.

[0054] The battery-grade high-purity manganese sulfate product obtained by this invention has a manganese content as high as 32.0%, with impurities such as calcium and magnesium ≤10ppm, aluminum ≤20ppm, and fluorine ≤50ppm. It can be used as a superior high-purity manganese-based raw material for the preparation of manganese tetroxide and lithium manganese oxide. This method is simple to operate, requires less reagents, produces less waste, is energy-saving and environmentally friendly, has low cost, and is easily scalable for large-scale industrial production. Attached Figure Description

[0055] Figure 1 This is a process flow diagram of the present invention for preparing battery-grade high-purity manganese sulfate from waste battery recycling manganese-containing waste liquid. Detailed Implementation

[0056] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0057] In some embodiments of the present invention, a method for preparing high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries is provided, comprising the following steps:

[0058] S1: Adjust the pH of the manganese-containing waste liquid from the recycling of waste batteries, add manganese fluoride as a precipitant, after the precipitation reaction is complete, add flocculant to continue the reaction, let it stand after the reaction is complete, and separate the precipitate to obtain calcium and magnesium removal solution;

[0059] S2: Using aluminum sulfate octadecylhydrate as a precipitant, a precipitating agent is added to prepare a defluorinating agent. This agent is then added to the calcium and magnesium removal solution, the pH is adjusted, and the mixture is continuously stirred to flocculate and precipitate. After standing, the precipitate is separated to obtain a manganese sulfate purified solution.

[0060] S3: Adjust the pH of the manganese sulfate purification solution, heat and evaporate to concentrate and crystallize, control the amount of crystallization evaporation, filter and separate the crystallization product to obtain high-purity manganese sulfate product.

[0061] It is understandable that Li, Ni, and Co have high added value in waste battery recycling solutions, and most companies recycle and reuse them through extraction. However, Mn has low value, and more than half of the companies generate large amounts of manganese-containing wastewater that urgently needs treatment. Waste battery manganese-containing wastewater itself contains high levels of calcium, aluminum, and fluorine, making it necessary to induce precipitation reactions under specific conditions to synergistically remove these elements. Therefore, this invention proposes a high-purity manganese sulfate removal technology that recovers manganese-containing wastewater from waste batteries, achieving manganese recycling. This technology features low reagent consumption, low energy consumption, and minimal waste residue.

[0062] It should be noted that the method of this invention, on the one hand, is an ion-controlled synergistic calcium and magnesium removal technology. Through chemical precipitation, it precisely controls the ion balance in the solution to synergistically remove calcium and magnesium ions, achieving low fluoride consumption and in-situ fluoride utilization. It produces less precipitated filter residue and allows for rapid separation, significantly reducing raw material and waste residue treatment costs. On the other hand, it is a highly efficient, low-consumption, and low-residue fluoride removal technology. It uses a precipitant-promoting agent to assist in precipitation and flocculation for fluoride removal, while simultaneously causing other impurity ions to undergo secondary flocculation, stabilizing the precipitation process and reducing and recyclable precipitated waste residue.

[0063] Furthermore, the manganese-containing wastewater of this invention is derived from the leachate of recycled waste batteries, and mainly includes impurity elements such as Ca, Mg, Al, F, Fe, and Na, with high contents of Ca, Al, and F. This invention fully utilizes the Ca, F, and Al salts in the manganese-containing wastewater, requiring only the addition of a small amount of precipitant to promote the in-situ precipitation reaction of Ca and F. Then, a precipitating agent is added to initiate the flocculation and precipitation of aluminum salts to remove fluoride, while simultaneously removing other impurity ions, enabling the product to meet the standards of battery-grade high-purity manganese sulfate.

[0064] Furthermore, the embodiments of the present invention have mild reaction conditions and simple operation. By using a precipitant to promote the full reaction of aluminum salts, deep defluorination is achieved. At the same time, other impurity ions are simultaneously flocculated, stabilizing the precipitation process. Moreover, the amount of aluminum sulfate used as a precipitant is greatly reduced, and the generation of precipitation waste is reduced, thus achieving the goal of saving costs.

[0065] In step S1, manganese fluoride is used as a precipitant. The manganese-containing waste liquid is adjusted to a certain temperature and pH, and manganese fluoride is added. After the precipitation reaction is completed, a flocculant is added to continue the reaction. After the reaction is completed, the mixture is allowed to stand for a certain period of time, and the precipitate is separated to obtain the calcium and magnesium removal solution. This method achieves deep removal of calcium and magnesium while minimizing the amount of precipitant used and reducing subsequent fluoride residue. It has the advantages of simple operation, low chemical consumption, and low cost.

[0066] In some embodiments of the present invention, in step S1:

[0067] pH ranges from 3.0 to 6.0.

[0068] pH can be 4.0, 5.0, 5.5, or a range of any two of these values.

[0069] The amount of manganese fluoride added is 2.5g to 12.5g per liter of manganese-containing waste liquid.

[0070] The amount of manganese fluoride added is 2.5g, 3.0g, 6.0g, or any two of these values ​​per liter of manganese-containing waste liquid.

[0071] The reaction temperature is 20℃~90℃.

[0072] The reaction temperature can be 40℃~60℃.

[0073] The precipitation reaction time is 1 to 4 hours.

[0074] The precipitation reaction time can be 2 to 4 hours.

[0075] pH-adjusting neutralizing agents include at least one of ammonia, manganese carbonate, manganese monoxide, and manganese powder.

[0076] All precipitation reactions were carried out under stirring. Stirring increases the probability of collisions between calcium and magnesium impurity ions and fluoride ions in manganese-containing wastewater, accelerates the precipitation reaction rate, and improves the removal rate of calcium and magnesium ions.

[0077] In some embodiments of the present invention, in step S2:

[0078] The flocculant includes at least one of aluminum sulfate octadechydrate and polyacrylamide.

[0079] The concentration of polyacrylamide in the flocculant can be 0.1%.

[0080] Flocculants facilitate the settling of fluorinated products, improve filtration performance, and enable rapid separation of filter residue.

[0081] In some embodiments of the present invention, the precipitant includes at least one of aluminum isopropoxide, aluminum acetate, and aluminum benzoate.

[0082] Using aluminum sulfate octadecahydrate as a precipitant and adding a precipitating agent to prepare a defluorination agent, this agent is added to the calcium and magnesium removal solution obtained in the first step. The reaction temperature and pH are controlled, and the mixture is stirred continuously for a certain period of time to allow fluoride ions and aluminum salts in the calcium and magnesium removal solution to precipitate and flocculate. After standing for a certain period of time, the precipitate is separated to obtain manganese sulfate purified solution. This is a highly efficient, low-consumption, and low-residue defluorination technology.

[0083] The pH ranges from 4.0 to 6.0.

[0084] pH can be 4.5, 5.0, 5.5, or a range of any two of these values.

[0085] The defluorination reaction time is 1 to 4 hours, specifically 2 hours, 4 hours, or a range thereof.

[0086] pH neutralizing agents include at least one of sodium hydroxide, ammonia, manganese carbonate, manganese monoxide, and manganese powder.

[0087] The mass percentage of sodium hydroxide can be 0.1% or 10%. In existing technologies, using sodium hydroxide or ammonia as a pH adjuster can easily cause localized over-alkalinity, leading to manganese loss. To reduce manganese loss and avoid introducing other impurities, manganese powder can be preferentially used for pH adjustment.

[0088] The precipitant accounts for 1% to 10% of the mass of aluminum sulfate octahydrate.

[0089] The precipitant accounts for 1.0%, 2.0%, 5.0% of the mass of aluminum sulfate octahydrate, or any two of these values ​​within a range.

[0090] The mass ratio of aluminum in the defluorinating agent to fluorine in the calcium and magnesium removal solution is 0.5 to 1.5.

[0091] The defluorination reaction temperature is 40℃~80℃, specifically 50℃, 60℃, or any two of these values.

[0092] The settling time can be from 1 to 48 hours, specifically 3 hours, 12 hours, 18 hours, 24 hours, 48 ​​hours, or any range of two of these values.

[0093] Solid-liquid separation methods include at least one of centrifugation and filtration.

[0094] In some embodiments of the present invention, in step S3:

[0095] The pH is 2.5–3.5.

[0096] pH can be 2.5, 2.9, 3.0, 3.5, or a range of any two of these values.

[0097] In some embodiments of the present invention, in step S3, the evaporation rate of the concentrated crystallization of manganese sulfate purification solution is 60% to 80%, specifically 65%, 70%, 80%, or any two of these values ​​forming a range.

[0098] Manganese sulfate purification solution is purified by adjusting the pH, heating to 200℃ for evaporation and crystallization, controlling the amount of crystallization and evaporation, and separating the solid and liquid to obtain wet manganese sulfate semi-finished product. After high-temperature drying, high-purity manganese sulfate product is obtained.

[0099] The drying temperature for semi-finished manganese sulfate can be 120℃.

[0100] The drying time for wet manganese sulfate semi-finished product is 4 to 12 hours, specifically 4 hours or 8 hours.

[0101] The remaining mother liquor from the concentrated crystallization of manganese sulfate purification solution can be recycled back into the system to participate in the crystallization process.

[0102] The method of this invention uses manganese fluoride as a precipitant to remove calcium and magnesium, making full use of the calcium, magnesium and fluoride ions originally present in the manganese-containing waste liquid, controlling the ion balance precipitation conditions, and can quickly and efficiently remove calcium and magnesium ions from the solution. The process is simple and easy to realize industrial continuous production, which greatly reduces the amount of precipitant and the amount of precipitated filter residue, reduces the residue of fluoride ions, and reduces the cost of raw materials and subsequent impurity removal.

[0103] Furthermore, this invention employs a precipitant to assist aluminum sulfate in flocculation and precipitation for fluoride removal. Through precise control of conditions such as pH and temperature, fluoride ions and other impurity ions in the solution are efficiently removed, with a fluoride ion removal rate of over 98%. This significantly reduces the amount of aluminum sulfate added as a precipitant. At the same time, the amount of fluoride removal waste is reduced, and the fluoride removal agent can be regenerated through further acid dissolution.

[0104] The battery-grade high-purity manganese sulfate product obtained by this invention has a manganese content as high as 32.0%, with impurities such as calcium and magnesium ≤10ppm, aluminum ≤20ppm, and fluorine ≤50ppm. It can be used as a superior high-purity manganese-based raw material for the preparation of manganese tetroxide and lithium manganese oxide. This method is simple to operate, requires less reagents, produces less waste, is energy-saving and environmentally friendly, has low cost, and is easily scalable for large-scale industrial production.

[0105] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0106] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0107] refer to Figure 1 This allows for a better understanding of the process flow for preparing battery-grade high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries, as provided in this embodiment of the invention. The manganese content in the waste liquid from waste batteries is 120-140 g / L. Manganese fluoride and aluminum sulfate are added sequentially, and after stirring and reaction, the mixture is allowed to stand and filtered to remove impurities such as calcium and magnesium, resulting in a calcium- and magnesium-removed solution. A defluorinating agent is then added, and the temperature and pH are adjusted. After stirring and reacting for a certain time, solid-liquid separation is achieved, yielding a purified manganese sulfate solution. Finally, the pH is adjusted, and the solution is heated, evaporated, and concentrated. Filtering yields a wet manganese sulfate semi-finished product, which is then dried to obtain battery-grade high-purity manganese sulfate. The following will further illustrate this with specific examples.

[0108] Example 1

[0109] This embodiment provides a method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid of waste batteries. The specific process is as follows:

[0110] A1. After filtering out solid suspended matter from the manganese-containing waste liquid, 200 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 2.0 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. 1.0 g of aluminum sulfate octahydrate was added, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0111] A2. Weigh 0.2g of aluminum isopropoxide and mix it evenly with 10.0g of aluminum sulfate octadechydrate to prepare a defluorinating agent for later use;

[0112] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0113] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0114] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0115] The content of each element in the manganese-containing waste liquid and the calcium and magnesium-removed liquid obtained from the purification process in step A1, the manganese sulfate purified liquid obtained in step A3, and the high-purity manganese sulfate product obtained in step A5 are shown in Table 1 below.

[0116] Table 1. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0117]

[0118] As shown in Table 1, after precipitation and impurity removal, the calcium content in the purified manganese sulfate solution decreased from 254.1 mg / L to 0.4 mg / L, the magnesium content decreased from 20.5 mg / L to 2.2 mg / L, and the fluorine content decreased from 1.3 g / L to 34.6 mg / L. The fluorine removal rate reached 97.3%. The manganese content in the high-purity manganese sulfate product was >32%, and other impurity elements such as calcium, magnesium, aluminum, fluorine, sodium, and iron all met the requirements of superior grade products.

[0119] Example 2

[0120] This embodiment provides a method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid of waste batteries. The specific process is as follows:

[0121] A1. After filtering to remove solid suspended matter from the manganese-containing waste liquid, 200 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 2.2 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 4.0. The mixture was stirred continuously for 60 min. 1.0 g of aluminum sulfate octahydrate was added, and manganese powder was added to adjust the pH to 4.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0122] A2. Weigh 0.24g of aluminum acetate and 12.0g of aluminum sulfate octadechydrate and mix them evenly to prepare a defluorinating agent for later use;

[0123] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0124] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0125] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0126] The content of each element in the manganese-containing waste liquid and the calcium and magnesium-removed liquid obtained from impurity removal in step A1, the manganese sulfate purified liquid obtained in step A3, and the high-purity manganese sulfate product obtained in step A5 are shown in Table 2 below.

[0127] Table 2. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0128]

[0129] As shown in Table 2, after precipitation and impurity removal, the calcium content in the purified manganese sulfate solution decreased from 325.3 mg / L to 2.1 mg / L, the magnesium content decreased from 12.2 mg / L to 0.5 mg / L, and the fluorine content decreased from 1.8 g / L to 21.6 mg / L. The fluorine removal rate reached 98.8%. The manganese content in the high-purity manganese sulfate product was >32%, and other impurity elements such as calcium, magnesium, aluminum, fluorine, sodium, and iron all met the requirements of superior grade products.

[0130] Example 3

[0131] This embodiment provides a method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid of waste batteries. The specific process is as follows:

[0132] A1. After filtering to remove solid suspended matter from the manganese-containing waste liquid, 200 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 2.5 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 4.0. The mixture was stirred continuously for 60 min. 1.0 g of aluminum sulfate octahydrate was added, and manganese powder was added to adjust the pH to 4.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0133] A2. Weigh 0.73g of aluminum benzoate and 14.5g of aluminum sulfate octadechydrate and mix them evenly to prepare a defluorinating agent for later use;

[0134] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0135] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0136] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0137] The content of each element in the manganese-containing waste liquid and the calcium and magnesium-removed liquid obtained from impurity removal in step A1, the manganese sulfate purified liquid obtained in step A3, and the high-purity manganese sulfate product obtained in step A5 are shown in Table 3 below.

[0138] Table 3. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0139]

[0140]

[0141] As shown in Table 3, after precipitation and impurity removal, the calcium content in the purified manganese sulfate solution decreased from 429.1 mg / L to 8.4 mg / L, the magnesium content decreased from 3.7 mg / L to 0.5 mg / L, and the fluorine content decreased from 1.6 g / L to 19.2 mg / L, achieving a fluorine removal rate of 98.8%. Simultaneously, due to precipitation and flocculation, the sodium content decreased from 123.6 mg / L to 40.6 mg / L, and the iron content decreased from 50.1 mg / L to 3.6 mg / L. The high-purity manganese sulfate product has a manganese content >32%, and other impurities such as calcium, magnesium, aluminum, fluorine, sodium, and iron all meet the requirements for superior-grade products.

[0142] Comparative Example 1

[0143] The method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid provided in this comparative example is basically the same as that in Example 1, except that the amount of manganese fluoride used in step A1 is only 0.5g.

[0144] The content of each element in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product is shown in Table 4 below.

[0145] Table 4. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0146]

[0147] Table 4 shows that when the amount of manganese fluoride is 0.5g, after the calcium and magnesium precipitation reaction, the calcium and magnesium contents in the decalcified solution are still relatively high. The calcium content decreased from 254.1mg / L to 212.6mg / L, and the magnesium content decreased from 20.5mg / L to 16.7mg / L, with ion removal rates of 16.3% and 18.5%, respectively. Compared with Example 1, no significant impurity removal effect was achieved. Under the conditions of this comparative example, it was insufficient to trigger the reaction between fluoride ions and calcium and magnesium ions in the manganese-containing wastewater, and the ion precipitation equilibrium condition was not reached, resulting in a low ion removal rate. Ion regulation and synergistic removal of calcium and magnesium is the key technology of this invention. By precisely controlling the amount of manganese fluoride added and controlling the reaction conditions, deep removal of calcium and magnesium ions can be achieved at the lowest possible dosage.

[0148] Comparative Example 2

[0149] The method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid provided in this comparative example is basically the same as that in Example 1, except that in steps A1 and A3, ammonia water is used instead of manganese powder to adjust the pH.

[0150] The content of each element in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product is shown in Table 5 below.

[0151] Table 5. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0152]

[0153] As shown in Table 5, using ammonia water instead of manganese powder to adjust the pH during the impurity removal process will not affect the removal of impurity ions such as calcium, magnesium, aluminum, and fluorine. However, ammonia water is prone to causing local over-alkaliness, resulting in a large loss of manganese. The manganese content in the manganese sulfate product is 29.7%, which does not meet the requirement of more than 32% for high-purity manganese sulfate.

[0154] Comparative Example 3

[0155] The method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid provided in this comparative example is basically the same as that in Examples 1-3, except that in step A2, only aluminum sulfate is used as a defluorinating agent, without adding the precipitating agents aluminum isopropoxide, aluminum acetate, and aluminum benzoate. The specific steps are as follows:

[0156] A1. After filtering out solid suspended matter from the manganese-containing waste liquid, 200 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 2.0 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. 1.0 g of aluminum sulfate octahydrate was added, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0157] A2. Weigh out 10.0g of aluminum sulfate octahydrate as a defluorinating agent for later use;

[0158] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0159] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0160] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0161] The content of each element in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product is shown in Table 6 below.

[0162] Table 6. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0163]

[0164] Table 6 shows that the content of impurities such as calcium, magnesium, and iron in the purified solution after impurity removal is relatively low, but the content of aluminum, fluorine, and sodium exceeds the standard, with the aluminum content reaching as high as 120.1 mg / L and the fluorine content reaching as high as 230.6 mg / L. Compared with Examples 1-3, the addition of precipitating agents aluminum isopropoxide, aluminum acetate, and aluminum benzoate is beneficial to the precipitation reaction between fluoride ions and aluminum ions, enhancing the flocculation and adsorption of aluminum, further reducing the residual amount of fluoride ions in the solution, and at the same time helping to further flocculate and remove other impurity ions.

[0165] Comparative Example 4

[0166] The method for preparing battery-grade high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries provided in this comparative example is basically the same as that in Examples 1-3, except that in step A2, no precipitant is added, and only aluminum sulfate is used as a defluorinating agent, thus increasing the amount of aluminum sulfate used. The specific steps are as follows:

[0167] A1. After filtering out solid suspended matter from the manganese-containing waste liquid, 200 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 2.0 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. 1.0 g of aluminum sulfate octahydrate was added, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0168] A2. Weigh out 45.0g of aluminum sulfate octadechydrate as a defluorinating agent for later use;

[0169] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0170] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0171] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0172] The content of each element in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate products is shown in Table 7 below.

[0173] Table 7. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate product.

[0174]

[0175] As shown in Table 7, the contents of impurities such as calcium, magnesium, iron, sodium, aluminum, and fluorine in the purified liquid after impurity removal all meet the requirements. Compared with Examples 1-3 and Comparative Example 2, aluminum sulfate alone can achieve the purification effect without adding precipitating agents such as aluminum isopropoxide, aluminum acetate, and aluminum benzoate. However, compared with adding precipitating agents, the amount of aluminum sulfate used increases by 4.5 times, which increases the consumption of chemicals and the amount of precipitated filter residue to be treated, and is not economically efficient.

[0176] Comparative Example 5

[0177] The method for preparing battery-grade high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries provided in this comparative example is basically the same as that in Example 1, except that in step A1, the amount of manganese-containing waste liquid to be processed is increased from 200 mL in Example 1 to 400 mL, and the amount of reagents consumed is increased by the same amount. The specific steps are as follows:

[0178] A1. After filtering to remove solid suspended matter from the manganese-containing waste liquid, 400 mL of the filtrate was measured into a beaker and placed in an oil bath at 60°C with stirring. 4.0 g of manganese fluoride was added to the manganese-containing waste liquid, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. 2.0 g of aluminum sulfate octadecylhydrate was added, and manganese powder was added to adjust the pH to 5.0. The mixture was stirred continuously for 60 min. After standing for 12 h, the precipitate was separated by centrifugation to obtain the calcium and magnesium-removed solution.

[0179] A2. Weigh 0.4g of aluminum isopropoxide and mix it evenly with 20.0g of aluminum sulfate octadechydrate to prepare a defluorinating agent for later use;

[0180] A3. Keep the calcium and magnesium removal solution described in A1 at 60°C, add the fluoride removal agent described in A2, add manganese powder to adjust the pH to 5.0, stir continuously for 60 min, let stand for 12 h, and separate the solid and liquid to obtain manganese sulfate purified solution.

[0181] A4. Add concentrated sulfuric acid dropwise to the manganese sulfate purification solution described in A3 to adjust the pH to 3.0, heat at 200℃ to evaporate and crystallize, control the evaporation rate to 80%, hot filter, and separate to obtain wet manganese sulfate semi-finished product;

[0182] A5. The wet manganese sulfate semi-finished product described in A4 is dried in an oven at 120°C for 12 hours to obtain battery-grade high-purity manganese sulfate.

[0183] The content of each element in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate products is shown in Table 8 below.

[0184] Table 8. Element content in manganese-containing waste liquid, calcium and magnesium removal solution, manganese sulfate purification solution, and high-purity manganese sulfate products.

[0185]

[0186]

[0187] As shown in Table 8, the main component manganese content in the purified liquid after impurity removal meets the standard, and the contents of impurities such as calcium, magnesium, iron, sodium, aluminum, and fluorine also meet the requirements. Compared with Example 1, the scale-up experiment has a comparable purification and impurity removal effect, indicating that the method has process stability and is easy to realize large-scale industrial production.

[0188] In summary, the method for preparing battery-grade high-purity manganese sulfate from recycled manganese-containing waste liquid provided by this invention employs ion-controlled synergistic calcium and magnesium removal technology. It precisely controls the ion balance in the solution through chemical precipitation to synergistically remove calcium and magnesium ions, while a precipitant assists in precipitation flocculation and fluoride removal. Simultaneously, other impurity ions undergo secondary flocculation, achieving stabilization of the precipitation process and reducing and recyclable precipitation waste. This method is simple to operate, has a high ion removal rate, good stability, and low cost, making it feasible for continuous industrial production.

[0189] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing high-purity manganese sulfate from manganese-containing waste liquid recovered from waste batteries, characterized in that, Includes the following steps: S1: Adjust the pH of the manganese-containing waste liquid from the recycling of waste batteries, add manganese fluoride as a precipitant, after the precipitation reaction is complete, add flocculant to continue the reaction, let it stand after the reaction is complete, and separate the precipitate to obtain calcium and magnesium removal solution; S2: Using aluminum sulfate octadecylhydrate as a precipitant, a precipitating agent is added to prepare a defluorinating agent, which is then added to the calcium and magnesium removal solution. The pH is adjusted, and the mixture is continuously stirred to flocculate and precipitate. After standing, the precipitate is separated to obtain a manganese sulfate purified solution. S3: Adjust the pH of the manganese sulfate purification solution, heat and evaporate to concentrate and crystallize, control the amount of crystallization evaporation, filter and separate the crystallization product to obtain high-purity manganese sulfate product; The precipitant includes at least one of aluminum isopropoxide, aluminum acetate, and aluminum benzoate. In step S2, the precipitant accounts for 1% to 10% of the mass of the aluminum sulfate octadecahydrate.

2. The method according to claim 1, characterized in that, In step S1, the pH is 3.0~6.

0.

3. The method according to claim 1, characterized in that, In step S1, the amount of manganese fluoride added is 2.5g to 12.5g per liter of manganese-containing waste liquid.

4. The method according to claim 1, characterized in that, The flocculant includes at least one of aluminum sulfate octadechydrate and polyacrylamide.

5. The method according to claim 1, characterized in that, In step S2, the pH is 4.0~6.

0.

6. The method according to claim 1, characterized in that, In step S2, the mass ratio of aluminum in the defluorinating agent to fluorine in the calcium and magnesium removal solution is 0.5 to 1.

5.

7. The method according to claim 1, characterized in that, In step S3, the pH is 2.5~3.

5.

8. The method according to claim 1, characterized in that, In step S3, the evaporation rate of the concentrated crystallization of manganese sulfate purification solution is 60%~80%.

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