A method for preparing battery-grade manganese sulfate by separating calcium and manganese crystals

Abstract

This invention belongs to the field of manganese sulfate preparation and impurity separation technology, specifically relating to a method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation. This application provides a method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation, comprising the following steps: concentration of calcium-manganese-containing solution: concentrating the calcium-manganese-containing solution to obtain a concentrated solution; cooling and calcium precipitation: cooling the concentrated solution to allow calcium ions to crystallize and precipitate, followed by aging and filtration to obtain a calcium-removed manganese solution; high-temperature evaporation crystallization: crystallizing the calcium-removed manganese solution at high temperature; centrifugal separation: centrifuging the calcium-removed manganese solution after high-temperature crystallization to remove the solution adhering to the surface of the manganese sulfate crystals, further reducing the calcium content in the manganese sulfate product, and obtaining battery-grade manganese sulfate. This invention utilizes the common ion effect and seed crystal action to achieve efficient and thorough separation of calcium. The high-temperature crystallization method requires only one crystallization to achieve efficient crystallization of manganese sulfate to obtain battery-grade products.

Description

Technical Field

[0001] This invention belongs to the field of manganese sulfate preparation and impurity separation technology, specifically relating to a method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation. Background Technology

[0002] Manganese sulfate is a very important basic manganese salt with a wide range of applications, including battery manufacturing, chemical industry, agriculture, and medicine. Currently, the main industrial methods for producing manganese sulfate include high-temperature roasting, acid leaching, acid-added ore and mineral leaching, sulfur dioxide leaching, and aniline reduction. The core difference between these methods lies in the leaching process of the manganese raw material, but the subsequent manganese sulfate crystallization process all employs atmospheric pressure evaporation crystallization. With the increasing depletion of global manganese-rich ore resources, manganese sulfate production has gradually shifted towards using low-manganese ores with a manganese content of less than 20% as raw materials or as byproducts from the leaching of other ores such as laterite nickel ore. This results in lower manganese sulfate content. When using the traditional atmospheric pressure evaporation crystallization process to produce manganese sulfate, a large amount of steam is required for evaporation and concentration to achieve the concentration needed for crystallization, leading to a significant increase in energy consumption and high production costs. Furthermore, manganese sulfate solutions often contain impurities such as calcium ions, which affect the purity of the manganese sulfate product. Existing calcium separation methods often employ simple cooling precipitation or multiple evaporation crystallization processes to obtain high-quality manganese sulfate products.

[0003] Researchers have found that industrial-grade manganese sulfate requires three crystallization purification processes to achieve the calcium ion content required for battery-grade manganese sulfate. [1] Patent application CN107963669A discloses a method for removing calcium from industrial-grade manganese sulfate, which involves dissolving industrial-grade manganese sulfate containing calcium impurities in water to obtain a solution at 15°C. A saturated or supersaturated manganese sulfate solution at 35°C is then subjected to solid-liquid separation to obtain a filtrate. The filtrate is then subjected to evaporation and crystallization to remove some water. The final temperature of the evaporation and crystallization is controlled at 70–100°C, and solid-liquid separation is maintained within this final temperature range to obtain calcium-free manganese sulfate.

[0004] Existing technologies are energy-intensive and costly, making them unsuitable for low-cost production from lean manganese ore. Furthermore, relying solely on multiple recrystallizations to remove calcium ions results in insufficient calcium ion extraction, poor separation, and an inability to reduce calcium ion concentration to low levels, impacting the purity of the manganese sulfate product. In addition, existing technologies involve cumbersome processes, with some manganese sulfate remaining in the mother liquor during multiple crystallizations, leading to significant manganese sulfate loss and low product recovery. Therefore, there is an urgent need to develop a low-energy-consumption, simplified process for preparing battery-grade manganese sulfate that can efficiently separate calcium and manganese.

[0005] References: [1] He Yulin, Li Fujie, Luo Zhihong, et al. Study on high temperature crystallization purification of industrial manganese sulfate to prepare battery-grade manganese sulfate [J]. Mining and Metallurgical Engineering, 2019, 39(3):4.DOI:CNKI:SUN:KYGC.0.2019-03-022. Summary of the Invention To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for preparing battery-grade manganese sulfate through calcium-manganese crystallization separation. The core of this method is to utilize the difference in solubility of calcium and manganese ions at different temperatures, combined with the common ion effect and seed crystal action, to achieve efficient and thorough separation of calcium. Furthermore, by controlling specific high-temperature crystallization parameters, and taking advantage of the reduced solubility of manganese sulfate under high temperature and pressure conditions, rapid and efficient crystallization of manganese sulfate is achieved. No additional recrystallization step is required to complete the removal of calcium impurities and the purification of manganese sulfate. The process is simple, efficient, and suitable for continuous industrial production.

[0006] Specifically, this is achieved through the following technical solution: In a first aspect, this application provides a method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation, comprising the following steps: (1) Concentration and enrichment of calcium- and manganese-containing liquid: The calcium- and manganese-containing liquid is concentrated to obtain concentrated liquid; (2) Cooling and calcium precipitation: Cool the concentrated liquid to allow calcium ions to crystallize and precipitate, then age and filter to obtain a calcium- and manganese-removed liquid; (3) High-temperature evaporation and crystallization: The calcium-removing manganese solution is subjected to high-temperature crystallization; (4) Centrifugal separation: The calcium-removed manganese solution that has completed high-temperature crystallization is centrifuged to remove the solution adhering to the surface of manganese sulfate crystals, further reducing the calcium content in the manganese sulfate product, and obtaining battery-grade manganese sulfate.

[0007] Furthermore, the concentration process employs conventional reduced pressure concentration or atmospheric pressure concentration methods. Furthermore, the concentration process is controlled at a temperature of 75-85°C; Furthermore, the concentration process avoids excessively high temperatures that could lead to decomposition of the liquid or premature precipitation of impurities. If the manganese content at the concentration endpoint is low, the subsequent common ion effect will have a poor effect on reducing calcium ion solubility, and the high-temperature crystallization rate will be low. If the manganese content at the concentration endpoint is high, a large amount of steam evaporation and concentration will be required, resulting in high energy consumption and high cost. Further, in step (1), the manganese content in the concentrated liquid is 110-160 g / L; Furthermore, the purpose of step (1) is to increase the concentration of manganese in the feed solution, so as to provide a suitable concentration basis for the subsequent precipitation of calcium ions and crystallization of manganese sulfate. Furthermore, in step (2), the calcium ion concentration in the calcium-removing manganese solution is <0.25 g / L; Further, in step (2), the concentrated liquid is cooled to 10-30°C; Furthermore, the aging time is 4-8 hours; Furthermore, the aging process involves stirring at a speed of 50-100 r / min; Furthermore, in step (2) the cooling and calcium precipitation process, relying on the common ion effect (referring to the effect of adding a strong electrolyte containing the same ion to a saturated solution of a sparingly soluble electrolyte to reduce the solubility of the sparingly soluble electrolyte; in this process, it is used to reduce the solubility of calcium ions and promote calcium crystal precipitation), the concentration of manganese ions is increased by evaporation and concentration, thereby reducing the solubility of calcium ions and further reducing the concentration of calcium ions in the manganese sulfate solution.

[0008] Furthermore, in step (2) the cooling and calcium precipitation process, through aging, the precipitated calcium crystals are used as seed crystals. Taking advantage of the characteristics that calcium ions are easy to crystallize and grow on the seed crystals and precipitate more thoroughly, the calcium ions in the solution are further precipitated, thereby reducing the calcium ion concentration in the manganese sulfate solution.

[0009] Furthermore, steam is the core energy cost in the production of manganese sulfate crystals. The high-temperature crystallization method used in the evaporation crystallization process of step (3) greatly reduces the amount of steam used and lowers the energy cost of production. The heat transfer efficiency under high temperature and high pressure crystallization conditions is much higher than that under normal temperature and pressure crystallization, and the energy of the heat source is utilized more fully without additional heat loss. Furthermore, the pressure for high-temperature crystallization in step (3) is 0.9-1.5 MPa; Furthermore, the high-temperature crystallization temperature in step (3) is 160-180℃; Furthermore, the holding time for high-temperature crystallization in step (3) is 10-30 min; Furthermore, the stirring rate for high-temperature crystallization in step (3) is 250-550 r / min; Furthermore, the crystallization rate of manganese sulfate in step (3) can reach 90%; Furthermore, in step (3) the evaporation and crystallization process, there is no need for repeated crystallization. Battery-grade manganese sulfate can be obtained through a single high-temperature crystallization, which simplifies the process and avoids the loss of manganese sulfate caused by multiple crystallizations.

[0010] Furthermore, in step (4), the centrifugation speed is 2000-3000 r / min; Furthermore, the centrifugation time in step (4) is 10-15 min; Furthermore, the mother liquor after centrifugation in step (4) can be recycled to the concentration and enrichment stage in step (1) for reuse, further reducing the waste of manganese resources and water consumption.

[0011] Furthermore, in step (4) centrifugal separation process, with the help of the high-speed rotation of the centrifuge, under the action of centrifugal force, the denser manganese sulfate crystals are trapped in the centrifuge drum, while the less dense adhering mother liquor and free mother liquor are quickly thrown away from the crystals and discharged through the liquid phase outlet of the centrifuge. This greatly reduces the water content of the manganese sulfate crystals, avoids the crystals from clumping and deliquescence due to excessive moisture, and reduces the residue of other trace impurities such as calcium dissolved in the adhering mother liquor. This achieves deep separation of manganese sulfate crystals and calcium impurity mother liquor, further reducing the calcium content in the product.

[0012] Secondly, this application provides the application of the above-mentioned method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation in the preparation of lithium-ion batteries.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention utilizes the common ion effect and seed crystal action to achieve efficient and thorough separation of calcium. By combining the solubility difference between calcium and manganese at low temperatures, the calcium ion concentration in calcium-manganese-containing solutions is reduced to below 0.25 g / L. This solves the technical problem in the prior art where calcium separation in calcium-manganese-containing solutions is incomplete, making it difficult to reduce the calcium ion concentration to a low level, which in turn affects the purity of manganese sulfate products. This invention achieves efficient separation of calcium and manganese without the need to add additional calcium removal reagents.

[0014] 2. This invention uses a high-temperature crystallization method and further limits the experimental parameters to achieve efficient crystallization of manganese sulfate, with a crystallization rate of up to 90%. Battery-grade products can be obtained with only one crystallization, which solves the problem of low manganese content in manganese sulfate solution in existing manganese sulfate production. The process is simple and efficient, and suitable for continuous industrial production. Detailed Implementation

[0015] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto. It should be noted that the implementation steps in the embodiments can be further adjusted according to the specific experimental environment, and the implementation steps not specified are usually conditions in conventional experiments. All compounds involved in the following embodiments are commercially available pharmaceutical products.

[0016] In a first aspect, this application provides a method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation, comprising the following steps: (1) Concentration and enrichment of calcium- and manganese-containing liquid: The calcium- and manganese-containing liquid is concentrated to obtain concentrated liquid; (2) Cooling and calcium precipitation: Cool the concentrated liquid to allow calcium ions to crystallize and precipitate, then age and filter to obtain a calcium- and manganese-removed liquid; (3) High-temperature evaporation and crystallization: The calcium-removing manganese solution is subjected to high-temperature crystallization; (4) Centrifugal separation: The calcium-removed manganese solution that has completed high-temperature crystallization is centrifuged to remove the solution adhering to the surface of manganese sulfate crystals, further reducing the calcium content in the manganese sulfate product, and obtaining battery-grade manganese sulfate.

[0017] Furthermore, the concentration process employs conventional reduced pressure concentration or atmospheric pressure concentration methods. Furthermore, the concentration process is controlled at a temperature of 75-85°C; Furthermore, the concentration process avoids excessively high temperatures that could lead to decomposition of the liquid or premature precipitation of impurities. If the manganese content at the concentration endpoint is low, the subsequent common ion effect will have a poor effect on reducing calcium ion solubility, and the high-temperature crystallization rate will be low. If the manganese content at the concentration endpoint is high, a large amount of steam evaporation and concentration will be required, resulting in high energy consumption and high cost. Further, in step (1), the manganese content in the concentrated liquid is 110-160 g / L; Furthermore, the purpose of step (1) is to increase the concentration of manganese in the feed solution, so as to provide a suitable concentration basis for the subsequent precipitation of calcium ions and crystallization of manganese sulfate. Furthermore, in step (2), the calcium ion concentration in the calcium-removing manganese solution is <0.25 g / L; Further, in step (2), the concentrated liquid is cooled to 10-30°C; Furthermore, the aging time is 4-8 hours; Furthermore, the aging process involves stirring at a speed of 50-100 r / min; Furthermore, in step (2) the cooling and calcium precipitation process, relying on the common ion effect (referring to the effect of adding a strong electrolyte containing the same ion to a saturated solution of a sparingly soluble electrolyte to reduce the solubility of the sparingly soluble electrolyte; in this process, it is used to reduce the solubility of calcium ions and promote calcium crystal precipitation), the concentration of manganese ions is increased by evaporation and concentration, thereby reducing the solubility of calcium ions and further reducing the concentration of calcium ions in the manganese sulfate solution.

[0018] Furthermore, in step (2) the cooling and calcium precipitation process, through aging, the precipitated calcium crystals are used as seed crystals. Taking advantage of the characteristics that calcium ions are easy to crystallize and grow on the seed crystals and precipitate more thoroughly, the calcium ions in the solution are further precipitated, thereby reducing the calcium ion concentration in the manganese sulfate solution.

[0019] Furthermore, steam is the core energy cost in the production of manganese sulfate crystals. The high-temperature crystallization method used in the evaporation crystallization process of step (3) greatly reduces the amount of steam used and lowers the energy cost of production. The heat transfer efficiency under high temperature and high pressure crystallization conditions is much higher than that under normal temperature and pressure crystallization, and the energy of the heat source is utilized more fully without additional heat loss. Furthermore, the pressure for high-temperature crystallization in step (3) is 0.9-1.5 MPa; Furthermore, the high-temperature crystallization temperature in step (3) is 160-180℃; Furthermore, the holding time for high-temperature crystallization in step (3) is 10-30 min; Furthermore, the stirring rate for high-temperature crystallization in step (3) is 250-550 r / min; Furthermore, the crystallization rate of manganese sulfate in step (3) can reach 90%; Furthermore, in step (3) the evaporation and crystallization process, there is no need for repeated crystallization. Battery-grade manganese sulfate can be obtained through a single high-temperature crystallization, which simplifies the process and avoids the loss of manganese sulfate caused by multiple crystallizations.

[0020] Furthermore, in step (4), the centrifugation speed is 2000-3000 r / min; Furthermore, the centrifugation time in step (4) is 10-15 min; Furthermore, the mother liquor after centrifugation in step (4) can be recycled to the concentration and enrichment stage in step (1) for reuse, further reducing the waste of manganese resources and water consumption.

[0021] Furthermore, in step (4) centrifugal separation process, with the help of the high-speed rotation of the centrifuge, under the action of centrifugal force, the denser manganese sulfate crystals are trapped in the centrifuge drum, while the less dense adhering mother liquor and free mother liquor are quickly thrown away from the crystals and discharged through the liquid phase outlet of the centrifuge. This greatly reduces the water content of the manganese sulfate crystals, avoids the crystals from clumping and deliquescence due to excessive moisture, and reduces the residue of other trace impurities such as calcium dissolved in the adhering mother liquor. This achieves deep separation of manganese sulfate crystals and calcium impurity mother liquor, further reducing the calcium content in the product.

[0022] Example 1 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 120 g / L to obtain a concentrated solution.

[0023] Calcium precipitation at room temperature: The concentrated liquid was sent to a cooling tank and cooled to 25°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 231 mg / L and the concentration of manganese ions was 121 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0024] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 160°C. The gauge pressure inside the kettle is adjusted to 0.9 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 84.0%.

[0025] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0026] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0027] Example 2 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 85℃ and the vacuum pressure at 0.08 MPa, and continue to concentrate until the manganese content in the solution is about 130 g / L to obtain a concentrated solution.

[0028] Calcium precipitation at room temperature: The concentrated liquid was sent to a cooling tank and cooled to 30°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 80 r / min for 6 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 225 mg / L and the concentration of manganese ions was 132 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0029] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 170°C. The pressure inside the kettle is adjusted to 1.2 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 83.7%.

[0030] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2500 r / min and the centrifugation time is 10 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.2%. After drying, the manganese content is measured to be 32.43% and the calcium content is 0.011%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and enrichment.

[0031] Example 3 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 75℃ and the vacuum pressure at 0.08 MPa, and continue to concentrate until the manganese content in the solution is about 160 g / L to obtain a concentrated solution.

[0032] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 10°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 100 r / min for 8 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 230 mg / L and the concentration of manganese ions was 130 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0033] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 180°C. The pressure inside the kettle is adjusted to 1.5 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 30 min. After crystallization is completed, the crystallization rate of manganese sulfate is 90.2%.

[0034] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 3000 r / min and the centrifugation time is 10 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.2%. After drying, the manganese content is measured to be 32.43% and the calcium content is 0.011%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and reconcentration.

[0035] Example 4 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 110 g / L to obtain a concentrated solution.

[0036] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 10°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 228 mg / L and the concentration of manganese ions was 120 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0037] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 160°C. The gauge pressure inside the kettle is adjusted to 1.1 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 88.0%.

[0038] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0039] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0040] Example 5 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 130 g / L to obtain a concentrated solution.

[0041] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 30°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 235 mg / L and the concentration of manganese ions was 128 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0042] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 165°C. The pressure inside the kettle is adjusted to 1.5 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 90.9%.

[0043] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0044] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0045] Example 6 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 140 g / L to obtain a concentrated solution.

[0046] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 25°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 236 mg / L and the concentration of manganese ions was 130 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0047] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 170°C. The pressure inside the kettle is adjusted to 1.1 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 89.7%.

[0048] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0049] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0050] Example 7 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 150 g / L to obtain a concentrated solution.

[0051] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 20°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 233 mg / L and the concentration of manganese ions was 129 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0052] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 175°C. The pressure inside the kettle is adjusted to 1.2 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 87.0%.

[0053] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0054] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0055] Example 8 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 155 g / L to obtain a concentrated solution.

[0056] Calcium precipitation at room temperature by cooling: The concentrated liquid was sent to a cooling tank and cooled to 15°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 227 mg / L and the concentration of manganese ions was 127 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0057] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 180°C. The pressure inside the kettle is adjusted to 1.3 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 88.5%.

[0058] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0059] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0060] Example 9 Concentration of calcium-manganese solution: Take a calcium-manganese solution containing 20 g / L of manganese and a saturated calcium concentration of ~0.5 g / L, and concentrate it using a vacuum evaporator. Control the concentration temperature at 80℃ and the vacuum pressure at 0.05 MPa, and continue to concentrate until the manganese content in the solution is about 115 g / L to obtain a concentrated solution.

[0061] Calcium precipitation at room temperature: The concentrated liquid was sent to a cooling tank and cooled to 10°C by forced cooling. The cooled liquid was then sent to an aging tank and aged at a low speed of 50 r / min for 4 h. After aging, the liquid was filtered and the concentration of calcium ions in the filtrate was measured to be 233 mg / L and the concentration of manganese ions was 133 g / L, thus obtaining a preliminary calcium and manganese removal solution.

[0062] High-temperature evaporation crystallization: The feed liquid is sent into a high-temperature and high-pressure crystallization kettle. After the kettle is closed, steam is introduced to raise the temperature to 180°C. The pressure inside the kettle is adjusted to 1.5 MPa. The stirring device is turned on and the stirring rate is controlled at 300 r / min. The temperature is maintained for crystallization for 10 min. After crystallization is completed, the crystallization rate of manganese sulfate is 90.5%.

[0063] Centrifugal separation: The crystallization liquid is fed into a horizontal centrifuge, and the centrifugation speed is controlled at 2000 r / min and the centrifugation time is 15 min for centrifugation separation. The mother liquor on the surface of manganese sulfate crystals is removed. After centrifugation, the solid crystals are collected and the water content is measured to be 6.7%. After drying, the manganese content is measured to be 32.4% and the calcium content is 0.012%, which is the battery grade manganese sulfate product. The mother liquor after centrifugation is recycled to a vacuum evaporator for concentration and re-concentration.

[0064] In this embodiment, the production of 1 t of manganese sulfate monohydrate requires 4.25 t of saturated steam at 1.6 MPa, which is equivalent to an energy consumption of approximately 2.0 GJ / t.

[0065] Comparative Example 1 The conventional method for removing calcium ions from calcium-containing manganese solutions was used, and all other conditions were the same as in Example 1.

[0066] After aging and filtration, the concentration of calcium ions in the filtrate was measured to be 450 mg / L and the concentration of manganese ions was 118 g / L, yielding a preliminary calcium and manganese-removed solution.

[0067] After high-temperature evaporation and crystallization, the crystallization rate of manganese sulfate was found to be 76%.

[0068] After centrifugation, the solid crystals were collected, dried, and the manganese content was found to be 31.8% and the calcium content was 0.035%.

[0069] Comparative Example 2 The conventional method for evaporating and crystallizing manganese sulfate in the prior art was used, and all other conditions were the same as in Example 1.

[0070] The industry standard atmospheric pressure evaporation crystallization process includes the following steps: the calcium- and manganese-removed liquid is fed into an atmospheric pressure evaporator crystallizer, the evaporation temperature is controlled at 105-110℃, and the crystallization is carried out under atmospheric pressure. The remaining concentration, cooling, aging, and centrifugation conditions are exactly the same as in Example 1. To achieve a similar crystallization rate, two recrystallization operations are required.

[0071] After aging and filtration, the concentration of calcium ions in the filtrate was measured to be 231 mg / L and the concentration of manganese ions was 121 g / L, yielding a preliminary calcium and manganese-removed solution.

[0072] After the first crystallization was completed by evaporation, the crystallization rate of manganese sulfate was 58%, and the final crystallization rate of manganese sulfate was 78%.

[0073] After centrifugation, the solid crystals were collected, dried, and the manganese content was found to be 32% and the calcium content was 0.022%.

[0074] In this comparative example, the production of 1 t of manganese sulfate monohydrate requires 7.00 t of saturated steam at 1.6 MPa, which translates to an energy consumption of approximately 3.3 GJ / t. Compared with Example 1, the energy consumption of the high-temperature crystallization method provided by this invention is only 60.7% of that of the conventional atmospheric pressure crystallization method, demonstrating significant energy-saving effects.

Claims

1. A method for preparing battery-grade manganese sulfate by calcium-manganese crystallization separation, characterized in that, Including the following steps: The calcium- and manganese-containing liquid was concentrated to obtain a concentrated liquid. The concentrated liquid is cooled to allow calcium ions to crystallize out. After aging and filtration, a calcium- and manganese-removed liquid is obtained. The calcium and manganese removal solution is subjected to high-temperature crystallization treatment; The crystals were separated by centrifugation to obtain battery-grade manganese sulfate.

2. The method for preparing battery-grade manganese sulfate according to claim 1, characterized in that, The concentration process is controlled at a temperature of 75-85℃.

3. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The manganese content in the concentrated liquid is 110-160 g / L.

4. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The concentrated cooling liquid is cooled to 10-30℃.

5. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The aging time is 4-8 hours.

6. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The high-temperature crystallization is carried out at a pressure of 0.9-1.5 MPa and a temperature of 160-180℃.

7. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The holding time for high-temperature crystallization is 10-30 min.

8. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The aging process involves stirring at a speed of 50-100 r / min.

9. The method for preparing battery-grade manganese sulfate according to claim 1 or 2, characterized in that, The centrifugation speed is 2000-3000 r / min, and the time is 10-15 min.

10. The application of a method for preparing battery-grade manganese sulfate as described in any one of claims 1-9 in the preparation of lithium-ion batteries.