Preparation method of battery grade manganese sesquioxide

Abstract

The invention discloses a preparation method of battery grade manganese sesquioxide. The method comprises the steps of raw material preparation, dehydration treatment, powder preparation, staged heating, oxygen supply, stirring and overturning, product collection and the like. Specifically, sulfate system manganese oxalate is selected as a raw material, and manganese oxalate powder suitable for roasting is obtained through dehydration treatment and powder preparation. In the roasting process, the manganese oxalate powder is ensured to be converted into high-purity battery-grade manganese sesquioxide through staged heating and accurate control of oxygen supply. In addition, an efficient solid-liquid separation and washing process is adopted, so that the purity and the particle size distribution of the product meet the requirements of a battery material. The preparation method has the beneficial effects that the prepared product has high purity and uniform particle size distribution, and the performance and the stability of the battery can be remarkably improved. In addition, the optimized process steps reduce the generation of wastewater and waste gas, meet the environmental protection requirement, simplify the production flow and improve the production efficiency and economical efficiency.

Description

Technical Field

[0001] The invention relates to the field of inorganic non-metallic materials, and in particular to a method for preparing battery-grade manganese trioxide. Background Art

[0002] With the rapid development of new energy technologies, the performance and cost-effectiveness of batteries, as key components for energy storage and conversion, have received widespread attention. Among many battery materials, manganese trioxide (MnO2) is widely used in energy storage devices such as lithium-ion batteries and supercapacitors due to its unique physical and chemical properties. However, the preparation process of battery-grade manganese trioxide is complicated, the cost is high, and the product quality is unstable. These problems limit its widespread application in the field of new energy.

[0003] At present, the preparation methods of manganese trioxide mainly include chemical precipitation method, sol-gel method, high temperature solid phase method, etc. Although these methods can prepare manganese trioxide, they have certain limitations in terms of purity, particle size distribution, crystallinity, etc. For example, although the chemical precipitation method is simple to operate, the purity of the obtained manganese trioxide is not high and the particle size is uneven; although the sol-gel method can prepare high-purity manganese trioxide, the cost is high and it is not suitable for large-scale production; the high temperature solid phase method has problems such as high energy consumption and long reaction time.

[0004] In addition, the existing technology does not accurately control the environment during the preparation process, resulting in unstable product performance and failure to meet the high standards for battery-grade manganese trioxide. In particular, there is a lack of effective technical means to ensure product quality in terms of raw material selection, dehydration treatment, and roasting process. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing battery-grade manganese trioxide.

[0006] The present invention is achieved through the following technical solutions: A method for preparing battery-grade manganese trioxide of the present invention comprises the following steps: Raw material preparation, select and prepare sulfate system manganese oxalate as raw material; in the process of preparing battery-grade manganese trioxide, raw material preparation is a key step. Sulfate system manganese oxalate is selected as the raw material because this system can provide high-purity manganese oxalate, ensuring the stability and product quality of subsequent steps.

[0007] Dehydration treatment is performed on the manganese oxalate to ensure that the water in it is completely removed; the water in the manganese oxalate will affect the subsequent roasting effect, so it is necessary to completely remove the water in it through dehydration treatment to ensure the smooth progress of the subsequent steps.

[0008] In preparation for roasting, the dehydrated manganese oxalate is crushed into powder for uniform heating and oxidation.

[0009] Stage heating: gradually heat the manganese oxalate powder in stages until the preset calcination temperature is reached, and then the heated manganese oxalate powder is calcined; stage heating is to gradually increase the temperature so that the manganese oxalate powder is evenly heated to ensure sufficient calcination. Stage heating can remove residual moisture and volatile substances and prevent uneven reactions at high temperatures. The high-temperature calcination in the final stage ensures that the manganese oxalate powder is completely converted into manganese trioxide, thereby meeting the quality standards of battery-grade products.

[0010] Oxygen supply: oxygen is continuously introduced during the heating and roasting process to ensure oxidation conditions. Oxygen supply: oxygen is continuously introduced during the heating and roasting process to ensure oxidation conditions. Maintaining a stable oxygen concentration in the roasting system can meet the oxidation conditions of manganese trioxide. Adequate oxygen supply is a key factor in ensuring the conversion of manganese oxalate into manganese trioxide.

[0011] Stirring and turning: During the roasting process, the manganese oxalate is continuously or periodically stirred and turned to keep it in a powder state; by stirring and turning, the powder can be prevented from agglomerating at high temperatures and the uniformity of the roasting process can be ensured.

[0012] Product collection: collect the calcined manganese trioxide to obtain battery-grade manganese trioxide.

[0013] Preferably, the preparation of the above-mentioned sulfate system manganese oxalate comprises the following steps: In the preparation of manganese suspension, the metal manganese flakes are ground into powder, ensuring that the mesh size is greater than 100 mesh, and then the manganese powder is mixed with water to prepare a uniform manganese suspension; this step ensures the uniform distribution and suspension of the manganese powder, providing good reaction conditions for subsequent reactions.

[0014] The preparation of manganese sulfate solution is to add sulfuric acid to the manganese suspension to prepare a manganese sulfate solution, wherein the manganese content is controlled at 40-150 g / L; by reasonably adding sulfuric acid and controlling the manganese content, a stable manganese sulfate solution can be obtained, which provides a basis for subsequent impurity removal and reaction steps.

[0015] In the impurity removal step, manganese powder is added to the manganese sulfate solution as an impurity remover, the solution is heated to 60-80° C., stirred at a speed of 220-260 rpm for 30-60 minutes, and after filtering the precipitate, the solution is allowed to return to room temperature; this process can remove most of the impurities and ensure the purity of the solution.

[0016] A mixed solution is prepared by double decomposition reaction, oxalic acid is added to a manganese sulfate solution, and the mass ratio of oxalic acid to manganese is controlled between 1:1 and 1.6; the mixed solution is heated to 20-55° C., and the reaction is maintained for 2-4 hours; this step can form a manganese oxalate precipitate, is an important step in preparing manganese oxalate, and controlling the reaction conditions can ensure the quality of the product.

[0017] Solid-liquid separation and washing: Use a filter press to separate the solid and liquid of the mixed liquid after the reaction to obtain a filter cake and a filtrate; then recover the filtrate and use it as a sulfuric acid raw material for preparing a manganese suspension, and then spray wash the filter cake, and set up N washing tanks, each tank containing a washing liquid; The washing liquid is recycled. The washing liquid is taken from the first washing tank to spray the filter cake, and then the washing liquid is recovered to the manganese sulfate solution preparation process; the washing liquid is taken from the second washing tank to spray the filter cake, and then the washing liquid is recovered to the first washing tank; and so on, until the washing liquid is taken from the Nth washing tank to spray the filter cake, and then the washing liquid is recovered to the N-1th washing tank; Drying and crushing: drying the filter cake after spray cleaning at 60-80°C for 2-4 hours; finally, crushing the dried filter cake into powder to obtain sulfate system manganese oxalate. The above reasonable step settings can ensure the quality and uniformity of manganese oxalate.

[0018] Preferably, the dehydration treatment of manganese oxalate comprises the following steps: Place the sulfate system manganese oxalate in a drying oven; Control the drying oven temperature at 100-150°C and preheat at a constant temperature for 1-3 hours; During the drying process, maintain constant temperature and ventilation to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate appears in a pink-white powder state.

[0019] The purpose of dehydrating manganese oxalate is to ensure that the water in manganese oxalate is completely removed, so as to ensure the smooth progress of the subsequent roasting process. The sulfate system manganese oxalate is placed in a drying oven, and the temperature of the drying oven is controlled at 100-150°C, and the constant temperature is preheated for 1-3 hours, so that the water in the manganese oxalate can be gradually evaporated. During the drying process, constant temperature and ventilation are maintained to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate presents a white powder state. The precise control of this step can ensure the dehydration effect of manganese oxalate and lay the foundation for the subsequent roasting process.

[0020] Preferably, the above-mentioned step of pulverizing the dehydrated manganese oxalate into powder comprises the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; Through the sieving operation, the particle size of the manganese oxalate powder is ensured to be between 50-100 microns for subsequent roasting treatment.

[0021] The purpose of pulverizing the dehydrated manganese oxalate into powder is to improve the uniformity and efficiency of the roasting process. Using a grinder or a pulverizer to break up the dehydrated manganese oxalate into a uniform powder can increase the surface area of ​​the powder, which is conducive to the conduction of heat and the reaction. By sieving to ensure that the particle size of the manganese oxalate powder is between 50-100 microns, the powder can be evenly heated during the roasting process to prevent incomplete roasting caused by uneven particle size.

[0022] Preferably, the stepwise heating of the manganese oxalate powder comprises the following steps: The manganese oxalate powder is placed in a muffle furnace, a high temperature furnace or a rotary calciner; The first stage: heating at 1-150℃ for 20 minutes to ensure that the manganese oxalate powder is evenly heated; The second stage: heating at 150-300℃ for 30-60 minutes to further remove residual moisture and volatile substances; Final stage: Continue to raise the temperature to 490-510°C and roast for 3-5 hours to ensure that the manganese oxalate powder is completely roasted.

[0023] The purpose of gradually heating the manganese oxalate powder in stages is to ensure that the manganese oxalate powder is evenly heated during the roasting process to avoid powder agglomeration or incomplete reaction caused by sudden temperature changes. The manganese oxalate powder is placed in a muffle furnace, a high-temperature furnace or a rotary calcining furnace. The residual moisture and volatile substances in the powder can be gradually removed by heating in stages to ensure the purity of the powder. The high-temperature roasting in the final stage can completely convert the manganese oxalate powder into manganese trioxide to ensure the quality of the product.

[0024] Preferably, the oxygen supply is to control the oxygen flow rate through an oxygen flow meter during the heating and roasting process to ensure a stable oxygen supply and maintain the oxygen concentration in the roasting system between 21% and 25% to meet the oxidation conditions of manganese trioxide.

[0025] During the heating and roasting process, oxygen supply is a key factor to ensure the conversion of manganese oxalate into manganese trioxide. By controlling the oxygen flow rate through an oxygen flow meter, the oxygen supply can be accurately adjusted to maintain the oxygen concentration in the roasting system between 21% and 25%. A stable oxygen supply can ensure the oxidation conditions during the roasting process, promote the full oxidation of manganese oxalate into manganese trioxide, and ensure the purity and quality of the product.

[0026] Preferably, the stirring and turning, when a rotary calcining furnace is used for roasting, utilizes its inherent stirring function to make the manganese oxalate powder turn evenly; When a muffle furnace or a high temperature furnace is used for roasting, the manganese oxalate powder is manually or mechanically stirred and turned every 30-60 minutes to ensure that it is always kept in a powder state for oxidation.

[0027] Preferably, the above product collection comprises the following steps: The calcined manganese trioxide is taken out from the calcining furnace and cooled to room temperature; Remove possible metal impurities through magnetic separation, flotation or pickling; Use high-efficiency filters to further remove trace impurities to obtain manganese trioxide with high purity and low impurity content; The final product is tested to ensure it meets the purity and quality standards for battery-grade manganese trioxide.

[0028] Product collection is the final step in preparing battery-grade manganese trioxide. Removing the calcined manganese trioxide from the calciner and cooling it to room temperature prevents the product from further reacting at high temperatures. Removing possible metal impurities through magnetic separation, flotation or acid washing can improve the purity of the product. Using high-efficiency filters to further remove trace impurities ensures the quality of manganese trioxide. The final product is strictly tested to ensure that it meets the purity and quality standards of battery-grade manganese trioxide to meet market demand.

[0029] Preferably, the dehydrated manganese oxalate is broken into powder, and the particle size of the manganese oxalate powder is ensured to be between 50 and 100 microns by sieving operation, so as to facilitate the subsequent roasting treatment, which specifically includes the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; The powder is sieved through a sieve with an aperture of 50-100 microns; The manganese oxalate powder that passes through the sieve, i.e., the particle size is between 50-100 microns, is collected and prepared for roasting; For the larger particles of manganese oxalate powder that do not pass through the sieve, perform the following treatment: The powder that does not pass through the screen is sent back to the grinder or pulverizer for secondary grinding; after grinding, the powder is screened again until the powder particle size reaches the requirement between 50-100 microns; the grinding and screening operations are repeated until all manganese oxalate powder meets the particle size requirements; The over-fine powder produced during the screening process, i.e., the particle size is less than 50 microns, is re-ground together with the larger particles of manganese oxalate powder that have not passed through the sieve through a mixing operation to ensure that the overall powder particle size is uniform.

[0030] The beneficial effects of the present invention are: The battery-grade manganese trioxide prepared by the present invention has extremely high purity, meets the strict requirements of battery materials, and can effectively improve the overall performance and service life of the battery.

[0031] Uniform particle size distribution: The prepared manganese trioxide powder has a uniform particle size distribution, which ensures the consistency and stability of the material in the battery, thereby improving the energy density and electrochemical performance of the battery.

[0032] Excellent roasting effect: The optimized roasting process ensures the complete conversion of manganese trioxide, which enhances the electrochemical properties and long-term stability of the product.

[0033] Environmentally friendly: The preparation process reduces the generation of wastewater and waste gas, meets environmental protection requirements, and is environmentally friendly.

[0034] Simplified production process: By optimizing the process steps, the production efficiency is improved, the production cost is reduced, and the industrial production of battery-grade manganese trioxide is more economical and operable. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments: Embodiment: A method for preparing battery-grade manganese trioxide comprises the following steps: Raw material preparation, select and prepare sulfate system manganese oxalate as raw material; in the process of preparing battery-grade manganese trioxide, raw material preparation is a key step. Sulfate system manganese oxalate is selected as the raw material because this system can provide high-purity manganese oxalate, ensuring the stability and product quality of subsequent steps.

[0036] Dehydration treatment is performed on the manganese oxalate to ensure that the water in it is completely removed; the water in the manganese oxalate will affect the subsequent roasting effect, so it is necessary to completely remove the water in it through dehydration treatment to ensure the smooth progress of the subsequent steps.

[0037] In preparation for roasting, the dehydrated manganese oxalate is crushed into powder for uniform heating and oxidation.

[0038] Stage heating: gradually heat the manganese oxalate powder in stages until the preset calcination temperature is reached, and then the heated manganese oxalate powder is calcined; stage heating is to gradually increase the temperature so that the manganese oxalate powder is evenly heated to ensure sufficient calcination. Stage heating can remove residual moisture and volatile substances and prevent uneven reactions at high temperatures. The high-temperature calcination in the final stage ensures that the manganese oxalate powder is completely converted into manganese trioxide, thereby meeting the quality standards of battery-grade products.

[0039] Oxygen supply: oxygen is continuously introduced during the heating and roasting process to ensure oxidation conditions. Oxygen supply: oxygen is continuously introduced during the heating and roasting process to ensure oxidation conditions. Maintaining a stable oxygen concentration in the roasting system can meet the oxidation conditions of manganese trioxide. Adequate oxygen supply is a key factor in ensuring the conversion of manganese oxalate into manganese trioxide.

[0040] Stirring and turning: During the roasting process, the manganese oxalate is continuously or periodically stirred and turned to keep it in a powder state; by stirring and turning, the powder can be prevented from agglomerating at high temperatures and the uniformity of the roasting process can be ensured.

[0041] Product collection: collect the calcined manganese trioxide to obtain battery-grade manganese trioxide.

[0042] Preferably, the preparation of the above-mentioned sulfate system manganese oxalate comprises the following steps: In the preparation of manganese suspension, the metal manganese flakes are ground into powder, ensuring that the mesh size is greater than 100 mesh, and then the manganese powder is mixed with water to prepare a uniform manganese suspension; this step ensures the uniform distribution and suspension of the manganese powder, providing good reaction conditions for subsequent reactions.

[0043] The preparation of manganese sulfate solution is to add sulfuric acid to the manganese suspension to prepare a manganese sulfate solution, wherein the manganese content is controlled at 40-150 g / L; by reasonably adding sulfuric acid and controlling the manganese content, a stable manganese sulfate solution can be obtained, which provides a basis for subsequent impurity removal and reaction steps.

[0044] In the impurity removal step, manganese powder is added to the manganese sulfate solution as an impurity remover, the solution is heated to 60-80° C., stirred at a speed of 220-260 rpm for 30-60 minutes, and after filtering the precipitate, the solution is allowed to return to room temperature; this process can remove most of the impurities and ensure the purity of the solution.

[0045] A mixed solution is prepared by double decomposition reaction, oxalic acid is added to a manganese sulfate solution, and the mass ratio of oxalic acid to manganese is controlled between 1:1 and 1.6; the mixed solution is heated to 20-55° C., and the reaction is maintained for 2-4 hours; this step can form a manganese oxalate precipitate, is an important step in preparing manganese oxalate, and controlling the reaction conditions can ensure the quality of the product.

[0046] Solid-liquid separation and washing: Use a filter press to separate the solid and liquid of the mixed liquid after the reaction to obtain a filter cake and a filtrate; then recover the filtrate and use it as a sulfuric acid raw material for preparing a manganese suspension, and then spray wash the filter cake, and set up N washing tanks, each tank containing a washing liquid; The washing liquid is recycled. The washing liquid is taken from the first washing tank to spray the filter cake, and then the washing liquid is recovered to the manganese sulfate solution preparation process; the washing liquid is taken from the second washing tank to spray the filter cake, and then the washing liquid is recovered to the first washing tank; and so on, until the washing liquid is taken from the Nth washing tank to spray the filter cake, and then the washing liquid is recovered to the N-1th washing tank; Drying and crushing: drying the filter cake after spray cleaning at 60-80°C for 2-4 hours; finally, crushing the dried filter cake into powder to obtain sulfate system manganese oxalate. The above reasonable step settings can ensure the quality and uniformity of manganese oxalate.

[0047] Preferably, the dehydration treatment of manganese oxalate comprises the following steps: Place the sulfate system manganese oxalate in a drying oven; Control the drying oven temperature at 100-150°C and preheat at a constant temperature for 1-3 hours; During the drying process, maintain constant temperature and ventilation to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate appears in a pink-white powder state.

[0048] The purpose of dehydrating manganese oxalate is to ensure that the water in manganese oxalate is completely removed, so as to ensure the smooth progress of the subsequent roasting process. The sulfate system manganese oxalate is placed in a drying oven, and the temperature of the drying oven is controlled at 100-150°C, and the constant temperature is preheated for 1-3 hours, so that the water in the manganese oxalate can be gradually evaporated. During the drying process, constant temperature and ventilation are maintained to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate presents a white powder state. The precise control of this step can ensure the dehydration effect of manganese oxalate and lay the foundation for the subsequent roasting process.

[0049] Preferably, the above-mentioned step of pulverizing the dehydrated manganese oxalate into powder comprises the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; Through the sieving operation, the particle size of the manganese oxalate powder is ensured to be between 50-100 microns for subsequent roasting treatment.

[0050] The purpose of pulverizing the dehydrated manganese oxalate into powder is to improve the uniformity and efficiency of the roasting process. Using a grinder or a pulverizer to break up the dehydrated manganese oxalate into a uniform powder can increase the surface area of ​​the powder, which is conducive to the conduction of heat and the reaction. By sieving to ensure that the particle size of the manganese oxalate powder is between 50-100 microns, the powder can be evenly heated during the roasting process to prevent incomplete roasting caused by uneven particle size.

[0051] Preferably, the stepwise heating of the manganese oxalate powder comprises the following steps: The manganese oxalate powder is placed in a muffle furnace, a high temperature furnace or a rotary calciner; The first stage: heating at 1-150℃ for 20 minutes to ensure that the manganese oxalate powder is evenly heated; The second stage: heating at 150-300℃ for 30-60 minutes to further remove residual moisture and volatile substances; Final stage: Continue to raise the temperature to 490-510°C and roast for 3-5 hours to ensure that the manganese oxalate powder is completely roasted.

[0052] The purpose of gradually heating the manganese oxalate powder in stages is to ensure that the manganese oxalate powder is evenly heated during the roasting process to avoid powder agglomeration or incomplete reaction caused by sudden temperature changes. The manganese oxalate powder is placed in a muffle furnace, a high-temperature furnace or a rotary calcining furnace. The residual moisture and volatile substances in the powder can be gradually removed by heating in stages to ensure the purity of the powder. The high-temperature roasting in the final stage can completely convert the manganese oxalate powder into manganese trioxide to ensure the quality of the product.

[0053] Preferably, the oxygen supply is to control the oxygen flow rate through an oxygen flow meter during the heating and roasting process to ensure a stable oxygen supply and maintain the oxygen concentration in the roasting system between 21% and 25% to meet the oxidation conditions of manganese trioxide.

[0054] During the heating and roasting process, oxygen supply is a key factor to ensure the conversion of manganese oxalate into manganese trioxide. By controlling the oxygen flow rate through an oxygen flow meter, the oxygen supply can be accurately adjusted to maintain the oxygen concentration in the roasting system between 21% and 25%. A stable oxygen supply can ensure the oxidation conditions during the roasting process, promote the full oxidation of manganese oxalate into manganese trioxide, and ensure the purity and quality of the product.

[0055] Preferably, the stirring and turning, when a rotary calcining furnace is used for roasting, utilizes its inherent stirring function to make the manganese oxalate powder turn evenly; When a muffle furnace or a high temperature furnace is used for roasting, the manganese oxalate powder is manually or mechanically stirred and turned every 30-60 minutes to ensure that it is always kept in a powder state for oxidation.

[0056] Preferably, the above product collection comprises the following steps: The calcined manganese trioxide is taken out from the calcining furnace and cooled to room temperature; Remove possible metal impurities through magnetic separation, flotation or pickling; Use high-efficiency filters to further remove trace impurities to obtain manganese trioxide with high purity and low impurity content; The final product is tested to ensure it meets the purity and quality standards for battery-grade manganese trioxide.

[0057] Product collection is the final step in preparing battery-grade manganese trioxide. Removing the calcined manganese trioxide from the calciner and cooling it to room temperature prevents the product from further reacting at high temperatures. Removing possible metal impurities through magnetic separation, flotation or acid washing can improve the purity of the product. Using high-efficiency filters to further remove trace impurities ensures the quality of manganese trioxide. The final product is strictly tested to ensure that it meets the purity and quality standards of battery-grade manganese trioxide to meet market demand.

[0058] Preferably, the dehydrated manganese oxalate is broken into powder, and the particle size of the manganese oxalate powder is ensured to be between 50 and 100 microns by sieving operation, so as to facilitate the subsequent roasting treatment, which specifically includes the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; The powder is sieved through a sieve with an aperture of 50-100 microns; The manganese oxalate powder that passes through the sieve, i.e., the particle size is between 50-100 microns, is collected and prepared for roasting; For the larger particles of manganese oxalate powder that do not pass through the sieve, perform the following treatment: The powder that does not pass through the screen is sent back to the grinder or pulverizer for secondary grinding; after grinding, the powder is screened again until the powder particle size reaches the requirement between 50-100 microns; the grinding and screening operations are repeated until all manganese oxalate powder meets the particle size requirements; The over-fine powder produced during the screening process, i.e., the particle size is less than 50 microns, is re-ground together with the larger particles of manganese oxalate powder that have not passed through the sieve through a mixing operation to ensure that the overall powder particle size is uniform.

[0059] The present invention provides a method for preparing battery-grade manganese trioxide. The following is an experimental record of a specific embodiment: Raw material preparation: Preparation of manganese suspension: Grind 2 kg of manganese flakes into powder, making sure the mesh size is greater than 100. Mix 1 kg of manganese powder with 10 liters of deionized water to make a uniform manganese suspension.

[0060] Preparation of manganese sulfate solution: Add 1 liter of sulfuric acid to the manganese suspension to prepare a manganese sulfate solution, in which the manganese content is controlled at 100 g / L.

[0061] Impurity removal step: add 200 grams of manganese powder as an impurity remover to the manganese sulfate solution, heat the solution to 70°C, stir at 240 rpm for 45 minutes, filter the precipitate, and then cool the solution naturally to room temperature.

[0062] Preparation of mixed solution by double decomposition reaction: Add 600 g of oxalic acid to the manganese sulfate solution, and control the mass ratio of oxalic acid to manganese to be 1.2:1. Heat the mixed solution to 40°C and keep the reaction for 3 hours to form manganese oxalate precipitate.

[0063] Solid-liquid separation and washing: Use a filter press to separate the solid and liquid of the reaction mixture to obtain 600 grams of filter cake and 10 liters of filtrate. The filtrate is recovered and used as sulfuric acid raw material. The filter cake is sprayed and washed, and 3 washing tanks are set up, each tank is filled with washing liquid. The washing liquid is recycled, and the washing liquid is taken from the first washing tank to spray the filter cake, and then recycled to the manganese sulfate solution preparation process; the washing liquid is taken from the second washing tank to spray the filter cake, and then recycled to the first washing tank; and so on, until the washing liquid is taken from the third washing tank to spray the filter cake, and then recycled to the second washing tank.

[0064] Drying and crushing: The filter cake after spray cleaning is dried at 70°C for 4 hours. The dried filter cake is crushed into powder to obtain 2 kg of sulfate system manganese oxalate.

[0065] Dehydration treatment: Place 2 kg of sulfate system manganese oxalate in a drying oven. Control the temperature of the drying oven at 120°C and preheat at a constant temperature for 2 hours. During the drying process, maintain constant temperature and ventilation to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate appears in a white powder state.

[0066] Powder preparation: Use a grinder to break up the dehydrated manganese oxalate into a uniform powder. Perform a sieving operation through a sieve, and the sieve aperture is set to 50 microns. For the larger particles of manganese oxalate powder that do not pass through the sieve, perform a secondary grinding and sieve again until the powder particle size reaches the requirement of 50-100 microns. For the overfine powder generated during the sieving process, that is, the particle size is less than 50 microns, it is re-ground together with the larger particles of manganese oxalate powder that do not pass through the sieve through a mixing operation to ensure that the overall powder particle size is uniform.

[0067] Heating in stages: The powdered manganese oxalate is placed in a muffle furnace for heating. In the first stage, the manganese oxalate powder is heated at 25-150°C for 20 minutes to ensure uniform heating. In the second stage, it is heated at 150-300°C for 45 minutes to further remove residual moisture and volatile substances. In the final stage, the temperature is continuously raised to 500°C and roasted for 4 hours to ensure that the manganese oxalate powder is completely converted into manganese trioxide.

[0068] Oxygen supply: During the heating and roasting process, the oxygen flow rate is controlled by an oxygen flow meter to maintain the oxygen concentration in the roasting system between 23% to ensure that the oxidation conditions meet the requirements of manganese trioxide.

[0069] Stirring and flipping: During the roasting process, the stirring function of the muffle furnace was used to manually stir and turn the manganese oxalate powder every 45 minutes to ensure that the powder was evenly heated and to avoid agglomeration.

[0070] Product Collection: The calcined manganese trioxide is taken out of the calciner and cooled to room temperature. The possible metal impurities are removed by magnetic separation, and the trace impurities are further removed by high-efficiency filters. The final product is tested to ensure that its purity meets the standard of battery-grade manganese trioxide, and the impurity content is less than 0.01%.

[0071] Through the above specific embodiments, the method of the present invention effectively prepares battery-grade manganese trioxide with high purity and uniform particle size, which meets the requirements of high-performance battery materials.

[0072] The battery-grade manganese trioxide produced by the method of the present invention has the following remarkable properties and characteristics: High chemical purity: After strict calcination and purification treatment, the manganese trioxide prepared by this method has high purity. The impurity content in the product is extremely low, meeting the high standards of battery-grade materials. This high-purity manganese trioxide has more stable and reliable performance in battery materials.

[0073] Excellent physical properties: This battery-grade manganese trioxide is in a fine powder form with uniform particle size, mainly concentrated between 50-100 microns. This uniform particle size distribution helps to improve the conductivity and reaction efficiency of battery materials and enhance the overall performance of the battery.

[0074] Good structural stability: Through staged heating and calcination, the crystal structure of manganese trioxide has been effectively optimized. The product has good structural stability, can maintain excellent performance during the charge and discharge cycle, and reduce battery degradation and loss.

[0075] Excellent electrochemical performance: Due to its high purity and uniform particle size distribution, this manganese trioxide exhibits excellent electrochemical performance. Its application in lithium-ion batteries can provide high capacity, high energy density and long cycle life, meeting the requirements of high-performance batteries.

[0076] Low specific surface area: After fine processing, manganese trioxide has a moderate specific surface area, which is of great significance for the application of battery materials. The lower specific surface area helps to reduce unnecessary surface reactions and reduce the self-discharge rate of the battery.

[0077] Excellent thermal stability: The manganese trioxide produced by this method maintains good thermal stability under high temperature conditions. Its thermal stability enables it to maintain stable performance under high temperature environments and is suitable for battery applications in various environments.

[0078] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing battery-grade manganese trioxide, characterized in that: The following steps are involved: Raw material preparation, selecting and preparing sulfate system manganese oxalate as raw material; Dehydration treatment: dehydration treatment is performed on manganese oxalate to ensure that the water inside is completely removed; In preparation for roasting, the dehydrated manganese oxalate is crushed into powder; Stage heating, gradually heating the manganese oxalate powder in stages until the preset roasting temperature is reached, and then roasting the heated manganese oxalate powder; Oxygen supply: oxygen is continuously introduced during heating and roasting to ensure oxidation conditions; Stirring and turning: During the roasting process, stir and turn the manganese oxalate continuously or periodically to keep it in a powder state; Product collection: collect the calcined manganese trioxide to obtain battery-grade manganese trioxide.

2. The method for preparing battery-grade manganese trioxide according to claim 1, characterized in that: The preparation of the sulfate system manganese oxalate comprises the following steps: The preparation of manganese suspension is to grind the metal manganese flakes into powder, ensuring that the mesh size is greater than 100 mesh, and then mix the manganese powder with water to prepare a uniform manganese suspension; Preparation of manganese sulfate solution: adding sulfuric acid to manganese suspension to prepare manganese sulfate solution, wherein the manganese content is controlled at 40-150g / L; an impurity removal step, adding manganese powder as an impurity remover to the manganese sulfate solution, heating the solution to 60-80° C., stirring at a speed of 220-260 rpm for 30-60 minutes, filtering the precipitate, and allowing the solution to return to room temperature; Prepare a mixed solution by double decomposition reaction, add oxalic acid to the manganese sulfate solution, and control the mass ratio of oxalic acid to manganese to be between 1:1 and 1.6; heat the mixed solution to 20-55° C. and keep reacting for 2-4 hours; Solid-liquid separation and washing: Use a filter press to separate the solid and liquid of the mixed liquid after the reaction to obtain a filter cake and a filtrate; then recover the filtrate and use it as a sulfuric acid raw material for preparing a manganese suspension, and then spray wash the filter cake, and set up N washing tanks, each tank containing a washing liquid; The washing liquid is recycled. The washing liquid is taken from the first washing tank to spray the filter cake, and then the washing liquid is recycled to the manganese sulfate solution preparation process; the washing liquid is taken from the second washing tank to spray the filter cake, and then the washing liquid is recycled to the first washing tank; and so on, until the washing liquid is taken from the Nth washing tank to spray the filter cake, and then the washing liquid is recycled to the N-1th washing tank; Drying and crushing: drying the filter cake after spray cleaning at 60-80°C for 2-4 hours; finally, crushing the dried filter cake into powder to obtain sulfate system manganese oxalate.

3. A method for preparing battery-grade manganese trioxide as claimed in claim 1 or 2, characterized in that: The dehydration treatment of manganese oxalate comprises the following steps: Place the sulfate system manganese oxalate in a drying oven; Control the drying oven temperature at 100-150°C and preheat at a constant temperature for 1-3 hours; During the drying process, maintain constant temperature and ventilation to ensure that the water in the manganese oxalate is completely removed until the manganese oxalate appears in a pink-white powder state.

4. A method for preparing battery-grade manganese trioxide as claimed in claim 1 or 2, characterized in that: The method of pulverizing the dehydrated manganese oxalate into powder comprises the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; Through the sieving operation, the particle size of the manganese oxalate powder is ensured to be between 50-100 microns for subsequent roasting treatment.

5. A method for preparing battery-grade manganese trioxide as claimed in claim 1 or 2, characterized in that: The stepwise heating of the manganese oxalate powder comprises the following steps: The manganese oxalate powder is placed in a muffle furnace, a high temperature furnace or a rotary calciner; The first stage: heating at 1-150℃ for 20 minutes to ensure that the manganese oxalate powder is evenly heated; The second stage: heating at 150-300℃ for 30-60 minutes to further remove residual moisture and volatile substances; Final stage: Continue to raise the temperature to 490-510°C and roast for 3-5 hours to ensure that the manganese oxalate powder is completely roasted.

6. A method for preparing battery-grade manganese trioxide as claimed in claim 1 or 2, characterized in that: The oxygen supply is to control the oxygen flow rate through an oxygen flow meter during the heating and roasting process to ensure a stable oxygen supply and maintain the oxygen concentration in the roasting system between 21% and 25% to meet the oxidation conditions of manganese trioxide.

7. A method for preparing battery-grade manganese trioxide according to claim 1 or 2, characterized in that: The stirring and turning, when using a rotary calcining furnace for roasting, utilizes its inherent stirring function to make the manganese oxalate powder turn evenly; When a muffle furnace or a high temperature furnace is used for roasting, the manganese oxalate powder is manually or mechanically stirred and turned every 30-60 minutes to ensure that it is always kept in a powder state for oxidation.

8. A method for preparing battery-grade manganese trioxide as claimed in claim 1 or 2, characterized in that: The product collection comprises the following steps: The calcined manganese trioxide is taken out from the calcining furnace and cooled to room temperature; Remove possible metal impurities through magnetic separation, flotation or pickling; Use high-efficiency filters to further remove trace impurities to obtain manganese trioxide with high purity and low impurity content; The final product is tested to ensure it meets the purity and quality standards for battery-grade manganese trioxide.

9. The method for preparing battery-grade manganese trioxide according to claim 4, characterized in that: The dehydrated manganese oxalate is broken into powder, and the particle size of the manganese oxalate powder is ensured to be between 50 and 100 microns by sieving so as to facilitate subsequent calcination treatment, which specifically includes the following steps: Use a grinder or pulverizer to break the dehydrated manganese oxalate into a uniform powder; The powder is sieved through a sieve with an aperture of 50-100 microns; The manganese oxalate powder that passes through the sieve, i.e., the particle size is between 50-100 microns, is collected and prepared for roasting; For the larger particles of manganese oxalate powder that do not pass through the sieve, perform the following treatment: The powder that does not pass through the screen is sent back to the grinder or pulverizer for secondary grinding; after grinding, the powder is screened again until the powder particle size reaches the requirement between 50-100 microns; the grinding and screening operations are repeated until all manganese oxalate powder meets the particle size requirements; The over-fine powder produced during the screening process, i.e., the particle size is less than 50 microns, is re-ground together with the larger particles of manganese oxalate powder that have not passed through the sieve through a mixing operation to ensure that the overall powder particle size is uniform.