Preparation method of manganous-manganic oxide with controllable tap density

Abstract

The invention belongs to the technical field of battery material preparation, discloses a preparation method of manganous-manganic oxide with controllable tap density, and aims to solve the problem that a manganous-manganic oxide preparation process in the prior art is difficult to effectively control the tap density of a product, and provides a preparation method of manganous-manganic oxide with controllable tap density based on deep research on growth characteristics of manganous-manganic oxide crystal particles. By optimizing process parameters and regulating and controlling behaviors of the particles in different growth stages, accurate prediction and accurate control of the tap density of the product are successfully realized. On the basis, the process conditions are further optimized, the controllability of the tap density of the product is ensured, the high-tap-density manganous-manganic oxide material is successfully prepared, and important guidance and practical reference are provided for controllable synthesis of battery-grade manganous-manganic oxide. In addition, according to the technology, the preparation process is simplified, the operation difficulty and energy consumption are reduced, and the obvious industrial application potential and industrialization value are achieved.

Description

Technical Field

[0001] The present invention relates to the preparation of battery materials, in particular to a method for preparing manganese manganese tetroxide in a short process, belonging to the technical field of battery material preparation. Background Art

[0002] With the rapid development of new energy vehicles and energy storage technologies, market demands for increasingly advanced battery performance are particularly pressing, particularly in terms of energy density, cycle stability, and rate capability. Manganese-based electrode materials are highly sought after due to their significant advantages, including high energy density, low cost, and non-toxicity. Among common manganese-based electrode materials, such as lithium manganate and lithium iron manganese phosphate, the manganese source primarily relies on electrolytic manganese dioxide (MnO2). However, electrolytic manganese dioxide is not only expensive to prepare but also prone to the introduction of impurities such as sulfur, sodium, and magnetic substances during the preparation process, which can adversely affect material performance. In contrast, using manganese tetraoxide (Mn3O4) as a manganese source not only significantly reduces material cost but also effectively reduces impurity content, thereby improving battery discharge capacity and cycle performance.

[0003] Manganese oxide materials with higher tap density can not only significantly improve the energy density and volumetric capacity of the battery, but also help improve the cycle stability and rate performance of the battery. However, the current mainstream methods for preparing manganese oxide are mainly solid-phase and liquid-phase methods, and these methods still face many challenges in practical applications. First, the solid-phase method usually requires calcination under high-temperature conditions, which easily leads to coarsening of the product particles, making it difficult to effectively control the tap density; secondly, although the liquid-phase method can prepare nano-scale particles, its process flow is relatively complicated, the cost is high, and the tap density stability of the product is poor; in addition, the existing preparation methods have limited means of regulating the tap density of manganese oxide, making it difficult to meet the needs of high-performance battery materials. Summary of the Invention

[0004] In response to the problem that it is difficult to effectively control the tap density of the product in the existing preparation process of manganese tetraoxide, the present invention provides a preparation method of manganese tetraoxide with controllable tap density. By studying the relationship between the change in pH value during the reaction of a manganese salt solution and an ammonia solution and the tap density of the target product, a prediction model for the tap density of the product and a pH control model are proposed. According to the guidance of the two models, the reaction process is intervened in a timely manner, and the production system of manganese tetraoxide products reaches the target tap density requirements.

[0005] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows: A method for preparing manganese manganese tetroxide with controllable tap density, the method comprising the following steps: S1: Under the condition of introducing oxidizing gas, a manganese salt solution and an ammonia solution are added to the reaction base liquid to carry out an initial reaction.

[0006] S2: After the initial reaction is completed, the pH of the current reaction system is detected in real time, and a prediction model for the tap density of the product is established based on the real-time pH of the current reaction system. If the predicted tap density of the product calculated according to the prediction model meets the target tap density requirement, the current operating conditions are maintained unchanged and the later reaction is continued. If the predicted tap density of the product calculated according to the prediction model does not meet the target tap density requirement, step S3 is performed.

[0007] It should be noted that the predicted tap density meeting the target tap density requirement means that the error between the predicted tap density and the target tap density is within 0.05 g / cm 3 Otherwise, the predicted tap density does not meet the target tap density requirement.

[0008] S3: A pH control model for the later reaction is established based on the target tap density of the product, and the target pH of the reaction system during the later reaction is calculated based on the pH control model. During the later reaction, the addition rate of the ammonia solution is adjusted so that the pH of the reaction system during the later reaction meets the target pH.

[0009] S4: After the end of the late reaction, the addition rate of the ammonia solution is adjusted so that the ammonia-manganese ratio of the raw materials added per unit time is 2±0.05 (preferably 2±0.03) and a fixed ratio reaction is carried out. After the fixed ratio reaction is completed, the addition of the manganese salt solution and the ammonia solution is stopped and an aging treatment is carried out. After the aging treatment is completed, a solid product is obtained by solid-liquid separation. The obtained solid product is washed and dried in sequence to obtain the target manganese tetraoxide.

[0010] Preferably, in step S2, the prediction model is: Y D =0.5045A1-C1 (1).

[0011] In formula (1), Y D is the predicted tap density of manganese dioxide, g / cm 3 A1 is the measured pH value of the reaction system after the initial reaction. C1 is the prediction constant, ranging from 1.41 to 1.45.

[0012] Preferably, in step S3, the pH control model is: A2=(T D +C2) / 0.332 (2).

[0013] In formula (1), A2 is the target pH value of the reaction system in the later stage of the reaction. DThe target tap density of manganese dioxide is 2~2.7g / cm 3 C2 is the adjustment constant, and its value ranges from 0.10 to 0.13.

[0014] It should be noted that all formulas and / or calculation models in the present invention are obtained by fitting by the inventors based on experiments and engineering applications, and all calculations are numerical values converted according to prescribed units, and are obtained by substituting the converted numerical values into the formulas (after converting the units, only the numerical values are substituted into the formulas for calculation, without substituting the units, and the units are only used to adjust the size of the numerical values).

[0015] Preferably, in step S1, the oxidizing gas is oxygen-rich gas.

[0016] Preferably, the oxygen volume concentration of the oxygen-rich gas is not less than 20% (for example, air can be used), preferably the oxygen volume concentration of the oxygen-rich gas is not less than 40%, and more preferably the oxygen volume concentration of the oxygen-rich gas is not less than 60%.

[0017] Preferably, the flow rate of the oxidizing gas is 0.3-2 L / min, preferably 0.5-1.8 L / min, and more preferably 0.8-1.2 L / min. It should be noted that the oxidizing gas must be continuously introduced throughout the reaction process to ensure that the reaction system is always in an oxidizing atmosphere.

[0018] Preferably, in step S1, the manganese salt solution is one or more of manganese sulfate solution, manganese chloride solution, manganese nitrate solution, and manganese acetate solution, preferably manganese sulfate solution.

[0019] It should be noted that the manganese salt solutions used are prepared by mixing a soluble manganese salt with deionized water in a certain ratio. The ammonia solution used is prepared by adding a certain proportion of deionized water to concentrated ammonia water. Wherein, soluble manganese salts include but are not limited to manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, etc., and their respective hydrates should also be included. For example, manganese sulfate includes anhydrous manganese sulfate, manganese sulfate monohydrate, manganese sulfate tetrahydrate, and hydrated manganese sulfates of other water contents.

[0020] Preferably, in step S1, the reaction base liquid is deionized water.

[0021] Preferably, in step S1, the concentration of the manganese salt solution is 1 to 4 mol / L, preferably 1.2 to 3 mol / L, more preferably 1.5 to 2 mol / L. The addition rate of the manganese salt solution is 0.2 to 2 mL / min, preferably 0.3 to 1.5 mL / min, more preferably 0.5 to 1.2 mL / min.

[0022] Preferably, in step S1, the concentration of the ammonia solution is 1.5 to 6 mol / L, preferably 1.8 to 5 mol / L, more preferably 2.5 to 4 mol / L. The rate of addition of the ammonia solution is 0.4 to 4 mL / min, preferably 0.6 to 3 mL / min, more preferably 1 to 2.4 mL / min.

[0023] Preferably, in step S1 and step S2, the temperature of the initial reaction and the later reaction is 40-90° C., preferably 50-85° C., more preferably 60-80° C. The duration of the initial reaction and the later reaction is 1-6 hours, preferably 1.5-5 hours, more preferably 2-4 hours.

[0024] Preferably, in step S4, the temperature of the fixed ratio reaction is 40-90° C., preferably 50-85° C., more preferably 60-80° C. The duration of the fixed ratio reaction is 4-20 h, preferably 5-15 h, more preferably 6-10 h.

[0025] Preferably, the initial reaction, the later reaction and the fixed ratio reaction are all stirred reactions, and the stirring rate is not less than 500 r / min, preferably 600-800 r / min.

[0026] Preferably, the aging treatment lasts no longer than 5 hours, preferably 1 to 4 hours, and the stirring rate during the aging treatment does not exceed 300 rpm, preferably 80 to 200 rpm.

[0027] Preferably, the solid-liquid separation is performed by either normal pressure filtration or reduced pressure filtration. The washing is performed multiple times (preferably 2-3 times) with deionized water. The drying is performed by oven drying (e.g., in an oven at 50-80°C for 0.5-12 hours).

[0028] Preferably, the manganese salt solution and the ammonia solution are preheated independently before being added to the reaction base solution for reaction. Preferably, the temperature of the manganese salt solution and the ammonia solution after preheating is consistent with the reaction temperature.

[0029] In the present invention, an oxidizing gas (e.g., pure oxygen) is used as the oxidant. After the reaction base liquid is heated to a predetermined reaction temperature, the oxidizing gas is introduced while stirring. By filling the reactor with a sufficient amount of oxidizing gas, the purpose of preparing manganese tetraoxide in a single step is achieved. The main reactions occurring during the preparation process are as follows: 6Mn 2+ +O2+12NH3·H2O=2Mn3O4+12NH4 + +6H2O.

[0030] During the reaction, Mn 2+Under the action of oxidant, Mn3O4 and H + , the generated H + It will lower the pH value of the system, making it difficult for the reaction to continue. Therefore, it is necessary to introduce an appropriate amount of base to neutralize the generated H + , to ensure the reaction proceeds. That is, ammonia water has two main functions in the system. One is to neutralize the H generated in the solution. + , to avoid the system pH from continuously decreasing, affecting the product phase and reaction rate, and secondly, with Mn 2+ Coordinate to form complexes and regulate the system Mn 2+ In the present invention, by accurately controlling the amount of ammonia solution introduced at different stages of the reaction according to the target tap density of the product, the product morphology and particle size distribution can be improved, thereby achieving the regulation of the tap density of the product. In this method, by controlling the appropriate reaction conditions to make Mn 2+ It is directly oxidized to Mn3O4 with a tap density that meets the working conditions. This method has a short process and simple operation. The resulting product has a uniform particle size distribution, a high tap density that can be stably controlled, and a uniform and good product morphology with very little impurity content.

[0031] In the present invention, in the process of preparing battery-grade manganese tetraoxide by a one-step oxidation method, the formation of Mn3O4 particles follows the processes of nucleation, growth, agglomeration, and agglomeration. Nucleation is the process in which crystals precipitate from the liquid phase, and the growth process is the process in which the formed nuclei grow into primary particles. Nucleation and growth are in a relationship of mutual growth and decline, and are also the key to improving particle size distribution and morphology, as well as the key to regulating the tap density of the product. In the initial stage of reacting a manganese salt solution with an aqueous ammonia solution, the nucleation process of the Mn3O4 particles generally occurs, and after the initial reaction, the particle size begins to grow. Through research, it was found that in the process of particle size growth, the change in pH has a decisive influence on the characteristics of the final product morphology. Therefore, after a large number of targeted practical studies, the inventor team summarized and found that there is a close relationship between the pH of the system and the final tap density of the product in the process of particle size growth, and further established a prediction model for the tap density of the product: Y D =0.5045A1-C1 (1).

[0032] In formula (1), Y D is the predicted tap density of manganese dioxide, g / cm 3. A1 is the measured pH value of the current reaction system after the initial reaction is completed. C1 is a prediction constant, which ranges from 1.41 to 1.45. Through the prediction model of formula (1), the predicted tap density of the product can be calculated based on the actual pH value of the system after the initial reaction is completed, thereby providing technical support for human intervention and regulation to obtain products with expected tap density. Generally speaking, if the predicted tap density of the product meets the target tap density requirements of the product, there is no need for human intervention and adjustment. The current process conditions are maintained unchanged to continue to complete the later reaction, and then a fixed ratio reaction and aging treatment are carried out to obtain a solid product that meets the expectations.

[0033] Furthermore, if the predicted tap density of the product does not meet the target tap density requirements of the product, manual intervention adjustment is required. After practical research, it was found that by adjusting the pH of the reaction system in the later reaction, a manganese oxide product that meets the target tap density requirements can be obtained, and further a pH control model for the later reaction is established according to the target tap density requirements of the product: A2=(T D +C2) / 0.332 (2).

[0034] In formula (1), A2 is the target pH value of the reaction system in the later stage of the reaction. D The target tap density of manganese dioxide is 2~3g / cm 3 C2 is the adjustment constant, which ranges from 0.10 to 0.13. The pH control model of formula (2) can provide technical support for preparing products with the expected tap density through human intervention in the later reaction when the actual pH value of the system after the initial reaction does not meet the working conditions of the prediction model.

[0035] In the present invention, it is found through research that, during the entire reaction process, increasing the pH of the reaction within a certain range (i.e., increasing the amount of ammonia water used per unit time) is beneficial to increasing the tap density of the product, but the pH should not be too high. After experimental verification, when the amount of ammonia water is increased to raise the pH to 9 or even higher, the tap density of the product not only decreases, but also other substances such as MnOOH are found through XRD analysis. The impurity phase, that is, the excessively high pH increases the redox potential of the system, which may cause excessive oxidation of manganese. In addition, in addition to requiring a higher tap density, battery-grade manganese dioxide also has certain requirements on particle size. This is because a larger particle size will prolong the Li +migration path, thereby reducing the battery capacity. However, although the tap density can be increased to a certain extent by increasing the amount of ammonia water, the particle size of the product also gradually increases. Therefore, by regulating the pH within a suitable range, the optimal tap density-particle size ratio can be achieved, thereby optimizing the performance of the battery. Therefore, in the present invention, in the early reaction process, the addition rate of the ammonia solution needs to make the pH of the reaction system maintain between 6.5 and 8.5 (preferably 7 to 8) (that is, A1 is controlled between 6.5 and 8.5 (preferably 7 to 8)). In the later reaction process, adjustments are made based on the actual working conditions on the basis of the early reaction, and generally it should be controlled between 6.5 and 8.5.

[0036] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1: Based on an in-depth study of the growth characteristics of manganese tetraoxide crystal particles, this invention successfully achieved accurate prediction and precise control of the product tap density by optimizing process parameters and regulating the behavior of particles at different growth stages. On this basis, the present invention further optimized process conditions, not only ensuring the controllability of the product tap density, but also successfully preparing manganese tetraoxide materials with high tap density, providing important guidance and practical reference for the controllable synthesis of battery-grade manganese tetraoxide.

[0037] 2: The one-step process employed in this invention not only greatly simplifies the preparation process but also significantly reduces operational complexity and energy consumption. This method has significant industrial application potential and provides a new solution for the efficient and low-cost preparation of battery-grade manganese dioxide products, with important industrial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an SEM image of manganese tetraoxide prepared in Example 1 of the present invention.

[0039] Figure 2 This is the SEM image of manganese tetraoxide prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments. Example 1

[0041] Preparation of manganese tetraoxide product with a tap density of 2.40 g / cm³: the proposed reaction temperature is 70°C, the stirring rate is 700 r / min, the initial reaction time is 3 h, the later reaction time is 3 h, and the fixed ratio reaction time is 5 h.

[0042] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0043] Under the current operating conditions, the predicted constant C1 is 1.4380, and the adjustment constant C2 is 0.1067. Monitoring shows that the pH value of the reaction system is 7.33 after the completion of the early reaction. According to formula (1), the predicted tap density of manganese tetraoxide is about 2.26g / cm³, which does not meet the requirement of (2.40±0.05)g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 7.55.

[0044] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 7.55, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.38 g / cm³. Example 2

[0045] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0046] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0047] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.31. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0048] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.55 g / cm³. Example 3

[0049] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0050] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 0.84 mL / min for preliminary reaction.

[0051] Under the current operating conditions, the predicted constant C1 is 1.4220, the adjustment constant C2 is 0.1061, and the pH value of the reaction system after the early reaction is 7.12. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.17 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0052] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.56 g / cm³. Example 4

[0053] Preparation of manganese tetraoxide product with a tap density of 2.20 g / cm³: the proposed reaction temperature is 70°C, the stirring rate is 700 r / min, the initial reaction time is 3 h, the later reaction time is 3 h, and the fixed ratio reaction time is 5 h.

[0054] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.68 mL / min for preliminary reaction.

[0055] Under the current operating conditions, the predicted constant C1 is 1.4299, the adjustment constant C2 is 0.1073, and the pH value of the reaction system after the early reaction is 7.83. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.52 g / cm³, which does not meet the requirement of (2.20 ± 0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 6.95.

[0056] The ammonia solution pumping rate was then reduced to stabilize the pH of the reaction system at 6.95, and the post-reaction phase was carried out under these conditions. After the post-reaction phase, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.22 g / cm³. Example 5

[0057] Preparation of manganese tetraoxide product with a tap density of 2.70 g / cm³: the proposed reaction temperature is 70°C, the stirring rate is 700 r / min, the initial reaction time is 3 h, the later reaction time is 3 h, and the fixed ratio reaction time is 5 h.

[0058] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.68 mL / min for preliminary reaction.

[0059] Under the current operating conditions, the predicted constant C1 is 1.4285, the adjustment constant C2 is 0.1087, and the pH value of the reaction system after the early reaction is 7.80. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.51 g / cm³, which does not meet the requirement of (2.70 ± 0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.46.

[0060] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.46, and the post-reaction phase was carried out under these conditions. After the post-reaction phase, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.71 g / cm³. Example 6

[0061] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 60℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0062] 2 L of deionized water was added to the reactor, the temperature was raised to 60°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0063] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.31. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0064] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.51 g / cm³. Example 7

[0065] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 80℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0066] 2 L of deionized water was added to the reactor, the temperature was raised to 80°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0067] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.31. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0068] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the products were filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.59 g / cm³. Example 8

[0069] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0070] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 0.8 mL / min for preliminary reaction.

[0071] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.08. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.15 g / cm³, which does not meet the requirement of (2.55 ± 0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0072] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.53 g / cm³. Example 9

[0073] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0074] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.6 mL / min for preliminary reaction.

[0075] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.75. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.48 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0076] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.56 g / cm³. Example 10

[0077] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0078] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.7 mL / min for preliminary reaction.

[0079] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the initial reaction is 7.84. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.53 g / cm³, which meets the requirement of (2.55 ± 0.05) g / cm³. Therefore, there is no need to adjust the ammonia flow rate in the later reaction.

[0080] After the late-stage reaction, the ammonia solution flow rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution flow rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, washed with deionized water, and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.54 g / cm³. Example 11

[0081] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0082] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 0.6 mL / min for preliminary reaction.

[0083] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 6.5. According to formula (1), the predicted tap density of manganese tetraoxide is about 1.85 g / cm³, which does not meet the requirement of (2.55 ± 0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0084] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.47 g / cm³. Example 12

[0085] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0086] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 0.5 mL / min for preliminary reaction.

[0087] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 6.00. According to formula (1), the predicted tap density of manganese tetraoxide is about 1.60 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0088] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.43 g / cm³. Example 13

[0089] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0090] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.7 mL / min for preliminary reaction.

[0091] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 8.10. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.66 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0092] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.48 g / cm³. Example 14

[0093] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0094] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, a 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and a 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.8 mL / min for preliminary reaction.

[0095] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 8.51. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.87 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0096] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.8 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the products were filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.44 g / cm³. Comparative Example 1

[0097] Preparation of manganese tetraoxide product with a tap density of 2.40 g / cm³: the proposed reaction temperature is 70°C, the stirring rate is 700 r / min, the initial reaction time is 3 h, the later reaction time is 3 h, and the fixed ratio reaction time is 5 h.

[0098] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0099] Under the current working conditions, the predicted constant C1 is 1.4380. After the early reaction, the pH value of the reaction system is 7.33. According to formula (1), the predicted tap density of manganese tetraoxide is about 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. The current working conditions are maintained unchanged and the later reaction is continued.

[0100] After the late-stage reaction, the ammonia solution flow rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution flow rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.28 g / cm³. Comparative Example 2

[0101] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0102] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 0.84 mL / min for preliminary reaction.

[0103] Under the current working conditions, the predicted constant C1 is 1.4257. After the early reaction, the pH value of the reaction system is 7.10. According to formula (1), the predicted tap density of manganese tetraoxide is about 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. The current working conditions are maintained unchanged and the later reaction is continued.

[0104] After the late-stage reaction, the ammonia solution flow rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution flow rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.16 g / cm³. Comparative Example 3

[0105] Preparation of manganese tetraoxide product with a tap density of 2.70 g / cm³: the proposed reaction temperature is 70°C, the stirring rate is 700 r / min, the initial reaction time is 3 h, the later reaction time is 3 h, and the fixed ratio reaction time is 5 h.

[0106] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1.68 mL / min for preliminary reaction.

[0107] Under the current working conditions, the predicted constant C1 is 1.4285. After the early reaction, the pH value of the reaction system is 7.85. According to formula (1), the predicted tap density of manganese tetraoxide is about 2.51 g / cm³, which does not meet the requirement of (2.70±0.05) g / cm³. The current working conditions are maintained unchanged and the later reaction is continued.

[0108] After the late-stage reaction, the ammonia solution flow rate was adjusted to achieve an ammonia-to-manganese ratio of 2 per unit time (i.e., the ammonia solution flow rate should be adjusted to 0.8 mL / min), and then a constant-ratio reaction was carried out. After the constant-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, washed with deionized water, and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.54 g / cm³. Comparative Example 4

[0109] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0110] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0111] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.31. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0112] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 2.1 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.84 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the product was filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.46 g / cm³. Comparative Example 5

[0113] Preparation of manganese tetraoxide product with a tap density of 2.55g / cm³: the proposed reaction temperature is 70℃, the stirring rate is 700r / min, the initial reaction time is 3h, the later reaction time is 3h, and the fixed ratio reaction time is 5h.

[0114] 2 L of deionized water was added to the reactor, the temperature was raised to 70°C, and oxygen with a volume concentration of 60% was introduced at a flow rate of 1 L / min. Then, under stirring conditions at a speed of 700 r / min, 1.5 mol / L manganese sulfate solution was pumped into the reactor at a rate of 0.8 mL / min, and at the same time, 3 mol / L ammonia solution was pumped into the reactor at a rate of 1 mL / min for preliminary reaction.

[0115] Under the current operating conditions, the predicted constant C1 is 1.4257, the adjustment constant C2 is 0.1071, and the pH value of the reaction system after the early reaction is 7.31. According to formula (1), the predicted tap density of manganese tetraoxide is approximately 2.26 g / cm³, which does not meet the requirement of (2.55±0.05) g / cm³. Therefore, according to formula (2), the pH of the reaction system during the later reaction should be 8.0.

[0116] The ammonia solution pumping rate was then increased to stabilize the pH of the reaction system at 8.0, and the post-reaction was carried out under these conditions. After the post-reaction was completed, the ammonia solution pumping rate was adjusted to achieve an ammonia-to-manganese ratio of 1.9 per unit time (i.e., the ammonia solution pumping rate should be adjusted to 0.76 mL / min), and then a fixed-ratio reaction was carried out. After the fixed-ratio reaction was completed, the manganese sulfate solution and ammonia solution were stopped, and the stirring rate was reduced to 100 r / min for 4 hours of aging. After the aging treatment, the products were filtered to obtain a solid product, which was then washed with deionized water and finally dried to obtain a manganese tetraoxide product with a tap density of approximately 2.42 g / cm³.

Claims

1. A method for preparing manganese manganese tetroxide with controllable tap density, characterized in that: The method comprises the following steps: S1: Under the condition of introducing oxidizing gas, adding manganese salt solution and ammonia solution to the reaction base solution to carry out the initial reaction; S2: After the initial reaction is completed, the pH of the current reaction system is detected in real time, and a prediction model for the tap density of the product is established based on the real-time pH of the current reaction system; if the predicted tap density of the product calculated according to the prediction model meets the target tap density requirement, the current operating conditions are maintained unchanged and the subsequent reaction is continued; if the predicted tap density of the product calculated according to the prediction model does not meet the target tap density requirement, step S3 is performed; S3: establishing a pH control model for the later reaction based on the target tap density requirement of the product, and calculating the target pH of the reaction system during the later reaction based on the pH control model; during the later reaction, adjusting the addition rate of the ammonia solution so that the pH of the reaction system during the later reaction meets the target pH; S4: After the end of the late reaction, the addition rate of the ammonia solution is adjusted so that the ammonia-manganese ratio of the raw materials added per unit time is 2±0.05 and a fixed ratio reaction is carried out. After the fixed ratio reaction is completed, the addition of the manganese salt solution and the ammonia solution is stopped and an aging treatment is carried out. After the aging treatment is completed, a solid product is obtained by solid-liquid separation. The obtained solid product is washed and dried in sequence to obtain the target manganese tetraoxide.

2. The preparation method according to claim 1, wherein: In step S2, the prediction model is: AND D =0.5045A1-C1 (1); In formula (1), Y D is the predicted tap density of manganese dioxide, g / cm 3 ; A1 is the measured pH value of the current reaction system after the initial reaction is completed; C1 is the prediction constant, which ranges from 1.41 to 1.

45.

3. The preparation method according to claim 1 or 2, characterized in that: In step S3, the pH control model is: A2=(T D +C2) / 0.332 (2); In formula (1), A2 is the target pH value of the reaction system in the later stage of the reaction; T D The target tap density of manganese dioxide is 2~3g / cm 3 ; C2 is the adjustment constant, and its value ranges from 0.10 to 0.

13.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step S1, the oxidizing gas is oxygen-rich gas; Preferably, the oxygen volume concentration of the oxygen-rich gas is not less than 20%, preferably the oxygen volume concentration of the oxygen-rich gas is not less than 40%, and more preferably the oxygen volume concentration of the oxygen-rich gas is not less than 60%.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In step S1, the manganese salt solution is one or more of manganese sulfate solution, manganese chloride solution, manganese nitrate solution, and manganese acetate solution, preferably manganese sulfate solution; and / or In step S1, the reaction base liquid is deionized water.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step S1, the concentration of the manganese salt solution is 1-4 mol / L, preferably 1.2-3 mol / L, more preferably 1.5-2 mol / L; the addition rate of the manganese salt solution is 0.2-2 mL / min, preferably 0.3-1.5 mL / min, more preferably 0.5-1.2 mL / min.

7. The preparation method according to any one of claims 1 to 6, characterized in that: In step S1, the concentration of the ammonia solution is 1.5-6 mol / L, preferably 1.8-5 mol / L, more preferably 2.5-4 mol / L; the addition rate of the ammonia solution is 0.4-4 mL / min, preferably 0.6-3 mL / min, more preferably 1-2.4 mL / min.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In step S1 and step S2, the temperature of the initial reaction and the later reaction is 40~90°C, preferably 50~85°C, more preferably 60~80°C; the duration of the initial reaction and the later reaction is 1~6h, preferably 1.5~5h, more preferably 2~4h.

9. The preparation method according to any one of claims 1 to 8, characterized in that: In step S4, the temperature of the fixed ratio reaction is 40-90° C., preferably 50-85° C., more preferably 60-80° C.; the duration of the fixed ratio reaction is 4-20 h, preferably 5-15 h, more preferably 6-10 h.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The initial reaction, the later reaction and the fixed ratio reaction are all stirred reactions, and the stirring rate is not less than 500 r / min, preferably 600-800 r / min; and / or The duration of the aging treatment does not exceed 5 hours, preferably 1 to 4 hours; the stirring rate during the aging treatment does not exceed 300 r / min, preferably 80 to 200 r / min.

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