Preparation method of trimanganese tetraoxide using recycled manganese liquid as raw material

Abstract

The application relates to the technical field of trimanganese tetraoxide preparation, in particular to a trimanganese tetraoxide preparation method taking recovered manganese liquid as raw material, which comprises the following steps: in the process of preparing trimanganese tetraoxide by adopting a manganese salt primary oxidation method and taking recovered manganese liquid as raw material in a reaction kettle, the possibility of particle agglomeration caused by uneven mixing of solutes in a reaction solution is evaluated; the significance of the particle agglomeration phenomenon is measured; the stirring speed of the reaction solution in the reaction kettle is adjusted in real time; after reaction, trimanganese tetraoxide suspension sediment is obtained, then the trimanganese tetraoxide suspension sediment is washed, dried and packaged to obtain a trimanganese tetraoxide product. The application aims to accurately measure the significant degree of particle agglomeration when solutes are unevenly mixed, so as to control and adjust the stirring speed in the process of preparing trimanganese tetraoxide, and improve the preparation quality of the trimanganese tetraoxide product.

Description

A method for preparing manganese tetroxide using recycled manganese liquid as raw material Technical Field

[0001] This application relates to the field of manganese tetroxide preparation technology, specifically to a method for preparing manganese tetroxide using recycled manganese liquid as raw material. Background Technology

[0002] With the rapid development of the new energy industry, the lithium battery industry is experiencing rapid growth. This growth has created a huge demand for basic materials such as lithium, nickel, cobalt, and manganese. As a key raw material for the preparation of lithium manganese oxide, manganese tetroxide (MTO) faces increasingly stringent requirements from the lithium battery industry regarding its crystal structure, morphology control, and tap density. Currently, to meet the requirements of low-carbon and environmentally friendly production, existing technologies use recycled manganese liquid from waste batteries as raw material to prepare MTO, enabling the recycling and reuse of waste batteries. However, during the preparation of MTO, its morphology and physicochemical properties continuously change. Therefore, to ensure the optimal morphology and physicochemical properties of MTO, it is necessary to adjust the process parameters during its preparation.

[0003] Currently, existing technologies use FTIR spectroscopy to collect infrared spectral data of the reaction solution in the reactor. This data is then used to analyze the uniformity of solute mixing in real time, allowing for control and adjustment of the stirring speed during manganese tetroxide preparation. This avoids uneven solute mixing due to excessively low stirring speed, or severe shear force problems due to excessively high stirring speed. However, because uneven solute mixing in the reaction solution easily leads to particle agglomeration, existing technologies do not accurately measure the degree of particle agglomeration caused by uneven solute mixing. This results in an inability to accurately control and adjust the stirring speed during manganese tetroxide preparation, affecting the quality of the prepared manganese tetroxide product. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for preparing manganese tetroxide using recycled manganese liquid as raw material, thereby resolving the existing issues.

[0005] The present application discloses a method for preparing manganese tetroxide using recycled manganese liquid as raw material, which adopts the following technical solution:

[0006] One embodiment of this application provides a method for preparing manganese tetroxide using recycled manganese liquid as raw material, the method comprising the following steps:

[0007] The prepared manganese recovery liquid is added to the mixing tank, and then a dispersant and surfactant are added to the mixing tank to obtain a manganese salt solution; an ammonia solution is stored in a storage tank; deionized water is added to the reactor as the base liquid and heated and stirred. After the temperature stabilizes, the manganese salt solution and the ammonia solution are sent to the reactor respectively, and a constant stirring speed is continued as the initial stirring speed.

[0008] Infrared spectral data of the reaction solution in the reactor are collected in real time at different measurement locations while the reaction solution in the reactor is stirred at the initial stirring speed.

[0009] The actual absorption peak points are extracted from the collected infrared spectral data, and the agglomeration assessment value is calculated based on the absorption accumulation degree and absorption peak position sequence of the infrared spectral data at different measurement locations. This value is used to assess the possibility that uneven mixing of solutes in the reaction solution leads to particle agglomeration.

[0010] By analyzing the increasing persistence of the aggregation assessment value over a short period of time, the aggregation significance is calculated to measure the significance of particle aggregation; the aggregation significance at the next collection time is predicted, and combined with the real-time set safety threshold, the stirring speed of the reaction solution in the reactor during the preparation of manganese tetroxide is adjusted in real time.

[0011] After the reaction is complete, a manganese tetroxide suspension is obtained, which is then washed, dried and packaged to obtain the manganese tetroxide product.

[0012] Preferably, the volume ratio of the recovered manganese solution, dispersant, surfactant, and ammonia solution is (1-2):(1-3):(1-5):(2-3).

[0013] Preferably, the dispersant is any one or a combination of sodium dodecyl sulfate, polyethylene glycol, dichloroethane, and sodium tartrate, and the surfactant is any one or a combination of stearic acid, sodium dioctyl succinate, and sodium dodecylbenzene sulfonate.

[0014] Preferably, the method for extracting the actual absorption peak point includes:

[0015] Obtain the peak and valley points in the infrared spectral data sequence at each measurement location at any acquisition time;

[0016] Cubic spline interpolation is performed on the infrared spectral data between the preceding and following valleys for each peak point to construct a characteristic peak sequence;

[0017] The abnormality of the characteristic peak sequence is calculated using permutation entropy, and the mean of the abnormality corresponding to all peak points is used as the judgment threshold. Peak points with abnormality less than the judgment threshold are regarded as absorption peak points.

[0018] Preferably, the aggregation assessment value is positively correlated with the difference between the maximum and minimum values ​​of the cumulative absorption of infrared spectral data at all measurement locations, and negatively correlated with the mean of the set similarity between the absorption peak position sequences of infrared spectral data at all measurement locations.

[0019] Preferably, the absorption accumulation of the infrared spectral data at the measurement location is the sum of the peak values ​​of all absorption peak points in the infrared spectral data at the measurement location.

[0020] Preferably, the clustering significance is positively correlated with the proportion of collection times that increase in a short period of time and the clustering evaluation value of the current collection time, and negatively correlated with the dispersion of the order of collection times that increase in a short period of time.

[0021] Preferably, the method for real-time adjustment of the stirring speed is as follows:

[0022] If the predicted aggregation significance at the next sampling time is greater than the aggregation significance at the current sampling time, then increase the stirring speed of the reaction solution.

[0023] Otherwise, if the aggregation significance at the current sampling time is less than or equal to the safety threshold at the current sampling time, the stirring speed of the reaction solution should be reduced.

[0024] Otherwise, maintain the current stirring speed.

[0025] Preferably, the stirring speed is adjusted within the range of 400–800 rpm / min, and the stirring speed is adjusted by ±(20,50) rpm / min in one operation; if the stirring speed after real-time adjustment exceeds the adjustment range, the current stirring speed is maintained unchanged.

[0026] Preferably, the initial stirring speed in the reactor is 600 rpm, the temperature control range of the bottom liquid in the reactor is 40–80℃, the reaction time is 12 hours, the volume ratio of the bottom liquid to the manganese salt solution is (0.6–1):1, and the oxidant is oxygen.

[0027] The beneficial effects of the above scheme are as follows:

[0028] (1) This invention analyzes the abruptness of the shape of false infrared absorption peaks, measures the degree of abnormality of absorbance changes in the characteristic peak sequence, and uses the judgment threshold method to accurately extract each absorption peak point in the infrared spectral data sequence, thereby more accurately reflecting the absorption peak characteristics of different solutes in the reaction solution on the infrared spectrum, and eliminating the adverse effects of false infrared absorption peaks on subsequent particle aggregation analysis.

[0029] (2) By analyzing the differences in the absorption degree and absorption peak position of various solutes on the infrared spectrum at different measurement positions, this invention can accurately measure the possibility of particle agglomeration when the solutes are not mixed evenly, thereby more clearly reflecting the changing characteristics of particle agglomeration in the reaction solution, which is beneficial to more accurately control and adjust the stirring speed in the preparation of manganese tetroxide.

[0030] (3) By analyzing the increasing persistence of agglomeration characteristics in the short time before the current collection time, this invention accurately measures the significance of particle agglomeration when the solute is not mixed evenly in the reaction solution. Then, it adopts a real-time prediction method to accurately control and adjust the stirring speed in the preparation of manganese tetroxide, so as to avoid the phenomenon of uneven mixing of solute in the reaction solution due to the stirring speed being too small, and at the same time, to avoid the serious shear force problem caused by the stirring speed being too large. Attached Figure Description

[0031] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a flowchart of a method for preparing manganese tetroxide using recycled manganese liquid as raw material provided in this application;

[0033] Figure 2 is a flowchart of a method for real-time adjustment of the stirring speed of the reaction solution in the reactor during the preparation of manganese tetroxide according to an embodiment of this application. Detailed Implementation

[0034] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method for preparing manganese tetroxide using recycled manganese liquid as raw material according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0036] The following describes in detail, with reference to the accompanying drawings, a specific scheme for preparing manganese tetroxide using recycled manganese liquid as raw material, as provided in this application.

[0037] This application provides a method for preparing manganese tetroxide using recycled manganese liquid as raw material. The preparation flow chart is shown in Figure 1, and the specific preparation process is as follows:

[0038] The prepared manganese recovery liquid is added to the mixing tank, and then a dispersant and surfactant are added to the mixing tank to obtain a manganese salt solution; an ammonia solution is stored in a storage tank; deionized water is added to the reactor as the base liquid and heated and stirred. After the temperature stabilizes, the manganese salt solution and the ammonia solution are sent to the reactor respectively, and a constant stirring speed is continued as the initial stirring speed.

[0039] While the reaction solution in the reactor is stirred at the initial stirring speed, the infrared spectral data of the reaction solution at different measurement positions in the reactor are analyzed, and the stirring speed of the reaction solution in the reactor is adjusted in real time during the preparation of manganese tetroxide.

[0040] After the reaction is complete, a manganese tetroxide suspension is obtained, which is then washed, dried and packaged to obtain the manganese tetroxide product.

[0041] Example 1

[0042] In industry, a purification process is often used to remove impurities from manganese-containing solutions recycled from waste batteries. After purification, a recovered manganese solution is obtained, which is a feed-grade manganese sulfate solution. Then, using the recovered manganese solution as raw material, manganese tetroxide is prepared by a one-step oxidation method with manganese salts.

[0043] Therefore, this invention obtains purified manganese liquid in a factory, uses the purified manganese liquid as raw material, and prepares manganese tetroxide using a one-step oxidation method with manganese salts. The process steps are as follows:

[0044] (1) Raw material preparation: First, prepare 1-2 mol / L of recovered manganese liquid and add it to the mixing tank. Then, add dispersant and surfactant to the mixing tank to obtain manganese salt solution. The amount of dispersant added is 1-3 g / L, and the amount of surfactant added is 1-5 g / L. At the same time, store 2-3 mol / L of ammonia solution in a clean, sealed storage tank that meets safety standards.

[0045] The volume ratio of the recovered manganese solution, dispersant, surfactant, and ammonia solution is (1-2):(1-3):(1-5):(2-3).

[0046] The dispersant may be any one or a combination of sodium dodecyl sulfate, polyethylene glycol, dichloroethane, and sodium tartrate, and the surfactant may be any one or a combination of stearic acid, sodium dioctyl succinate, and sodium dodecylbenzene sulfonate.

[0047] In this embodiment, the prepared manganese recovery solution is 1 mol / L, and the amount of dispersant and surfactant added to the mixing tank is 1 g / L and 1 g / L respectively. The ammonia solution is stored at 2 mol / L. The dispersant is sodium dodecyl sulfate, and the surfactant is sodium dioctyl succinate sulfonate.

[0048] (2) Oxidation reaction: Deionized water was added to the reactor as the base liquid, and the stirring and heating devices of the reactor were started to control the temperature of the base liquid to 40-80℃ and to stir at a constant stirring speed, which was adjusted within the range of 400-800 rpm / min. After the temperature stabilized, the manganese salt solution and ammonia solution were respectively sent to the reactor, and the stirring speed was continued at a constant initial speed. The stirring speed was adjusted in real time according to the actual reaction of the reaction solution in the reactor. The volume ratio of the base liquid to the manganese salt solution was controlled at (0.6-1):1. At the same time, oxygen was introduced into the reactor as an oxidant to carry out the oxidation reaction. The reaction time was 12h. After the reaction was completed, manganese tetroxide suspension was obtained.

[0049] In this embodiment, the temperature of the bottom liquid in the reactor is controlled to reach 40°C, and the preset initial stirring speed is 600 rpm / min. The volume ratio of the bottom liquid to the manganese salt solution is 1:1.

[0050] To more accurately control and adjust the stirring speed during the preparation of manganese tetroxide, this embodiment provides a flowchart of a method for real-time adjustment of the stirring speed of the reaction solution in the reactor during the preparation of manganese tetroxide. Please refer to Figure 2. The specific method for adjusting the stirring speed is as follows:

[0051] Step 1: While stirring the reaction solution in the reactor at the initial stirring speed, infrared spectral data at different measurement locations in the reaction solution in the reactor are acquired in real time.

[0052] In this embodiment, FTIR spectroscopy is used to collect infrared spectral data of the reaction solution in the reaction vessel.

[0053] Specifically, K fiber optic probes of an online in-situ FTIR REMSPEC infrared spectrometer are inserted into the reaction solution in the reactor. The infrared spectral data of K measurement locations in the reaction solution are acquired in real time using the fiber optic probes of the online in-situ FTIR REMSPEC infrared spectrometer. The K measurement locations are evenly distributed within the reactor.

[0054] In this embodiment, the number of fiber optic probes K is 6, and the acquisition time interval is 1 second. Infrared spectral data sequences can be obtained for each measurement location at each acquisition time. The data within these sequences are absorbance data within the infrared wavelength range, used to monitor local concentration fluctuations and light scattering baseline drift caused by particle aggregation due to solute mixing in the reaction solution.

[0055] Step 2: Extract the true absorption peak points from the collected infrared spectral data, and calculate the agglomeration assessment value based on the absorption accumulation degree and absorption peak sequence set of infrared spectral data at different measurement locations. This value is used to assess the possibility that uneven mixing of solutes in the reaction solution may lead to particle agglomeration.

[0056] Generally, uneven mixing of solutes in a reaction solution easily leads to particle agglomeration. However, current techniques lack the ability to accurately measure the degree of particle agglomeration caused by uneven solute mixing, making it impossible to accurately control the stirring speed during the preparation of manganese tetroxide. Therefore, to more accurately control the stirring speed during manganese tetroxide preparation, it is necessary to accurately measure the degree of particle agglomeration caused by uneven solute mixing based on changes in infrared spectral data.

[0057] To more accurately analyze the phenomenon of particle agglomeration when solutes are not uniformly mixed in the reaction solution, for any acquisition time, the infrared spectral data sequence of each measurement location is used as the input to the peak detection algorithm. The peak detection algorithm can be the AMPD peak detection algorithm or the derivative-based peak detection algorithm. In this embodiment, the derivative-based peak detection algorithm is used to obtain all peak points and valley points in the infrared spectral data sequence of each measurement location. The peak points can characterize the absorption peak intensity characteristics of different solutes in the reaction solution to the infrared spectrum, which is beneficial for more accurately measuring the degree of particle agglomeration when solutes are not uniformly mixed.

[0058] However, due to the interference of external noise during the acquisition of infrared spectral data, false infrared absorption peaks often appear in the infrared spectral data sequence. These false infrared absorption peaks have abrupt shapes and exhibit abnormal absorbance changes.

[0059] Therefore, the infrared spectral data between the preceding and following valleys of each peak point in the infrared spectral data sequence are arranged in ascending order of wavelength. Cubic spline interpolation is then used to interpolate the data. The interpolated sequence is recorded as the characteristic peak sequence of each peak point. The anomalousness of the characteristic peak sequence of each peak point is calculated. The anomalousness can be measured by permutation entropy or sample entropy. In this embodiment, permutation entropy is used to measure the anomalousness. The greater the anomalousness, the greater the degree of anomalousness in the absorbance change in the characteristic peak sequence, and the more it reflects the abrupt shape of the false infrared spectral absorption peak.

[0060] Furthermore, in order to eliminate the adverse effects of false infrared absorption peaks on subsequent particle aggregation analysis, the mean value of the anomalies corresponding to all peak points is used as the judgment threshold. Each peak point with an anomaly less than the judgment threshold is recorded as an absorption peak point in the infrared spectral data sequence of each measurement location, thereby more accurately reflecting the absorption peak characteristics of different solutes in the reaction solution on the infrared spectrum.

[0061] Generally, if the solutes in the reaction solution are not mixed uniformly and particles agglomerate, there will be significant differences in the degree of absorption of the infrared spectrum and the position of the absorption peaks at different measurement locations.

[0062] Therefore, for each acquisition time, this application records the sum of the peak values ​​of all absorption peak points in the infrared spectral data sequence of each measurement location as the absorption accumulation degree of the infrared spectral data at each measurement location, which characterizes the overall level of absorption of the infrared spectrum by various solutes at that measurement location; at the same time, the set of the positional order of all absorption peak points in the infrared spectral data sequence of each measurement location is recorded as the absorption peak positional set of the infrared spectral data at each measurement location, which characterizes the absorption peak position of various solutes in the infrared wavelength range at that measurement location.

[0063] Based on the above analysis, an aggregation assessment value is calculated based on the absorption accumulation degree and absorption peak sequence set of infrared spectral data from different measurement locations. This value is used to assess the possibility of particle aggregation due to uneven solute mixing in the reaction solution. The aggregation assessment value is positively correlated with the difference between the maximum and minimum values ​​of the absorption accumulation degree of infrared spectral data from all measurement locations, and negatively correlated with the mean set similarity among the absorption peak sequence sets of infrared spectral data from all measurement locations.

[0064] It is understandable that a positive correlation means that the dependent variable increases as the independent variable increases, and decreases as the independent variable decreases; a negative correlation means that the dependent variable decreases as the independent variable increases, and increases as the independent variable decreases. This is determined by the actual application, and this application does not impose any special restrictions.

[0065] Preferably, in this embodiment, the difference between the maximum and minimum values ​​is determined by the ratio of the maximum and minimum values. In other embodiments, the difference between the maximum and minimum values ​​can also be determined by dividing the result by the average of the absorption accumulation of infrared spectral data at all measurement locations. The specific method can be set by the implementer.

[0066] Specifically, in this embodiment, the aggregation evaluation value at each acquisition time is calculated as follows:

[0067]

[0068] In the formula, and These represent the maximum and minimum values ​​of the cumulative absorption of infrared spectral data at all measurement locations. This is the mean of the set similarity among the absorption peak position sequences of infrared spectral data from all measurement locations. The set similarity can be measured using either the Jaccard similarity coefficient or the Dessian similarity coefficient. In this embodiment, the Jaccard similarity coefficient is chosen to measure the set similarity. This is a division constant, used to prevent the denominator from being 0. Its value range is (0.01, 0.1), and in this embodiment, it is 0.05.

[0069] In other embodiments of this invention, the method for calculating the aggregation assessment value at each acquisition time may also be:

[0070]

[0071] In the formula, This is the average of the cumulative absorption of infrared spectral data from all measurement locations; all other parameters are the same as those in the previous calculation method.

[0072] It should be noted that in existing feature measurement methods, ratios or differences can be used to measure the differences between different data. The ratio method focuses on the relative differences between different data, while the difference method focuses on the absolute differences between different data. Therefore, in the first calculation method, the ratio of the maximum value to the minimum value is used to characterize the difference in solute absorption of the infrared spectrum at different measurement locations. In the second calculation method, the difference between the maximum value and the minimum value is used, and then the difference is divided by the mean to eliminate the physical dimensions of the infrared absorption spectrum, thereby characterizing the difference in solute absorption of the infrared spectrum at different measurement locations.

[0073] Furthermore, set similarity and set difference are inversely proportional. When existing technologies measure features by taking an inverse relationship, they can use a fractional form, where the denominator of the fraction is inversely proportional to the feature index. Therefore, both the first and second calculation methods use a fractional form for feature measurement.

[0074] The agglomeration assessment value reflects the possibility of particle agglomeration when the solute is not mixed evenly. The higher the agglomeration assessment value, the greater the possibility of particle agglomeration when the solute is not mixed evenly in the reaction solution. This makes it easier to affect the uniformity of particle size distribution in the reaction solution. Therefore, it is necessary to control and adjust the stirring speed more accurately during the preparation of manganese tetroxide.

[0075] Step 3: Calculate the aggregation significance by analyzing the increasing persistence of the aggregation evaluation value over a short period of time, which is used to measure the significance of particle aggregation.

[0076] To more accurately control and adjust the stirring speed during the preparation of manganese tetroxide, the increasing persistence of agglomeration characteristics appearing in the short period before the current sampling time was measured.

[0077] Specifically, in this embodiment, the aggregation evaluation values ​​of the current collection time and all collection times within 1 minute before the current collection time are arranged in chronological order to obtain the aggregation characteristic sequence of the current collection time, which reflects the particle aggregation characteristics in the reaction solution within a short period of 1 minute before the current collection time.

[0078] Furthermore, the first-order difference sequence of the agglomeration change sequence in the short period before the current sampling time is calculated to reflect the changes in the particle agglomeration characteristics in the reaction solution in the short period before the current sampling time.

[0079] Generally, the larger the ratio between the number of all elements greater than 0 in the first-order difference sequence and the total number, and the more concentrated the position of all elements greater than 0 in the first-order difference sequence, the more significant the increasing persistence of particle agglomeration characteristics in the short period before the current sampling time. At the same time, the larger the agglomeration evaluation value at the current sampling time, the more accurately it can reflect the significance of particle agglomeration caused by uneven mixing of solute in the reaction solution, which is beneficial for accurately controlling and adjusting the stirring speed during the preparation of manganese tetroxide.

[0080] Based on the above analysis, this application calculates the aggregation significance by analyzing the increasing persistence of aggregation evaluation values ​​over a short period of time, which is used to measure the significance of particle aggregation. Specifically, the aggregation significance is positively correlated with the proportion of sampling times showing an increase over a short period of time and the aggregation evaluation value at the current sampling time, and negatively correlated with the dispersion of the order of sampling times showing an increase over a short period of time.

[0081] The acquisition time that increases within a short period of time is determined by arranging the clustering evaluation values ​​of all acquisition times within a preset short period of time before the current acquisition time into a sequence in chronological order, and calculating the next acquisition time corresponding to the difference value when the difference value is greater than 0.

[0082] Specifically, in this embodiment, the clustering significance at the current acquisition time... One calculation method is as follows:

[0083]

[0084] In the formula, It is the ratio between the number of all elements greater than 0 in the first-order difference sequence corresponding to the current acquisition time and the total number of elements. It can also be represented as the proportion of acquisition times that show an increasing trend in the short period before the current acquisition time. This is the clustering evaluation value at the current acquisition time after normalization of the maximum value. This represents the dispersion of the positional order of all elements greater than 0 in the first-order difference sequence corresponding to the current acquisition time. It can also be characterized as the dispersion of the positional order of acquisition times that show an increasing sequence in the short period preceding the current acquisition time. The dispersion can be measured by variance, standard deviation, or the coefficient of variation. In this embodiment, standard deviation is used. This is a division-by-zero constant, the same as the one set in the formula for calculating the reunion assessment value.

[0085] It should be noted that, in order to ensure consistency in the total number, the total number of the ratio between the number of all elements greater than 0 in the first-order difference sequence corresponding to the current acquisition time and the total number of the proportion of acquisition times that showed an increase in a short period of time before the current acquisition time are both set to the number of elements in the clustering feature sequence of the current acquisition time minus 1.

[0086] In other embodiments, the clustering significance at the current acquisition time The calculation method can also be:

[0087]

[0088] In the formula, It is an exponential function with the natural constant as the base, and all other parameters are the same as those in the previous calculation method.

[0089] It should be noted that in existing feature measurement methods, when measuring feature indicators through direct and inverse proportional relationships, a fractional form can be used, where the feature parameters in the numerator are all feature parameters that are directly proportional to the feature indicator, and the feature parameters in the denominator are all feature parameters that are inversely proportional to the feature indicator. The first method for calculating cluster significance uses the existing fractional measurement method.

[0090] Alternatively, a function mapping method can be used to negatively map the inversely proportional feature parameters, which can then be used as a product factor for the feature index measurement. This makes the overall part after the function mapping proportional to the feature index, thereby achieving the degree of the feature index. The second method for calculating cluster significance is precisely the existing function mapping-based measurement method.

[0091] Agglomeration significance reflects the magnitude of particle agglomeration caused by uneven solute mixing in the reaction solution. The greater the agglomeration significance, the more significant the particle agglomeration in the reaction solution. In this case, the stirring speed of the reaction solution should be increased to avoid uneven solute mixing due to insufficient stirring speed. Conversely, the smaller the agglomeration significance, the lower the magnitude of particle agglomeration in the reaction solution. In this case, the stirring speed should be decreased to avoid severe shear force problems caused by excessive stirring speed.

[0092] Step 4: Predict the aggregation significance at the next collection time, and adjust the stirring speed of the reaction solution in the reactor in real time during the preparation of manganese tetroxide, based on the real-time set safety threshold.

[0093] Furthermore, the stirring speed during the preparation of manganese tetroxide is controlled and adjusted in real time using a real-time prediction method. The agglomeration significance calculated in real time is used as the input of the ARIMA autoregressive integral moving average model. The model has a preset autoregressive term of 10, a difference term of 2, and a moving average term of 3. The predicted agglomeration significance of the next acquisition time is obtained through the ARIMA autoregressive integral moving average model.

[0094] Meanwhile, the safety threshold is set in real time. In this embodiment, the 3Sigma range of the cluster significance of all acquisition times in the historical process before the current acquisition time is calculated, and the lower limit of the 3Sigma range is used as the safety threshold for the current acquisition time.

[0095] Furthermore, this application combines a real-time set safety threshold to adjust the stirring speed of the reactor during the preparation of manganese tetroxide in real time. The specific method is as follows:

[0096] If the predicted aggregation significance at the next sampling time is greater than that at the current sampling time, it indicates that the particle aggregation phenomenon in the reaction solution at the next sampling time is more significant. At this time, the stirring speed of the reaction solution should be increased to avoid uneven mixing of solutes in the reaction solution due to insufficient stirring speed.

[0097] Otherwise, if the predicted aggregation significance at the next sampling time is less than or equal to the aggregation significance at the current sampling time, and the aggregation significance at the current sampling time is less than or equal to the safety threshold at the current sampling time, it indicates that the particle aggregation phenomenon in the reaction solution at the next sampling time is relatively low. In order to avoid serious shear force problems caused by excessive stirring speed, the stirring speed of the reaction solution should be reduced at this time.

[0098] Otherwise, if the predicted aggregation significance at the next sampling time is less than or equal to the aggregation significance at the current sampling time, and the aggregation significance at the current sampling time is greater than the safety threshold at the current sampling time, it indicates that the particle aggregation phenomenon in the reaction solution at the next sampling time has not worsened but is still in a high-risk state. In this case, the stirring speed of the reaction solution at the current sampling time should be kept unchanged.

[0099] Therefore, based on the above method, the stirring speed can be controlled and adjusted during the preparation of manganese tetroxide, and manganese tetroxide suspension is obtained after the reaction is completed.

[0100] It should also be noted that the stirring speed adjustment range is 400-800 rpm / min, and it is not allowed to exceed the adjustment range. The stirring speed adjustment amount in one step is ±(20,50) rpm / min. In this embodiment, the stirring speed adjustment amount in one step is ±30. If the stirring speed after real-time adjustment exceeds the adjustment range, the current stirring speed will be maintained unchanged.

[0101] (3) Washing: After the oxidation reaction, the manganese tetroxide suspension obtained is placed in a centrifuge and washed repeatedly with deionized water by vacuum filtration 5-8 times to obtain the cake.

[0102] In this embodiment, the cake is obtained by repeated dehydration, filtration and washing with deionized water five times.

[0103] (4) Drying and packaging: The washed material cake is added to a flash steamer for drying, and the dried manganese tetroxide is packaged to obtain manganese tetroxide product.

[0104] Thus, an invention of a method for preparing manganese tetroxide using recycled manganese liquid as raw material has been completed.

[0105] Example 2

[0106] (1) Raw material preparation: In this embodiment, the prepared manganese recovery liquid is 1.5 mol / L, and the amount of dispersant and surfactant added to the mixing tank is 2 g / L and 3 g / L, respectively. The ammonia solution is stored at 2.5 mol / L. The dispersant is a combination of polyethylene glycol and dichloroethane, and the surfactant is a combination of stearic acid and sodium dodecylbenzenesulfonate.

[0107] (2) Oxidation reaction: In this embodiment, the temperature of the bottom liquid in the reactor is controlled to reach 60°C, and the preset initial stirring speed is 600 rpm / min. The volume ratio of the bottom liquid to the manganese salt solution is 0.8:1.

[0108] (3) Washing: In this embodiment, the cake is obtained by repeated dehydration, filtration and washing with deionized water 7 times.

[0109] (4) Drying and packaging.

[0110] In this embodiment, the parts not mentioned in Embodiment 1 are all implemented in the same way as in Embodiment 1, and will not be described in detail here.

[0111] Example 3

[0112] (1) Raw material preparation: In this embodiment, the prepared manganese recovery liquid is 2 mol / L, and the amount of dispersant and surfactant added to the mixing tank is 3 g / L and 5 g / L, respectively. The ammonia solution is stored at 3 mol / L. The dispersant is a combination of polyethylene glycol, dichloroethane and sodium tartrate, and the surfactant is a combination of stearic acid, sodium dioctyl succinate sulfonate and sodium dodecylbenzene sulfonate.

[0113] (2) Oxidation reaction: In this embodiment, the temperature of the bottom liquid in the reactor is controlled to reach 80°C, and the preset initial stirring speed is 600 rpm / min. The volume ratio of the bottom liquid to the manganese salt solution is 0.6:1.

[0114] (3) Washing: In this embodiment, the cake is obtained by repeated dehydration, filtration and washing with deionized water 8 times.

[0115] (4) Drying and packaging.

[0116] In this embodiment, the parts not mentioned in Embodiment 1 are all implemented in the same way as in Embodiment 1, and will not be described in detail here.

[0117] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0118] It should be noted that, unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such article or device. Without further limitations, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0119] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not invented in this application.

[0120] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for preparing manganese tetroxide using recycled manganese liquid as raw material, characterized in that, The method includes the following steps: adding the prepared recovered manganese liquid to a mixing tank, then adding a dispersant and a surfactant to the mixing tank to obtain a manganese salt solution; storing an ammonia solution in a storage tank; adding deionized water as a base liquid to a reaction vessel and heating and stirring; after the temperature stabilizes, sending the manganese salt solution and ammonia solution to the reaction vessel separately, and continuing to stir at a constant initial stirring speed; while stirring the reaction solution in the reaction vessel at the initial stirring speed, real-time acquisition of infrared spectral data at different measurement positions in the reaction vessel; extracting the true absorption peak points from the acquired infrared spectral data, and calculating an agglomeration assessment value based on the absorption accumulation degree and absorption peak sequence set of the infrared spectral data at different measurement positions, used to assess the possibility of particle agglomeration due to uneven solute mixing in the reaction solution; and analyzing the evolution of the agglomeration assessment value over a short period of time. To enhance persistence, the aggregation significance is calculated to measure the significance of particle aggregation. The aggregation significance at the next acquisition time is predicted, and the stirring speed of the reaction solution in the reactor is adjusted in real time during the preparation of manganese tetroxide, combined with a real-time set safety threshold. After the reaction, a manganese tetroxide suspension is obtained, which is then washed, dried, and packaged to obtain the manganese tetroxide product. The method for extracting the true absorption peak points includes: acquiring the peak points and valley points in the infrared spectral data sequence of each measurement position at any acquisition time; performing cubic spline interpolation on the infrared spectral data between the previous valley point and the next valley point for each peak point to construct a characteristic peak sequence; calculating the anomaly of the characteristic peak sequence using permutation entropy, and using the mean of the anomalies corresponding to all peak points as the judgment threshold, and taking the peak points with anomalies less than the judgment threshold as absorption peak points.

2. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The volume ratio of the recovered manganese solution, dispersant, surfactant, and ammonia solution is (1-2):(1-3):(1-5):(2-3).

3. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The dispersant is any one or a combination of sodium dodecyl sulfate, polyethylene glycol, dichloroethane, and sodium tartrate, and the surfactant is any one or a combination of stearic acid, sodium dioctyl succinate, and sodium dodecylbenzene sulfonate.

4. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The aggregation assessment value is positively correlated with the difference between the maximum and minimum values ​​of the cumulative absorption of infrared spectral data at all measurement locations, and negatively correlated with the mean set similarity between the absorption peak position sequences of infrared spectral data at all measurement locations.

5. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The cumulative absorption of the infrared spectral data at the measurement location is the sum of the peak values ​​of all absorption peak points in the infrared spectral data at the measurement location.

6. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The clustering significance is positively correlated with the proportion of collection times that increase in a short period of time and the clustering evaluation value of the current collection time, and negatively correlated with the dispersion of the order of collection times that increase in a short period of time.

7. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The real-time adjustment method for the stirring speed is as follows: if the predicted aggregation significance at the next acquisition time is greater than the aggregation significance at the current acquisition time, then the stirring speed of the reaction solution is increased; otherwise, if the aggregation significance at the current acquisition time is less than or equal to the safety threshold at the current acquisition time, then the stirring speed of the reaction solution is decreased; otherwise, the current stirring speed is maintained unchanged.

8. The method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 1, characterized in that, The stirring speed can be adjusted within the range of 400–800 rpm / min, and the adjustment amount for each stirring speed is ±(20,50) rpm / min. If the stirring speed after real-time adjustment exceeds the adjustment range, the current stirring speed will be maintained.

9. A method for preparing manganese tetroxide using recycled manganese liquid as raw material as described in claim 2 or 8, characterized in that, The initial stirring speed in the reactor was 600 rpm, the temperature control range of the bottom liquid in the reactor was 40–80℃, the reaction time was 12 hours, the volume ratio of the bottom liquid to the manganese salt solution was (0.6–1):1, and the oxidant was oxygen.

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