On-line monitoring device and method for cobalt hydroxide synthesis based on multi-dimensional turbidity characteristics

Abstract

This invention discloses an online monitoring device and method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, belonging to the fields of hydrometallurgy and lithium-ion battery cathode material precursor preparation. The steps include acquiring the turbidity at detection locations at different distances from the feed inlet within the reactor; calculating the turbidity difference between the two locations when the turbidity does not exceed a preset turbidity range; determining an abnormal mixing warning when the turbidity difference is greater than a preset spatial difference; calculating the rate of turbidity decrease or increase at the detection location when the turbidity is lower or higher than the preset turbidity range; and determining stagnant sedimentation or nucleation explosion when the rate of turbidity decrease or increase is greater than a preset rate of decrease or increase. This invention leverages the principle that the closer to the feed inlet, the higher the reagent concentration and the more vigorous the reaction. By monitoring the turbidity values, turbidity difference, and turbidity change rate at two locations, it can distinguish abnormal types and provide directional guidance for intervention.

Description

Technical Field

[0001] This invention relates to an online monitoring device and method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, belonging to the technical field of hydrometallurgy and lithium-ion battery cathode material precursor preparation. Background Technology

[0002] Cobalt hydroxide (Co(OH)2) is a key precursor for cathode materials in lithium-ion batteries (such as lithium cobalt oxide and ternary materials). The particle size, particle size distribution, sphericity, tap density, and crystal structure of its product directly affect the electrochemical performance of the final battery material. Industrially, it is typically synthesized using a liquid-phase co-precipitation method, where a cobalt salt solution and a precipitant (such as sodium hydroxide) undergo a controlled precipitation reaction in the presence of a complexing agent (such as ammonia). This reaction is a typical nucleation-growth-conversion competitive process, extremely sensitive to the local chemical environment within the reactor. Currently, industrial monitoring of the reaction process mainly relies on indirect parameters such as pH, temperature, and stirring current.

[0003] The limitations of existing technologies include: Lag in detection parameters: pH and temperature have a lag in responding to changes in solid phase morphology (such as particle size distribution, agglomeration state, crystal growth, etc.), making it impossible to detect nucleation bursts or material sedimentation in a timely manner.

[0004] The stirring current has poor specificity: In the early stages of cobalt hydroxide synthesis (nucleation and early growth phases), the amount of solid particles generated is limited, the slurry concentration is low, and the impact on the overall viscosity of the slurry is small. Changes in the stirring current are usually within the fluctuation range of the motor current, making them difficult to identify effectively. Furthermore, changes in the stirring current can be caused by various factors, including changes in mechanical transmission efficiency, material level changes, and voltage fluctuations, and have a weak correlation with abnormalities in the reaction process, easily leading to misjudgments. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides an online monitoring device and method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, which monitors the reaction process in a timely and accurate manner by monitoring the turbidity at different locations.

[0006] The technical solution adopted by this invention to solve its technical problem is: Firstly, this application provides an online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, the steps of which include: The turbidity at different detection locations within the reactor is obtained; the detection locations include a first location and a second location, wherein the first location is closer to the cobalt liquid inlet than the second location; When the turbidity at all the detection locations does not exceed the preset turbidity range, the turbidity difference between the first location and the second location is calculated; when the turbidity difference is greater than the preset spatial difference, a mixing anomaly warning signal is output. When the turbidity at any of the detection locations is lower than the preset turbidity range, the turbidity decrease rate at that detection location is calculated; when the turbidity decrease rate is greater than the preset decrease rate, a stagnation sedimentation alarm signal is output. When the turbidity at any of the detection locations is higher than the preset turbidity range, the turbidity rise rate at that detection location is calculated; when the turbidity rise rate is greater than the preset rise rate, a nucleation burst alarm signal is output.

[0007] The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics provided in this application can simultaneously monitor turbidity values, change rates, and spatial distribution differences, thereby providing early warning and accurate identification of anomalies in cobalt hydroxide synthesis.

[0008] Furthermore, the preset turbidity range includes the time-turbidity correspondence for each of the detection positions, and the time-turbidity correspondence includes an upper limit relationship and a lower limit relationship; the upper limit relationship is the correspondence between the time elapsed in the cobalt hydroxide synthesis of the corresponding detection position and the upper limit of turbidity under that elapsed time; the lower limit relationship is the correspondence between the time elapsed in the cobalt hydroxide synthesis of the corresponding detection position and the lower limit of turbidity under that elapsed time.

[0009] The time-based turbidity correlation allows the upper and lower limits of turbidity at each detection location to dynamically change with the reaction process, matching the liquid phase turbidity changes caused by the continuous precipitation of crystals at each stage. The two detection locations are at different distances from the feed inlet; the feed inlet side has priority contact with fresh cobalt liquid over a longer period, resulting in an earlier nucleation start time and a higher instantaneous solid phase production. The independent time-bound upper and lower limits for each location can accommodate the differences in solid phase generation amount and rate between the two locations, ensuring that the turbidity judgment standard aligns with the objective reaction law of cobalt hydroxide precipitation over time, thus improving the accuracy of full-cycle condition identification.

[0010] Furthermore, the time turbidity correspondence is a time-division envelope, which includes an upper limit envelope and a lower limit envelope; the upper limit envelope is made according to the upper limit relationship, and the lower limit envelope is made according to the lower limit relationship.

[0011] Unlike discrete thresholds, which can only match fixed time points and lack reference standards for intermediate periods, continuous envelopes enable rapid comparison of instantaneous turbidity with standard limits at any given moment. The interval enclosed by two envelopes defines the normal turbidity fluctuation range for the entire reaction cycle at the corresponding detection location. If the turbidity value collected at any instant falls outside the envelope interval, it can be determined that the solid content at the current detection location deviates from the standard operating conditions, which is beneficial for providing visual monitoring.

[0012] Furthermore, the steps for establishing the time-turbidity correspondence include: Historical data from multiple normal production processes that yielded qualified cobalt hydroxide products were collected. The historical data included the turbidity at the detection location and the elapsed time corresponding to that turbidity. The historical data is grouped according to the elapsed time, and the average turbidity and standard deviation of turbidity for each group are calculated. The upper limit of turbidity over the corresponding elapsed time is the sum of the average turbidity value and twice the standard deviation of turbidity. The difference between the average turbidity value and twice the standard deviation of turbidity is taken as the lower limit of turbidity over the corresponding elapsed time.

[0013] The grouped statistical processing method corresponds to the segmented characteristics of reaction time. Production conditions under the same reaction time tend to be consistent. Centralized accounting of data in the same group can avoid the lowering of limit accuracy due to data mixing across time periods. The generated upper and lower limits match the solid phase formation rules of the corresponding reaction stages. After defining the normal turbidity fluctuation boundary, only the turbidity rise and fall rate exceeding the boundary will be identified as abnormal fluctuation, which greatly reduces the frequency of alarms triggered by small fluctuations inherent in production.

[0014] Furthermore, while outputting the stagnation and settling alarm signal, the stirring speed of the reactor is increased.

[0015] A rapid decrease in turbidity indicates that a large number of cobalt hydroxide crystals in the reactor are overcoming the suspending force of the liquid phase and depositing downwards. Once deposited, the accumulation of solid phase at the bottom of the reactor reduces the number of effectively suspended crystals in the liquid phase. Continued accumulation can also prevent some raw materials from contacting the solid phase to complete crystal growth, resulting in a wide particle size distribution in the final product. Simultaneously increasing the stirring speed during the alarm intensifies the turbulence in the liquid phase within the reactor. The shear force generated by the turbulence begins to aggregate and settle crystal clusters, breaking up the initially clustered and sinking fine crystals, and re-dispersing and suspending them within the liquid phase system, replenishing the suspended particle content and slowing the continuous decrease in turbidity. The increased stirring speed also clears the existing low-speed flow dead zones within the reactor. These dead zones are prone to continuous crystal accumulation due to fluid stagnation. After the disturbance optimization, the remaining deposited particles in the dead zones gradually return to a suspended state, simultaneously improving the mixing uniformity of materials throughout the reactor. Accelerated stirring intervenes before large-scale sedimentation and formation, preventing the crystals from completely solidifying at the bottom of the reactor and becoming unable to be resuspended. This reduces raw material waste while ensuring that the crystals inside the liquid phase are in a stable suspension growth environment, resulting in a more uniform crystal growth rate. This helps maintain product indicators such as concentrated cobalt hydroxide particle size distribution and regular sphericity, enabling anomaly identification and automatic on-site process control.

[0016] Furthermore, while outputting the nucleation and explosion alarm signal, the cobalt liquid feed rate is reduced.

[0017] Reducing the cobalt solution feed rate slows down the continuous inflow of fresh cobalt salts into the area surrounding the feed inlet, gradually diluting the excessively enriched cobalt ions near the feed inlet, lowering the local supersaturation level, cutting off the supply of raw materials for the rapid precipitation of new crystal nuclei, and curbing the continued abnormal surge in turbidity. After reducing the feed rate, the existing precipitant and complexing agent in the reactor can gradually consume the excess cobalt ions near the feed inlet, allowing the local precipitation reaction to return to an orderly grain growth pattern.

[0018] Secondly, this application provides an online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, including at least two sets of turbidity detection probes, which are respectively installed in a first position and a second position in the reactor. The first position is closer to the cobalt liquid inlet than the second position. The turbidity detection probes are connected to a controller signal. The controller is used for: The turbidity at different detection locations within the reactor is obtained from the turbidity detection probe; the detection locations include the first location and the second location; When the turbidity at all the detection locations does not exceed the preset turbidity range, the turbidity difference between the first location and the second location is calculated; when the turbidity difference is greater than the preset spatial difference, a mixing anomaly warning signal is output. When the turbidity at any of the detection locations is lower than the preset turbidity range, the turbidity decrease rate at that detection location is calculated; when the turbidity decrease rate is greater than the preset decrease rate, a stagnation sedimentation alarm signal is output. When the turbidity at any of the detection locations is higher than the preset turbidity range, the turbidity rise rate at that detection location is calculated; when the turbidity rise rate is greater than the preset rise rate, a nucleation burst alarm signal is output.

[0019] Furthermore, the online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics also includes an alarm, which is signal-connected to the controller. After receiving the mixing anomaly warning signal, the stagnation and sedimentation alarm signal, or the nucleation and explosion alarm signal, the alarm will issue different alarm prompts accordingly.

[0020] Furthermore, a feed pipe is provided inside the reactor, and the cobalt liquid inlet is located at the end of the feed pipe. The feed pipe is connected to a feed pump outside the reactor. The feed pump is signal-connected to the controller. When the controller outputs a nucleation explosion alarm signal, it instructs the feed pump to reduce the cobalt liquid feed rate.

[0021] By reducing the supply of raw materials before excessive crystal nuclei solidify, there is no need to wait for batches of products to fail before stopping the machine for rectification. This reduces the raw material loss caused by the production of defective precursors and allows the sediment in the reactor to return to a balanced competitive state between nucleation and grain growth, ensuring that the cobalt hydroxide grains generated subsequently are of uniform size.

[0022] Furthermore, the reactor is equipped with a stirrer, which is signal-connected to the controller. While outputting the stagnation and settling alarm signal, the controller instructs the stirrer to increase the stirring speed of the reactor.

[0023] The beneficial effects of this invention are: by monitoring turbidity difference at multiple locations, this invention can detect problems in a localized stage before the anomaly spreads to the entire reactor, thus gaining valuable time for intervention. One detection location is close to the cobalt liquid inlet, and the other detection location is far from the cobalt liquid inlet. Based on the principle that the closer to the inlet, the higher the reagent concentration and the more vigorous the reaction, by monitoring the turbidity value, turbidity difference, and turbidity change rate at the two locations, the type of anomaly can be distinguished, providing directional guidance for intervention.

[0024] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics provided in an embodiment of this application.

[0026] Figure 2 This is a flowchart of an online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, provided in an embodiment of this application.

[0027] Figure 3 It is a time-division envelope for detecting location.

[0028] Attached reference numerals: 1. Turbidity detection probe; 2. Stirrer; 3. Cobalt liquid feed pipe; 4. Controller; 5. Host computer; 6. Alarm. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0031] Reference Figure 1 This application provides an online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, including at least two sets of turbidity detection probes 1, which are respectively installed in a first position and a second position in the reactor. The first position is closer to the cobalt liquid inlet than the second position. The turbidity detection probes are connected to a controller 4.

[0032] Controller 4 is used to execute the following online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics: Turbidity is obtained from different detection locations inside the reactor using a turbidity detection probe; the detection locations include a first location and a second location, with the first location being closer to the cobalt liquid inlet than the second location; When the turbidity at all detection locations does not exceed the preset turbidity range, the turbidity difference between the first and second locations is calculated; when the turbidity difference is greater than the preset spatial difference, a mixing anomaly warning signal is output. When the turbidity at any detection location is lower than the preset turbidity range, calculate the turbidity decrease rate at that detection location; when the turbidity decrease rate is greater than the preset decrease rate, output a stagnation sedimentation alarm signal. When the turbidity at any detection location is higher than the preset turbidity range, the turbidity rise rate at that detection location is calculated; when the turbidity rise rate is greater than the preset rise rate, a nucleation burst alarm signal is output.

[0033] Specifically, the first position is near the end of the cobalt liquid feed pipe 3, for example, within 20cm (or 10cm, 5cm, 2cm, 30cm, etc.) of the feed inlet. The second position can be at the bottom of the reactor. Typically, the stirrer 2 is located in the center of the reactor, and the turbidity detection probe 1 needs to avoid the stirrer 2. Therefore, the first position is not in the center of the reactor, so the second position can be set symmetrically to the center of the reactor's central axis along the first position. Each turbidity detection probe is used to collect the turbidity signal of the slurry at its corresponding location in real time.

[0034] The turbidity detection probe can be a backscattering online turbidity meter with a range of 0-4000 NTU. It uses an 860nm infrared LED light source, a 316 stainless steel housing, a sapphire optical window, an IP68 protection rating, and a response time T90 ≤ 10 seconds. The backscattering measurement principle makes its signal intensity positively correlated with particle concentration, making it particularly suitable for processes like cobalt hydroxide synthesis where solid content continuously increases from zero to high concentrations. It can cover the entire process monitoring from low turbidity during nucleation to high solid content in the later stages of growth.

[0035] The cobalt hydroxide precipitation reaction has multiple stages, including nucleation and grain growth. The concentrations of cobalt ions and hydroxide ions in the liquid phase change continuously at different reaction stages. The complexing agent is gradually consumed, changing the precipitation equilibrium. The concentration of suspended particles at the same detection location differs significantly between the initial stage and the middle and later stages of the reaction under normal operating conditions. Fixed numerical thresholds cannot adapt to changes in operating conditions throughout the entire cycle, which can easily lead to false alarms triggered by normal production data or minor anomalies being masked by the threshold.

[0036] Therefore, in practice, when obtaining turbidity, it is necessary to simultaneously record the time at which that turbidity was obtained. For example... Figure 2 First, the turbidity at different detection locations within the reactor is measured, along with the reaction time. Then, it is determined whether the turbidity at any detection location exceeds a preset turbidity range after the current elapsed time. If it does not exceed the preset range, the turbidity difference is further measured to see if it is greater than a preset spatial difference. If it also does not exceed the preset range, it is considered normal, and the next round of turbidity measurement continues. If the turbidity difference exceeds the preset spatial difference, it is considered an abnormal mixing. In determining whether the turbidity at any detection location exceeds the preset turbidity range, if the turbidity at any detection location exceeds the preset range, the rate of increase of turbidity at that location is further measured to see if it is greater than a preset rate of increase. If so, it is considered a nucleation explosion; otherwise, it is considered normal accumulation. In determining whether the turbidity at any detection location exceeds the preset turbidity range, if the turbidity at any detection location is less than the preset range, the rate of decrease of turbidity at that location is further measured to see if it is greater than a preset rate of decrease. If so, it is considered stagnant sedimentation; otherwise, it is considered normal crystallization. Note that the preset rate of decrease and the preset rate of increase can be different for different detection locations.

[0037] In a preferred embodiment, when obtaining the turbidity at different detection locations within the reactor, the judgment conditions can be ignored first, and the turbidity change rate can be directly calculated. If the turbidity decrease rate at any of the detection locations is greater than a preset decrease rate but the turbidity at that location is still within the preset turbidity range, a stagnation sedimentation warning can be issued, only reminding the workers without automatic intervention. If the turbidity increase rate at any of the detection locations is greater than a preset increase rate but the turbidity at that location is still within the preset turbidity range, a nucleation explosion warning can be issued, only reminding the workers without automatic intervention.

[0038] The preset turbidity range includes the time-turbidity correspondence for each detection location. The time-turbidity correspondence includes an upper limit relationship and a lower limit relationship. The upper limit relationship is the correspondence between the time elapsed during the cobalt hydroxide synthesis of the corresponding detection location and the upper limit of turbidity under that time elapsed. The lower limit relationship is the correspondence between the time elapsed during the cobalt hydroxide synthesis of the corresponding detection location and the lower limit of turbidity under that time elapsed.

[0039] The steps for establishing the time-turbidity correspondence include: Historical data was collected during the production process when the product was produced normally and qualified cobalt hydroxide was produced multiple times. The historical data included the turbidity at the detection location and the time elapsed for that turbidity. The historical data were grouped by elapsed time, and the average turbidity and standard deviation of turbidity were calculated for each group. The upper limit of turbidity over the corresponding elapsed time is the sum of the average turbidity and twice the standard deviation of turbidity. The lower limit of turbidity over the corresponding elapsed time is the difference between the average turbidity value and twice the standard deviation of turbidity.

[0040] However, scatter plots cannot be used to monitor the entire reaction process. Preferably, the time-to-turbidity correspondence is a time-division envelope, which includes an upper and lower bound envelope. The upper bound envelope is constructed based on the upper bound relationship, specifically by fitting the upper bound of the turbidity of the scatter plots to a curve; the lower bound envelope is constructed based on the lower bound relationship, specifically by fitting the lower bound of the turbidity of the scatter plots to a curve. This will yield similar results. Figure 3 The time-division envelope is plotted, with the horizontal axis representing time in minutes and the vertical axis representing turbidity in NTUs. The range between the upper and lower envelopes represents the interval where the turbidity at the detection location does not exceed the preset turbidity range.

[0041] The time-sharing envelope reflects the inherent turbidity evolution of the cobalt hydroxide precipitation reaction: Nucleation stage: When cobalt salt comes into contact with the precipitant, it forms a highly supersaturated state and undergoes explosive homogeneous nucleation to generate a large number of nano-sized α-Co(OH)2 colloidal particles, resulting in a steep increase in turbidity. In the early stage of growth: the number of particles is stable, the particle size gradually increases, α-Co(OH)2 colloid begins to transform into β-Co(OH)2 crystals, and the turbidity drops slightly from the peak or fluctuates at a high level; Late growth / crystal transformation period: Particles become denser, specific surface area decreases, and turbidity shows a continuous and slow downward trend.

[0042] Preferably, each turbidity detection probe is equipped with a flow-stabilizing sleeve at its front end to eliminate interference from air bubbles generated by turbulent stirring within the reactor on the optical path detection. The probe is also equipped with a mechanical scraper-type self-cleaning device to periodically remove cobalt slag crystals adhering to the optical window, ensuring continuous, real-time turbidity signal acquisition without interrupting the reaction or requiring static sampling.

[0043] Implementation Cases Reactor: 10m³ glass-lined reactor, equipped with a variable frequency stirring motor, cobalt liquid feed pipe, and alkali liquid feed pipe.

[0044] The first turbidity detection probe is a backscattering online turbidity meter with a range of 0-4000 NTU, an 860nm infrared LED light source, a 316 stainless steel housing, a sapphire optical window, IP68 protection rating, and a response time T90≤10 seconds. It is installed approximately 30cm directly above the cobalt solution inlet (inside the cobalt solution inlet pipe; note: the area near the vessel wall is considered outside, and the area near the stirrer is considered inside), to monitor high-risk areas near the inlet.

[0045] The second turbidity probe is the same model as the first turbidity probe and is installed in the lower part (outer part) of the vessel wall to monitor the control area far from the feed inlet.

[0046] Anti-interference measures: Each probe is equipped with a stainless steel flow-stabilizing sleeve at its front end to eliminate the instantaneous interference of high-speed turbulent bubbles on the optical path. The probe is equipped with a mechanical scraper-type self-cleaning device, which automatically scrapes and cleans the optical window every 15 minutes to remove cobalt slag crystals adhering to it.

[0047] Controller: Siemens S7-1200 series PLC, configured with analog input module (receives 4-20mA turbidity signal) and digital output module (drives alarm 6 and relay).

[0048] Host computer 5 (connected to the controller): Siemens TP700 touch screen, used to display real-time turbidity curves, historical data, alarm records and parameter settings.

[0049] Signal path: Turbidity detection probe → 4-20mA signal line → PLC analog input module → PLC internal logic operation (turbidity value / rate of change / difference between different positions) → digital output → alarm.

[0050] Establishment of time-division turbidity envelope and rate threshold: Step 1: Historical Data Collection Turbidity data were collected for 12 batches of normally produced cobalt hydroxide products (D50 target value 2±0.5μm) throughout the entire production process. For each batch, the turbidity values ​​of the first and second turbidity probes and the corresponding elapsed time were recorded.

[0051] Step 2: Time-sharing envelope generation Align the 12 batches of data by time and calculate the mean turbidity value and standard deviation σ at each time point. Definition: Upper envelope = average value + 2σ; The lower bound envelope = average value - 2σ.

[0052] Step 3: Determining the rate of change threshold Based on historical turbidity detection data from cobalt hydroxide synthesis, the rate of change threshold was set at ±40 NTU / min. That is, when the turbidity exceeds the upper limit and the rate of increase is >40 NTU / min, it is determined to be a nucleation explosion; if the rate of increase is ≤40 NTU / min, it is determined to be normal particle accumulation.

[0053] Example 1 When batch QJG2512001 has been running for 60 minutes (early growth stage): The turbidity value of the turbidity probe at the first location is 2250 NTU; the turbidity value of the turbidity probe at the second location is 2090 NTU. The turbidity at the first location is currently within the allowable range. The preset spatial difference is 250 NTU, and the actual difference is 160 NTU, which is also within the allowable range. The reaction process is judged to be normal. There is no alarm output; normal monitoring continues.

[0054] Example 2 When batch QJG2511003 reached the 35th minute of operation (the transition phase between the end of the nucleation period and the early stage of growth): The turbidity reading at the first location spiked from 2250 NTU to 2630 NTU within one minute (a rate of increase of 380 NTU / min). While the current allowable limit is 2700 NTU (not yet exceeded), the rate of change far exceeds the threshold of 40 NTU / min. A nucleation explosion warning is issued. The alarm's yellow warning light flashes, and the controller sends an alarm message: "Abnormal turbidity rise rate; it is recommended to check feed dispersion."

[0055] The worker did not intervene, and one minute later: The turbidity detected by the turbidity probe at the first location continued to rise to 2850 NTU, exceeding the current allowable upper limit of 2700 NTU. The rate of increase remained above 40 NTU / min, exceeding the threshold, confirming an abnormal nucleation eruption. The red audible and visual alarm was activated; the feed pump connected to the cobalt solution feed pipe was instructed to reduce the cobalt solution feed rate.

[0056] Example 3 When batch QJG251108 reached the 120-minute mark (late growth stage): The turbidity value of the turbidity probe at the first location is 1890 NTU (within the allowable range of 1600-2000); the turbidity value of the turbidity probe at the second location is 1620 NTU (within the allowable range of 1500-1900). The current allowable spatial difference is 200 NTU. This spatial difference exceeds the threshold. Although the individual turbidity values ​​of both probes are within the allowable range, the significant exceedance of the spatial difference indicates a large difference in mixing uniformity between the area near the feed inlet and the far end, potentially indicating localized oversaturation or a mixing dead zone. A mixing anomaly warning is issued. The alarm's yellow warning light flashes, and the controller pushes an alarm message: "Please check the mixing effect and feed dispersion."

[0057] The online monitoring device and method for cobalt hydroxide synthesis designed in this application, by introducing a rate of change judgment, can distinguish between "normal particle accumulation" and "abnormal nucleation bursts," avoiding frequent alarm triggers due to normal turbidity increases, thus improving system availability and operator confidence. Based on the severity and urgency of different anomaly types, it outputs different levels of response signals, such as warnings and alarms, to avoid excessive or insufficient intervention. Specifically targeting the high risk of localized oversaturation at the feed inlet of the cobalt hydroxide synthesis reactor and the natural decrease in turbidity due to α→β crystal transformation, it achieves precise monitoring of key process nodes through time-division envelope and rate analysis. Using a backscattering in-situ turbidimeter in conjunction with a flow-stabilizing guide sleeve and a self-cleaning device, it achieves continuous real-time detection under stirring conditions, overcoming the detection lag defects of traditional offline sampling schemes.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0059] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for online monitoring of cobalt hydroxide synthesis based on multidimensional turbidity characteristics, characterized in that the steps include... include: Obtain the turbidity at different detection locations inside the reactor; The detection positions include a first position and a second position, wherein the first position is closer to the cobalt liquid inlet than the second position; When the turbidity at all the detection locations does not exceed the preset turbidity range, the turbidity difference between the first location and the second location is calculated; When the turbidity difference is greater than a preset spatial difference, a mixing anomaly warning signal is output; When the turbidity at any of the detection locations is lower than the preset turbidity range, calculate the turbidity decrease rate at that detection location; When the turbidity decrease rate is greater than the preset decrease rate, an alarm signal for stagnant sedimentation is output. When the turbidity at any of the detection locations is higher than the preset turbidity range, the turbidity rise rate at that detection location is calculated; when the turbidity rise rate is greater than the preset rise rate, a nucleation burst alarm signal is output.

2. The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 1, characterized in that, The preset turbidity range includes the time turbidity correspondence for each of the detection locations. The time turbidity correspondence includes an upper limit relationship and a lower limit relationship. The upper limit relationship is the correspondence between the time elapsed during the cobalt hydroxide synthesis of the corresponding detection location and the upper limit of turbidity under that time elapsed. The lower limit relationship is the correspondence between the time elapsed during the cobalt hydroxide synthesis of the corresponding detection location and the lower limit of turbidity under that time elapsed.

3. The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 2, characterized in that, The time-turbidity correspondence is a time-division envelope, which includes an upper limit envelope and a lower limit envelope. The upper limit envelope is made according to the upper limit relationship, and the lower limit envelope is made according to the lower limit relationship.

4. The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 2, characterized in that, The steps for establishing the time-turbidity correspondence include: Historical data from multiple normal production processes that yielded qualified cobalt hydroxide products were collected. The historical data included the turbidity at the detection location and the elapsed time corresponding to that turbidity. The historical data is grouped according to the elapsed time, and the average turbidity and standard deviation of turbidity for each group are calculated. The upper limit of turbidity over the corresponding elapsed time is the sum of the average turbidity value and twice the standard deviation of turbidity. The difference between the average turbidity value and twice the standard deviation of turbidity is taken as the lower limit of turbidity over the corresponding elapsed time.

5. The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 1, characterized in that, While outputting the stagnation and settling alarm signal, the stirring speed of the reactor is increased.

6. The online monitoring method for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 1, characterized in that, While outputting the nucleation and explosion alarm signal, the cobalt liquid feed rate is reduced.

7. An online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics, characterized in that, It includes at least two sets of turbidity detection probes, which are respectively installed at a first position and a second position inside the reactor. The first position is closer to the cobalt liquid inlet than the second position. The turbidity detection probes are connected to a controller signal. The controller is used for: The turbidity at different detection locations within the reactor is obtained from the turbidity detection probe; the detection locations include the first location and the second location; When the turbidity at all the detection locations does not exceed the preset turbidity range, the turbidity difference between the first location and the second location is calculated; When the turbidity difference is greater than a preset spatial difference, a mixing anomaly warning signal is output; When the turbidity at any of the detection locations is lower than the preset turbidity range, calculate the turbidity decrease rate at that detection location; When the turbidity decrease rate is greater than the preset decrease rate, an alarm signal for stagnant sedimentation is output. When the turbidity at any of the detection locations is higher than the preset turbidity range, the turbidity rise rate at that detection location is calculated; when the turbidity rise rate is greater than the preset rise rate, a nucleation burst alarm signal is output.

8. The online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 7, characterized in that, It also includes an alarm device, which is connected to the controller via a signal. After receiving the mixed abnormality warning signal, the stagnant sedimentation alarm signal, or the nucleation and eruption alarm signal, the alarm device will issue different alarm prompts accordingly.

9. The online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 7, characterized in that, The reactor is equipped with a feed pipe, and the cobalt liquid inlet is located at the end of the feed pipe. The feed pipe is connected to a feed pump outside the reactor. The feed pump is signal-connected to the controller. When the controller outputs a nucleation explosion alarm signal, it instructs the feed pump to reduce the cobalt liquid feed rate.

10. The online monitoring device for cobalt hydroxide synthesis based on multidimensional turbidity characteristics according to claim 7, characterized in that, The reactor is equipped with a stirrer, which is signal-connected to the controller. When the controller outputs a stagnation and settling alarm signal, it instructs the stirrer to increase the stirring speed of the reactor.

Images