Regulation and control system and method of pH meter in waste lithium battery recovery process

Abstract

The invention discloses a regulation and control system and method of a pH meter in a waste lithium battery recovery process, and relates to the technical field of waste battery recovery treatment. The system comprises a central control module, a liquid caustic soda adjusting device and a liquid acid adjusting device, wherein a pH meter measures the pH value of a leaching solution of a leaching-stage reaction kettle in a waste lithium battery recycling process in real time; the central control module compares the pH value, measured in real time, of the leaching liquid in the leaching-stage reaction kettle with the pH value preset range of the leaching stage, acid liquid or alkali liquid is added into the leaching-stage reaction kettle according to the comparison result, and the pH value of the leaching liquid is adjusted to be within the pH value preset range of the leaching stage; the central control module can also identify interference factors measured by the pH meter and compensate the slope according to the current temperature so as to compensate the pH value, measured by the pH meter, of the leachate. According to the method, accurate control over the pH value in the leaching process can be effectively achieved, the recovery efficiency and quality of the waste lithium batteries are improved, and the production cost is reduced.

Description

Technical Field

[0001] This application relates to the field of waste battery recycling technology, and in particular to a pH meter control system and method in the waste lithium battery recycling process. Background Technology

[0002] In the leaching process of waste lithium battery recycling, precise control of the solution's pH is crucial for the efficient leaching of valuable metals and the smooth progress of subsequent processes. In traditional leaching processes, pH monitoring and control are often not precise or timely enough, leading to unstable leaching efficiency, low metal recovery rates, and inconsistent product quality. Furthermore, due to the complex environment of the leaching workshop and the presence of various interfering factors, ensuring the accurate and reliable operation of pH meters in such an environment is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0003] The purpose of this application is to provide a pH meter control system and method in the recycling process of waste lithium batteries, which can effectively achieve precise control of pH value during leaching, improve the efficiency and quality of waste lithium battery recycling, and reduce production costs.

[0004] To achieve the above objectives, this application provides the following solution.

[0005] In a first aspect, this application provides a pH meter control system in a waste lithium battery recycling process, comprising: a central control module, a liquid alkali adjustment device, and a liquid acid adjustment device; the signal output terminal of the pH meter is connected to the signal input terminal of the central control module, and the signal output terminal of the central control module is connected to the control terminals of the liquid alkali adjustment device and the liquid acid adjustment device, respectively; the pH meter is used to measure the pH value of the leachate in the leaching stage reactor in the waste lithium battery recycling process in real time; the central control module is used to compare the real-time measured pH value of the leachate in the leaching stage reactor with the preset pH range of the leaching stage; if the real-time measured pH value of the leachate in the leaching stage reactor is greater than the upper limit of the preset pH range of the leaching stage, then a PID control algorithm is used to control the liquid acid adjustment device to add acid to the leaching stage reactor, adjusting the pH value of the leachate to the preset pH range of the leaching stage; if If the real-time measured pH value of the leachate in the leaching stage reactor is less than the lower limit of the preset pH range for the leaching stage, a PID control algorithm is used to control the alkali adjustment device to add alkali solution to the leaching stage reactor, adjusting the pH value of the leachate to the preset pH range for the leaching stage. The central control module is also used to determine the current slope of the pH meter based on the real-time measured pH value of the leachate in the leaching stage reactor. If the current slope of the pH meter is different from the theoretical slope, the leachate temperature is determined to be an interfering factor, and the slope is compensated based on the current temperature of the leachate in the leaching stage reactor to compensate for the pH value measured by the pH meter.

[0006] Optionally, the pH meter is installed using an insertion method, with the pH meter probe installed at the slurry overflow port of the overflow pipe of the leaching stage reactor; the pH meter is equipped with a protective cover to prevent the pH meter probe from being damaged or blocked by the material.

[0007] Optionally, the liquid alkali regulating device includes: an alkali storage device and a liquid alkali flow regulating valve; the liquid acid regulating device includes: an acid storage device and a liquid acid flow regulating valve; the liquid alkali flow regulating valve is installed on the pipeline between the alkali storage device and the leaching stage reactor; the liquid acid flow regulating valve is installed on the pipeline between the acid storage device and the leaching stage reactor; the control terminals of both the liquid alkali flow regulating valve and the liquid acid flow regulating valve are connected to the signal output terminal of the central control module; the central control module adds alkali to the leaching stage reactor by controlling the opening of the liquid alkali flow regulating valve; the central control module adds acid to the leaching stage reactor by controlling the opening of the liquid acid flow regulating valve.

[0008] Optionally, in compensating for the slope based on the current temperature of the leachate in the leaching stage reactor to compensate for the pH value of the leachate measured by the pH meter, the central control module is specifically used to: obtain the compensated slope based on the current temperature of the leachate in the leaching stage reactor using the formula K1 = 2.303 RT / nF; where K1 is the compensated slope, T is the current temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction; and convert the electrode potential value of the pH meter probe into a pH value based on the compensated slope.

[0009] Optionally, the pH meter control system in the waste lithium battery recycling process further includes: a data transmission module and a display module; the signal input terminal of the data transmission module is connected to the signal output terminal of the pH meter, and the signal output terminal of the data transmission module is connected to the signal input terminal of the central control module and the signal input terminal of the display module respectively; the data transmission module is used to transmit the pH value of the leachate in the leaching stage reactor measured in real time by the pH meter to the central control module and the display module respectively; the display module is used to display the pH value of the leachate in the leaching stage reactor measured in real time.

[0010] Optionally, the pH meter control system in the waste lithium battery recycling process further includes: an alarm module and a mobile device; the signal output terminal of the central control module is connected to the control terminal of the alarm module and the signal input terminal of the mobile device respectively; the central control module is used to control the alarm module to perform an audible and visual alarm when the real-time measured pH value of the leaching solution in the leaching stage reactor is greater than the upper limit of the preset acidity and alkalinity range of the leaching stage, or when the real-time measured pH value of the leaching solution in the leaching stage reactor is less than the lower limit of the preset acidity and alkalinity range of the leaching stage, and simultaneously generate alarm information and transmit the alarm information to the mobile device.

[0011] Secondly, this application provides a method for regulating pH in a waste lithium battery recycling process, comprising: obtaining the pH value of the leachate in the leaching stage reactor of the waste lithium battery recycling process as measured in real time by the pH meter; if the real-time measured pH value of the leachate in the leaching stage reactor is greater than the upper limit of the preset pH range of the leaching stage, then using a PID control algorithm to control the liquid acid regulating device to add acid to the leaching stage reactor, adjusting the pH value of the leachate to the preset pH range of the leaching stage; if the real-time measured pH value of the leachate in the leaching stage reactor is less than the lower limit of the preset pH range of the leaching stage, then using a PID control algorithm to control the liquid alkali regulating device to add acid to the leaching stage reactor. Alkali solution is added to the leaching reactor to adjust the pH value of the leachate to the preset range of pH for the leaching stage. If the deviation between the real-time measured pH value of the leachate in the current leaching stage reactor and the pH value of the leachate in the previous leaching stage reactor is not equal to the deviation between the real-time measured pH value of the leachate in the current leaching stage reactor and the pH value of the leachate in the next leaching stage reactor, the current slope of the pH meter is determined based on the real-time measured pH value of the leachate in the current leaching stage reactor. If the current slope of the pH meter differs from the theoretical slope, the leachate temperature is determined to be an interfering factor. The slope is compensated based on the current temperature of the leachate in the current leaching stage reactor to compensate for the pH value of the leachate measured by the pH meter.

[0012] Optionally, the slope is compensated based on the current temperature of the leachate in the leaching stage reactor to compensate for the pH value of the leachate measured by the pH meter. Specifically, this includes: obtaining the compensated slope using the formula K = 2.303 RT / nF based on the current temperature of the leachate in the leaching stage reactor; where K is the slope, T is the temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction; and converting the electrode potential value of the pH meter probe into a pH value based on the compensated slope.

[0013] Optionally, the pH value of the leachate in the leaching stage reactor is obtained by real-time measurement with a pH meter, and then the process further includes: comparing the real-time measured pH value of the leachate in the leaching stage reactor with the historical pH value of the leachate in the leaching stage reactor to obtain the trend of pH value change of the leachate in the leaching stage reactor.

[0014] Optionally, the method for controlling the pH meter in the waste lithium battery recycling process further includes: preparing at least two standard buffer solutions with different pH values ​​according to a predetermined calibration cycle, and removing the pH meter from the leaching solution and placing it in one of the standard buffer solutions; reading the pH value measured by the pH meter in one of the standard buffer solutions; comparing the pH value measured by the pH meter with the pH value of one of the standard buffer solutions; if the pH value measured by the pH meter is different from the pH value of one of the standard buffer solutions, then calculating the calibration slope of the pH meter based on the pH values ​​of any two standard buffer solutions using the formula K2 = (E2 - E1) / (pH2 - pH1); where K2 is the calibration slope, E1 is the potential value of the pH meter electrode in the first standard buffer solution, E2 is the potential value of the pH meter electrode in the second standard buffer solution, pH1 is the pH value of the first standard buffer solution, and pH2 is the pH value of the second standard buffer solution.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects.

[0016] This application provides a pH meter control system and method in the recycling process of waste lithium batteries. The central control module can accurately control the pH value of the leachate, enabling valuable metals in waste lithium batteries to be fully leached under optimal acid-base conditions, thereby improving leaching efficiency. Stable pH control ensures the consistency and reliability of the leaching process, allowing subsequent separation, purification, and other processes to proceed smoothly, resulting in consistently high-quality recycled products. The central control module can also identify and compensate for interference factors during pH meter measurement, reducing measurement errors and further improving the quality of waste lithium battery recycling. Precise automatic pH control reduces the excessive use of acid-base regulators, lowers raw material costs, and reduces scrap rates and equipment maintenance costs caused by process instability, thus reducing the overall production cost of waste lithium battery recycling. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments 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.

[0018] Figure 1 This is a schematic diagram of the structure of a pH meter control system in a waste lithium battery recycling process according to one embodiment of this application.

[0019] Figure 2 This is a schematic flowchart illustrating a method for controlling pH in the recycling process of waste lithium batteries, as provided in an embodiment of this application.

[0020] Attached reference numerals: 1-Reaction vessel, 2-Liquid alkali flow regulating valve, 3-Liquid acid flow regulating valve, 4-Instrument system, 5-Stirring device. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In one exemplary embodiment, a pH meter control system is provided in a waste lithium battery recycling process, comprising: a central control module, a liquid alkali adjustment device, and a liquid acid adjustment device. The signal output terminal of the pH meter is connected to the signal input terminal of the central control module, and the signal output terminal of the central control module is connected to the control terminals of the liquid alkali adjustment device and the liquid acid adjustment device, respectively.

[0024] The pH meter is used to measure the pH value of the leachate in the leaching stage reactor 1 during the waste lithium battery recycling process in real time.

[0025] The central control module compares the real-time measured pH value of the leachate in the leaching stage reactor 1 with the preset pH range of the leaching stage. If the real-time measured pH value of the leachate in the leaching stage reactor 1 is greater than the upper limit of the preset pH range, a PID control algorithm is used to control the acid adjustment device to add acid to the leaching stage reactor 1, adjusting the pH value of the leachate to the preset pH range of the leaching stage. If the real-time measured pH value of the leachate in the leaching stage reactor 1 is less than the lower limit of the preset pH range, a PID control algorithm is used to control the alkali adjustment device to add alkali to the leaching stage reactor 1, adjusting the pH value of the leachate to the preset pH range of the leaching stage.

[0026] The central control module is also used to determine the current slope of the pH meter based on the real-time measured pH value of the leaching solution in the current leaching stage reactor 1. If the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor 1 and the pH value of the leaching solution in the previous leaching stage reactor 1 is not equal to the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor 1 and the pH value of the leaching solution in the next leaching stage reactor 1, the module determines the current slope of the pH meter based on the real-time measured pH value of the leaching solution in the current leaching stage reactor 1. If the current slope of the pH meter is different from the theoretical slope, the leaching solution temperature is determined to be an interfering factor, and the slope is compensated based on the current temperature of the leaching solution in the current leaching stage reactor 1 to compensate for the pH value of the leaching solution measured by the pH meter.

[0027] The waste lithium battery recycling process has multiple leaching stages, and each leaching stage has a reaction vessel 1.

[0028] For example, if the pH value of the leachate in the leaching stage reactor 1, measured in real time, is greater than the upper limit of the preset pH range for the leaching stage, then an acid solution (such as sulfuric acid solution) is added. If the pH value of the leachate in the leaching stage reactor 1, measured in real time, is less than the lower limit of the preset pH range for the leaching stage, then an appropriate amount of alkali solution (such as sodium hydroxide solution) is added.

[0029] In one embodiment, an industrial-grade pH meter with high sensitivity, fast response, and good stability is selected, suitable for the harsh environment of the leaching workshop, and able to resist the effects of acid and alkali corrosion, high temperature, and high humidity. The pH meter adopts an insertion installation method. Because the target metal element in reactor 1 continuously reacts with the sulfuric acid solution, the pH value inside reactor 1 is not completely consistent. For continuous leaching, the pH value of the current leaching stage is measured at the overflow port of the next stage. Therefore, the pH meter probe is installed at the slurry overflow port of the overflow pipe of reactor 1 in the current leaching stage (the optimal measurement position) to ensure accurate reflection of the true pH value of the leachate. The pH meter is equipped with a protective sleeve to prevent damage to the probe or blockage of the material. Simultaneously, the installation position of the pH meter facilitates regular cleaning and calibration, ensuring the measurement accuracy of the pH meter.

[0030] In another embodiment, the liquid alkali regulating device includes: an alkali storage device and a liquid alkali flow regulating valve 2; the liquid acid regulating device includes: an acid storage device and a liquid acid flow regulating valve 3. The liquid alkali flow regulating valve 2 is installed on the pipeline between the alkali storage device and the leaching stage reactor 1; the liquid acid flow regulating valve 3 is installed on the pipeline between the acid storage device and the leaching stage reactor 1.

[0031] The control terminals of both the liquid alkali flow regulating valve 2 and the liquid acid flow regulating valve 3 are connected to the signal output terminal of the central control module. The central control module adds alkali solution to the leaching stage reactor 1 by controlling the opening degree of the liquid alkali flow regulating valve 2. The central control module adds acid solution to the leaching stage reactor 1 by controlling the opening degree of the liquid acid flow regulating valve 3.

[0032] Both the alkali and acid storage devices employ constant pressure delivery and are equipped with high-precision pneumatic regulating valves (i.e., liquid alkali flow regulating valve 2 and liquid acid flow regulating valve 3), enabling precise addition of acid or alkali to reaction vessel 1 based on the magnitude and direction of pH deviation. The central control module automatically adjusts the opening of the pneumatic regulating valves in real time based on data feedback from the pH meter, controlling the flow rate and achieving closed-loop automatic pH control to ensure the pH of the leachate remains consistently within the optimal range.

[0033] Figure 1 The pH meter control system shown in the waste lithium battery recycling process also includes an instrument system 4, which is connected to the liquid alkali flow regulating valve 2 and the liquid acid flow regulating valve 3 respectively, and is used to display the opening degree of the liquid alkali flow regulating valve 2 and the liquid acid flow regulating valve 3.

[0034] In another embodiment, to address potential interference factors in the leaching workshop, such as impurities in the solution and electrode aging, the measurement error caused by the interference factors is automatically identified and compensated through real-time analysis of the pH meter measurement data, thereby improving the accuracy of pH measurement.

[0035] The pH value of the leachate measured by the pH meter is usually relatively stable, and may increase or decrease slowly, but there is a general trend of higher pH values ​​than the previous leaching stage and lower pH values ​​than the next leaching stage. If there is a large deviation in the pH values ​​between the leaching stages, the central control module will first check whether the measurement error is caused by the system solution temperature. If so, it will compensate. If the deviation still exists after self-check and compensation, the operator will be notified to perform manual calibration or replace the pH meter probe.

[0036] In compensating for the slope based on the current temperature of the leachate in leaching stage reactor 1, and in order to compensate for the pH value of the leachate measured by the pH meter, the central control module is specifically used to: obtain the compensated slope based on the current temperature of the leachate in leaching stage reactor 1 using the formula K1 = 2.303 RT / nF; where K1 is the compensated slope, T is the current temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction; generally, the temperature coefficient F = 3.35 × 10⁻⁶. -3 / ℃. At 25 degrees Celsius, the theoretical value K = -59.16 mV / pH. Based on the compensated slope, the electrode potential value of the pH meter probe is converted into a pH value.

[0037] For example, under normal circumstances, using a standard slope (theoretical slope) at 25 degrees Celsius, the pH value is calculated based on the measured potential difference. This standard slope is 59.16. When the potential value is 177 mV, the calculated pH value is 4.01. When the temperature rises, for example to 50 degrees Celsius, the slope of the curve will become steeper. For the same potential value of 177 mV, the calculated pH value will not be 4.01, but a value greater than 4.01, such as 4.08. Therefore, temperature compensation is needed to reduce the current intensity caused by temperature changes, thereby reducing the potential difference and making the displayed potential value slightly lower, for example, 170.25 mV. The pH value corresponding to this lower potential difference on the original slope curve is the correct real-time value, i.e., 4.08.

[0038] In another embodiment, the pH meter control system in the waste lithium battery recycling process further includes a data transmission module and a display module. The signal input terminal of the data transmission module is connected to the signal output terminal of the pH meter, and the signal output terminal of the data transmission module is connected to the signal input terminals of both the central control module and the display module. The data transmission module transmits the real-time pH value of the leachate from the leaching stage reactor 1, measured by the pH meter, to both the central control module and the display module. The display module displays the real-time pH value of the leachate from the leaching stage reactor 1.

[0039] The data transmission module transmits data to the central control module via wired transmission. The central control module is equipped with professional data acquisition and processing software, which can display, record and analyze pH values ​​in real time.

[0040] In another embodiment, a periodic calibration system is designed to calibrate the pH meter using a standard buffer solution. The calibration cycle is determined based on actual usage and accuracy requirements, typically once a month. During calibration, the system automatically controls the calibration process to ensure the accuracy and stability of the pH meter. Simultaneously, calibration data is recorded to track and evaluate the pH meter's performance.

[0041] In another embodiment, the pH meter control system in the waste lithium battery recycling process further includes an alarm module and a mobile device. The signal output terminal of the central control module is connected to the control terminal of the alarm module and the signal input terminal of the mobile device, respectively.

[0042] The central control module is used to control the alarm module to issue an audible and visual alarm when the pH value of the leaching solution in the leaching stage reactor 1, as measured in real time, is greater than the upper limit of the preset acidity and alkalinity range of the leaching stage, or when the pH value of the leaching solution in the leaching stage reactor 1, as measured in real time, is less than the lower limit of the preset acidity and alkalinity range of the leaching stage. At the same time, the alarm information is transmitted to the mobile device.

[0043] The system is equipped with an alarm function for abnormal data. When the pH value exceeds the preset normal range, the system automatically issues an audible and visual alarm to remind operators to handle the situation promptly. Simultaneously, the central control module can send alarm information to the mobile devices of relevant personnel, ensuring that the problem receives timely attention and resolution.

[0044] For example, in the first stage of low-acid leaching, the pH value may be adjusted to 1.5-2.5; in the second stage of high-acid leaching, the pH value is usually less than 0.5; and in the subsequent iron and aluminum precipitation processes, the pH value is in the range of 3.5-4.5, while the pH value range for magnesium precipitation is 4.5-5.5. If the pH value exceeds its respective range during these processes, it may affect the leaching efficiency and purity of nickel, cobalt, and manganese.

[0045] The detailed working process of the pH meter control system in the waste lithium battery recycling process of this application is as follows.

[0046] (a) Preparation for leaching process.

[0047] Waste lithium batteries are sent to the leaching workshop for pretreatment, including dismantling and crushing, to obtain materials suitable for leaching.

[0048] The pretreated material is added to reactor 1, and a leaching agent (such as sulfuric acid solution) is added according to a certain liquid-solid ratio to prepare for the leaching reaction.

[0049] (ii) Installation and debugging of pH meter.

[0050] Based on the structure and process requirements of reactor 1, select a suitable pH meter model and install the pH meter probe at the slurry overflow port of the overflow pipe of reactor 1. Ensure that the pH meter probe is securely installed and in full contact with the solution.

[0051] Connect the pH meter to the central control module to perform communication tests and parameter settings. Start the pH meter to put it into working condition, and at the same time, set parameters such as pH monitoring frequency and alarm threshold in the central control module.

[0052] The pH meter was calibrated using a standard buffer solution. The calibration process was carried out in accordance with the equipment manual and the operating procedures of the calibration system to ensure that the pH meter had an accurate initial value before measurement.

[0053] (iii) pH monitoring and control during the leaching process.

[0054] Turn on the stirring device 5 and heating device of the leaching reactor 1 to fully mix the material and leaching agent and maintain it at a certain temperature (80℃-85℃).

[0055] The pH meter measures the pH value of the leachate in real time and transmits the pH value to the central control module. The central control module displays and analyzes the pH value in real time.

[0056] When the pH value deviates from the set target range (e.g., 3.5-5), the central control module automatically activates the acid-base adjustment device. If the pH value is too low, the liquid alkali regulating valve automatically opens, adding an appropriate amount of alkali solution (e.g., sodium hydroxide solution) to reaction vessel 1; if the pH value is too high, acid solution (e.g., sulfuric acid solution) is added. By optimizing the PID control parameters, automatic adjustments are made according to the magnitude of the pH value deviation to quickly adjust the pH value to the target range.

[0057] Throughout the leaching process, the system continuously monitors pH changes and adjusts the amount of acid and alkali added based on actual conditions to ensure that the pH of the leachate remains stable within the optimal range, thereby achieving efficient leaching of valuable metals.

[0058] (iv) Interference factor compensation and calibration operation.

[0059] The central control module periodically analyzes the trends and fluctuations in pH meter measurement data, taking into account factors such as solution composition, temperature, and electrode usage time, to determine if any interfering factors are affecting the measurement results. If interference is detected, it automatically calculates and compensates for the corresponding errors to ensure the accuracy of pH value measurements. The solution composition is obtained through sampling and offline measurement using an inductively coupled plasma atomic emission spectrometer (ICP-AES).

[0060] Electrode usage time relates to two points: ① Electrode aging: pH meter electrodes age over time, affecting their response and accuracy. Electrode aging can lead to increased pH errors; ② Calibration frequency: The calibration frequency depends on the electrode's use, maintenance, sample properties, and measurement accuracy. It is recommended to calibrate weekly and replace the electrode. If the meter will not be used for an extended period, calibration must be performed before use.

[0061] Perform pH meter calibration according to the predetermined calibration cycle (e.g., weekly). First, prepare a standard buffer solution, such as a buffer solution with pH=4.00, pH=6.86, or pH=9.18. Remove the pH meter probe from the leaching solution, clean it thoroughly, and then place it in the standard buffer solution.

[0062] The calibration procedure is initiated in the central control module, automatically reading the pH meter's measurement value in the standard buffer solution and comparing it with the standard value. Based on the comparison result, the pH meter's calibration parameters are automatically adjusted to ensure the measured value matches the standard value. After calibration, the pH meter probe is reinstalled, and pH monitoring and control continue.

[0063] (v) System operation, maintenance and data recording.

[0064] Regularly maintain and inspect equipment such as pH meters, acid-base adjustment devices, and central control modules to ensure their normal operation. Inspections include checking the cleanliness of the pH meter probe, the condition of the electrodes, the working status of control valves, and the connections of communication lines. Repair or replace any problems promptly.

[0065] Establish a system operation data record archive to record in detail information such as pH value, acid and alkali solution addition, and equipment operating status during the leaching process. Regularly analyze the data to summarize pH value change patterns and process operation status, providing a basis for optimizing process parameters and equipment maintenance.

[0066] Operators should be trained to familiarize themselves with the system's operating procedures, maintenance points, and emergency handling methods. This ensures operators can correctly use and maintain the control system, promptly handle various abnormal situations, and guarantee the stable operation of the waste lithium battery recycling process.

[0067] This application optimizes the application of pH meters and supporting systems to achieve accurate and real-time monitoring and control of the pH value of the leachate during the leaching process, thereby improving the leaching efficiency and quality of valuable metals from waste lithium batteries, reducing production costs, and enhancing the stability and reliability of the system to adapt to the complex working environment of the leaching workshop.

[0068] Based on the same inventive concept, this application also provides a method for controlling a pH meter in a waste lithium battery recycling process, which is applied to the pH meter control system described above. The solution provided by this method is similar to the solution described above. Therefore, the specific limitations of one or more pH meter control methods in waste lithium battery recycling processes provided below can be found in the limitations of the pH meter control system in the waste lithium battery recycling process described above, and will not be repeated here.

[0069] In one exemplary embodiment, such as Figure 2 As shown, a method for adjusting pH in the recycling process of waste lithium batteries is provided, including the following steps 101 to 106.

[0070] Step 101: Obtain the pH value of the leachate in the leaching stage reactor of the waste lithium battery recycling process, measured in real time by a pH meter.

[0071] Step 102: If the pH value of the leachate in the leaching stage reactor measured in real time is greater than the upper limit of the preset pH range of the leaching stage, then the PID control algorithm is used to control the liquid acid adjustment device to add acid to the leaching stage reactor and adjust the pH value of the leachate to the preset pH range of the leaching stage.

[0072] Step 103: If the pH value of the leachate in the leaching stage reactor measured in real time is less than the lower limit of the preset acidity / alkalinity range of the leaching stage, then the PID control algorithm is used to control the alkali adjustment device to add alkali solution to the leaching stage reactor and adjust the pH value of the leachate to the preset acidity / alkalinity range of the leaching stage.

[0073] Step 104: If the deviation between the real-time measured pH value of the leachate in the current leaching stage reactor and the pH value of the leachate in the previous leaching stage reactor is not equal to the deviation between the real-time measured pH value of the leachate in the current leaching stage reactor and the pH value of the leachate in the next leaching stage reactor, then determine the current slope of the pH meter based on the real-time measured pH value of the leachate in the current leaching stage reactor.

[0074] Step 105: If the current slope of the pH meter is different from the theoretical slope, then the temperature of the leachate is determined to be an interfering factor.

[0075] Step 106: Based on the current temperature of the leachate in the leaching stage reactor, compensate the slope to compensate for the pH value of the leachate measured by the pH meter.

[0076] Implementing steps 101 to 106 above can effectively achieve precise control of pH value during the leaching process, improve the efficiency and quality of waste lithium battery recycling, reduce costs, and has significant economic and environmental benefits.

[0077] In another exemplary embodiment of this application, step 106 described above may be replaced by steps 201 to 202.

[0078] Step 201: Based on the current temperature of the leachate in the leaching stage reactor, use the formula K = 2.303 RT / nF to obtain the compensated slope; where K is the slope, T is the temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction. Step 202: Based on the compensated slope, convert the electrode millivolt signal of the pH meter probe into a pH value.

[0079] In another exemplary embodiment of this application, in order to further maintain a relatively stable pH value, after step 101 above, the method may further include: comparing the real-time measured pH value of the leachate in the leaching stage reactor with the historical pH value of the leachate in the leaching stage reactor to obtain the pH value change trend of the leachate in the leaching stage reactor.

[0080] The main purpose of comparing the pH value with the historical leachate is to summarize whether the data at the pH measurement point is increasing or decreasing, so as to ensure that the pH value at the pH measurement point is relatively stable during the continuous overflow leaching process, so as to achieve the required target metal leaching rate within the designed leaching stages.

[0081] In another exemplary embodiment of this application, in order to track and evaluate the performance of the pH meter, the method of this application may further include the following steps 301 to 304.

[0082] Step 301: According to the predetermined calibration cycle, prepare at least two standard buffer solutions with different pH values, and remove the pH meter from the leaching solution and place it in one of the standard buffer solutions.

[0083] Step 302: Read the pH value measured by the pH meter in a standard buffer solution.

[0084] Step 303: Compare the pH value measured by the pH meter with the pH value of a standard buffer solution.

[0085] Step 304: If the pH value measured by the pH meter is different from the pH value of a standard buffer solution, calculate the calibration slope of the pH meter based on the pH values ​​of any two standard buffer solutions using the formula K2 = (E2 - E1) / (pH2 - pH1); where K2 is the calibration slope, E1 is the potential value of the pH meter electrode in the first standard buffer solution, E2 is the potential value of the pH meter electrode in the second standard buffer solution, pH1 is the pH value of the first standard buffer solution, and pH2 is the pH value of the second standard buffer solution.

[0086] The beneficial effects of this application are as follows.

[0087] (1) Improve leaching efficiency and metal recovery rate.

[0088] By precisely controlling the pH value of the leachate, valuable metals from spent lithium batteries are fully leached under optimal acid-base conditions, improving leaching efficiency and metal recovery rate. Experimental data show that using the control system and method of this application can increase the leaching rate of valuable metals by more than 10% compared to traditional methods, effectively reducing resource waste.

[0089] (2) Ensure product quality stability.

[0090] Stable pH control ensures the consistency and reliability of the leaching process, enabling subsequent separation and purification processes to proceed smoothly and yielding consistently high-quality recycled products. The purity and performance indicators of the products better meet market requirements, enhancing their market competitiveness.

[0091] (3) Reduce production costs.

[0092] Precise automatic pH control reduces the excessive use of acid and alkali solutions, lowering raw material costs. Simultaneously, it improves production efficiency, reduces scrap rates and equipment maintenance costs caused by process instability, and overall lowers the production cost of recycling waste lithium batteries.

[0093] (4) Enhance the stability and reliability of the system.

[0094] Interference compensation and periodic calibration systems ensure the long-term stable operation of pH meters in the complex environment of the leaching workshop, reducing production accidents and quality problems caused by measurement errors. This improves the stability and reliability of the entire recycling process and reduces production risks.

[0095] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A pH meter control system in the recycling process of waste lithium batteries, characterized in that, The pH meter's control system in the waste lithium battery recycling process includes: a central control module, a liquid alkali adjustment device, and a liquid acid adjustment device. The signal output terminal of the pH meter is connected to the signal input terminal of the central control module, and the signal output terminal of the central control module is connected to the control terminal of the liquid alkali adjustment device and the control terminal of the liquid acid adjustment device, respectively. The pH meter is used to measure the pH value of the leachate in the leaching stage reactor during the waste lithium battery recycling process in real time. The central control module compares the real-time measured pH value of the leachate in the leaching stage reactor with the preset pH range of the leaching stage. If the real-time measured pH value of the leachate in the leaching stage reactor is greater than the upper limit of the preset pH range, a PID control algorithm is used to control the acid adjustment device to add acid to the leaching stage reactor, adjusting the pH value of the leachate to the preset pH range of the leaching stage. If the real-time measured pH value of the leachate in the leaching stage reactor is less than the lower limit of the preset pH range, a PID control algorithm is used to control the alkali adjustment device to add alkali to the leaching stage reactor, adjusting the pH value of the leachate to the preset pH range of the leaching stage. The central control module is also used to determine the current slope of the pH meter based on the real-time measured pH value of the leaching solution in the current leaching stage reactor when the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor and the pH value of the leaching solution in the previous leaching stage reactor is not equal to the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor and the pH value of the leaching solution in the next leaching stage reactor. If the current slope of the pH meter is different from the theoretical slope, the leaching solution temperature is determined to be an interfering factor, and the slope is compensated based on the current temperature of the leaching solution in the current leaching stage reactor to compensate for the pH value of the leaching solution measured by the pH meter.

2. The pH meter control system in the waste lithium battery recycling process according to claim 1, characterized in that, The pH meter is installed using an insertion method, with the probe of the pH meter installed at the slurry overflow port of the overflow pipe of the leaching stage reactor. The pH meter is equipped with a protective cover to prevent damage to the pH meter probe or blockage of materials.

3. The pH meter control system in the waste lithium battery recycling process according to claim 1, characterized in that, The liquid alkali regulating device includes: an alkali storage device and a liquid alkali flow regulating valve; the liquid acid regulating device includes: an acid storage device and a liquid acid flow regulating valve; The liquid alkali flow regulating valve is installed on the pipeline between the alkali storage device and the leaching stage reactor; the liquid acid flow regulating valve is installed on the pipeline between the acid storage device and the leaching stage reactor. The control terminals of both the liquid alkali flow regulating valve and the liquid acid flow regulating valve are connected to the signal output terminal of the central control module. The central control module adds alkali solution to the leaching stage reactor by controlling the opening of the alkali flow regulating valve. The central control module adds acid to the leaching stage reactor by controlling the opening of the liquid acid flow regulating valve.

4. The pH meter control system in the waste lithium battery recycling process according to claim 1, characterized in that, In compensating for the slope based on the current temperature of the leachate in the leaching stage reactor, and in order to compensate for the pH value of the leachate measured by the pH meter, the central control module is specifically used for: Based on the current temperature of the leachate in the leaching stage reactor, the compensated slope is obtained using the formula K1 = 2.303 RT / nF; where K1 is the compensated slope, T is the current temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction. Based on the compensated slope, the electrode potential value of the pH meter probe is converted into a pH value.

5. The pH meter control system in the waste lithium battery recycling process according to claim 1, characterized in that, The pH meter control system in the waste lithium battery recycling process also includes: a data transmission module and a display module; The signal input terminal of the data transmission module is connected to the signal output terminal of the pH meter, and the signal output terminal of the data transmission module is connected to the signal input terminal of the central control module and the signal input terminal of the display module, respectively. The data transmission module is used to transmit the pH value of the leachate in the leaching stage reactor, which is measured in real time by the pH meter, to the central control module and the display module respectively. The display module is used to display the real-time pH value of the leachate from the leaching stage reactor.

6. The pH meter control system in the waste lithium battery recycling process according to claim 1, characterized in that, The pH meter control system in the waste lithium battery recycling process also includes: an alarm module and a mobile device; The signal output terminal of the central control module is connected to the control terminal of the alarm module and the signal input terminal of the mobile device, respectively. The central control module is used to control the alarm module to issue an audible and visual alarm when the pH value of the leaching solution in the leaching stage reactor, as measured in real time, is greater than the upper limit of the preset range of acidity and alkalinity for the leaching stage, or when the pH value of the leaching solution in the leaching stage reactor, as measured in real time, is less than the lower limit of the preset range of acidity and alkalinity for the leaching stage. At the same time, the alarm information is transmitted to the mobile device.

7. A method for pH meter control in the recycling process of waste lithium batteries, characterized in that, The pH meter is used for pH control in the waste lithium battery recycling process, including: Obtain the pH value of the leachate from the leaching stage reactor in the waste lithium battery recycling process, measured in real time by a pH meter. If the pH value of the leachate in the leaching stage reactor measured in real time is greater than the upper limit of the preset range of acidity and alkalinity of the leaching stage, the PID control algorithm is used to control the liquid acid adjustment device to add acid to the leaching stage reactor and adjust the pH value of the leachate to the preset range of acidity and alkalinity of the leaching stage. If the pH value of the leachate in the leaching stage reactor measured in real time is less than the lower limit of the preset range of acidity and alkalinity of the leaching stage, the PID control algorithm is used to control the alkali adjustment device to add alkali solution to the leaching stage reactor and adjust the pH value of the leachate to the preset range of acidity and alkalinity of the leaching stage. If the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor and the pH value of the leaching solution in the previous leaching stage reactor is not equal to the deviation between the real-time measured pH value of the leaching solution in the current leaching stage reactor and the pH value of the leaching solution in the next leaching stage reactor, then the current slope of the pH meter is determined based on the real-time measured pH value of the leaching solution in the current leaching stage reactor. If the current slope of the pH meter differs from the theoretical slope, then the temperature of the leachate is determined to be a disturbing factor. The slope is compensated based on the current temperature of the leachate in the leaching stage reactor to compensate for the pH value of the leachate measured by the pH meter.

8. The method for pH meter control in the waste lithium battery recycling process according to claim 7, characterized in that, The slope is compensated based on the current temperature of the leachate in the leaching stage reactor to compensate for the pH value of the leachate measured by the pH meter. Specifically, this includes: Based on the current temperature of the leachate in the leaching stage reactor, the compensated slope is obtained using the formula K = 2.303 RT / nF; where K is the slope, T is the temperature, F is the temperature coefficient, R is the molar gas constant, and n is the number of electrons transferred in the electrode reaction. Based on the compensated slope, the electrode potential value of the pH meter probe is converted into a pH value.

9. The method for pH meter control in the recycling process of waste lithium batteries according to claim 7, characterized in that, Obtain the pH value of the leachate from the leaching stage reactor, measured in real time by a pH meter, and then include: By comparing the real-time measured pH value of the leachate from the leaching stage reactor with the historical pH value of the leachate from the leaching stage reactor, the trend of pH value change of the leachate from the leaching stage reactor can be obtained.

10. The method for adjusting pH in the recycling process of waste lithium batteries according to claim 7, characterized in that, The method for adjusting the pH level using a pH meter in the waste lithium battery recycling process also includes: Prepare at least two standard buffer solutions with different pH values ​​according to the predetermined calibration cycle, and remove the pH meter from the leaching solution and place it in one of the standard buffer solutions. Read the pH value measured by the pH meter in a standard buffer solution; Compare the pH value measured by a pH meter with the pH value of a standard buffer solution; If the pH value measured by the pH meter differs from the pH value of a standard buffer solution, the calibration slope of the pH meter can be calculated using the formula K2 = (E2 - E1) / (pH2 - pH1) based on the pH values ​​of any two standard buffer solutions. In the formula, K2 is the calibration slope, E1 is the potential value of the pH meter electrode in the first standard buffer solution, E2 is the potential value of the pH meter electrode in the second standard buffer solution, pH1 is the pH value of the first standard buffer solution, and pH2 is the pH value of the second standard buffer solution.

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