Continuous crystallization mother liquor concentration regulation and impurity removal device and method

Abstract

The application provides a continuous crystallization mother liquor concentration regulation and impurity removal device and method, and belongs to the technical field of continuous crystallization equipment. A suction circulating pipe is designed outside the crystallization tank to ensure that the mother liquor fully flows in the whole continuous crystallization system, the concentration of the crystallization mother liquor is homogenized, and local supersaturation and thermal crystallization are avoided. A first inner pipe is arranged above the working liquid level in the crystallization tank to draw out the upper impurities and the accumulated light component mother liquor of the crystallization tank. In combination with the design of the open mother liquor and the impurity separation device, not only can the crystallization rate be reduced due to the too low local concentration, but also the impurities enriched at the top of the crystallization tank can be discharged, so that the influence of the impurities on the crystal quality is greatly reduced. In combination with the mother liquor parameter monitoring device arranged on the outer circulating pipe, the parameters of the crystallization mother liquor can be monitored in real time, the mother liquor extraction and circulation amount are more controllable, the crystallization environment stability is improved, and the efficient and stable generation of large particle crystals is facilitated.

Description

Technical Field

[0001] This invention relates to the field of continuous crystallization equipment technology, and more specifically, to a device and method for adjusting and removing impurities from the concentration of mother liquor in continuous crystallization. Background Technology

[0002] Evaporation crystallization is the final step in the industrial production of nickel sulfate and cobalt sulfate crystals. The concentration management and impurity control of the mother liquor in the crystallizer are crucial factors determining the quality of the crystalline product. To avoid the impact of impurities accumulated in the crystallization system on the crystallization rate and product quality, and to adjust the solution concentration, maintain appropriate supersaturation, promote uniform crystal growth, and improve product quality, it is necessary to partially open the mother liquor. Opening a low-concentration mother liquor prevents the solution concentration from becoming too low, maintains a certain level of supersaturation, and allows for rapid adjustment of the mother liquor concentration within the crystallizer, ensuring the crystallization process remains within a benign and controllable range. Impurities accumulated in the mother liquor can inhibit crystallization or affect product purity; opening the liquor helps to remove these impurities, ensuring the high quality of the final product.

[0003] However, current technologies cannot accurately detect the concentration of mother liquor in continuous crystallization equipment in real time, requiring manual observation and sampling for verification. This leads to lag in process adjustment, difficulty in control, low production efficiency, and the need for routine manual intervention. The concentration of crystallization mother liquor can only be indirectly adjusted by modifying the operating parameters of the front-end evaporation system, making it difficult to achieve steady-state operation. Furthermore, nickel sulfate mother liquor can only be purified and partially opened after centrifugation and filtration to collect the crystal slurry. It cannot effectively purify the light components and impurities retained in the accumulated layer of the crystallizer. As a result, these impurities are carried over to the product during solid-liquid separation, leading to unstable product quality and even difficulty in crystallizing in the crystallizer. Purifying the collected mother liquor after centrifugation and filtration dilutes the impurities with a large amount of mother liquor, increasing the amount of open-circuit mother liquor and reducing purification efficiency. When the purified mother liquor returns to the front-end production process, it increases the overall solution volume of the production system, leading to higher equipment investment and operating costs.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a continuous crystallization mother liquor concentration control and impurity removal device and method to solve the problems in the prior art, such as the inability to accurately detect the concentration of mother liquor in the continuous crystallization equipment in real time, requiring manual observation and sampling inspection and verification, resulting in lag in process adjustment, high control difficulty, low production efficiency, and difficulty in forming steady-state operation; and the inability to effectively purify light component liquid and impurities retained in the crystallizer accumulation layer, resulting in unstable product quality.

[0006] The continuous crystallization mother liquor concentration control and impurity removal device provided by this invention is used for concentration control and impurity removal of the mother liquor during the continuous crystallization process of nickel sulfate or cobalt sulfate; it includes a suction circulation pipe, an impurity separation device, and a mother liquor parameter monitoring device; wherein,

[0007] The suction circulation pipe includes a first inner tube and a second inner tube respectively disposed above and below the working liquid level inside the crystallization tank, and an outer circulation pipe respectively connected to the first inner tube and the second inner tube; wherein...

[0008] The external circulation pipe includes an upper mother liquor suction pipe connected to the first inner tube, a delivery pipe connected to the upper mother liquor suction pipe and delivering the upper mother liquor to each processing stage of the continuous crystallization system, a return pipe connected to each processing stage, a circulation pump connected to the return pipe, a circulation main pipe connected to the circulation pump, a mother liquor circulation pipe and a mother liquor open circuit connected to the circulation main pipe respectively; the outlet end of the mother liquor circulation pipe is connected to the inlet end of the second inner tube;

[0009] The inlet of the impurity separation device is open-circuited with the mother liquor; the outlet of the mother liquor of the impurity separation device is connected to the raw liquid inlet of the continuous crystallization system.

[0010] The mother liquor parameter monitoring device is installed on the external circulation pipe.

[0011] Furthermore, in a preferred embodiment, the return pipe is connected to the circulation pump via a main manifold.

[0012] Furthermore, a preferred embodiment includes an overflow port on the inner wall of the crystallization tank; a mother liquor overflow pipe at the overflow port; the mother liquor overflow pipe connected to the upper mother liquor suction pipe; an overflow baffle at the overflow port inside the crystallization tank; the overflow baffle includes a horizontal plate and a vertical plate vertically disposed at one end of the horizontal plate; the top of the vertical plate is flush with the working liquid level; the horizontal plate is disposed near the overflow port and flush with the bottom of the overflow port.

[0013] Furthermore, a preferred embodiment includes a central control mechanism; the central control mechanism includes a data analysis and comparison module and a control command generation module connected to the data analysis and comparison module; the data analysis and comparison module is connected to the mother liquor parameter monitoring device; and the control command generation module is connected to the crystallization parameter control mechanism of the continuous crystallization system.

[0014] Furthermore, a preferred embodiment is that a first flow control valve is installed on the mother liquor circulation pipe; a second flow control valve is installed on the mother liquor open line; and both the first automatic switching valve and the second automatic switching valve are connected to the control command generation module.

[0015] In addition, a preferred embodiment is that the mother liquor parameter monitoring device includes an online hydrometer, a concentration sensor, a temperature sensor, and an online turbidity meter.

[0016] Furthermore, in a preferred embodiment, the impurity separation equipment includes a dilution and dissolution device and a filter press connected to the dilution and dissolution device; the dilution and dissolution device is provided with a dilution water inlet and a mother liquor inlet openly connected to the mother liquor; the mother liquor outlet of the filter is connected to the raw liquid inlet of the continuous crystallization system via a pipeline.

[0017] Furthermore, in a preferred embodiment, the dilution water inlet is connected to the condensate outlet of the continuous crystallization system via a condensate pipe.

[0018] In addition, a preferred embodiment is that the filtration equipment is a filter press, a belt filter, a fine filter, a disc filter, or a rotary filter.

[0019] The continuous crystallization mother liquor concentration control and impurity removal method provided by the present invention uses the continuous crystallization mother liquor concentration control and impurity removal device as described above to control the concentration and remove impurities from the continuous crystallization mother liquor, and includes the following steps:

[0020] The mother liquor accumulated on the upper layer of the working liquid level is drawn into the upper mother liquor suction tube through the first inner tube;

[0021] The mother liquor in the upper mother liquor suction pipe is transported to each processing stage of the continuous crystallization system through the delivery pipe by the circulation pump under the action of the circulation pump, and then returned to the circulation main pipe through the return pipe.

[0022] Based on the mother liquor parameters in the external circulation pipe monitored by the mother liquor parameter monitoring device, the concentration of the continuous crystallization mother liquor is regulated by controlling the flow rate of the reflux mother liquor in the circulation main pipe into the mother liquor circulation pipe and the flow rate into the mother liquor open circuit.

[0023] The mother liquor in the mother liquor circulation pipe is circulated back to the crystallization tank through the second inner tube; and the mother liquor in the mother liquor open circuit is introduced into the impurity separation device.

[0024] The mother liquor is subjected to impurity separation treatment by the impurity separation equipment, and the mother liquor after impurity separation treatment is sent back to the continuous crystallization system to remove impurities from the continuous crystallization mother liquor.

[0025] As can be seen from the above technical solution, the continuous crystallization mother liquor concentration control and impurity removal device and method provided by the present invention, through the structural design of the suction circulation pipe, can ensure that the mother liquor flows fully throughout the continuous crystallization system, homogenize the concentration of the crystallization mother liquor, promote the generation of coarse crystals, avoid local supersaturation and thermal crystallization, and generate a large number of fine crystals. By using the first inner insertion pipe set above the working liquid level in the crystallization tank, the upper impurities and accumulated light component mother liquor in the crystallization tank are extracted. Combined with the design of mother liquor open circuit and impurity separation equipment, it can not only avoid local low concentration reducing the crystallization rate, but also quickly adjust the supersaturation of the mother liquor in the crystallizer, and also discharge the impurities accumulated at the top of the crystallization tank, thereby greatly reducing the impact of impurities on crystal quality. By using the external circulation pipe combined with the mother liquor parameter monitoring device set on the external circulation pipe, the parameters of the crystallization mother liquor can be monitored in real time, making the extraction and circulation volume of the mother liquor more controllable, ensuring a more uniform concentration distribution of the mother liquor in the crystallization tank, reducing the disturbance of the fluid in the crystallization tank by the mother liquor circulation, improving the stability of the crystallization environment, and contributing to the efficient and stable generation of large particle crystals.

[0026] To achieve the foregoing and related objectives, one or more aspects of the invention include the features that will be described in detail below. The following description and accompanying drawings illustrate certain exemplary aspects of the invention. However, these aspects indicate only a few of the various ways in which the principles of the invention can be used. Furthermore, the invention is intended to encompass all such aspects and their equivalents. Attached Figure Description

[0027] Other objects and results of the invention will become more apparent and readily understood with reference to the following description taken in conjunction with the accompanying drawings, and with a more complete understanding of the invention.

[0028] Figure 1 This is a schematic diagram of the suction circulation tube according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the overflow baffle according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of the suction circulation tube and the overflow baffle according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the layout of the mother liquor parameter monitoring device according to an embodiment of the present invention;

[0032] Figure 5 This is a process flow diagram of a continuous crystallization mother liquor concentration control and impurity removal method according to an embodiment of the present invention;

[0033] Figure 6 This is a flowchart illustrating the continuous crystallization mother liquor concentration control and impurity removal method according to an embodiment of the present invention.

[0034] In the attached diagram, 1-suction circulation pipe, 11-first inner insertion pipe, 12-second inner insertion pipe, 13-upper layer mother liquor suction pipe, 14-circulation pump, 15-circulation main pipe, 16-mother liquor circulation pipe, 17-mother liquor open circuit, 18-main collection pipe, 21-online hydrometer, 22-concentration sensor, 23-temperature sensor, 24-online turbidity meter, 3-crystallization tank, 31-working liquid level, 32-overflow port, 33-mother liquor overflow pipe, 4-overflow baffle, 41-horizontal plate, 42-vertical plate, 51-first automatic switching valve, 52-second automatic switching valve.

[0035] In all the accompanying drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed Implementation

[0036] In response to the aforementioned problems, such as the inability to accurately detect the concentration of mother liquor in continuous crystallization equipment in real time in the existing technology, which requires manual observation and sampling for verification, resulting in delayed process adjustment, high control difficulty, low production efficiency, and difficulty in achieving steady-state operation; and the inability to effectively purify light component liquid and impurities retained in the crystallizer accumulation layer, leading to unstable product quality, a continuous crystallization mother liquor concentration control and impurity removal device and method is proposed.

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] To illustrate the continuous crystallization mother liquor concentration control and impurity removal device and method provided by the present invention Figure 1 The structure of the suction circulation tube according to an embodiment of the present invention is shown; Figure 2 The structure of the overflow baffle according to an embodiment of the present invention is shown; Figure 3 The structure of the suction circulation tube combined with the overflow baffle according to an embodiment of the present invention is shown; Figure 4 The arrangement of a mother liquor parameter monitoring device according to an embodiment of the present invention is shown; Figure 5 The process flow of a continuous crystallization mother liquor concentration control and impurity removal method according to an embodiment of the present invention is shown; Figure 6 The flowchart illustrates the steps of a continuous crystallization mother liquor concentration control and impurity removal method according to an embodiment of the present invention.

[0039] like Figures 1 to 4 As shown in the figure, the continuous crystallization mother liquor concentration control and impurity removal device provided by the present invention is used for controlling and removing impurities from the mother liquor during the continuous crystallization process of nickel sulfate or cobalt sulfate; it includes a suction circulation pipe 1, an impurity separation device (not shown in the figure), and a mother liquor parameter monitoring device; wherein,

[0040] The suction circulation pipe 1 includes a first inner tube 11 and a second inner tube 12 respectively disposed above and below the working liquid level 31 in the crystallization tank 3, and an outer circulation pipe respectively connected to the first inner tube 11 and the second inner tube 12; wherein...

[0041] The external circulation pipe includes an upper mother liquor suction pipe 13 connected to the first inner insertion pipe 11, a delivery pipe (not shown in the figure) connected to the upper mother liquor suction pipe 13 and delivering the upper mother liquor to each processing stage (not shown in the figure) of the continuous crystallization system, a return pipe (not shown in the figure) connected to each processing stage, a circulation pump 14 connected to the return pipe, a circulation main pipe 15 connected to the circulation pump 14, a mother liquor circulation pipe 16 and a mother liquor open circuit 17 respectively connected to the circulation main pipe 15; the outlet end of the mother liquor circulation pipe 16 is connected to the inlet end of the second inner insertion pipe 12;

[0042] The inlet of the impurity separation equipment is connected to the mother liquor open circuit 17; the mother liquor outlet of the impurity separation equipment is connected to the raw liquid inlet of the continuous crystallization system.

[0043] The mother liquor parameter monitoring equipment is installed on the external circulation pipe.

[0044] The structural design of the suction circulation pipe 1 ensures that the mother liquor flows fully throughout the continuous crystallization system, homogenizing the concentration of the mother liquor, promoting the formation of coarse crystals, and avoiding local oversaturation that could lead to thermal crystallization and the formation of a large number of fine crystals. The first internal insertion pipe 11, positioned above the working liquid level 31 in the crystallization tank 3, extracts the upper impurities and accumulated light component mother liquor from the crystallization tank 3. Combined with the design of the mother liquor open-circuit 17 and impurity separation equipment, this not only prevents localized low concentrations and reduced crystallization rate but also removes impurities accumulated at the top of the crystallization tank 3, significantly reducing the impact of impurities on crystal quality. The external circulation pipe, combined with a mother liquor parameter monitoring device installed on it, allows for real-time monitoring of the crystallization mother liquor parameters, making the extraction and circulation volume more controllable. This ensures a more uniform concentration distribution of the mother liquor within the crystallization tank 3, reduces disturbance to the fluid within the crystallization tank 3 during mother liquor circulation, improves the stability of the crystallization environment, and contributes to the efficient and stable formation of large-particle crystals. Installing mother liquor parameter monitoring equipment on the external circulation pipe can not only avoid the impact of the complex environment inside crystallizer 3 on the accuracy of the instrument, but also facilitate timely maintenance.

[0045] As a preferred embodiment of the present invention, the return pipe is connected to the circulation pump 14 through the main manifold 18.

[0046] Specifically, the continuous crystallization system may include multiple processing stages, and therefore there may be multiple reflux pipes connected to each processing stage. In order to facilitate the unified collection and reflux of the mother liquor flowing through each processing stage, the reflux pipe is connected to the circulation pump 14 through the main collection pipe 18.

[0047] As a preferred embodiment of the present invention, an overflow port 32 is provided on the inner side wall of the crystallization tank 3; a mother liquor overflow pipe 33 is provided at the overflow port 32; the mother liquor overflow pipe 33 is connected to the upper mother liquor suction pipe 13; an overflow baffle 4 is provided at the overflow port 32 inside the crystallization tank 3; the overflow baffle 4 includes a horizontal plate 41 and a vertical plate 42 vertically provided at one end of the horizontal plate 41; the top of the vertical plate 42 is flush with the working liquid level 31; the horizontal plate 41 is provided close to the overflow port 32 and is flush with the bottom end of the overflow port 32.

[0048] Specifically, the overflow baffle 4 is a baffle of appropriate height set inside the crystallization tank 3. When the liquid level of the mother liquor in the crystallization tank 3 exceeds the height of the overflow baffle 4, the mother liquor will automatically overflow to a specific channel (i.e., enter the mother liquor overflow pipe 33 through the overflow port 32) and finally enter the subsequent processing flow. The setting height of the overflow baffle 4 can be adjusted according to the specific requirements of the crystallization process to ensure that the amount and quality of the overflowing mother liquor meet the needs of system operation. Generally, the upper end is level with the working liquid level 31. The overflow baffle 4 not only maintains the stability of the liquid level in the crystallization tank 3, but also reduces the entrainment of liquid crystals in the outflow, and automatically discharges the light components and impurities of the upper layer of liquid material retained in the crystallization tank 3.

[0049] As a preferred embodiment of the present invention, it further includes a central control mechanism (not shown in the figure); the central control mechanism includes a data analysis and comparison module (not shown in the figure) and a control command generation module (not shown in the figure) connected to the data analysis and comparison module; the data analysis and comparison module is connected to a mother liquor parameter monitoring device; the control command generation module is connected to a crystallization parameter control mechanism of the continuous crystallization system.

[0050] Specifically, the mother liquor parameter monitoring equipment transmits the real-time collected mother liquor status (parameter) data to the central control unit. The central control unit can use advanced data processing algorithms to quickly analyze and process this data to accurately determine the current state of the mother liquor and instruct the crystallization parameter control unit of the continuous crystallization system to make corresponding parameter adjustments.

[0051] As an example, the data analysis and comparison module can classify and collect the mother liquor parameter data collected online in real time by the mother liquor parameter monitoring equipment, along with data from raw material analysis, product analysis, and other workshops, into a server data pool to provide data support for automated control. The data analysis and comparison module is preferably a crystallization parameter prediction model based on a neural network algorithm. This model can predict the development trend of the crystallization process based on the real-time monitored mother liquor parameters such as temperature, concentration, specific gravity, and product particle size, and send the predicted structure to the control command generation module to automatically adjust relevant process parameters and achieve the best crystallization effect.

[0052] The central control unit can also determine the amount of open-circuit raw material that the upstream mother liquor receiving point can consume based on raw material monitoring and online monitoring data collected from previous processes, thereby automatically adjusting the amount of open-circuit mother liquor in the continuous crystallization system. This improves the response speed of process parameter adjustments, significantly reduces the fluctuations caused by changes in the amount of mother liquor in the open-circuit system to previous processes, reduces unnecessary manual operations, and achieves coordinated control throughout the entire process.

[0053] The mother liquor parameter monitoring equipment can be automatically calibrated online. After manual periodic sampling and testing, the results are entered into the overall industrial control system. The system uses artificial intelligence algorithms to automatically compare the calculated values ​​and the monitored values ​​to analyze the error points of the mother liquor parameter monitoring equipment and quickly calibrate the mother liquor parameter monitoring equipment online, or provide analysis reports to guide on-site engineers in calibrating the mother liquor parameter monitoring equipment.

[0054] It can also be set up to support remote operation and maintenance management, allowing operators to remotely monitor the production process and adjust parameters via the network, thereby improving the convenience and efficiency of production management.

[0055] As a preferred embodiment of the present invention, a first automatic switching valve 51 is provided on the mother liquor circulation pipe 16; a second automatic switching valve 52 is provided on the mother liquor open circuit 17; both the first automatic switching valve 51 and the second automatic switching valve 52 are connected to the control command generation module.

[0056] Specifically, the first automatic switching valve 51 and the second automatic switching valve 52 control the mother liquor flowing back into the crystallizer 3 and the mother liquor entering the mother liquor open circuit 17, respectively, thereby regulating the concentration of the mother liquor in the crystallizer 3, i.e., the concentration of the mother liquor during the continuous crystallization process. By connecting both the first automatic switching valve 51 and the second automatic switching valve 52 to the control command generation module, the switching valves can be automatically switched by the central control mechanism, thus facilitating the automated regulation of the mother liquor concentration in the crystallizer 3.

[0057] As a preferred embodiment of the present invention, the mother liquor parameter monitoring device includes an online hydrometer 21, a concentration sensor 22, a temperature sensor 23, and an online turbidity meter 24.

[0058] It should be noted that the mother liquor parameter monitoring equipment in this invention includes, but is not limited to, an online hydrometer 21, a concentration sensor 22, a temperature sensor 23, and an online turbidity meter 24.

[0059] Specifically, taking continuous crystallization of nickel sulfate as an example, in the process of adjusting the concentration and removing impurities from the mother liquor, the monitoring equipment for mother liquor parameters includes an online hydrometer 21, a concentration sensor 22, a temperature sensor 23, and an online turbidity meter 24. Among these,

[0060] The online hydrometer 21 is used to measure the specific gravity of the mother liquor in real time; the concentration sensor 22 is used to accurately detect the concentration of Ni, K, Na and other ions in the mother liquor; the temperature sensor 23 is used to monitor the temperature of the mother liquor in real time; and the online turbidimeter 24 is used to directly measure the concentration of particulate matter in the mother liquor and reflect the change in solid content in real time.

[0061] The central control unit compares and analyzes the real-time online monitoring data of the mother liquor status with the preset crystallization process parameters. If the specific gravity of the mother liquor deviates from the set range, it immediately issues an instruction to start the corresponding adjustment mechanism. For example, when the concentration of the mother liquor is too high, the evaporation system parameters are automatically adjusted. The concentration of the evaporated mother liquor can be reduced by adjusting the compressor frequency, vacuum degree, etc. At the same time, the circulation rate of the mother liquor in the system is increased by adjusting the circulation pump 14, so that the crystallization mother liquor is efficiently homogenized.

[0062] If the specific gravity of the mother liquor is too low, the system will automatically open the circuit for mother liquor with insufficient concentration and instruct the evaporation system to appropriately increase the evaporation temperature and evaporation rate to rapidly increase the specific gravity of the mother liquor. During the adjustment process, the central control unit continuously monitors the state changes of the mother liquor and dynamically adjusts the operating parameters of the continuous crystallization system based on real-time feedback data to ensure that the concentration and specific gravity of the mother liquor can be quickly and stably restored to the set range.

[0063] When the state of the mother liquor changes, the central control unit can simultaneously make corresponding adjustments to the relevant parts of the continuous crystallization system to ensure that the entire continuous crystallization system operates under stable process conditions. For example, when the concentration of the mother liquor is adjusted, the speed of the stirring device may be adjusted appropriately as needed to promote the uniform distribution of solute in the mother liquor, which is beneficial to crystal growth.

[0064] As a preferred embodiment of the present invention, the impurity separation device includes a dilution and dissolution device (not shown in the figure) and a filtration device (not shown in the figure) connected to the dilution and dissolution device; the dilution and dissolution device is provided with a dilution water inlet (not shown in the figure) and a mother liquor inlet (not shown in the figure) connected to the mother liquor open circuit 17; the mother liquor outlet of the filtration device is connected to the raw liquid inlet of the continuous crystallization system through a pipeline (not shown in the figure).

[0065] As a preferred embodiment of the present invention, the dilution water inlet is connected to the condensate outlet (not shown in the figure) of the continuous crystallization system via a condensate pipe (not shown in the figure).

[0066] As a preferred embodiment of the present invention, the filtration equipment is a filter press, a belt filter, a fine filter, a disc filter, or a rotary filter.

[0067] Specifically, taking continuous crystallization of nickel sulfate as an example, the mother liquor containing impurities drawn from crystallization tank 3 is diluted to a certain concentration with condensate generated by evaporation to a level below the solution saturation, which promotes the dissolution of nickel crystals and causes accumulated impurities such as silicon to precipitate. Filtration equipment such as a filter press is used to remove the solid impurities precipitated from the mother liquor. After filtration, based on the impurity content analyzed by sampling, part of the diluted mother liquor is treated open-circuit. The remaining mother liquor is sent back to the evaporation system of continuous evaporation crystallization, recovering nickel sulfate while maintaining the impurity concentration at a low level. The open-circuit mother liquor is diluted with evaporation condensate and fully utilized in upstream processes such as leaching and extraction, achieving water resource recycling.

[0068] It should be noted that the filtration equipment in this invention is preferably, but not limited to, a filter press, a belt filter, a fine filter, a disc filter, or a rotary filter, and can be selected according to the actual working conditions.

[0069] like Figure 5 Combination Figure 6 As shown in the figure, the continuous crystallization mother liquor concentration control and impurity removal method provided by the present invention uses the continuous crystallization mother liquor concentration control and impurity removal device described above to control the concentration and remove impurities from the continuous crystallization mother liquor, and includes the following steps:

[0070] Step S1: The mother liquor accumulated on the upper layer of the working liquid level 31 is drawn into the upper mother liquor suction tube 13 through the first inner insertion tube 11;

[0071] Step S2: The mother liquor in the upper mother liquor suction pipe 13 is transported to each processing stage of the continuous crystallization system through the delivery pipe under the action of the circulation pump 14, and then returned to the circulation main pipe 15 through the return pipe.

[0072] Step S3: Based on the mother liquor parameters in the external circulation pipe monitored by the mother liquor parameter monitoring device, the concentration of the continuous crystallization mother liquor is regulated by controlling the flow rate of the reflux mother liquor in the circulation main pipe 15 into the mother liquor circulation pipe 16 and the flow rate into the mother liquor open circuit 17.

[0073] Step S4: Circulate the mother liquor in the mother liquor circulation pipe 16 back to the crystallization tank 3 through the second inner insertion pipe 12; and allow the mother liquor in the mother liquor open circuit 17 to enter the impurity separation device.

[0074] Step S5: The mother liquor is subjected to impurity separation treatment using an impurity separation device, and the mother liquor after impurity separation treatment is sent back to the continuous crystallization system to remove impurities from the continuous crystallization mother liquor.

[0075] To better illustrate the continuous crystallization mother liquor concentration control and impurity removal device and method provided by the present invention, and the technical effects achieved therein, specific embodiments are verified as follows:

[0076] Example 1

[0077] According to the continuous crystallization mother liquor concentration control and impurity removal method provided by this invention, refined nickel sulfate after extraction is used as raw material for evaporation and crystallization. A high-purity nickel sulfate solution is produced using an MVR evaporation and continuous crystallization process.

[0078] A continuous crystallization mother liquor concentration control and impurity removal device is installed on the continuous crystallization system, and the circulation pump 14 operates at 10 m³ / h. 3 The mother liquor is drawn from the top of crystallizer 3 at a rate of / h and returned to crystallizer 3 through a pipeline. A hydrometer and thermometer are installed on the external circulation pipe to monitor the concentration (accuracy ±0.1%) and temperature of the circulating mother liquor in real time.

[0079] The crystal slurry produced by the continuous crystallization system is filtered using a belt filter, and the crystals are then fed into a reverse dissolution process to prepare a high-purity nickel sulfate solution. The mother liquor obtained from the belt filter has a Ni concentration of ~155 g / L, which is mixed with the nickel sulfate solution before evaporation to prepare a solution with a Ni concentration of ~100 g / L. After the mixture is filtered through a porous filter press to remove precipitated insoluble impurities, the filtrate is returned to the evaporation feed tank of the continuous crystallization system and fed into the nickel evaporation crystallization system at a stable concentration.

[0080] The concentration of the mother liquor in crystallizer tank 3 is monitored in real time by a hydrometer, and the evaporation rate is adjusted in real time in conjunction with the continuous evaporation system to maintain the nickel concentration of the mother liquor at the ideal crystallization concentration. The thermometer is interlocked with the crystallizer surface cooler and vacuum pump to keep the temperature inside crystallizer tank 3 stable within the design temperature range. The hydrometer and flow meter of the mother liquor tank are interlocked with the dilution water control valve. Real-time signal transmission is established between the central control mechanism and the intelligent control system. A concentration prediction model is built based on an LSTM neural network, and the control model is continuously learned and corrected based on real-time operation and data. The system can predict the trend of mother liquor concentration changes in advance, automatically adjust the evaporation temperature, and control the circulation and discharge of the upper layer of mother liquor. To maintain the crystal slurry concentration at around 40%, the system automatically adjusts the control conditions such as the feeding and discharging of the crystallizer tank, achieving intelligent control throughout the entire process.

[0081] Actual operation data shows that the continuous crystallization system controls the Ni concentration fluctuation in the high-purity nickel sulfate solution to ≤1%, reduces the total content of insoluble impurities to <5ppm, and reduces the energy consumption of the evaporation system by 22%, significantly improving product quality and production efficiency.

[0082] It should be noted that the above specific embodiments are merely for verifying the effect of the continuous crystallization mother liquor concentration control and impurity removal device and method provided by the present invention in actual experimental process, and do not limit the technical solution provided by the present invention.

[0083] As can be seen from the above specific embodiments, the continuous crystallization mother liquor concentration control and impurity removal device and method provided by the present invention, through the structural design of the suction circulation pipe, can ensure that the mother liquor flows fully throughout the continuous crystallization system, homogenize the concentration of the crystallization mother liquor, promote the generation of coarse crystals, avoid local oversaturation and thermal crystallization, and generate a large number of fine crystals. By using the first internal insertion pipe set above the working liquid level in the crystallization tank, the upper impurities and accumulated light component mother liquor in the crystallization tank are extracted. Combined with the design of mother liquor open circuit and impurity separation equipment, it can not only avoid local low concentration reducing the crystallization rate, but also discharge the impurities enriched at the top of the crystallization tank, thereby significantly reducing the impact of impurities on crystal quality. By using the external circulation pipe in conjunction with the mother liquor parameter monitoring device set on the external circulation pipe, the parameters of the crystallization mother liquor can be monitored in real time, making the extraction and circulation volume of mother liquor more controllable, ensuring a more uniform concentration distribution of mother liquor in the crystallization tank, reducing the disturbance of the fluid in the crystallization tank by the mother liquor circulation, improving the stability of the crystallization environment, and contributing to the efficient and stable generation of large-particle crystals.

[0084] The continuous crystallization mother liquor concentration control and impurity removal apparatus and method according to the present invention have been described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various modifications can be made to the continuous crystallization mother liquor concentration control and impurity removal apparatus and method proposed in the present invention without departing from the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the contents of the appended claims.

Claims

1. A continuous crystallization mother liquor concentration control and impurity removal device, used for concentration control and impurity removal of the mother liquor during the continuous crystallization process of nickel sulfate or cobalt sulfate; characterized in that, This includes suction circulation pipes, impurity separation equipment, and mother liquor parameter monitoring equipment; among which, The suction circulation pipe includes a first inner tube and a second inner tube respectively disposed above and below the working liquid level inside the crystallization tank, and an outer circulation pipe respectively connected to the first inner tube and the second inner tube; wherein... The external circulation pipe includes an upper mother liquor suction pipe connected to the first inner tube, a delivery pipe connected to the upper mother liquor suction pipe and delivering the upper mother liquor to each processing stage of the continuous crystallization system, a return pipe connected to each processing stage, a circulation pump connected to the return pipe, a circulation main pipe connected to the circulation pump, a mother liquor circulation pipe and a mother liquor open circuit connected to the circulation main pipe respectively; the outlet end of the mother liquor circulation pipe is connected to the inlet end of the second inner tube; The inlet of the impurity separation device is open-circuited with the mother liquor; the outlet of the mother liquor of the impurity separation device is connected to the raw liquid inlet of the continuous crystallization system. The mother liquor parameter monitoring device is installed on the external circulation pipe; An overflow port is provided on the inner wall of the crystallization tank; a mother liquor overflow pipe is provided at the overflow port; the mother liquor overflow pipe is connected to the upper mother liquor suction pipe; An overflow baffle is provided at the overflow port inside the crystallization tank; The overflow baffle includes a horizontal plate and a vertical plate vertically disposed at one end of the horizontal plate; The top of the vertical plate is flush with the working liquid level; the horizontal plate is located near the overflow port and is flush with the bottom of the overflow port. The impurity separation equipment includes a dilution and dissolution device and a filtration device connected to the dilution and dissolution device; The dilution and dissolution device is provided with a dilution water inlet and a mother liquor inlet that is openly connected to the mother liquor. The mother liquor outlet of the filtration device is connected to the raw liquor inlet of the continuous crystallization system via a pipeline. The dilution water inlet is connected to the condensate outlet of the continuous crystallization system via a condensate pipe.

2. The continuous crystallization mother liquor concentration control and impurity removal device according to claim 1, characterized in that, The return pipe is connected to the circulation pump via a main manifold.

3. The continuous crystallization mother liquor concentration control and impurity removal device according to claim 1, characterized in that, It also includes a central control body; The central control mechanism includes a data analysis and comparison module and a control command generation module connected to the data analysis and comparison module; The data analysis and comparison module is connected to the mother liquor parameter monitoring device; The control command generation module is connected to the crystallization parameter control mechanism of the continuous crystallization system.

4. The continuous crystallization mother liquor concentration control and impurity removal device according to claim 3, characterized in that, A first automatic switching valve is installed on the mother liquor circulation pipe; A second automatic switching valve is installed on the mother liquor circuit; Both the first automatic switching valve and the second automatic switching valve are connected to the control command generation module.

5. The continuous crystallization mother liquor concentration control and impurity removal device according to claim 1, characterized in that, The mother liquor parameter monitoring equipment includes an online hydrometer, a concentration sensor, a temperature sensor, and an online turbidity meter.

6. The continuous crystallization mother liquor concentration control and impurity removal device according to claim 1, characterized in that, The filtration equipment is a filter press, belt filter, fine filter, disc filter, or drum filter.

7. A method for adjusting the concentration of mother liquor during continuous crystallization and removing impurities, characterized in that, The continuous crystallization mother liquor concentration control and impurity removal device as described in any one of claims 1-6 is used to control the concentration and remove impurities from the continuous crystallization mother liquor, comprising the following steps: The mother liquor accumulated on the upper layer of the working liquid level is drawn into the upper mother liquor suction tube through the first inner tube; The mother liquor in the upper mother liquor suction pipe is transported to each processing stage of the continuous crystallization system through the delivery pipe by the circulation pump under the action of the circulation pump, and then returned to the circulation main pipe through the return pipe. Based on the mother liquor parameters in the external circulation pipe monitored by the mother liquor parameter monitoring device, the concentration of the continuous crystallization mother liquor is regulated by controlling the flow rate of the reflux mother liquor in the circulation main pipe into the mother liquor circulation pipe and the flow rate into the mother liquor open circuit. The mother liquor in the mother liquor circulation pipe is circulated back to the crystallization tank through the second inner tube; and the mother liquor in the mother liquor open circuit is introduced into the impurity separation device. The mother liquor is subjected to impurity separation treatment by the impurity separation equipment, and the mother liquor after impurity separation treatment is sent back to the continuous crystallization system to remove impurities from the continuous crystallization mother liquor.

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