Full-membrane method phosphoric acid iron white concentrate purification system based on water supplement recycling control

Abstract

The application relates to the technical field of membrane separation process control, and provides a full-membrane-method iron phosphate white material concentration and purification system based on make-up water recycling regulation, which comprises a white material tank, a pre-concentration and washing unit, an intermediate white material storage tank, a washing and concentration unit and a purified white material storage tank which are sequentially connected; and a white material analysis module which judges the membrane inlet state into four types of normal material membrane inlet, abnormal material flow, local mixed abnormality or overall high salt load by taking the uniformity of solid content as a pre-check and combining with the conductivity distribution characteristics; a membrane section evaluation module which evaluates the effectiveness of the make-up water through the double indexes of desalination release degree and filtration resistance; a hierarchical decision module which determines the full-membrane-section average make-up water or local membrane-section make-up water strategy and hierarchically allocates the make-up water membrane section based on the effectiveness. Through the synergistic control of accurate identification of the membrane inlet state and quantitative evaluation of the make-up water effectiveness, the system significantly reduces the energy waste and concentration load caused by invalid make-up water.

Description

Technical Field

[0001] This invention relates to the field of membrane separation process control technology, specifically to a full-membrane method for the concentration and purification of iron phosphate white material based on water replenishment and reuse regulation. Background Technology

[0002] In chemical, hydrometallurgical, and battery material production processes, membrane washing technology is often used to desalinate and purify slurries (white materials) to reduce the soluble salt content in the product. The desalination effect of membrane washing is closely related to the uniformity of the feed slurry, salt distribution, and water replenishment strategy. Currently, industrial production often relies on operators' experience for timed sampling or fixed threshold alarms, making it difficult to distinguish the material state in the white material storage tank in real time and accurately: for example, abnormal flowability due to sedimentation and stratification, uneven mixing caused by localized salt enrichment, and different operating conditions such as an overall high salt load in the system.

[0003] In addition, the water replenishment method generally adopts a fixed ratio or uniform distribution, lacking dynamic assessment of the actual desalination release capacity and filtration impedance of the membrane segment. This often leads to substandard desalination or excessive water replenishment, which not only increases the energy consumption of ineffective dilution and subsequent concentration, but also easily causes membrane fouling and operational fluctuations.

[0004] Therefore, an intelligent control method is needed that can accurately identify the membrane inlet status and make decisions based on the effectiveness of water replenishment. Summary of the Invention

[0005] To address this, the present invention provides a full-membrane method for the concentration and purification of ferric phosphate white material based on water replenishment and reuse regulation. This system overcomes the problems in the prior art, such as the inability to distinguish the multi-level abnormal states of white material entering the membrane in real time and the lack of effective judgment on the desalination release capacity and filtration impedance of the membrane segment by the water replenishment strategy. These problems result in blind water replenishment, low desalination efficiency, high operating energy consumption, and poor membrane system stability.

[0006] To achieve the above objectives, this invention provides a full-membrane method for concentrating and purifying iron phosphate white material based on water replenishment and reuse regulation. The system comprises a white material tank, a pre-concentration and washing unit, an intermediate white material storage tank, a washing and concentration unit, and a purified white material storage tank connected in sequence. The pre-concentration and washing unit includes a concentration ceramic membrane system and a primary washing ceramic membrane system. The washing and concentration unit includes a secondary washing ceramic membrane system, a first-stage system, a second-stage system, a third-stage system, and a fourth-stage system connected in sequence. The system also includes: The data monitoring module includes a tank monitoring unit for collecting the conductivity and solid content of the white material at different height positions in the intermediate white material storage tank, and a membrane segment monitoring unit for collecting the conductivity and permeate flow rate of each membrane segment in the washing and concentration unit on the feed side, product side and permeate side. The white material analysis module is used to determine the white material status of the film-feeding material based on the white material conductivity and solid content at different height positions. The white material status includes normal material feeding, abnormal material flow, abnormal local mixing, and overall high salt load. The membrane segment evaluation module is used to determine the desalination release degree of the corresponding membrane segment based on the conductivity of the feed side, feed side and permeate side of each membrane segment, to determine the filtration impedance of the corresponding membrane segment based on the permeate flow rate and feed side conductivity of the corresponding membrane segment, and to determine the water replenishment effectiveness of the corresponding membrane segment by combining the desalination release degree and the filtration impedance. The hierarchical decision module is used to determine the water replenishment strategy for the membrane segment based on the determination result of the state of the incoming white material. The water replenishment membrane segment is determined based on the triggering result of local membrane segment water replenishment and the water replenishment effectiveness of each membrane segment. The membrane segment water replenishment strategy includes average water replenishment across the entire membrane segment and localized water replenishment within the membrane segment.

[0007] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water replenishment and reuse regulation, the white material analysis module determines the state of the white material entering the membrane based on the conductivity and solid content of the white material at different height positions, including: In response to the uneven solid content at different height positions, the state of the feed white material is determined to be abnormal material flow; In response to the uniformity of solid content at different height positions, the state of the white material entering the membrane is determined in conjunction with the conductivity of the white material, wherein: Based on the results of determining the non-uniformity of conductivity at different height positions, the state of the white material entering the membrane was determined to be a localized mixing abnormality. Based on the determination of uniform conductivity at different height positions, the state of the white material entering the membrane is determined to be high salt load if the average conductivity at each height position is higher than the conductivity threshold, or the state of the white material entering the membrane is determined to be normal material entry into the membrane if the average conductivity at each height position is not higher than the conductivity threshold.

[0008] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water replenishment and reuse regulation, the graded decision module determines the membrane section water replenishment strategy according to the determination result of the state of the incoming white material, including: If the material feed into the membrane is normal, no water replenishment strategy is formulated for the membrane segment. In response to the abnormal material flow, the membrane segment water replenishment strategy is determined to be that no water replenishment is performed on the intermediate white material storage tank. In response to the overall high salt load or the localized mixing anomaly, membrane segment replenishment is performed, wherein: Based on the overall high salt load assessment, the membrane section water replenishment strategy is determined to be average water replenishment across the entire membrane section. Based on the results of the local mixing anomaly assessment, the membrane segment water replenishment strategy was determined to be local membrane segment water replenishment.

[0009] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water replenishment and reuse regulation, the hierarchical decision module responds to the judgment result of local mixing anomalies and controls the operation of the membrane segment evaluation module to calculate the desalination release degree and filtration impedance of each membrane segment.

[0010] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water reuse regulation, the membrane segment evaluation module determines the desalination release degree of each membrane segment according to the conductivity difference between the feed side and the product side of each membrane segment and the conductivity of the permeate side, wherein: Based on the determination that the conductivity difference is not less than a preset difference and the conductivity on the permeate side is not less than a preset conductivity, the corresponding membrane segment is determined to have a high degree of desalination release. Conversely, it indicates that the corresponding membrane segment has a low degree of desalination release.

[0011] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water reuse regulation, the membrane segment evaluation module determines the permeate flow rate variation and the product side conductivity decrease based on the permeate flow rate and product side conductivity of the corresponding membrane segment, respectively, to determine the filtration impedance of the corresponding membrane segment, including: When the change in permeate flow rate is greater than the preset flow rate change value and the decrease in conductivity on the feed side is less than the preset conductivity decrease value, the corresponding membrane segment is determined to be high filtration impedance. Conversely, the corresponding membrane segment is determined to have low filtration impedance.

[0012] As a preferred technical solution for a membrane-based iron phosphate white material concentration and purification system based on water reuse regulation, the membrane segment evaluation module determines the water replenishment effectiveness of the corresponding membrane segment by combining the degree of desalination release and the filtration impedance, including: Based on the judgment results of high desalination release and low filtration impedance, the water replenishment effectiveness of the corresponding membrane segment is determined to be manifest effective water replenishment; Based on the determination results of high desalination release or low filtration impedance, the water replenishment effectiveness of the corresponding membrane segment is determined to be implicit effective water replenishment. Based on the judgment results of low desalination release and high filtration impedance, the water replenishment effectiveness of the corresponding membrane segment was determined to be ineffective.

[0013] As a preferred technical solution for the all-membrane method for ferric phosphate white material concentration and purification system based on water replenishment and reuse regulation, in response to triggering local membrane segment water replenishment, the hierarchical decision module determines the visible effective water replenishment membrane segment as the direct water replenishment membrane segment and replenishes the membrane segment with fresh water.

[0014] As a preferred technical solution for the whole membrane method for ferric phosphate white material concentration and purification system based on water replenishment and reuse regulation, in response to triggering local membrane segment water replenishment, the hierarchical decision module also identifies the hidden effective water replenishment membrane segment as the treatment water replenishment membrane segment, and pre-dilutes the permeate of the membrane segment before replenishing it with fresh water.

[0015] Compared with existing technologies, the beneficial effects of this invention are as follows: The whole-membrane method for ferric phosphate white material concentration and purification system based on water replenishment and reuse regulation provided by this invention, through the construction of a three-dimensional parameter monitoring system for the white material storage tank and a membrane segment state classification evaluation mechanism, achieves multi-level identification of the feed state of the membrane washing system and on-demand precise control of the water replenishment strategy: It obtains the solid content and conductivity at different heights in the intermediate white material storage tank, and by calculating the dispersion of solid content, it can effectively identify whether the slurry has settled, stratified, or agglomerated, thereby verifying the premise that the conductivity data truly reflects the salt distribution; based on this, combined with the dispersion and average value of conductivity, the white material feed state is automatically classified into four types: normal material feed into the membrane, abnormal material flow, overall high salt load, and local abnormal mixing, and different formulations are developed for each state. This automated control strategy fundamentally solves the problems of misjudgment caused by traditional single-point monitoring and ineffective dilution due to blind water replenishment. When entering the local membrane segment water replenishment mode, a dual-dimensional evaluation of desalination release degree and filtration impedance is introduced. By using parameters such as the difference in conductivity between the feed and product sides, the conductivity and flow rate of the permeate, and the decrease in the conductivity of the product, the effectiveness of water replenishment is divided into three categories: explicit effective, implicit effective, and ineffective. Based on this, explicit effective membrane segments are prioritized for direct water replenishment, while implicitly effective membrane segments are replenished after pre-dilution with permeate. This achieves precise allocation of water resources to high-value desalination stages. This hierarchical decision-making system not only significantly improves the salt removal efficiency per unit of water replenishment but also reduces the subsequent concentration energy consumption and membrane fouling risk caused by excessive water replenishment, ensuring the long-term stable and efficient operation of the membrane system and demonstrating good engineering adaptability.

[0016] In particular, the spatial distribution of solid content in the slurry within the white material storage tank during membrane washing directly determines the representativeness of conductivity measurement and the reliability of water replenishment decisions. This invention sets up multiple sampling points vertically within the storage tank. An online density meter acquires the solid content of each layer in real time based on the density-solid content calibration relationship and calculates its dispersion. When the dispersion exceeds a preset threshold, it indicates significant sedimentation, stratification, or local agglomeration of the slurry. At this point, the spatial distribution of solid particles is no longer uniform, and the liquid salt concentration reflected by conductivity will be severely distorted due to particle accumulation effects and liquid retention. If water is replenished based on conductivity data at this time, the washing liquid cannot penetrate uniformly into the material, the mass transfer channels are blocked, and water replenishment not only fails to achieve desalination but also exacerbates slurry rheology due to local dilution. Fluctuations in solid content can cause drastic changes in membrane flux or even blockage. This invention uses the uniformity of solid content as the primary prerequisite for judging the effectiveness of salt distribution. Once an abnormal material flow is determined, the water replenishment strategy is directly locked, and the stirring device is activated first to restore homogeneity of the material in the storage tank. No water replenishment to any membrane segment is allowed before the restoration of homogeneity is verified. This mechanism of homogenization before water replenishment completely cuts off the erroneous water replenishment chain caused by abnormal material structure. Only when the uniformity of solid content meets the condition is the dispersion and mean of conductivity of each layer further analyzed, so as to accurately distinguish different salt distribution states such as overall high salt load and local mixing abnormalities. This provides a reliable information basis for subsequent precise water replenishment strategies and fundamentally avoids energy waste and membrane system disturbance caused by abnormal material structure.

[0017] In particular, this invention proposes a desalination release degree index, which determines whether salt has been effectively separated from the slurry and successfully carried out by the permeate by comparing the conductivity difference between the feed and product sides of the membrane segment and the conductivity level of the permeate side. Only when the feed-product conductivity decreases significantly and the permeate conductivity reaches a preset value is it confirmed that the salt has achieved a complete migration from the solid phase to the liquid phase. Simultaneously, a filtration impedance index is introduced, using the change in permeate flow rate relative to the performance stabilization period and the decrease in product side conductivity during the evaluation period to comprehensively evaluate membrane flux decay and mass transfer resistance. These two dimensions jointly determine the actual effect of water replenishment: i.e., a high desalination release degree and excessive... Membrane segments with low filtration impedance are identified as overtly effective makeup water zones, where makeup water can immediately play a desalination role. Membrane segments with high desalination release but high filtration impedance, or low desalination release but low filtration impedance, are identified as latently effective makeup water zones. This indicates that the membrane segment has salt release potential but is limited by mass transfer, or has good flux but insufficient driving force. In this case, pre-dilution with permeate is necessary to reduce local salt concentration or improve flow conditions before makeup water can be added to activate its desalination potential. This quantitative effectiveness classification method ensures that makeup water resources are allocated to the most productive membrane segments, avoiding the futile water supply to fouled or non-release membrane segments, and significantly increasing the proportion of limited wash water converted into substantial salt removal.

[0018] In particular, when triggering local membrane segment water replenishment, this invention considers that when salt is locally enriched, uniform water replenishment globally would lead to redundant water replenishment in non-rich areas and insufficient water replenishment in rich areas, thus limiting the overall desalination efficiency. Based on the water replenishment effectiveness classification results, differentiated resource allocation is performed: membrane segments with visible effective water replenishment are designated as directly replenished membrane segments, while those with hidden effective water replenishment are designated as treatment replenishment membrane segments requiring pre-dilution of the permeate before water replenishment. Through effectiveness classification, this invention prioritizes water replenishment resources to membrane segments with strong desalination release capacity and low filtration impedance. For membrane segments with potential but limited by mass transfer, pre-dilution of the permeate reduces the local salt concentration gradient and improves the mass transfer driving force before water replenishment, activating their desalination potential with minimal auxiliary cost. This graded allocation mechanism, in scenarios with abnormal local mixing, significantly improves the desalination output per unit water replenishment volume compared to uniform water replenishment across the entire membrane segment, while reducing the system's total energy consumption and concentration load.

[0019] In particular, this invention achieves a systematic reduction in system energy consumption through the coordinated control of four-level membrane entry status determination and water replenishment effectiveness classification, addressing the water replenishment source, process execution, and subsequent treatment. The energy consumption of the membrane system mainly originates from post-water replenishment concentration and recovery, flux decline due to ineffective circulation, and membrane fouling cleaning; all three are directly related to the accuracy of water replenishment decisions. When the material entry into the membrane is determined to be normal, no water replenishment is required, eliminating the evaporation energy consumed by ineffective dilution and subsequent concentration at the source. When a high overall salt load is determined, average water replenishment is applied across the entire membrane segment, utilizing the synergistic desalination capacity of each segment to achieve the target salt load with minimal water replenishment, avoiding repeated replenishment due to insufficient replenishment. When a localized mixing anomaly is determined, water is replenished only to the visibly effective membrane segment, reducing the amount of water replenished compared to uniform replenishment across the entire membrane segment, directly lowering the heat load and pumping energy consumption of the subsequent concentration stage. Simultaneously, real-time monitoring of filtration impedance can identify mass transfer obstruction trends before a substantial decline in membrane flux occurs, preventing the system from accumulating additional energy consumption due to continuous operation under high impedance conditions, thus achieving proactive energy saving. Attached Figure Description

[0020] Figure 1 This is a connection diagram of the all-membrane method for concentrating and purifying ferric phosphate white material based on water replenishment and reuse regulation, according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the water replenishment and reuse control process in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0022] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0024] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Please see Figures 1-2 As shown, these are, respectively, the connection diagram of the all-membrane method for ferric phosphate white material concentration and purification system based on water reuse regulation in an embodiment of the present invention, and the workflow diagram of water reuse regulation in an embodiment of the present invention.

[0026] This invention provides a membrane-based iron phosphate white material concentration and purification system based on water replenishment and reuse regulation, comprising a white material tank, a pre-concentration and washing unit, an intermediate white material storage tank, a washing and concentration unit, a purified white material storage tank, a washing liquid storage tank, and a washing water replenishment system connected in sequence. The pre-concentration washing unit includes a concentration ceramic membrane system and a primary washing ceramic membrane system. The recovery rate of the concentration ceramic membrane system is set to 50%–67%, and it is used to pre-concentrate the white material to increase the solid content and reduce the amount of makeup water required for subsequent washing. The recovery rate of the primary washing ceramic membrane system is set to 50%. The washing and concentration unit comprises a two-stage washing ceramic membrane stage 1 system, a two-stage washing ceramic membrane stage 2 system, a three-stage washing ceramic membrane stage 3 system, and a four-stage washing and concentration ceramic membrane stage 4 system connected in sequence; wherein the recovery rate of the two-stage washing ceramic membrane stage 1 system, the two-stage washing ceramic membrane stage 2 system, and the three-stage washing ceramic membrane stage 3 system is set to 50%, and the recovery rate of the two-stage washing and concentration ceramic membrane stage 4 system is set to 50%–67%. Specifically, the white material tank, intermediate white material storage tank, and purified white material storage tank are all equipped with a mixer for homogenizing the white material; The washing water replenishment system is connected to the inlet of the primary washing ceramic membrane system, the inlet of the secondary washing ceramic membrane three-stage system, and the inlet of the secondary washing concentration ceramic membrane four-stage system to provide fresh washing water. The water supply end of the washing water replenishment system is equipped with a conductivity meter, and the flow rate of fresh washing water entering the primary washing ceramic membrane system, the secondary washing ceramic membrane three-stage system, and the secondary washing concentration ceramic membrane four-stage system are monitored by three flow meters respectively.

[0027] In practice, after the iron phosphate white material enters the white material tank, it enters the concentration ceramic membrane system for pre-concentration. The concentrated white material is mixed with the permeate or washing makeup water of the secondary washing ceramic membrane three-stage system and then enters the primary washing ceramic membrane system for primary washing. The feed end of the pre-concentration washing unit is equipped with a flow meter and a conductivity meter, and the output end is also equipped with a flow meter and a conductivity meter. The permeate from the concentrated ceramic membrane system enters the washing liquid storage tank; the permeate from the primary washing ceramic membrane system enters the washing liquid storage tank, and a flow meter and conductivity meter are installed at the permeate end. The white material processed by the pre-concentration washing unit enters the intermediate white material storage tank. The intermediate white material storage tank is equipped with a flow meter and a conductivity meter at the water supply end for the reuse of the effluent to monitor the flow rate and conductivity of the reused effluent entering the intermediate white material storage tank. The white material in the intermediate white material storage tank is mixed with the permeate from the four-stage system of the secondary washing and concentration ceramic membrane and then enters the first stage system of the secondary washing ceramic membrane for washing. A conductivity meter is installed at the feed end of the first stage system of the secondary washing ceramic membrane, and a flow meter and conductivity meter are installed at the permeate end. The white material treated by the first stage of the secondary washing ceramic membrane system is mixed with the permeate from the fourth stage of the secondary washing and concentration ceramic membrane system and then enters the second stage of the secondary washing ceramic membrane system for washing. A flow meter is installed on the water supply pipeline of the washing liquid at the feed end of the second stage of the secondary washing ceramic membrane system, and a conductivity meter is installed at the production end. A flow meter and a conductivity meter are installed at the permeate end. The permeate from the first and second stages of the secondary washing ceramic membrane system enters the washing liquid storage tank. The white material treated by the second stage of the secondary washing ceramic membrane system is mixed with the permeate from the fourth stage of the secondary washing concentrated ceramic membrane system or the washing makeup water, and then enters the third stage of the secondary washing ceramic membrane system for washing. A flow meter is installed on the permeate makeup water pipeline and the fresh washing water makeup water pipeline of the third stage of the secondary washing ceramic membrane system. A conductivity meter is installed at the feed end, and a flow meter and conductivity meter are installed at the permeate end. The permeate from the third stage of the secondary washing ceramic membrane system is returned to the pre-concentration washing unit for use in the first stage washing ceramic membrane system for white material washing. After the white material is treated by the three-stage system of secondary washing ceramic membrane, it is mixed with the washing water and then enters the four-stage system of secondary washing and concentration ceramic membrane for washing and concentration. A flow meter is installed in the fresh washing water replenishment pipeline of the four-stage system of secondary washing and concentration ceramic membrane, and a conductivity meter is installed at the production end. The white material processed by the four-stage ceramic membrane washing and concentration system enters the purified white material storage tank; the permeate from the four-stage ceramic membrane washing and concentration system is returned to the intermediate white material storage tank, the feed end of the two-stage ceramic membrane washing system, and / or the feed end of the three-stage ceramic membrane washing system for reuse as washing liquid; a conductivity meter is installed on the main permeate reuse pipeline of the four-stage ceramic membrane washing and concentration system.

[0028] Specifically, the data monitoring module includes a tank monitoring unit for collecting the conductivity and solid content of white material at different height positions in the intermediate white material storage tank, and a membrane segment monitoring unit for collecting the conductivity and permeate flow rate of each membrane segment in the washing and concentration unit on the feed side, product side and permeate side. Specifically, the tank monitoring unit is installed in the intermediate white material storage tank, including a bypass-type online conductivity meter and an online density meter installed in the upper, middle, lower and outlet positions of the intermediate white material storage tank, respectively; wherein, the bypass-type online conductivity meter is used to collect the conductivity of the white material at the corresponding height position, and the online density meter is used to collect the solid content of the white material at the corresponding height position. Specifically, the membrane segment monitoring unit includes: conductivity meters installed on the feed side of the first, second, third, and fourth segment systems respectively; conductivity meters installed on the permeate side of the first, second, third, and fourth segment systems respectively; and conductivity meters installed on the feed side of the first, second, third, and fourth segment systems respectively. In implementation, sampling branch pipes are installed at the upper, middle, and lower layers of the intermediate white material storage tank and at the discharge port. Each sampling branch pipe is connected to a corresponding bypass online conductivity meter and an online density meter. The online density meter determines the solid content of the white material at the corresponding location based on the calibration relationship between the density and solid content of the white material slurry. Preferably, at least two sampling branch pipes are installed at each layer of the intermediate white material storage tank.

[0029] Specifically, the white material analysis module is used to determine the state of the white material entering the film based on the white material conductivity and solid content at different height positions. In implementation, the white material analysis module determines the distribution of the white material system based on the solid content at different heights in the intermediate white material storage tank. Specifically, it determines whether the solid content is uniform by comparing the dispersion of solid content at each height. In practice, the ratio of the difference between the maximum and minimum values ​​to the average value is usually used as the judgment index. When the dispersion of solid content is less than the solid content uniformity threshold, the solid content distribution is considered uniform; otherwise, it is considered non-uniform. The solid content uniformity threshold is usually around 0.1. It is understandable that solid content reflects the structural state and fluidity of the white material, which is a prerequisite for the validity of conductivity determination. Uniform solid content indicates that the white material slurry is evenly distributed in the storage tank, without obvious sedimentation or stratification, and the system has good fluidity and mixing state. In response to the uneven solid content at different height positions, the state of the white material entering the film is determined to be abnormal material flow. It can be understood that uneven solid content indicates that the white material has sedimentation, stratification or agglomeration, and the system has abnormal fluidity. At this time, the conductivity distribution is easily distorted by the material structure. Therefore, the state of the white material entering the film is directly determined to be abnormal material flow. Only when the solid content is uniform and the system structure is stable can the conductivity truly reflect the spatial distribution of salts, i.e., responding to the uniformity of solid content at different heights. The state of the white material entering the membrane is determined by combining the conductivity of the white material, specifically including: Based on the results of determining the non-uniformity of conductivity at different heights, the state of the white material entering the membrane is determined to be locally mixed abnormally. It should be understood that, under the premise of uniform solid content distribution, the salt distribution is judged based on the conductivity at different heights to determine whether there is a local abnormality in salt content. The uniformity of conductivity is also determined by the degree of dispersion of conductivity (calculated in the same way as the dispersion of solid content, and the conductivity uniformity threshold is usually taken as 0.1). When the conductivity distribution is non-uniform, it indicates that there is local enrichment or insufficient mixing of salt in the storage tank, and the state of the white material entering the membrane is determined to be locally mixed abnormally. Based on the determination of uniform conductivity at different height positions, the state of the white material entering the film is determined to be high overall salt load if the average conductivity at each height position is higher than the conductivity threshold, or normal material entry into the film if the average conductivity at each height position is not higher than the conductivity threshold. It can be understood that when the conductivity distribution is uniform, it indicates that the salt content is uniformly distributed throughout the system. In this case, it is necessary to judge whether the overall salt load is too high by checking the overall conductivity level, thereby achieving graded identification of the white material entry state. Therefore, by comparing the average conductivity at each height position with the conductivity threshold, if the average conductivity is higher than the conductivity threshold, it indicates that the overall salt load of the system is too high; if the average conductivity is not higher than the conductivity threshold, it indicates that the salt content of the system is at a normal level, and the material entry into the film is determined to be normal. In practice, the conductivity threshold is determined based on the relationship between the soluble salt content and conductivity in the white material system, typically ranging from 2500 μS / cm to 4000 μS / cm; in addition, it can be dynamically adjusted by production personnel based on their experience.

[0030] The hierarchical decision-making module is used to determine the membrane segment water replenishment strategy based on the determination result of the state of the incoming white material, including: In response to the normal material feeding into the membrane, no membrane segment water replenishment strategy is formulated. It is understood that when the white material feeding into the membrane is normal, it indicates that the solid-liquid distribution in the white material system is stable and the fluidity is good. At the same time, the soluble salt load in the system is within the normal range, and there is no obvious salt removal requirement in the membrane segment washing process. Therefore, continuing to perform water replenishment operation under this state will not only fail to significantly improve the desalination effect, but may also lead to ineffective dilution, increase the subsequent concentration load and energy consumption. Therefore, no membrane segment water replenishment strategy is formulated, and the current operating state can be maintained. In response to the aforementioned abnormal material flow, the membrane segment water replenishment strategy is determined to be to stir the intermediate white material storage tank without replenishing the membrane segment. It is understood that when the incoming white material exhibits abnormal flow, it indicates that the white material has settled, stratified, or locally agglomerated within the storage tank, resulting in poor system fluidity. Under these circumstances, the conductivity distribution cannot accurately reflect the salt content, and the membrane segment feed exhibits instability. If membrane segment water replenishment is directly performed, the washing liquid cannot uniformly enter the material system, mass transfer is hindered, and the water replenishment effect is poor. Therefore, it is prioritized to rehomogenize the material through the stirring intermediate white material storage tank to improve system fluidity and uniformity. Membrane segment water replenishment is not performed until the uniform state is restored, thereby avoiding ineffective water replenishment and membrane load fluctuations. In response to the overall high salt load or the localized mixing anomaly, membrane segment replenishment is performed, wherein: Based on the overall high salt load assessment, the membrane section water replenishment strategy is determined to be average water replenishment across the entire membrane section. It can be understood that when the feed material is under overall high salt load, it indicates uniform solids and conductivity distribution, but the average conductivity at each height point is higher than the conductivity threshold, suggesting that salt is evenly distributed throughout the system and has a high overall concentration. In this case, the high salt load in each membrane section leads to a holistic washing requirement. Therefore, it is necessary to introduce washing liquid throughout the entire process through water replenishment, allowing the salt to migrate step-by-step along each membrane section and be carried out by the permeate. Thus, the membrane section water replenishment strategy is determined to be average water replenishment across the entire membrane section, i.e., evenly distributing the water replenishment amount across multiple key membrane sections to improve overall desalination efficiency. Based on the determination of localized mixing anomalies, the membrane segment water replenishment strategy is determined to be localized membrane segment water replenishment. It is understood that when the feed material exhibits localized mixing anomalies, it indicates a uniform solids content distribution but an uneven conductivity distribution. This suggests a stable material structure, but with localized salt accumulation or insufficient mixing, such as enrichment in the upper mother liquor or inadequate mixing of localized recycled liquid. In this case, the salt load problem is localized rather than systemic. Using full-segment water replenishment would result in redundant water replenishment in some membrane segments. Therefore, water replenishment should be adjusted specifically for membrane segments corresponding to high conductivity areas, concentrating water replenishment on segments with higher water replenishment effectiveness. This improves the targeting of washing and the efficiency of water utilization, thus determining the membrane segment water replenishment strategy as localized membrane segment water replenishment.

[0031] The hierarchical decision module responds to the judgment result of local mixing anomaly and controls the operation of the membrane segment evaluation module to calculate the desalination release degree and filtration impedance of each membrane segment; The membrane segment evaluation module determines the degree of desalination release of each membrane segment based on the conductivity of the feed side, product side, and permeate side. Specifically, the degree of desalination release characterizes whether a certain membrane segment can effectively transfer soluble salts from the raw material to the permeate side, i.e., whether the salt is successfully washed out and discharged. The difference in conductivity between the feed and product sides reflects the degree of salt removal from the raw material by that membrane segment, while the conductivity on the permeate side reflects whether the removed salts actually enter the permeate system. When the difference in conductivity between the feed and product sides is large and the permeate conductivity is high, it indicates that the salts are both effectively released from the raw material and carried out by the permeate, thus indicating a high degree of desalination release. Conversely, a small difference indicates that the salts have not effectively migrated or been carried out, indicating a low degree of desalination release. It is understandable that membrane system design takes into account feed salt load, washing water volume, recovery rate, membrane area, flux, interstage reuse relationship, and final product conductivity requirements. Therefore, each membrane segment should have a target conductivity reduction range. Thus, the preset difference value matches the desalination task designed for the corresponding membrane segment, and different membrane segments have different preset difference values. The preset difference value can be determined based on the feed-side conductivity, product-side conductivity, target impurity removal amount, and historical stable operation data of the corresponding membrane segment under design conditions. The preset conductivity on the permeate side is used to determine whether there is sufficient salt load in the permeate. It is usually set below the conductivity threshold and set to 1000-3000 μS / cm to avoid misjudging the situation of local concentration but not being discharged as effective desalination.

[0032] The membrane segment evaluation module determines the permeate flow rate variation and the feed-side conductivity decrease based on the permeate flow rate and feed-side conductivity of the corresponding membrane segment, thereby determining the filtration impedance of the corresponding membrane segment. It can be understood that filtration impedance characterizes the degree to which a membrane segment impedes fluid flow, reflecting membrane flux decay and mass transfer limitation. In practice, the permeate flow rate variation is calculated as follows: (Average permeate flow rate during the stable performance period of a membrane segment - Average permeate flow rate during the current evaluation period) ÷ Average permeate flow rate during the stable performance period of a membrane segment × 100%. The feed-side conductivity decrease is calculated as follows: (Feed-side conductivity at the beginning of the current evaluation period - Feed-side conductivity at the end of the current evaluation period) ÷ Feed-side conductivity at the beginning of the current evaluation period × 100%. Specifically: When the change in permeate flow rate exceeds a preset flow rate change value and the decrease in product-side conductivity is less than a preset conductivity decrease value, the corresponding membrane segment is determined to have high filtration impedance. This means that a large change in permeate flow rate indicates a significant decrease in flow rate compared to the stable performance period, suggesting a significant decline in membrane flux, membrane fouling, increased concentration polarization, or channel blockage, thus reflecting increased filtration impedance. Simultaneously, a small decrease in product-side conductivity indicates that the washing liquid failed to effectively remove salts after entering the system, indicating impaired mass transfer. Therefore, a large change in permeate flow rate and a small decrease in product-side conductivity can be considered a high filtration impedance. Conversely, when the change in permeate flow rate is not greater than a preset flow rate change value and / or the decrease in product-side conductivity is not less than a preset conductivity decrease value, the membrane segment still exhibits good flux and mass transfer capabilities, and the corresponding membrane segment is determined to have low filtration impedance. In practice, the current evaluation cycle is determined based on the membrane system cycle time, material residence time, or production cycle time, and can generally be taken as 10 to 30 minutes, or as an integer multiple of a complete cycle; the performance stability period refers to the baseline operating stage of the membrane segment under normal operation and without obvious pollution or abnormalities; It is understandable that membrane systems typically experience natural fluctuations within 5% during stable operation. When the flow rate drops beyond this range, it often indicates membrane fouling, increased concentration polarization, or channel blockage. Therefore, the preset flow rate change value is preferably set between 5% and 15%. When it is below this range, the flow rate change can be considered a normal fluctuation of the system. When it exceeds this range, it indicates that the membrane flux has substantially decreased, and it can be determined that there is a trend of increasing filtration impedance. Understandably, a small decrease in conductivity within an evaluation period indicates that despite water replenishment or circulation, salt has not effectively migrated to the permeate side, resulting in impaired mass transfer or low washing efficiency. Therefore, the preset conductivity decrease value should be able to distinguish between effective and ineffective washing. In engineering practice, normal effective washing typically achieves a conductivity decrease of more than 10%, while a decrease below this range indicates a weak washing effect. Therefore, the preset conductivity decrease value is preferably set between 10% and 25%, which covers the effective desalination capacity of different membrane segments under different salt loads, while avoiding misjudging small fluctuations in a short period of time as effective washing.

[0033] The membrane segment evaluation module determines the effectiveness of makeup water for the corresponding membrane segment by combining the desalination release degree and the filtration impedance. It can be understood that makeup water effectiveness is used to determine whether makeup water can be converted into actual desalination effect. Specifically: when the desalination release degree is high and the filtration impedance is low, it indicates that the membrane segment has both salt release capacity and good flux, and makeup water can be directly converted into a desalination effect, thus it is judged as overtly effective makeup water; when the desalination release degree is high but the filtration impedance is high, or the desalination release degree is low but the filtration impedance is low, it indicates that the membrane segment has some conditions but is limited, such as salt being present but difficult to remove, or good flux but insufficient salt release. In this case, makeup water may still have an effect but requires auxiliary conditions, thus it is judged as latently effective makeup water; when the desalination release degree is low and the filtration impedance is high, it indicates that there is neither salt release driving force nor mass transfer resistance, and makeup water is unlikely to produce an actual desalination effect, thus it is judged as ineffective makeup water.

[0034] The hierarchical decision-making module determines the water-replenishing membrane segment based on the triggering result of local membrane segment water replenishment and the water replenishment effectiveness of each membrane segment; Specifically, when the system triggers local membrane segment replenishment, the replenishment resources should be allocated to the membrane segment that can produce the best desalination effect. The visible effective replenishment membrane segment has both high desalination release capacity and low filtration impedance, and can produce a desalination effect immediately after replenishment. Therefore, it is given priority as the direct replenishment membrane segment. Although the invisible effective replenishment membrane segment has certain potential, it has mass transfer or distribution limitations. It needs to be pre-diluted with permeate to improve the local salt concentration or flow state before it can play a replenishment role. Therefore, it is determined as the treatment replenishment membrane segment and requires pre-diluted with permeate before replenishment. The effective hierarchical allocation mechanism can improve the replenishment utilization efficiency and reduce system energy consumption.

[0035] Understandably, the evaluation of water replenishment effectiveness covers all membrane segments, but water replenishment implementation is limited to membrane segments equipped with fresh water replenishment interfaces, thereby achieving optimal allocation of water replenishment resources while ensuring the stability of the system structure.

[0036] In practice, if the results of the water replenishment effectiveness analysis are the same, the hierarchical decision module will select the membrane segment with better data as the target water replenishment membrane segment based on the calculation results of the specific conductivity difference, permeate side conductivity, permeate flow rate change range and feed side conductivity decrease range, and perform water replenishment operation in the membrane segment with water replenishment conditions.

[0037] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A membrane-based iron phosphate white material concentration and purification system based on water reuse regulation, comprising a white material tank, a pre-concentration and washing unit, an intermediate white material storage tank, a washing and concentration unit, and a purified white material storage tank connected in sequence, wherein the pre-concentration and washing unit includes a concentration ceramic membrane system and a primary washing ceramic membrane system, and the washing and concentration unit includes a secondary washing ceramic membrane system, a first-stage system, a second-stage system, a third-stage system, and a fourth-stage system connected in sequence, characterized in that, Also includes: The data monitoring module includes a tank monitoring unit for collecting the conductivity and solid content of the white material at different height positions in the intermediate white material storage tank, and a membrane segment monitoring unit for collecting the conductivity and permeate flow rate of each membrane segment in the washing and concentration unit on the feed side, product side and permeate side. The white material analysis module is used to determine the white material status of the film-feeding material based on the white material conductivity and solid content at different height positions. The white material status includes normal material feeding, abnormal material flow, abnormal local mixing, and overall high salt load. The membrane segment evaluation module is used to determine the desalination release degree of the corresponding membrane segment based on the conductivity of the feed side, feed side and permeate side of each membrane segment, to determine the filtration impedance of the corresponding membrane segment based on the permeate flow rate and feed side conductivity of the corresponding membrane segment, and to determine the water replenishment effectiveness of the corresponding membrane segment by combining the desalination release degree and the filtration impedance. The hierarchical decision module is used to determine the water replenishment strategy for the membrane segment based on the determination result of the state of the incoming white material. The water replenishment membrane segment is determined based on the triggering result of local membrane segment water replenishment and the water replenishment effectiveness of each membrane segment. The membrane segment water replenishment strategy includes average water replenishment across the entire membrane segment and localized water replenishment within the membrane segment.

2. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The white material analysis module determines the state of the white material entering the film based on the conductivity and solid content of the white material at different height positions, including: In response to the uneven solid content at different height positions, the state of the feed white material is determined to be abnormal material flow; In response to the uniformity of solid content at different height positions, the state of the white material entering the membrane is determined in conjunction with the conductivity of the white material, wherein: Based on the results of determining the non-uniformity of conductivity at different height positions, the state of the white material entering the membrane was determined to be a localized mixing abnormality. Based on the determination of uniform conductivity at different height positions, the state of the white material entering the membrane is determined to be high salt load if the average conductivity at each height position is higher than the conductivity threshold, or the state of the white material entering the membrane is determined to be normal material entry into the membrane if the average conductivity at each height position is not higher than the conductivity threshold.

3. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The hierarchical decision-making module determines the membrane segment water replenishment strategy based on the determination result of the state of the incoming white material, including: If the material feed into the membrane is normal, no water replenishment strategy is formulated for the membrane segment. In response to the abnormal material flow, the membrane segment water replenishment strategy is determined to be that no water replenishment is performed on the intermediate white material storage tank. In response to the overall high salt load or the localized mixing anomaly, membrane segment replenishment is performed, wherein: Based on the overall high salt load assessment, the membrane section water replenishment strategy is determined to be average water replenishment across the entire membrane section. Based on the results of the local mixing anomaly assessment, the membrane segment water replenishment strategy was determined to be local membrane segment water replenishment.

4. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The hierarchical decision module responds to the determination result of local mixing anomalies and controls the membrane segment evaluation module to calculate the desalination release degree and filtration impedance of each membrane segment.

5. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The membrane segment evaluation module determines the desalination release degree of each membrane segment based on the conductivity difference between the feed and product sides and the conductivity of the permeate side, wherein: Based on the determination that the conductivity difference is not less than a preset difference and the conductivity on the permeate side is not less than a preset conductivity, the corresponding membrane segment is determined to have a high degree of desalination release. Conversely, it indicates that the corresponding membrane segment has a low degree of desalination release.

6. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The membrane segment evaluation module determines the permeate flow rate variation and the feed-side conductivity decrease based on the permeate flow rate and feed-side conductivity of the corresponding membrane segment, respectively, to determine the filtration impedance of the corresponding membrane segment, including: When the change in permeate flow rate is greater than the preset flow rate change value and the decrease in conductivity on the feed side is less than the preset conductivity decrease value, the corresponding membrane segment is determined to be high filtration impedance. Conversely, the corresponding membrane segment is determined to have low filtration impedance.

7. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 1, characterized in that, The membrane segment evaluation module determines the water replenishment effectiveness of the corresponding membrane segment by combining the degree of desalination release and the filtration impedance, including: Based on the judgment results of high desalination release and low filtration impedance, the water replenishment effectiveness of the corresponding membrane segment is determined to be manifest effective water replenishment; Based on the determination results of high desalination release or low filtration impedance, the water replenishment effectiveness of the corresponding membrane segment is determined to be implicit effective water replenishment. Based on the judgment results of low desalination release and high filtration impedance, the water replenishment effectiveness of the corresponding membrane segment was determined to be ineffective.

8. The all-membrane method for ferric phosphate white material concentration and purification based on water replenishment and reuse regulation according to claim 7, characterized in that, In response to triggering local membrane segment water replenishment, the hierarchical decision module identifies the visible effective water replenishment membrane segment as the direct water replenishment membrane segment and replenishes the membrane segment with fresh water.

9. The all-membrane method for concentrating and purifying ferric phosphate white material based on water replenishment and reuse regulation according to claim 8, characterized in that, In response to triggering local membrane segment water replenishment, the hierarchical decision module also identifies the latent effective water replenishment membrane segment as the treatment water replenishment membrane segment, and pre-dilutes the permeate in the membrane segment before replenishing it with fresh water.

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