Integrated system for efficiently purifying fine phosphate

Abstract

The invention discloses a fine phosphate high-efficiency purification integrated system, and relates to the technical field of fine chemical engineering purification, and the system is characterized in that a raw material pretreatment circulation module mixes raw materials and reflux mother liquor for concentration regulation and preheating, and then conveys the raw materials and reflux mother liquor to an organic and inorganic impurity synergistic removal module through a flow stabilization subsystem; carrying out plasma treatment and filtration, and then sending to a phosphate concentration and enrichment module; the concentrated material enters a composite field crystal form regulation and control module and then is conveyed to a product separation quality guarantee module, mother liquor is recycled, and a product is output after crystals are treated and detected; a multi-module collaborative integrated system is constructed, raw material pretreatment and impurity removal are deeply fused, enrichment is enhanced, concentration stability is guaranteed, product purity is improved, a composite physical field and a cooling regulation and control technology are integrated to optimize a crystal structure, quality is ensured through multi-stage purification detection, emission is reduced through circular design, efficient purification and green production are achieved, and the method is suitable for industrial production. The high-quality requirement is met.

Description

Technical Field

[0001] This invention relates to the field of fine chemical purification technology, specifically to an integrated system for the efficient purification of fine phosphates. Background Technology

[0002] Fine phosphates are indispensable raw materials in the chemical industry, with applications spanning multiple important sectors and directly impacting the performance and quality of related products. As industrial production moves towards refinement and high quality, the market demands higher standards for the purity, crystal regularity, and particle size uniformity of fine phosphates. Purification processes, as the core of fine phosphate production, directly determine the application value of the product, and their technological advancement has become a key driver of industry development. In actual production, it is necessary to achieve efficient removal of organic and inorganic impurities from raw materials, concentration and enrichment of target components, precise control of crystal structure, and stable product quality assurance. The coordinated operation of each stage is crucial for purification effectiveness. Currently, the chemical industry has an increasingly urgent need for efficient, energy-saving, and environmentally friendly purification technologies, driving the development of purification systems towards integration, intelligence, and circularity to meet the stringent requirements of fine phosphates in different application scenarios.

[0003] Traditional fine phosphate purification technologies have many limitations and are difficult to adapt to the high-quality and high-efficiency requirements of modern production. In the impurity removal stage, traditional methods often use single treatment methods, which cannot achieve simultaneous purification of organic and inorganic impurities, resulting in high impurity residues. This affects the subsequent concentration and crystal form control effects. During the concentration process, commonly used technologies often suffer from high energy consumption and insufficient recovery rate of target components. Moreover, core components such as membrane separation are easily contaminated, resulting in high maintenance costs and poor stability. In terms of crystal form control, traditional technologies lack coordinated control of the physical field and cooling process, making it difficult to accurately control the crystal growth state. This results in irregular crystal forms and uneven particle size distribution, which in turn affects the application performance. At the same time, the traditional process has loose connections between various stages, and the mother liquor recovery rate is low, which not only wastes resources but may also cause environmental pollution. In addition, traditional detection methods are not comprehensive enough to accurately monitor key indicators such as product purity and crystal form in real time, resulting in large fluctuations in product quality and poor batch consistency. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an integrated system for the efficient purification of fine phosphates. This system utilizes multiple modules working collaboratively, including raw material pretreatment recycling, synergistic removal of organic and inorganic impurities, phosphate concentration and enrichment, composite field crystal form control, and product separation and quality assurance. It employs composite processing and specific separation technologies to achieve simultaneous impurity purification and target component enrichment. Combined with a composite physical field and multi-stage cooling control for precise intervention in crystal growth, and featuring a full-process cyclical design and online detection methods, it achieves material recycling and full-cycle quality control of products. The system's tightly integrated processes ensure product purity, crystal form, and particle size uniformity while reducing energy consumption and material loss, minimizing environmental impact, improving production efficiency and batch stability, and meeting the high-quality requirements of various application scenarios for fine phosphates.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an integrated system for high-efficiency purification of fine phosphates, the system comprising:

[0006] Raw material pretreatment circulation module: Receives phosphate raw materials to be purified and mother liquor returned from the product separation quality assurance module, mixes them in proportion and adjusts the concentration to 12% to 18% mass fraction, preheats to 55 to 75℃, controls the conveying rate to 40 to 60L / h through the flow stabilization subsystem, and continuously conveys the material to the organic and inorganic impurity co-removal module.

[0007] Organic and inorganic impurity synergistic removal module: Receives the conveyed material, treats it with dielectric barrier discharge plasma, then filters it through an acid-resistant ceramic filter channel, and conveys the clarified material to the phosphate concentration and enrichment module.

[0008] Phosphate concentration and enrichment module: Receives the conveyed clarified material, uses a modified polytetrafluoroethylene hollow fiber membrane for membrane distillation separation in a cross-flow manner, and the concentrated material is conveyed to the composite field crystal form control module through an insulated pipeline.

[0009] Composite field crystal form control module: Receives the conveyed concentrated material, initiates a multi-stage programmed cooling process, and simultaneously applies a composite physical field of ultrasonic waves and weak pulse electric fields or ultrasonic waves and specific wavelength infrared radiation. Through the composite field-cooling linkage crystal form control algorithm, it controls various operating parameters and conveys the crystalline material to the product separation quality assurance module.

[0010] Product Separation Quality Assurance Module: Receives the conveyed crystalline material, separates the crystals from the mother liquor through a solid-liquid separation device, and sends the separated mother liquor to the raw material pretreatment recycling module for reuse. After drying and sieving, the crystals are tested by an online detection device and output as refined phosphate products.

[0011] Furthermore, the raw material pretreatment circulation module includes a raw material buffer tank, a static mixer, a mechanical stirring device, an online density meter, and a shell-and-tube heat exchanger. The mixing ratio of raw material to reflux mother liquor is 3 to 5:1. The stirring speed of the mechanical stirring device is 300 to 500 rpm. The online density meter adjusts the material concentration through a linkage deionized water replenishment valve and a concentrated mother liquor replenishment valve, with a concentration control accuracy of ±0.5%. The shell-and-tube heat exchanger uses 0.3 to 0.5 MPa high-temperature steam as the heat exchange medium, with a temperature control accuracy of ±1℃. The flow stabilization subsystem consists of a variable frequency metering pump and an electromagnetic flow sensor, with flow fluctuations controlled within ±5%.

[0012] Furthermore, the dielectric barrier discharge plasma reaction chamber of the organic-inorganic impurity synergistic removal module adopts a dual-electrode structure. The electrode material is titanium alloy, the dielectric layer is alumina ceramic with a thickness of 2 to 3 mm, the electrode spacing is set to 5 to 10 mm, the output voltage range of the high-frequency high-voltage power supply is 10 to 30 kV, the frequency is 1 to 10 kHz, the processing is carried out under normal pressure and 50 to 80°C, the discharge power is 50 to 150 W, and the residence time of the material in the reaction chamber is 30 to 90 min.

[0013] Furthermore, the acid-resistant ceramic filter channel of the organic-inorganic impurity synergistic removal module uses an α-Al2O3 or SiC material filter membrane with a pore size of 0.05 to 0.1 μm and a porosity of ≥45%. It operates in a cross-flow filtration mode with a membrane surface velocity of 1 to 2 m / s and an operating pressure of 0.1 to 0.3 MPa. The system is equipped with an automatic backwashing device with compressed air as the backwashing medium, a backwashing pressure of 0.3 to 0.4 MPa, a backwashing time of 30 to 60 s, and a backwashing cycle of 2 to 3 h.

[0014] Furthermore, the modified polytetrafluoroethylene hollow fiber membrane of the phosphate concentration and enrichment module undergoes plasma surface modification treatment, resulting in a membrane surface contact angle ≥150°, a membrane fiber pore size of 0.1 to 0.5 μm, a porosity of 70% to 85%, and an effective membrane area of ​​5 to 10 m² for a single membrane module. 2 The membrane filaments number 1000 to 1500, the membrane distillation module housing is made of 316L stainless steel, and the module is equipped with a chemical cleaning unit.

[0015] Furthermore, the membrane distillation process of the phosphate concentration and enrichment module adopts a direct contact operation mode. The material side is heated by a jacket to maintain the temperature at 60 to 90°C. The cooling medium of the cooling circulation system is deionized water at 20 to 30°C. The permeate side temperature is controlled at 25 to 35°C. The pressure on the permeate side is adjusted by a vacuum pump to stabilize the pressure difference across the membrane at 0.01 to 0.05 MPa. After purification by ion exchange resin, the conductivity of the permeate is ≤10 μS / cm, and the permeate recovery rate is ≥90%.

[0016] Furthermore, the ultrasonic generation system of the composite field crystal form control module consists of 4 to 6 ultrasonic transducers, which are evenly distributed on the outer wall of the crystallizer, with an operating frequency of 20 to 80 kHz and a power density of 0.5 to 2.0 W / cm². 2 The weak pulsed electric field unit features concentric ring-shaped platinum electrodes in 2 to 4 groups, with an electrode spacing of 10 to 15 cm, an electric field strength of 0.5 to 5 kV / cm, a pulse frequency of 10 to 100 Hz, and a pulse width of 10 to 100 μs. The infrared radiator of the specific wavelength infrared radiation unit is mounted on top of the crystallizer, with a radiation wavelength of 2.5 to 5.0 μm and a radiation power density of 10 to 50 mW / cm². 2 .

[0017] Furthermore, the multi-stage programmed cooling process of the composite field crystal form control module is divided into four stages: the first stage cools from 60 to 80°C to 50 to 55°C at a cooling rate of 15 to 20°C / h; the second stage cools from 50 to 55°C to 35 to 40°C at a cooling rate of 8 to 12°C / h; the third stage cools from 35 to 40°C to 20 to 25°C at a cooling rate of 5 to 8°C / h; and the fourth stage cools from 20 to 25°C to 10 to 15°C at a cooling rate of 2 to 5°C / h, with a total cooling range of 40 to 60°C.

[0018] Furthermore, the composite physical field of the composite field crystal form control module regulates various operating parameters through a composite field-cooling linkage crystal form control algorithm. The mathematical expression of the composite field-cooling linkage crystal form control algorithm is as follows: ,in, It is a crystal growth regulator. It is the coupling coefficient of the composite field. It is the contribution coefficient of the ultrasonic field. It is the ultrasonic power density. It is an ultrasonic frequency. These are auxiliary physical field weighting coefficients. It is the characteristic function of the auxiliary physical field, the weak pulse electric field: , For electric field strength, The pulse frequency, Given the pulse width, the infrared radiation field is: , For radiative power density, The wavelength of radiation. It is the first The weight of the cooling phase, It is the first cooling rate of segment, It is the concentration correction factor. This is the current material concentration. This is the baseline concentration. This indicates the total number of cooling stages. The process of controlling various operating parameters through the composite physical field-cooling linkage crystal form control algorithm involves real-time acquisition of the operating parameters of the composite physical field and the parameters of the cooling process. The operating parameters of the composite physical field include ultrasonic power density and ultrasonic frequency. If the composite physical field consists of ultrasound and a weak pulse electric field, it also includes the electric field strength, pulse frequency, and pulse width of the weak pulse electric field. If the composite physical field consists of ultrasound and infrared radiation of a specific wavelength, it also includes the radiation power density and radiation wavelength of the infrared radiation. The parameters of the cooling process include the cooling rate and cooling intensity of each stage. The weights and current material concentration are used as parameters to calculate the crystal growth control factor η using the composite field-cooling linkage crystal form control algorithm. Based on the value of η, the operating parameters of the composite physical field and the parameters of the cooling process are adjusted. Specifically, the ultrasonic power density or ultrasonic frequency is changed, the electric field strength, pulse frequency, or pulse width of the weak pulse electric field is changed, or the radiation power density or radiation wavelength of infrared radiation is changed. At the same time, the cooling rate or cooling weight of the corresponding segment in the cooling process is adjusted. After adjustment, the parameters are collected again and substituted into the algorithm to recalculate η. The above process is continued until η is within the set range.

[0019] Furthermore, the solid-liquid separation device of the product separation quality assurance module adopts a horizontal spiral sedimentation centrifuge with a drum diameter of 300 to 500 mm, a separation factor of 3000 to 5000 g, and a separation time of 10 to 20 min. The separated mother liquor is filtered through a precision filter membrane with a pore size of 0.02 μm, and then the pH value of the mother liquor is adjusted to 4.5 to 6.5 by a pH adjustment device. The crystals enter a vacuum freeze dryer, with the drying chamber temperature controlled at -40℃ to -20℃, the vacuum degree at 10 to 50 Pa, and the drying time at 4 to 6 h.

[0020] Furthermore, the online detection device of the product separation quality assurance module includes a high-performance liquid chromatograph, an X-ray diffractometer, and a laser particle size analyzer. The detection accuracy of the high-performance liquid chromatograph is 0.001%, the spectral similarity comparison accuracy of the X-ray diffractometer is ≥98%, and the particle size measurement accuracy of the laser particle size analyzer is ±1μm. The dried crystals are pulverized by an air jet mill at a pulverization pressure of 0.6 to 0.8 MPa, and then screened by a 200 to 300 mesh stainless steel sieve. After screening, the content of large particle impurities is ≤0.5%.

[0021] Compared with existing technologies, this integrated system for efficient purification of fine phosphates has the following advantages:

[0022] I. This invention integrates raw material pretreatment and impurity removal processes by constructing a multi-module collaborative integrated system. It employs a composite treatment method on the materials to simultaneously purify both organic and inorganic impurities, reducing interference from impurities in subsequent processes. Utilizing specific material filtration and membrane separation technologies, it enhances the enrichment of target components in the materials. Simultaneously, precise control of temperature, pressure, and other conditions ensures the stability and continuity of the concentration process. The cyclical design in the pretreatment stage allows for the full recovery and utilization of the mother liquor, improving resource utilization and reducing material loss. Combined with efficient separation technology, it enhances the purity of phosphate products, laying a solid foundation for subsequent crystal form control. The overall process is tightly integrated, avoiding quality fluctuations in intermediate stages. Through the efficient cooperation of each module, it achieves high efficiency and refinement in the purification process, reducing ineffective consumption and improving overall production efficiency.

[0023] II. This invention integrates composite physical fields and multi-stage cooling control technology to achieve precise intervention in the crystal growth process, optimize the crystal structure and particle size distribution, and improve the physicochemical properties of the product. The product separation stage employs multi-stage purification and detection methods, controlling the entire process from solid-liquid separation to drying and sieving, and then to online detection, ensuring the consistency and reliability of the final product's quality. Relying on the precise monitoring and screening mechanism of the online detection device, unqualified particles are effectively removed, ensuring that the product meets high standards. Simultaneously, the full-process circular design and efficient separation technology reduce waste emissions, lower energy consumption and environmental impact, achieving resource recycling and greening of the production process. The coordinated control of multiple modules and the full-process quality management not only ensure the stability between product batches but also improve the controllability of the production process.

[0024] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0026] Figure 1 A flowchart of an integrated system for the efficient purification of fine phosphates;

[0027] Figure 2 This is a framework diagram of an integrated system for the efficient purification of fine phosphates.

[0028] Figure 3 This is a process flow diagram for the composite field crystal form control module. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0030] Example 1:

[0031] Example of fine purification of industrial-grade potassium dihydrogen phosphate.

[0032] The raw material pretreatment circulation module receives industrial-grade potassium dihydrogen phosphate raw material to be purified and mother liquor returned from the product separation and quality assurance module. These are then fed into a static mixer at a 3:1 mixing ratio, while a mechanical agitator is activated at 300 rpm for uniform mixing, ensuring thorough integration of the raw material and the returned mother liquor and preventing uneven concentration in certain areas. The material concentration is monitored in real-time by an online density meter, which, in conjunction with the deionized water and concentrated mother liquor replenishment valves, precisely adjusts the material concentration to 12% by mass, achieving a concentration control accuracy of ±0.5%, providing a stable material concentration for subsequent processing. The material then enters a shell-and-tube heat exchanger, where high-temperature steam at 0.3 MPa is used as the heat exchange medium to preheat the material to 55°C, with a temperature control accuracy of ±1°C, enhancing material activity for subsequent impurity removal operations. The preheated material is then continuously fed to the organic-inorganic impurity co-removal module at a rate of 40 L / h via a flow stabilization subsystem composed of a variable frequency metering pump and an electromagnetic flow sensor. Flow fluctuations are controlled within ±5%, ensuring stable and orderly feeding to subsequent modules. Figure 1 As shown.

[0033] The organic-inorganic impurity co-removal module receives the incoming material and first processes it through a dielectric barrier discharge plasma reaction chamber. This chamber employs a dual-electrode structure with titanium alloy electrodes and a 2mm thick alumina ceramic dielectric layer, with an electrode spacing of 5mm. A high-frequency, high-voltage power supply is activated, adjusting the output voltage to 10kV and the frequency to 1kHz. Under normal pressure and 50℃ conditions, the material is processed with a discharge power of 50W, and the residence time within the reaction chamber is 30 minutes, effectively decomposing organic impurities and disrupting the stable structure of inorganic impurities. The plasma-treated material then enters an acid-resistant ceramic filter channel. This channel uses an α-Al₂O₃ membrane with a pore size of 0.05μm and a porosity ≥45%, operating in a cross-flow filtration mode. The membrane surface flow rate is controlled at 1m / s, and the operating pressure is 0.1MPa, efficiently retaining pre-treated inorganic impurities and undecomposed fine particles. The system is equipped with an automatic backwashing device that starts every 2 hours, using 0.3MPa compressed air as the backwashing medium. The backwashing time lasts for 30 seconds to prevent the filter membrane from clogging and keep the filter channel unobstructed. The filtered clarified material is then transported to the phosphate concentration and enrichment module.

[0034] After receiving the clarified material, the phosphate concentration and enrichment module uses a modified polytetrafluoroethylene hollow fiber membrane for cross-flow membrane distillation separation. This hollow fiber membrane undergoes plasma surface modification treatment, resulting in a membrane surface contact angle ≥150°, a pore size of 0.1 μm, a porosity of 70%, and an effective membrane area of ​​5 m² for a single membrane module. 2 The membrane distillation unit has 1000 membrane fibers and a shell made of 316L stainless steel. It is equipped with a chemical cleaning unit to prevent membrane fouling and ensure distillation efficiency. The membrane distillation process uses a direct contact operation mode. The material side temperature is maintained at 60℃ through jacket heating, while the cooling circulation system uses 20℃ deionized water as the cooling medium to control the permeate side temperature at 25℃. The permeate side pressure is regulated by a vacuum pump to stabilize the pressure difference across the membrane at 0.01MPa, quickly achieving the separation of water and phosphate in the material. The permeate, after purification by ion exchange resin, has a conductivity ≤10μS / cm and can be recycled to reduce water waste. The permeate recovery rate is ≥90%. The concentrated material is transported through an insulated pipeline to the composite field crystal form control module, providing a suitable concentration of material for crystal growth, such as... Figure 3 As shown.

[0035] After receiving the concentrated material, the composite field crystal form control module initiates a multi-stage programmed cooling process and applies a composite physical field of ultrasonic waves and a weak pulsed electric field. The ultrasonic wave generation system consists of four ultrasonic transducers, which are evenly distributed on the outer wall of the crystallizer. The operating frequency is 20kHz, and the power density is 0.5W / cm³. 2The weak pulsed electric field unit features two sets of concentric ring platinum electrodes with a spacing of 10 cm, an electric field strength of 0.5 kV / cm, a pulse frequency of 10 Hz, and a pulse width of 10 μs, guiding the crystals to grow in a specific direction and improving crystal regularity. The multi-stage programmed cooling process consists of four stages: the first stage reduces the temperature from 60℃ to 50℃ at a rate of 15℃ / h; the second stage reduces the temperature from 50℃ to 35℃ at a rate of 8℃ / h; the third stage reduces the temperature from 35℃ to 20℃ at a rate of 5℃ / h; and the fourth stage reduces the temperature from 20℃ to 10℃ at a rate of 2℃ / h, with a total cooling range of 40℃ and a temperature control accuracy of ±0.5℃, creating a stable temperature environment for crystal growth. The composite field-cooling linkage crystal form control algorithm is run, and parameters such as ultrasonic power density, ultrasonic frequency, electric field strength, pulse frequency, pulse width of the weak pulse electric field, cooling rate of each segment, cooling weight of each segment, and current material concentration are collected in real time. The mathematical expression of the composite field-cooling linkage crystal form control algorithm is as follows: ,in, It is a crystal growth regulator. It is the coupling coefficient of the composite field. It is the contribution coefficient of the ultrasonic field. It is the ultrasonic power density. It is an ultrasonic frequency. These are auxiliary physical field weighting coefficients. It is the characteristic function of the auxiliary physical field, the weak pulse electric field: , For electric field strength, The pulse frequency, Given the pulse width, the infrared radiation field is: , For radiative power density, The wavelength of radiation. It is the first The weight of the cooling phase, It is the first cooling rate of segment, It is the concentration correction factor. This is the current material concentration. This is the baseline concentration. This indicates the total number of cooling stages. Based on the algorithm, the above operating parameters are precisely controlled to ensure that the crystal growth state is stable and the crystal form meets the requirements of fine products. The crystalline material is then transported to the product separation and quality assurance module.

[0036] After receiving crystalline material, the product separation quality assurance module separates the crystals from the mother liquor using a horizontal spiral sedimentation centrifuge. This centrifuge has a drum diameter of 300mm, a separation factor of 3000g, and a separation time of 10 minutes, efficiently separating the crystals and mother liquor to improve separation efficiency. The separated mother liquor is filtered through a precision filter membrane with a pore size of 0.02μm, and then the pH value is adjusted to 4.5 by a pH adjustment device to remove residual fine impurities and adjust the acidity / alkalinity. It is then transferred to the raw material pretreatment circulation module for recycling, reducing raw material loss. The separated crystals enter a vacuum freeze dryer. The drying chamber temperature is controlled at -40℃, the vacuum degree is 10Pa, and the drying time is 4 hours. This low-temperature vacuum environment removes moisture from the crystals without damaging their structure. The dried crystals are then pulverized by an air jet mill at a pressure of 0.6MPa, and then screened by a 200-mesh stainless steel sieve. After screening, the content of large particles is ≤0.5%, ensuring uniform product particle size. Finally, the product was tested using an online testing device including a high-performance liquid chromatograph (HPLC), an X-ray diffractometer, and a laser particle size analyzer. The HPLC had a detection accuracy of 0.001%, accurately detecting the purity of the product. The X-ray diffractometer had a pattern similarity comparison accuracy of ≥98%, confirming that the crystal structure met the standard. The laser particle size analyzer had a particle size measurement accuracy of ±1μm, ensuring that the particle size met the standard. After passing the tests, the product was output as a fine potassium dihydrogen phosphate product.

[0037] In summary, this embodiment utilizes a high-efficiency integrated system for the purification of fine phosphates, completing the purification of industrial-grade potassium dihydrogen phosphate through a process of raw material pretreatment, synergistic impurity removal, concentration and enrichment, crystal form control, and separation assurance. The raw material and reflux mother liquor are mixed at a 3:1 ratio, with the concentration precisely controlled to 12% and the temperature to 55°C before stable delivery. Organic and inorganic impurities are efficiently removed through titanium alloy electrode plasma treatment and α-Al₂O₃ membrane filtration. Modified polytetrafluoroethylene hollow fiber membrane distillation concentration is employed to achieve over 90% permeate recovery. Crystal form is optimized through a composite physical field of ultrasound and weak pulsed electric field, combined with a four-stage programmed cooling and a composite field-cooling linkage crystal form control algorithm. Finally, after horizontal spiral sedimentation centrifugation, vacuum freeze-drying, and precise multi-device testing, a high-purity, well-defined, and uniformly sized fine product is produced. The entire process involves material recycling, balancing purification efficiency and resource conservation.

[0038] Example 2:

[0039] Example of fine purification of food-grade tricalcium phosphate.

[0040] The raw material pretreatment circulation module receives the food-grade tricalcium phosphate raw material to be purified and the mother liquor returned from the product separation and quality assurance module. It is fed into a static mixer at a 5:1 mixing ratio, and a mechanical agitator is activated at 500 rpm to ensure thorough mixing and prevent localized material accumulation that could affect subsequent processing. The material concentration is adjusted to 18% by mass via an online density meter and related replenishment valves, with a concentration control accuracy of ±0.5%, ensuring the initial concentration meets the requirements for food-grade purification. After entering the tubular heat exchanger, the material is preheated to 75°C using 0.5 MPa high-temperature steam as the heat exchange medium, with a temperature control accuracy of ±1°C, further activating the material's properties and preparing it for subsequent deep impurity removal. Regulated by the flow stabilization subsystem, the material is continuously conveyed to the organic-inorganic impurity co-removal module at a rate of 60 L / h, with flow fluctuations controlled within ±5%, ensuring stable feed to subsequent processing stages and improving overall purification efficiency. Figure 2 As shown.

[0041] After entering the organic-inorganic impurity co-removal module, the material first undergoes treatment in a dielectric barrier discharge plasma reaction chamber. The chamber's dual electrodes are made of titanium alloy, with a 3mm thick alumina ceramic dielectric layer and a 10mm electrode spacing. A high-frequency, high-voltage power supply outputs 30kV at 10kHz, treating the material at 80℃ and 150W of discharge power for 90 minutes. This process deeply decomposes organic pollutants and trace harmful impurities, meeting the stringent impurity content requirements for food-grade products. Subsequently, the material enters an acid-resistant ceramic filter channel using a SiC membrane with a pore size of 0.1μm and a porosity ≥45%. During cross-flow filtration, the membrane surface velocity is 2m / s, and the operating pressure is 0.3MPa. This efficiently traps inorganic impurities and fine particles precipitated after plasma treatment, ensuring material clarity. The automatic backwashing device starts every 3 hours, backwashing for 60 seconds with compressed air at 0.4MPa to promptly remove impurities adhering to the membrane surface, maintain the unobstructed flow of the filtration channel and filtration efficiency, and then transports the filtered clarified material to the phosphate concentration and enrichment module.

[0042] The phosphate concentration and enrichment module uses a modified polytetrafluoroethylene hollow fiber membrane for membrane distillation separation. This membrane has a contact angle ≥150°, a pore size of 0.5 μm, a porosity of 85%, and an effective membrane area of ​​10 m² for a single membrane module. 2The membrane module has 1500 filaments and a 316L stainless steel outer shell equipped with a chemical cleaning unit, enhancing its corrosion resistance and service life and ensuring stable distillation. Membrane distillation employs direct contact operation. The material side is maintained at 90°C via jacket heating, with deionized water at 30°C as the cooling medium. The permeate side temperature is controlled at 35°C, and the pressure difference across the membrane is stabilized at 0.05 MPa by a vacuum pump, achieving rapid and efficient material concentration and increasing the tricalcium phosphate concentration. After purification by ion exchange resin, the permeate has a conductivity ≤10 μS / cm and a recovery rate ≥90%, achieving efficient water resource recycling and reducing water consumption costs. The concentrated material is transported via insulated pipeline to the composite field crystal form control module, providing a high-quality material basis for the growth of food-grade crystals.

[0043] The composite field crystal form control module initiates a multi-stage programmed cooling process while simultaneously applying a composite physical field of ultrasonic waves and infrared radiation of a specific wavelength. The ultrasonic wave generation system consists of six transducers, evenly distributed on the outer wall of the crystallizer, operating at a frequency of 80 kHz and a power density of 2.0 W / cm². 2 This accelerates crystal nucleus formation and promotes uniform crystal growth; the infrared radiator of the specific wavelength infrared radiation unit is installed on top of the crystallizer, with a radiation wavelength of 2.5 to 5.0 μm and a radiation power density of 50 mW / cm². 2 This process assists in regulating the crystal growth environment, improving crystal purity and regularity. The multi-stage programmed cooling consists of four phases: the first phase reduces the temperature from 80℃ to 55℃ at a rate of 20℃ / h; the second phase reduces it from 55℃ to 40℃ at a rate of 12℃ / h; the third phase reduces it from 40℃ to 25℃ at a rate of 8℃ / h; and the fourth phase reduces it from 25℃ to 15℃ at a rate of 5℃ / h, with a total cooling range of 60℃ and a temperature control accuracy of ±0.5℃, providing stable and gradual temperature conditions for crystal growth. The composite field-cooling linkage crystal form control algorithm is run, collecting real-time ultrasonic parameters, infrared radiation parameters, and various parameters during the cooling process. The algorithm precisely adjusts these parameters. The mathematical expression for the composite field-cooling linkage crystal form control algorithm is: ,in, It is a crystal growth regulator. It is the coupling coefficient of the composite field. It is the contribution coefficient of the ultrasonic field. It is the ultrasonic power density. It is an ultrasonic frequency. These are auxiliary physical field weighting coefficients. It is the characteristic function of the auxiliary physical field, the weak pulse electric field: , For electric field strength, The pulse frequency, Given the pulse width, the infrared radiation field is: , For radiative power density, The wavelength of radiation. It is the first The weight of the cooling phase, It is the first cooling rate of segment, It is the concentration correction factor. This is the current material concentration. This is the baseline concentration. This indicates the total number of cooling stages, ensuring stable crystal growth and that the crystal form meets the stringent standards for food-grade products. The crystalline material is then transported to the product separation and quality assurance module.

[0044] After the crystalline material enters the product separation and quality assurance module, it is separated by a horizontal spiral sedimentation centrifuge with a drum diameter of 500mm, a separation factor of 5000g, and a separation time of 20 minutes. This efficiently and thoroughly separates the crystals from the mother liquor, reducing mother liquor residue in the crystals. The separated mother liquor is filtered through a 0.02μm precision filter membrane, and after the pH is adjusted to 6.5, it is returned to the raw material pretreatment circulation module to maximize raw material recovery and reduce waste. The crystals then enter a vacuum freeze dryer. The drying chamber temperature is -20℃, the vacuum degree is 50Pa, and the drying time is 6 hours. This low-temperature vacuum environment thoroughly removes moisture from the crystals while maintaining their original structure and purity, meeting food-grade requirements. The dried crystals are then pulverized by an air jet mill at a pressure of 0.8MPa and screened by a 300-mesh stainless steel sieve. The content of large particle impurities is ≤0.5%, ensuring that the product has a uniform and fine particle size. The product was tested using an online detection device. The high-performance liquid chromatograph had a detection accuracy of 0.001%, accurately detecting the purity of the product. The X-ray diffraction pattern similarity comparison accuracy was ≥98%, confirming that the crystal structure met the standards. The laser particle size analyzer had a particle size measurement accuracy of ±1μm, ensuring that the particle size met the standards. After passing the tests, the product was output as a food-grade fine tricalcium phosphate.

[0045] In summary, this embodiment addresses the stringent purification requirements of food-grade tricalcium phosphate by employing an integrated system to control quality throughout the entire process. Raw materials and reflux mother liquor are mixed at a 5:1 ratio, and the concentration is adjusted to 18% and the temperature raised to 75°C before stable feeding. High-intensity plasma deep treatment and SiC membrane precision filtration meet food-grade impurity control standards. Modified PTFE membrane distillation with a large effective membrane area efficiently concentrates the material and recovers water resources. A composite physical field combining ultrasound and specific wavelength infrared radiation, along with a four-stage gradient cooling and a composite field-cooling linkage crystal form control algorithm, ensures crystal purity and regularity. High separation factor centrifugation, low-temperature vacuum drying, 300-mesh sieving, and multi-dimensional online detection ensure that the product contains ≤0.5% large particle impurities, meets purity and crystal form standards, and simultaneously achieves mother liquor recycling, meeting the high-efficiency, environmentally friendly, and high-quality requirements of food-grade production.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An integrated system for the efficient purification of fine phosphates, characterized in that, The system includes; Raw material pretreatment circulation module: Receives phosphate raw materials to be purified and mother liquor returned from the product separation quality assurance module, mixes them in proportion and adjusts the concentration to 12% to 18% mass fraction, preheats to 55 to 75℃, controls the conveying rate to 40 to 60L / h through the flow stabilization subsystem, and continuously conveys the material to the organic and inorganic impurity co-removal module. Organic and inorganic impurity synergistic removal module: Receives the conveyed material, treats it with dielectric barrier discharge plasma, then filters it through an acid-resistant ceramic filter channel, and conveys the clarified material to the phosphate concentration and enrichment module. Phosphate concentration and enrichment module: Receives the conveyed clarified material, uses a modified polytetrafluoroethylene hollow fiber membrane for membrane distillation separation in a cross-flow manner, and the concentrated material is conveyed to the composite field crystal form control module through an insulated pipeline. Composite field crystal form control module: Receives the conveyed concentrated material, initiates a multi-stage programmed cooling process, and simultaneously applies a composite physical field of ultrasonic waves and weak pulse electric fields or ultrasonic waves and specific wavelength infrared radiation. Through the composite field-cooling linkage crystal form control algorithm, it controls various operating parameters and conveys the crystalline material to the product separation quality assurance module. Product Separation Quality Assurance Module: Receives the conveyed crystalline material, separates the crystals from the mother liquor through a solid-liquid separation device, and sends the separated mother liquor to the raw material pretreatment recycling module for reuse. After drying and sieving, the crystals are tested by an online detection device and output as refined phosphate products.

2. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The raw material pretreatment circulation module includes a raw material buffer tank, a static mixer, a mechanical stirring device, an online density meter, and a shell-and-tube heat exchanger. The mixing ratio of raw material to reflux mother liquor is 3 to 5:

1. The stirring speed of the mechanical stirring device is 300 to 500 rpm. The online density meter adjusts the material concentration through a linkage deionized water replenishment valve and a concentrated mother liquor replenishment valve. The shell-and-tube heat exchanger uses 0.3 to 0.5 MPa high-temperature steam as the heat exchange medium. The flow stabilization subsystem consists of a variable frequency metering pump and an electromagnetic flow sensor.

3. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The dielectric barrier discharge plasma reaction chamber of the organic-inorganic impurity synergistic removal module adopts a dual-electrode structure with an electrode spacing of 5 to 10 mm. The output voltage range of the high-frequency high-voltage power supply is 10 to 30 kV. The processing is carried out under normal pressure and at 50 to 80°C. The residence time of the material in the reaction chamber is 30 to 90 minutes.

4. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The acid-resistant ceramic filter channel of the organic-inorganic impurity synergistic removal module uses an α-Al2O3 or SiC material filter membrane with a pore size of 0.05 to 0.1 μm and a porosity of ≥45%. It operates in a cross-flow filtration mode with a membrane surface velocity of 1 to 2 m / s and an operating pressure of 0.1 to 0.3 MPa. The system is equipped with an automatic backwashing device with compressed air as the backwashing medium, a backwashing pressure of 0.3 to 0.4 MPa, a backwashing time of 30 to 60 s, and a backwashing cycle of 2 to 3 h.

5. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The modified polytetrafluoroethylene hollow fiber membrane of the phosphate concentration and enrichment module undergoes plasma surface modification treatment, resulting in a membrane surface contact angle ≥150°, a membrane fiber pore size of 0.1 to 0.5 μm, a porosity of 70% to 85%, and an effective membrane area of ​​5 to 10 m² for a single membrane module. 2 The number of membrane filaments is 1,000 to 1,500, and the module is equipped with a chemical cleaning unit.

6. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The membrane distillation process of the phosphate concentration and enrichment module adopts a direct contact operation mode. The material side is heated by jacket heating to maintain the temperature at 60 to 90°C. The cooling medium of the cooling circulation system is deionized water at 20 to 30°C. The permeate side temperature is controlled at 25 to 35°C. The permeate side pressure is adjusted by a vacuum pump.

7. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The ultrasonic generation system of the composite field crystal form control module consists of 4 to 6 ultrasonic transducers, which are evenly distributed on the outer wall of the crystallizer; the ring platinum electrodes of the weak pulse electric field unit are arranged in concentric circles; the infrared radiator of the specific wavelength infrared radiation unit is installed on the top of the crystallizer, with a radiation wavelength of 2.5 to 5.0 μm and a radiation power density of 10 to 50 mW / cm². 2 .

8. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The multi-stage programmed cooling process of the composite field crystal form control module is divided into four stages. The first stage cools the temperature from 60 to 80°C to 50 to 55°C at a rate of 15 to 20°C / h. The second stage cools the temperature from 50 to 55°C to 35 to 40°C at a rate of 8 to 12°C / h. The third stage cools the temperature from 35 to 40°C to 20 to 25°C at a rate of 5 to 8°C / h. The fourth stage cools the temperature from 20 to 25°C to 10 to 15°C at a rate of 2 to 5°C / h, with a total cooling range of 40 to 60°C.

9. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The solid-liquid separation device of the product separation quality assurance module adopts a horizontal spiral sedimentation centrifuge with a separation time of 10 to 20 minutes. The separated mother liquor is filtered through a precision filter membrane with a pore size of 0.02 μm, and then the pH value of the mother liquor is adjusted to 4.5 to 6.5 by a pH adjustment device. The crystals enter a vacuum freeze dryer, with the drying chamber temperature controlled at -40℃ to -20℃, the vacuum degree at 10 to 50 Pa, and the drying time at 4 to 6 hours.

10. The integrated system for high-efficiency purification of fine phosphates according to claim 1, characterized in that, The online detection device of the product separation quality assurance module includes a high-performance liquid chromatograph, an X-ray diffractometer, and a laser particle size analyzer; the dried crystals are pulverized by an air jet mill at a pulverization pressure of 0.6 to 0.8 MPa, and then screened by a 200 to 300 mesh stainless steel sieve, after which the content of large particle impurities is ≤0.5%.

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