CN118439641A - Precipitated calcium carbonate production and recovery process - Google Patents

Abstract

The invention discloses a precipitated calcium carbonate production and recovery process. In the production of precipitated calcium carbonate, by adding calcium carbonate seeds of specific crystal form and particle size, the newly generated calcium carbonate can be induced to grow directional according to the crystal plane of the seeds, so as to accurately control the particle size and distribution of the final product, which has an important influence on the mechanical properties, optical properties, filling properties, etc. of the material. The intelligent control system can dynamically adjust parameters such as the seed addition amount and reaction conditions according to real-time feedback data to achieve more accurate and flexible control of the carbonation process. By optimizing the use of seeds, unnecessary energy consumption in the production process can be reduced. The seed-controlled carbonation technology greatly improves the customization degree and added value of precipitated calcium carbonate products, which is beneficial for enterprises to occupy a dominant position in market competition, and is also beneficial for the effective utilization of resources and environmental protection.

Description

A production and recovery process of precipitated calcium carbonate

Technical Field

The invention belongs to the technical field of precipitated calcium carbonate, in particular to a production and recovery process of precipitated calcium carbonate.

Background technique

Precipitated calcium carbonate is a very important inorganic chemical product with a wide range of uses. For example, it is widely used as a functional filler in materials such as pigments, papermaking, coatings, inks, plastics or sealants. Other applications of precipitated calcium carbonate include in the food, cosmetics and pharmaceutical industries.

The classic production process characteristics of precipitated calcium carbonate are described as follows: limestone is calcined in a calcining furnace to decompose into quicklime and carbon dioxide gas. Quicklime is digested with water to obtain slaked lime, i.e. calcium hydroxide emulsion. Carbon dioxide gas and slaked lime are carbonized under certain controlled conditions to obtain precipitated calcium carbonate. The produced precipitated calcium carbonate is dehydrated, dried, crushed and packaged to become the finished precipitated calcium carbonate.

However, if the "seed-controlled carbonation" and "intelligent control optimization technology" are lacking in the precipitated calcium carbonate production and recycling process, the company will be significantly restricted in its pursuit of high-quality, high-value-added calcium carbonate products, which will not only affect product quality and increase production costs, but also hinder the company's progress in environmental protection and sustainable development, because intelligent control technology helps to reduce energy consumption and pollutant emissions. In addition, failure to adapt to rapid market changes and technological iterations will gradually weaken the company's market share and profitability. The lack of intelligent control technology means that it is impossible to respond to changes in production conditions in a timely manner, and may miss the best time to optimize resource utilization, such as failing to make the most efficient use of raw materials and energy, while also increasing the risk of waste emissions.

After searching, the existing Chinese patent publication number: CN104418376A is a production process for precipitated calcium carbonate, including: removing carbon dioxide gas generated during the calcination of limestone, adding a solvent before the digestion reaction, adding a dispersant during the digestion reaction, using quicklime and water to perform a digestion reaction to obtain slaked lime, adding carbon dioxide gas during the carbonization reaction of slaked lime, and recovering the product.

The same problem also exists in the cited patent documents. The lack of "seed-controlled carbonation" and "intelligent control and optimization technology" will not only affect product quality and increase production costs, but also hinder the company's progress in environmental protection and sustainable development.

Summary of the invention

The object of the present invention is to provide a precipitated calcium carbonate production and recovery process to solve the problems raised in the background technology.

To achieve the above object, the present invention provides the following technical solution: a precipitated calcium carbonate production and recovery process, comprising the following steps:

S1, raw material preparation stage: limestone is calcined in a rotary kiln to obtain quicklime (CaO);

S2, quicklime digestion: reacting the calcined quicklime with water to generate calcium hydroxide solution;

S3, carbonation reaction and precipitation: using surface-modified seed crystals to promote uniform precipitation of calcium carbonate, and optimizing crystal morphology and particle size distribution by controlling the reactant ratio, pH value and the number of added seed crystals;

S4. Intelligent control and optimization: Data-driven production optimization: Use online sensors to monitor reaction parameters and input data into the algorithm model to adjust reaction conditions in real time to achieve calcium carbonate production and quality;

S5. Wastewater circulation and recovery:

S5.1, Separation in sedimentation tank: The slurry after precipitation enters the sedimentation tank and is left to stand to allow the calcium carbonate particles to settle;

S5.2, Membrane filtration and ion exchange: wastewater is separated by advanced membrane technology to remove impurities, while ion exchange resin is used to recover Ca2+ and other valuable ions. Chemical reaction example: Ca2++2ROH→CaR2+20H- (ion exchange reaction, R represents the resin functional group);

S6. Drying and crushing:

S6.1, solid-liquid separation: the precipitated calcium carbonate slurry is subjected to solid-liquid separation by centrifugal dehydration or filter press dehydration;

S6.2, Drying and subsequent treatment: The dehydrated calcium carbonate filter cake is sent to a dryer for drying and is graded by a pulverizer to produce a product of the desired particle size;

S7. Resource recovery: Carbon dioxide capture and utilization: Consider capturing the carbon dioxide generated by calcining limestone and converting it into other useful chemicals to achieve a carbon circular economy.

S8, Energy recovery: including waste heat recovery and water resource recovery;

S8.1. The quicklime digestion process releases a large amount of heat, which is collected by a dedicated waste heat recovery device and reused in preheating raw materials or heating in the auxiliary production process;

S8.2. In the production of light calcium carbonate, the filter press water produced is treated and recycled into the production system.

Preferably, in S1, the limestone is crushed into particles of a desired size using a crusher and is screened and graded to ensure that it can be evenly heated and reacted inside the lime kiln.

In this scheme, preferably, in S2, inside the digester, quicklime is quantitatively added to pre-prepared water or water is sprayed onto quicklime, which process will release heat violently to generate calcium hydroxide emulsion CaO+H20+Ca(OH)2;

The digestion reaction releases a large amount of heat, and digesters are often equipped with cooling and waste heat recovery systems.

The preferred solution of this scheme is that in S3, Ca(OH)2+Na2C03+2NaOH+CaCO3↓ or Ca(OH)2+C02+CaC03↓+H20;

Seeded carbonation is used in the preparation of light calcium carbonate (PCC) to control the size and morphology of calcium carbonate crystals.

The preferred solution of this invention is to realize intelligent control and optimization technology in S4 by installing online sensors, data collection and transmission, algorithm model training, dynamic optimization control, closed-loop feedback, and deep learning of algorithm models.

Preferably, in the present scheme, during the precipitation of calcium carbonate, the reaction conditions and particle characteristics can be controlled through the participation of intelligent regulation and optimization technology, wherein the reaction conditions include temperature control and concentration control.

Preferably, the temperature control of this scheme is: monitoring and adjusting the temperature in the reactor in real time through a PID controller to a desired reaction range to promote the formation of calcium carbonate;

The concentration control: using online sensors to detect the concentration of the raw material solution and the carbon dioxide flow rate, and maintaining a suitable molar ratio through a feedback control system to ensure sufficient reaction.

Preferably, the particle property regulation in this solution includes particle size control and crystal form selection;

Among them, particle size control: regulating the growth of calcium carbonate crystals by changing the stirring speed, adding crystal seeds or pH value, and applying the crystallization kinetics model to assist decision-making;

Crystal form selection: Depending on the desired product type, the crystal form formation of calcium carbonate can be influenced by adjusting the reaction conditions.

Preferably, in S8, the energy recovery also includes by-product recycling and continuous crystallization and classification technology, wherein the product recycling includes wastewater treatment, and the wastewater treatment removes harmful substances and recovers valuable salts or other minerals by treating production wastewater, and the treated water is reused after reaching the required standards.

Preferably, in the refined production of precipitated calcium carbonate, continuous crystallization and classification equipment is used to optimize product quality while controlling the crystal size distribution.

Compared with the prior art, the technical effects and advantages of the present invention are as follows:

The precipitated calcium carbonate production and recycling process, seed-regulated carbonation. In the production of precipitated calcium carbonate, by adding calcium carbonate seeds of specific crystal form and particle size, the newly generated calcium carbonate can be induced to grow in a directional manner according to the crystal plane of the seeds, thereby accurately controlling the particle size and distribution of the final product, which has an important impact on the mechanical properties, optical properties, filling properties, etc. of the material. The finely regulated seeds can cause the generated calcium carbonate particles to have an ideal crystal form, such as cubic, needle-shaped or spherical, etc. Calcium carbonate of different crystal forms exhibits different performance advantages in specific applications. For example, cubic calcium carbonate is popular in the plastics and coatings industries due to its high brightness and excellent hiding power.

By optimizing the use of crystal seeds, unnecessary energy consumption in the production process can be reduced. For example, by controlling the amount of crystal seeds and growth conditions, the expected product performance can be achieved with lower energy input, thereby saving energy and production costs. The crystal seed-regulated carbonation technology has greatly improved the customization and added value of precipitated calcium carbonate products, which is conducive to enterprises occupying an advantageous position in market competition, and is also conducive to the effective use of resources and environmental protection.

By integrating intelligent control and optimization with carbonation reaction and precipitation in the precipitated calcium carbonate production and recovery process:

1. Improve the degree of refinement: The intelligent control system can dynamically adjust parameters such as seed addition amount and reaction conditions based on real-time feedback data to achieve more accurate and flexible control of the carbonation process.

2. Energy saving and emission reduction: By predicting and optimizing the production process through intelligent algorithms, ineffective operations and energy waste can be reduced, which is in line with the concept of green manufacturing.

3. Improved product quality stability: Intelligent regulation helps maintain the consistency of production processes, reduce fluctuations in product quality between batches, and improve overall product quality and market competitiveness.

4. Accelerate the development of new products: Through data analysis and simulation, the best seed control solution can be found more quickly, shortening the new material development cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

Fig. 1 is a flow chart of the production and recovery process of precipitated calcium carbonate of the present invention.

Detailed ways

In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

Unless otherwise defined, the up, down, left, right, front, back, inside and outside directions involved in this document are based on the up, down, left, right, front, back, inside and outside directions in the figures shown in the present invention, and are explained here together.

This embodiment discloses a precipitated calcium carbonate production and recovery process as shown in FIG1, comprising the following steps:

S1, raw material preparation stage: using a rotary kiln or other high-temperature equipment to calcine limestone to obtain quicklime (CaO);

S2, quicklime digestion: reacting the calcined quicklime with water to generate calcium hydroxide solution (lime water);

S3, Carbonation reaction and precipitation: Use surface-modified seeds to promote uniform precipitation of calcium carbonate, and optimize crystal morphology and particle size distribution by precisely controlling the reactant ratio, pH value and the number of added seeds;

S4. Intelligent control and optimization: Data-driven production optimization: Use online sensors to monitor reaction parameters (such as pH, temperature, dissolved oxygen content, etc.), and input the data into the AI algorithm model to adjust the reaction conditions in real time to achieve the optimal calcium carbonate yield and quality;

S5. Wastewater circulation and recycling:

S5.1, Separation in sedimentation tank: The slurry after precipitation enters the sedimentation tank and is left to stand to allow the calcium carbonate particles to settle;

S5.2, Membrane filtration and ion exchange: wastewater is separated by advanced membrane technology to remove impurities, while ion exchange resin is used to recover Ca2+ and other valuable ions. Chemical reaction example: Ca2++2ROH→CaR2+20H- (ion exchange reaction, R represents the resin functional group);

S6. Drying and crushing:

S6.1, solid-liquid separation: the precipitated calcium carbonate slurry is subjected to solid-liquid separation by centrifugal dehydration or filter press dehydration;

S6.2, Drying and subsequent treatment: The dehydrated calcium carbonate filter cake is sent to the dryer for drying and is graded by the pulverizer to produce products with the required particle size;

S7. Resource recovery: Carbon dioxide capture and utilization: Consider capturing the carbon dioxide generated by calcining limestone, and converting it into other useful chemicals through technical means such as compression, liquefaction or catalysis to achieve a carbon recycling economy. The entire process focuses on low-carbon and environmental protection, improves the quality of calcium carbonate through innovative seed control technology, and uses intelligent optimization algorithms to achieve refined management of the production process, strengthen resource recycling, and reduce waste emissions, which is in line with the development trend of green chemical industry.

S8, Energy recovery: including waste heat recovery and water resource recovery;

S8.1. The lime digestion process releases a large amount of heat. A dedicated waste heat recovery device is designed to collect this heat and reuse it for preheating raw materials or heating in auxiliary production processes, thereby improving the energy efficiency of the entire process;

S8.2. In the production of light calcium carbonate, the filter press water produced is recycled into the production system after treatment, for example, it is reused in the preparation or cleaning steps of lime milk, reducing the consumption of fresh water.

In this embodiment, in S1, limestone is crushed into particles of the required size using a crusher to ensure that it can be evenly heated and fully reacted inside the lime kiln. The crushed limestone also needs to be screened and graded to remove oversized or undersized particles and impurities to ensure that the limestone particle size entering the calcining system meets the process requirements;

The pre-treated limestone is sent to the lime kiln, where it gradually heats up in the preheating zone and then enters the calcining zone, where it undergoes a calcination reaction at a high temperature of 1300-1450 degrees Celsius: CaCO3 = high temperature = CaO + CO2↑. In this process, the limestone (calcium carbonate) decomposes into calcium oxide (quicklime) and carbon dioxide gas. The kiln may use a co-current or counter-current method, where the limestone particles are heated and reacted at high temperatures by rotation or other means.

The calcium oxide (CaO) produced by calcination will then go through a cooling process to quickly reduce the temperature to a safe range to prevent it from reacting with moisture in the air to form calcium hydroxide and affecting subsequent processing. The decomposed carbon dioxide (CO2) is usually captured and stored, and may be recycled in some industrial production.

The process of calcium oxide digestion and calcium carbonate precipitation in which the cooled quicklime (CaO) reacts with water to form calcium hydroxide (Ca(OH)2) is called digestion. The calcium hydroxide solution then reacts with other substances containing carbonate ions, such as sodium carbonate (Na2CO3), to form precipitated calcium carbonate (CaCO3) through chemical precipitation.

In summary, limestone calcination is one of the key steps in the production process of precipitated calcium carbonate. Calcium oxide is obtained by high-temperature decomposition of limestone, and then precipitated calcium carbonate products are finally produced through chemical reactions.

In this embodiment, in S2, inside the digester, quicklime is quantitatively added to pre-prepared water or water is sprayed onto the quicklime. This process will release heat violently and generate calcium hydroxide emulsion (commonly known as slaked lime slurry or slaked lime milk): CaO+H20+Ca(OH)2.

The digestion process requires strict control of water temperature and water volume to ensure sufficient reaction and avoid uneven reaction or safety problems due to local overheating. In order to improve efficiency and control the reaction rate, the digester generally uses a stirring device to promote the mixing contact of lime and water.

Since the digestion reaction releases a large amount of heat, the digester is often equipped with a cooling and waste heat recovery system to control the reaction temperature and recover part of the heat. The steam and other waste gases generated are usually treated through dust removal, dehumidification and air purification equipment to reduce the impact on the environment; the calcium hydroxide emulsion generated by the reaction can then be used in subsequent processes, such as carbonization (introducing carbon dioxide) or reacting with other compounds to precipitate calcium carbonate: Ca(0H)2+C02+CaC03↓+H20.

In this embodiment, in S3, Ca(OH)2+Na2C03+2NaOH+CaCO3↓ or Ca(OH)2+C02+CaC03↓+H20.

Seed-controlled carbonation is mainly used in the preparation of light calcium carbonate (PCC), especially when the size and morphology of calcium carbonate crystals need to be precisely controlled to meet specific application requirements. The following is a possible specific embodiment based on the seed-controlled theory:

Calcium carbonate is precipitated by chemical reaction, using calcium hydroxide (Ca(OH)2) and carbon dioxide (CO2) to react to form calcium carbonate (CaCO3). In order to achieve seed regulation, the specific steps may include:

Limestone is calcined to make quicklime (CaO), which is then digested with water to produce a calcium hydroxide suspension (Ca(OH)2). Calcium carbonate particles with the target crystal form are selected as seeds and surface modified, such as coating with a layer of special surfactants or inorganic modifiers. This can help improve the dispersibility and stability of the seeds in the solution, while guiding the growth direction of subsequent calcium carbonate crystals.

Under strictly controlled conditions (such as constant temperature, stirring rate and pH value), carbon dioxide gas is slowly introduced into the calcium hydroxide suspension to produce the following reaction: Ca(OH)2+C02+CaC03↓+H20. During this process, modified seeds are added in a timely manner to allow the newly generated calcium carbonate crystals to grow around the seeds, thereby obtaining a crystal form and particle size distribution similar to the seeds.

Adjust the ratio of reactants, such as calcium hydroxide concentration, carbon dioxide introduction rate, etc., to control the precipitation rate and crystal growth state of calcium carbonate. By adjusting the pH value and other reaction conditions, the crystallization process can be further optimized to ensure that the crystals are uniform and have a moderate particle size. After carbonation is completed, the formed calcium carbonate precipitate is subjected to solid-liquid separation, washing, drying, crushing and classification to obtain a light calcium carbonate product with a specified particle size distribution and good physical properties.

In this embodiment, in S4, the intelligent control and optimization technology can be implemented through the following specific embodiments: (1) Installation of online sensors: pH meters, temperature sensors, dissolved oxygen sensors and other necessary detection equipment, such as concentration sensors, are installed at key locations of the precipitated calcium carbonate production line to monitor the key parameters in the reactor in real time; (2) Data collection and transmission: The data collected by the sensor in real time is automatically transmitted to the central control system or cloud database through the Internet of Things (IoT) technology; (3) The algorithm model is trained based on historical data and laboratory experimental results to establish a relationship model between reaction parameters and calcium carbonate output and quality, receive and analyze data from the sensor in real time, and identify the current production status and the ideal production status. state deviation; (4) Dynamic optimization control: When the algorithm model finds that the pH value deviates from the optimal range, it can automatically instruct to add acid or alkali for adjustment. If the temperature is too high or too low, affecting the reaction rate and product quality, the cooling or heating system is automatically adjusted. For the dissolved oxygen content that affects the precipitation rate and purity of calcium carbonate, the algorithm model can adjust the aeration volume or stirring rate according to the current data; (5) Closed-loop feedback: After receiving the instructions from the algorithm model, the control system quickly executes the corresponding operation and fine-tunes the production process to ensure that the reaction conditions are always kept within the optimal range; (6) Deep learning of the algorithm model: As the data set expands, the model prediction accuracy and control effect can be continuously improved, thereby realizing the refined management of the entire calcium carbonate production process.

Through the above methods, the entire precipitated calcium carbonate production process has achieved intelligent, automated and efficient operation, which can not only increase production but also ensure product stability and quality standards.

In addition, it can not only achieve real-time monitoring and precise control of reaction parameters to improve quality, but also bring a series of additional beneficial effects, such as: (1) Optimization of resource utilization: Through real-time monitoring and prediction, the dosage of raw materials (such as limestone, carbon dioxide and chemicals) can be accurately controlled to reduce waste, improve resource utilization efficiency, and optimize energy consumption. For example, the output of the combustion or cooling system can be automatically adjusted according to the temperature sensor data to save energy costs; (2) Reduction of emissions and environmental benefits: Monitoring and controlling the dissolved oxygen content helps to reduce unnecessary oxygen consumption, while also reducing the generation of harmful by-products such as nitrogen oxides. By optimizing process control, the discharge of unreacted substances and wastewater can be reduced, which is beneficial to environmental protection. Compliance and sustainable development; (3) Fault warning and maintenance: The algorithm model can be used to analyze abnormal data to warn of possible equipment problems in advance, arrange preventive maintenance in a timely manner, and avoid downtime losses caused by equipment failure; (4) Product quality stability: Achieve precise control of microscopic properties such as precipitated calcium carbonate particle size distribution and crystal structure to ensure product quality consistency and meet the strict requirements of different downstream application fields; (5) Production flexibility: Quickly adjust production parameters according to market changes or customer needs, adapt to different product specification requirements, and enhance the company's market competitiveness; (6) Automation: Intelligent control reduces manual intervention and reduces the labor intensity of workers, while improving the operational efficiency of the entire production process.

In summary, the application of intelligent control and optimization technology in the production and recovery process of precipitated calcium carbonate can achieve comprehensive improvement in economic benefits, social benefits and environmental benefits from multiple dimensions.

In this embodiment, during the precipitation of calcium carbonate, the reaction conditions and particle characteristics can be controlled through the participation of intelligent control optimization technology, wherein the reaction conditions include temperature control and concentration control;

Temperature control: Through the PID controller, the temperature in the reactor is monitored and adjusted in real time to the required reaction range to promote the effective formation of calcium carbonate, for example, by controlling the opening and closing of the steam valve to adjust the heat input;

Concentration control: Use online sensors to detect the concentration of the raw material solution (lime milk) and the carbon dioxide flow rate, and use feedback control systems to maintain the appropriate molar ratio to ensure sufficient reaction. For example, use fuzzy logic.

Particle property regulation includes particle size control and crystal form selection;

Among them, particle size control: regulating the growth of calcium carbonate crystals by changing the stirring speed, adding crystal seeds or pH value, and applying the crystallization kinetics model to assist decision-making;

Crystal form selection: According to the desired product type, the crystal form formation of calcium carbonate is affected by adjusting the reaction conditions (such as temperature, type and amount of additives). This requires the establishment of a multivariable optimization model based on experimental data.

In this embodiment, the participation of intelligent control optimization technology also has the following functions: (1) Energy consumption optimization: using intelligent algorithms to calculate the optimal heat exchange efficiency, dynamically adjust the energy supply system, and reduce energy consumption. For example, solving an optimization problem with an objective function that minimizes energy consumption constrained by chemical reaction rate and product quality conditions; (2) Equipment health status monitoring: Based on vibration analysis, pattern recognition, infrared thermal imaging and other technologies, equipment operation data is collected, and pattern recognition algorithms are used to warn of potential faults to ensure stable operation of the production line.

In this embodiment, in S8, energy recovery also includes by-product recovery and utilization and continuous crystallization and classification technology, wherein product recovery and utilization includes wastewater treatment and solid waste treatment, and wastewater treatment removes harmful substances and recovers valuable salts or other minerals by subjecting production wastewater to a series of physical, chemical or biological treatments, and the treated water is reused after it meets the required standards.

Solid waste treatment: Solid waste that may be generated during the production process, such as settled impurities, can be separated and recycled through effective means, and may be used as raw materials for other industrial production or further processed into products.

In this embodiment, in the refined production of precipitated calcium carbonate, continuous crystallization and classification equipment is used to optimize product quality and improve the control accuracy of crystal particle size distribution, which also helps to improve resource utilization and product added value, and achieve the goals of energy conservation, emission reduction and circular economy.

It should be noted that, in this article, relational terms such as one and two are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "includes an element defined by ... does not exclude the existence of other identical elements in the process, method, article or device including the element".

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. A precipitated calcium carbonate production and recovery process, characterized in that it comprises the following steps: S1, raw material preparation stage: limestone is calcined in a rotary kiln to obtain quicklime (CaO); S2, quicklime digestion: reacting the calcined quicklime with water to generate calcium hydroxide solution; S3, carbonation reaction and precipitation: using surface-modified seed crystals to promote uniform precipitation of calcium carbonate, and optimizing crystal morphology and particle size distribution by controlling the reactant ratio, pH value and the number of added seed crystals; S4. Intelligent control and optimization: Data-driven production optimization: Use online sensors to monitor reaction parameters and input data into the algorithm model to adjust reaction conditions in real time to achieve calcium carbonate production and quality; S5. Wastewater circulation and recovery: S5.1, Separation in sedimentation tank: The slurry after precipitation enters the sedimentation tank and is left to stand to allow the calcium carbonate particles to settle; S5.2, Membrane filtration and ion exchange: wastewater is separated by advanced membrane technology to remove impurities, while ion exchange resin is used to recover Ca2+ and other valuable ions. Chemical reaction example: Ca2++2ROH→CaR2+20H- (ion exchange reaction, R represents the resin functional group); S6. Drying and crushing: S6.1, solid-liquid separation: the precipitated calcium carbonate slurry is subjected to solid-liquid separation by centrifugal dehydration or filter press dehydration; S6.2, Drying and subsequent treatment: The dehydrated calcium carbonate filter cake is sent to a dryer for drying and is graded by a pulverizer to produce a product of the desired particle size; S7. Resource recovery: Carbon dioxide capture and utilization: Consider capturing the carbon dioxide generated by calcining limestone and converting it into other useful chemicals to achieve a carbon circular economy. S8, Energy recovery: including waste heat recovery and water resource recovery; S8.1. The quicklime digestion process releases a large amount of heat, which is collected by a dedicated waste heat recovery device and reused in preheating raw materials or heating in the auxiliary production process; S8.2. In the production of light calcium carbonate, the filter press water produced is treated and recycled into the production system. 2. A precipitated calcium carbonate production and recovery process according to claim 1, characterized in that: in S1, the limestone is crushed into particles of a desired size using a crusher and screened and classified to ensure that it can be evenly heated and reacted inside a lime kiln. 3. A precipitated calcium carbonate production and recovery process according to claim 2, characterized in that: in S2, inside the digester, quicklime is quantitatively added to pre-prepared water or water is sprayed onto the quicklime, and this process is highly exothermic to generate calcium hydroxide emulsion CaO+H2O+Ca(OH)2; The digestion reaction releases a large amount of heat, and digesters are often equipped with cooling and waste heat recovery systems. 4. A precipitated calcium carbonate production and recovery process according to claim 3, characterized in that: in S3, Ca(OH)2+Na2C03+2NaOH+CaCO3↓ or Ca(OH)2+C02+CaC03↓+H20; Seeded carbonation is used in the preparation of light calcium carbonate (PCC) to control the size and morphology of calcium carbonate crystals. 5. A precipitated calcium carbonate production and recovery process according to claim 4, characterized in that: in S4, intelligent control and optimization technology is realized by installing online sensors, data acquisition and transmission, algorithm model training, dynamic optimization control, closed-loop feedback, and algorithm model deep learning. 6. A precipitated calcium carbonate production and recovery process according to claim 5, characterized in that: in the process of precipitating calcium carbonate, the reaction conditions and particle characteristics can be controlled through the participation of intelligent control optimization technology, wherein the reaction conditions include temperature control and concentration control. 7. A precipitated calcium carbonate production and recovery process according to claim 1, characterized in that: the temperature control: through a PID controller, real-time monitoring and adjustment of the temperature in the reactor to the required reaction range to promote the formation of calcium carbonate; The concentration control: using online sensors to detect the concentration of the raw material solution and the carbon dioxide flow rate, and maintaining a suitable molar ratio through a feedback control system to ensure sufficient reaction. 8. A precipitated calcium carbonate production and recovery process according to claim 7, characterized in that: the particle property regulation includes particle size control and crystal form selection; Among them, particle size control: regulating the growth of calcium carbonate crystals by changing the stirring speed, adding crystal seeds or pH value, and applying the crystallization kinetics model to assist decision-making; Crystal form selection: Depending on the desired product type, the crystal form formation of calcium carbonate can be influenced by adjusting the reaction conditions. 9. A precipitated calcium carbonate production and recovery process according to claim 8, characterized in that: in S8, the energy recovery also includes by-product recycling and continuous crystallization and classification technology, wherein the product recycling includes wastewater treatment, and the wastewater treatment removes harmful substances and recovers valuable salts or other minerals by treating production wastewater, and the treated water is reused after reaching the required standards. 10. A precipitated calcium carbonate production and recovery process according to claim 9, characterized in that: in the refined production of the precipitated calcium carbonate, continuous crystallization and classification equipment is used to optimize product quality and control the crystal size distribution at the same time.