Preparation method and preparation system of calcium hydroxide with high specific surface area

Abstract

The invention relates to the technical field of calcium hydroxide preparation methods, in particular to a high-specific-surface-area calcium hydroxide preparation method and a high-specific-surface-area calcium hydroxide preparation system.The high-specific-surface-area calcium hydroxide preparation method comprises the following steps of raw material pretreatment, first-stage digestion, second-stage digestion, third-stage digestion and aftertreatment, the third-stage digestion process is used for replacing the drying step, and energy consumption is reduced; a composite dispersant formula is used for improving particle dispersity and ensuring that the specific surface area is greater than or equal to 45 m / g; the production efficiency of the calcium hydroxide is improved by utilizing the high-activity calcium oxide raw material of the rotary kiln, the specific surface area and the reaction activity of the calcium hydroxide are remarkably improved by optimizing the key steps of raw material pretreatment, primary digestion, secondary digestion, tertiary digestion, post-treatment and the like, and meanwhile, the energy consumption and the cost are reduced. The preparation method not only solves the technical bottleneck in the traditional calcium hydroxide preparation process, but also provides powerful support for realizing large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium hydroxide preparation methods, and more particularly, to a method for preparing high specific surface area calcium hydroxide and its preparation system. Background Art

[0002] In the field of industrial desulfurization, calcium hydroxide has become an important raw material for dry desulfurization due to its low cost and moderate reaction activity. However, there are three core problems in traditional preparation processes, which severely limit its industrial application: 1. High energy consumption and complex process: Existing technologies (such as CN119750923A) rely on a secondary drying step, with an energy consumption of up to 120 kWh per ton of product, accounting for more than 30% of the total cost. This not only increases production costs but also goes against the current industry trend of low-carbon manufacturing.

[0003] 2. Particle agglomeration and insufficient specific surface area: Conventional processes use a single dispersant (such as CN119018922A), which cannot effectively inhibit the agglomeration of calcium hydroxide particles, resulting in a specific surface area of only 35 - 40 m / g, making it difficult to meet the requirements of dry desulfurization for highly active adsorbents (≥40 m / g).

[0004] 3. Uneven raw material activity and low reaction efficiency: Ordinary calcium oxide (CaO purity ≤ 90%) has large activity differences due to unstable calcination processes, incomplete digestion reactions, and a proportion of unreacted particles exceeding 5%, directly affecting the reaction efficiency of the final product.

[0005] In view of the above problems, the industry urgently needs a method for preparing calcium hydroxide with low energy consumption, high dispersibility, and high activity, while meeting the requirements of large-scale continuous production. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for preparing high specific surface area calcium hydroxide to improve the problems of high energy consumption and complex process, particle agglomeration and insufficient specific surface area, and uneven raw material activity and low reaction efficiency in the traditional calcium hydroxide preparation process.

[0007] To achieve the above objective, the embodiments of the present application provide the following technical solutions: On the one hand, the embodiments of the present application provide a method for preparing high specific surface area calcium hydroxide, including the following steps: (1) Raw material pretreatment: Crushing the highly active calcium oxide obtained by rotary kiln calcination into 0 - 20 mm particles, where the calcium oxide purity ≥ 93%; (2) Primary digestion: Mixing the crushed calcium oxide with water at a mass ratio of water to calcium of 1:3, and mechanically stirring for 30 minutes at 80 - 90°C to form a primary digestion slurry; (3)Secondary digestion: Add a composite dispersant to the primary digestion slurry. The composite dispersant is composed of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium silicate in a mass ratio of 5:3:2, and the addition amount is 0.5 - 1.2% of the total mass of the slurry. React at a constant temperature of 60 - 70 °C for 1 hour to form a secondary digestion slurry; (4)Tertiary digestion: Age the secondary digestion slurry at room temperature for 2 hours to promote the formation of a microporous structure and obtain a calcium hydroxide product; (5)Post-treatment: Separate unreacted particles from the calcium hydroxide product through a 325-mesh screening device and directly package the finished product; Among them, the entire tertiary digestion process does not require a drying step, and the specific surface area of the final calcium hydroxide is ≥45 m / g, which is suitable for dry desulfurization.

[0008] Preferably, the calcination temperature of the calcium oxide raw material is 900 - 1100 °C, and the calcination time is 2 - 4 hours.

[0009] Preferably, the mechanical stirring speed in step (2) is 200 - 400 rpm, and the stirring paddle has a double-layer inclined blade structure.

[0010] Preferably, the polycarboxylate is an acrylic acid - maleic anhydride copolymer with a molecular weight of 3000 - 5000 g / mol.

[0011] Preferably, during step (3), the viscosity of the slurry is monitored in real time, and when the viscosity exceeds 200 cP, the dispersant is automatically added to the upper limit of 1.2%.

[0012] Preferably, the aging process in step (4) is carried out in a closed container, and the relative humidity is controlled at 60 - 80%.

[0013] Preferably, the screening device in step (5) is equipped with an ultrasonic vibration module with a vibration frequency of 20 - 40 kHz.

[0014] The beneficial effects of the present invention are as follows: The method and system for preparing calcium hydroxide with a high specific surface area provided by the present invention have achieved remarkable breakthroughs in three aspects: energy conservation and consumption reduction, product performance improvement, and industrial application through an innovative tertiary digestion process and a composite dispersant formula.

[0015] First, in terms of energy conservation and consumption reduction, the three-stage digestion process completely eliminates the drying step necessary in the traditional process. Through staged treatment, including rapid start-up of the reaction by high-temperature digestion in the first stage, optimization of particle dispersion by medium-temperature digestion in the second stage, and stabilization of pore structure by normal-temperature aging in the third stage, the overall energy consumption is reduced by more than 20%, and the cost per ton of product can be saved by about 15%, truly realizing green and low-carbon production. Secondly, in terms of product performance, the unique composite dispersant formula (50% polycarboxylate, 30% fatty alcohol polyoxyethylene ether, 20% sodium silicate) through the synergistic effect of each component enables the specific surface area of calcium hydroxide to stably reach 45 - 48 m / g, which is more than 30% higher than that of the traditional process. At the same time, the particle agglomeration rate is reduced by 35%, and the pore size distribution is more uniform. These characteristics make it show excellent reaction activity and sulfur capacity in dry desulfurization applications.

[0016] In terms of industrial application, the system adopts modular design combined with an intelligent control system to achieve fully automated production from raw material pretreatment to finished product packaging. The annual production capacity of a single line can reach 50,000 tons, and the product performance fluctuation range is controlled within ±2%, fully meeting the stability and economic requirements of large-scale industrial production. Practical applications show that when calcium hydroxide produced by this method replaces baking soda in SDS dry desulfurization, the desulfurization efficiency can reach 92 - 95%, and the operating cost is reduced by 18 - 25%, with significant economic and environmental benefits.

[0017] These innovations not only solve the long-standing technical problems such as high energy consumption, unstable product performance, and low industrialization level in the traditional calcium hydroxide preparation process, but also provide an efficient, economical, and sustainable solution for the environmental protection desulfurization field, which is of great significance for promoting the technological progress of the industry.

[0018] Secondly, this embodiment provides a preparation system for the method of preparing calcium hydroxide with high specific surface area, including: A raw material pretreatment module for calcining limestone into highly active calcium oxide and performing crushing treatment, including a rotary kiln calcination device and a jaw crusher. The rotary kiln calcination device calcines limestone at 900 - 1100 °C for 2 - 4 hours to obtain calcium oxide with a CaO content ≥ 93%, and the jaw crusher crushes the calcined calcium oxide into 0 - 20 mm particles; A first-stage digestion module for performing high-temperature mixing reaction of the crushed calcium oxide and water, including a first-stage digestion kettle and a temperature control stirring device. The first-stage digestion kettle mixes raw materials at a mass ratio of water to calcium of 1:3 and reacts at 80 - 90 °C with a stirring speed of 200 - 400 rpm for 30 minutes; The secondary digestion module is used to add a composite dispersant to the primary digestion slurry for a secondary reaction, including a secondary digestion kettle and a dispersant automatic addition device. Among them, the secondary digestion kettle reacts at a constant temperature of 60 - 70 °C for 1 hour, and the dispersant automatic addition device adds a composite dispersant composed of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium silicate in a ratio of 5:3:2 according to 0.5 - 1.2% of the total mass of the slurry; The tertiary digestion module is used to age the secondary digestion slurry, including a tertiary aging bin and a humidity control device. Among them, the tertiary aging bin ages the slurry at room temperature for 2 hours, and the humidity control device controls the relative environmental humidity at 60 - 80%; The post - treatment module is used to screen and package the aged calcium hydroxide product, including an ultrasonic vibration screening machine and a dust - free packaging machine. Among them, the ultrasonic vibration screening machine separates unreacted particles through a 325 - mesh sieve at a frequency of 20 - 40 kHz, and the dust - free packaging machine directly packages the qualified products; The central control module is used to monitor and adjust the operating parameters of each module, including a PLC controller and a sensor system. Among them, the PLC controller receives temperature, viscosity, and humidity signals from each module and correspondingly adjusts the stirring speed, dispersant addition amount, and screening frequency.

[0019] Other features and advantages of the present invention will be described in the subsequent specification, and, in part, will become apparent from the specification or be understood by implementing the embodiments of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification, claims, and drawings. Brief Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other relevant drawings can also be obtained based on these drawings.

[0021] Figure 1 It is a schematic flow chart of a method for preparing calcium hydroxide with a high specific surface area described in the embodiments of the present invention; Figure 2 It is a schematic structural diagram of a preparation system of a method for preparing calcium hydroxide with a high specific surface area described in the embodiments of the present invention. Detailed Embodiments

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and illustrated herein generally can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0023] It should be noted that like reference numerals or letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0024] Embodiment 1:

[0025] As Figure 1 shown, this embodiment provides a method for preparing calcium hydroxide with a high specific surface area. The method includes step S100, step S200, step S300, step S400, and step S500.

[0026] Step S100, raw material pretreatment: crushing the highly active calcium oxide obtained by rotary kiln calcination into 0 - 20 mm particles, where the purity of calcium oxide is ≥93%; Step S200, primary digestion: mixing the crushed calcium oxide with water at a mass ratio of water to calcium of 1:3, and mechanically stirring at 80 - 90 °C for 30 minutes to form a primary digestion slurry; Step S300, secondary digestion: adding a composite dispersant to the primary digestion slurry. The composite dispersant is composed of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium silicate in a mass ratio of 5:3:2, and the addition amount is 0.5 - 1.2% of the total mass of the slurry. React at a constant temperature of 60 - 70 °C for 1 hour to form a secondary digestion slurry; Step S400, tertiary digestion: aging the secondary digestion slurry at room temperature for 2 hours to promote the formation of a microporous structure and obtain a calcium hydroxide product; Step S500, post-treatment: separating unreacted particles of the calcium hydroxide product through a 325-mesh screening device and directly packaging the finished product; Among them, the entire tertiary digestion process does not require a drying step, and the final specific surface area of calcium hydroxide is ≥45 m / g, which is suitable for dry desulfurization.

[0027] Among them, in step S100 of this embodiment, the calcination temperature of the calcium oxide raw material is 900 - 1100 °C, and the calcination time is 2 - 4 hours.

[0028] Among them, in step S200 of this embodiment, the mechanical stirring speed is 200 - 400 rpm, and the stirring paddle has a double-layer inclined blade structure.

[0029] Among them, in step S300 of this embodiment, the polycarboxylate is an acrylic-maleic anhydride copolymer, and the molecular weight is 3000 - 5000 g / mol.

[0030] Among them, in step S300 of this embodiment, the slurry viscosity is monitored in real time, and when the viscosity exceeds 200 cP, a dispersant is automatically added to the upper limit of 1.2%.

[0031] Among them, in step S400 of this embodiment, the aging process is carried out in a closed container, and the relative humidity is controlled at 60 - 80%.

[0032] Among them, in step S500 of this embodiment, the screening device is equipped with an ultrasonic vibration module, and the vibration frequency is 20 - 40 kHz.

[0033] This embodiment adopts the rotary kiln temperature control calcination technology to calcine limestone at 900 - 1100 °C for 2 - 4 hours to ensure that the calcium oxide purity ≥ 93%. Subsequently, a jaw crusher is used to crush the calcined calcium oxide into uniform particles of 0 - 20 mm to meet the requirements of the subsequent digestion process.

[0034] Through precise temperature control calcination, high-purity calcium oxide (CaO ≥ 93%) is obtained, providing a high-quality raw material basis for the subsequent digestion reaction; the jaw crusher crushes the raw materials into uniform particles, improving the uniformity and efficiency of the digestion reaction and reducing the generation of residual particles; the high-purity calcium oxide and uniform particles ensure the consistency of the raw material activity and lay a solid foundation for the subsequent process.

[0035] In this embodiment, at 80 - 90 °C, the crushed calcium oxide and water are mixed at a water-to-calcium ratio of 1:3, and a double-layer inclined blade stirring paddle (200 - 400 rpm) is used for forced stirring for 30 minutes to form a primary digestion slurry. The high-temperature environment of 80 - 90 °C accelerates the reaction between calcium oxide and water, enabling the reaction to start quickly; the double-layer inclined blade stirring paddle provides a strong stirring effect, making the slurry uniformity reach more than 95%, avoiding problems such as local overheating or incomplete reaction.

[0036] Compared with the traditional process, this embodiment significantly reduces energy consumption by optimizing the stirring conditions and temperature control.

[0037] In this embodiment, a composite dispersant is added to the primary digested slurry. The dispersant is composed of polycarboxylate (50%), fatty alcohol polyoxyethylene ether (30%) and sodium silicate (20%) by mass ratio, and the addition amount is 0.5 - 1.2% of the total mass of the slurry. It is kept at a constant temperature of 60 - 70 °C for 1 hour to form a secondary digested slurry. Meanwhile, the viscosity of the slurry is monitored in real time, and when the viscosity exceeds 200 cP, the dispersant is automatically replenished to the upper limit of 1.2%. Composite dispersant: Through the synergistic effect of polycarboxylate, fatty alcohol polyoxyethylene ether and sodium silicate, the agglomeration phenomenon of calcium hydroxide particles is effectively inhibited, and the specific surface area is significantly increased (45 - 48 m / g). Monitoring the slurry viscosity in real time and automatically replenishing the dispersant ensure the stability of the digestion process and the dispersion effect. Compared with a single dispersant, the use of the composite dispersant reduces the particle agglomeration rate by 35%, and the pore size distribution is more uniform (D50 = 2 - 5 μm).

[0038] In this embodiment, the secondary digested slurry is transferred to a closed container and aged at room temperature for 2 hours. At the same time, the environmental relative humidity is controlled at 60 - 80% through a humidity control device to promote the stable formation of the microporous structure. The closed container effectively isolates the influence of the external environment on the aging process and ensures the stability of the pore structure. By precisely controlling the environmental relative humidity through the humidity control device, the uniform formation of the microporous structure is promoted, and the microporous volume is increased (increased by 20%). The three-stage digestion process narrows the fluctuation range of the specific surface area of calcium hydroxide to ±1 m / g, improving the stability and consistency of the product.

[0039] In this embodiment, an ultrasonic vibrating screen (20 - 40 kHz) is used in combination with a 325-mesh screen to screen the calcium hydroxide product to remove unreacted particles and impurities. Subsequently, a dust-free packaging machine is used to directly package the qualified product into finished products without secondary treatment. The ultrasonic vibrating screen effectively prevents the screen from being blocked through high-frequency vibration, and the screening efficiency is increased to 98%, and the removal rate of unreacted particles is > 99.5%. Dust-free packaging: The dust-free packaging machine ensures the cleanliness of the finished product during the packaging process, avoiding secondary pollution; direct packaging without secondary treatment significantly reduces the production cost and labor input.

[0040] II. Verification of the effects of the embodiment Analysis of the comparative example To verify the technical effects of this embodiment, a comparative example experiment was conducted. In the comparative example, a composite dispersant and a three-stage digestion process were not used, and calcium hydroxide was prepared only by a traditional process. The results showed that the specific surface area of the calcium hydroxide prepared in the comparative example was only 36.5 m / g, the desulfurization efficiency was 72%, and the energy consumption was as high as 110 kWh / ton.

[0041] Effects of the embodiment of the present invention The specific surface area of the calcium hydroxide prepared in the embodiment of the present invention reaches 47.3 m / g (data of Example 1), the desulfurization efficiency is increased to 94%, and the energy consumption is reduced to 82 kWh / ton. This significant improvement benefits from the synergistic effect of the three-stage digestion process and the composite dispersant, as well as the optimized control of each step.

[0042] This embodiment elaborates in detail a method for preparing calcium hydroxide with a high specific surface area. By optimizing key steps such as raw material pretreatment, primary digestion, secondary digestion, tertiary digestion, and post-treatment, the specific surface area and reaction activity of calcium hydroxide are significantly improved, while the energy consumption and cost are reduced. This preparation method not only solves the technical bottleneck in the traditional calcium hydroxide preparation process but also provides strong support for large-scale industrial production.

[0043] Looking ahead, with the increasingly strict environmental protection policies and the growing demand for industrial desulfurization, high-specific-surface-area calcium hydroxide, as an efficient and economical desulfurizer, will play a more important role in the field of dry desulfurization. At the same time, with the continuous progress of technology and the continuous optimization of the process, the preparation cost of calcium hydroxide will be further reduced, and its performance will be more excellent, making greater contributions to environmental protection. The method for preparing calcium hydroxide with a high specific surface area provided in this embodiment has made significant breakthroughs in three aspects: energy conservation and consumption reduction, product performance improvement, and industrial application, through an innovative three-stage digestion process and a composite dispersant formula.

[0044] First, in terms of energy conservation and consumption reduction, the three-stage digestion process completely eliminates the drying step that is essential in the traditional process. Through the staged treatment of rapid reaction initiation at high temperature in the primary digestion, optimized particle dispersion at medium temperature in the secondary digestion, and stable pore structure at normal temperature in the tertiary digestion, the overall energy consumption is reduced by more than 20%, and the cost per ton of product can be saved by about 15%, truly realizing green and low-carbon production. Second, in terms of product performance, the unique composite dispersant formula (50% polycarboxylate, 30% fatty alcohol polyoxyethylene ether, 20% sodium silicate) through the synergistic effect of each component, enables the specific surface area of calcium hydroxide to stably reach 45 - 48 m / g, an increase of more than 30% compared with the traditional process. At the same time, the particle agglomeration rate is reduced by 35%, and the pore size distribution is more uniform. These characteristics make it show excellent reaction activity and sulfur capacity in dry desulfurization applications.

[0045] In terms of industrial application, the system adopts a modular design combined with an intelligent control system to achieve fully automated production from raw material pretreatment to finished product packaging. The annual single-line production capacity can reach 50,000 tons, and the fluctuation range of product performance is controlled within ±2%, fully meeting the stability and economic requirements of large-scale industrial production. Practical applications show that when the calcium hydroxide produced by this method replaces baking soda in SDS dry desulfurization, the desulfurization efficiency can reach 92 - 95%, and the operating cost is reduced by 18 - 25%, with significant economic and environmental benefits.

[0046] These innovations not only solve the long-standing technical problems in traditional calcium hydroxide preparation processes, such as high energy consumption, unstable product performance, and low industrialization level, but also provide an efficient, economical, and sustainable solution for the environmental protection desulfurization field, which is of great significance for promoting the technological progress of the industry.

[0047] Example 2:

[0048] As Figure 2 shown, this example provides a preparation system for high specific surface area calcium hydroxide, including: A raw material pretreatment module 71 for calcining limestone into highly active calcium oxide and performing crushing treatment, including a rotary kiln calcination device and a jaw crusher. The rotary kiln calcination device calcines limestone at 900 - 1100 °C for 2 - 4 hours to obtain calcium oxide with a CaO content ≥ 93%, and the jaw crusher crushes the calcined calcium oxide into 0 - 20 mm particles; A primary digestion module 72 for performing a high-temperature mixing reaction between the crushed calcium oxide and water, including a primary digestion kettle and a temperature control stirring device. The primary digestion kettle mixes raw materials at a water-to-calcium mass ratio of 1:3 and reacts at 80 - 90 °C with a stirring speed of 200 - 400 rpm for 30 minutes; A secondary digestion module 73 for adding a composite dispersant to the primary digestion slurry for a secondary reaction, including a secondary digestion kettle and a dispersant automatic addition device. The secondary digestion kettle reacts at a constant temperature of 60 - 70 °C for 1 hour, and the dispersant automatic addition device adds a composite dispersant composed of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium silicate in a ratio of 5:3:2 according to 0.5 - 1.2% of the total mass of the slurry; A tertiary digestion module 74 for aging the secondary digestion slurry, including a tertiary aging bin and a humidity control device. The tertiary aging bin ages the slurry at room temperature for 2 hours, and the humidity control device controls the environmental relative humidity at 60 - 80%; A post-treatment module 75 for screening and packaging the aged calcium hydroxide product, including an ultrasonic vibration screening machine and a dust-free packaging machine. The ultrasonic vibration screening machine separates unreacted particles through a 325-mesh sieve at a frequency of 20 - 40 kHz, and the dust-free packaging machine directly packages the qualified products; A central control module 76 for monitoring and adjusting the operating parameters of each module, including a PLC controller and a sensor system. The PLC controller receives temperature, viscosity, and humidity signals from each module and correspondingly adjusts the stirring speed, dispersant addition amount, and screening frequency.

[0049] It should be noted that regarding the devices in the above embodiments, the specific manners in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated herein.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing calcium hydroxide with high specific surface area, characterized in that, It includes the following steps: Crush the highly active calcium oxide obtained by calcining in a rotary kiln into 0-20 mm particles, where the purity of calcium oxide is ≥93%; Mix the crushed calcium oxide with water at a mass ratio of water to calcium of 1:3, and mechanically stir at 80-90°C for 30 minutes to form a primary digestion slurry; Add a composite dispersant to the primary digestion slurry. The composite dispersant is composed of polycarboxylate, fatty alcohol polyoxyethylene ether and sodium silicate in a mass ratio of 5:3:2, and the addition amount is 0.5-1.2% of the total mass of the slurry. React at a constant temperature of 60-70°C for 1 hour to form a secondary digestion slurry; Age the secondary digestion slurry at room temperature for 2 hours to promote the formation of a microporous structure and obtain a calcium hydroxide product; Separate the unreacted particles of the calcium hydroxide product through a 325-mesh screening device and directly package the finished product.

2. The preparation method according to claim 1, wherein: The calcination temperature of the calcium oxide raw material is 900-1100°C, and the calcination time is 2-4 hours.

3. The preparation method according to claim 1, characterized in that: The mechanical stirring speed in step (2) is 200-400 rpm, and the stirring paddle has a double-layer inclined blade structure.

4. The preparation method according to claim 1, characterized in that: The polycarboxylate is an acrylic acid-maleic anhydride copolymer with a molecular weight of 3000-5000 g / mol.

5. The preparation method according to claim 1, wherein: During step (3), the viscosity of the slurry is monitored in real time. When the viscosity exceeds 200 cP, the dispersant is automatically added to the upper limit of 1.2%.

6. The preparation method according to claim 1, wherein: The aging process in step (4) is carried out in a closed container, and the relative humidity is controlled at 60-80%.

7. The preparation method according to claim 1, characterized in that: The screening device in step (5) is equipped with an ultrasonic vibration module with a vibration frequency of 20-40 kHz.

8. A preparation system for implementing the method according to any one of claims 1-7, characterized in that, It includes: A raw material pretreatment module for calcining limestone into highly active calcium oxide and performing crushing treatment, including a rotary kiln calcination device and a jaw crusher. The rotary kiln calcination device calcines limestone at 900-1100°C for 2-4 hours to obtain calcium oxide with a CaO content ≥93%, and the jaw crusher crushes the calcined calcium oxide into 0-20 mm particles; A primary digestion module for performing high-temperature mixing reaction of the crushed calcium oxide and water, including a primary digestion kettle and a temperature-controlled stirring device. The primary digestion kettle mixes raw materials at a mass ratio of water to calcium of 1:3 and reacts at a stirring speed of 200-400 rpm at 80-90°C for 30 minutes; A secondary digestion module for adding a composite dispersant to the primary digestion slurry for a secondary reaction, including a secondary digestion kettle and a dispersant automatic addition device. The secondary digestion kettle reacts at a constant temperature of 60-70°C for 1 hour, and the dispersant automatic addition device adds a composite dispersant composed of polycarboxylate, fatty alcohol polyoxyethylene ether and sodium silicate in a ratio of 5:3:2 at 0.5-1.2% of the total mass of the slurry; A tertiary digestion module for aging the secondary digestion slurry, including a tertiary aging bin and a humidity control device. The tertiary aging bin ages the slurry at room temperature for 2 hours, and the humidity control device controls the ambient relative humidity at 60-80%; A post-processing module, which is used for screening and packaging the aged calcium hydroxide product, includes an ultrasonic vibrating screen and a dust-free packaging machine. The ultrasonic vibrating screen separates unreacted particles through a 325-mesh screen at a frequency of 20 - 40 kHz, and the dust-free packaging machine directly packages the qualified products; A central control module, which is used for monitoring and adjusting the operating parameters of each module, includes a PLC controller and a sensor system. The PLC controller receives the temperature, viscosity, and humidity signals from each module and correspondingly adjusts the stirring speed, the addition amount of the dispersant, and the screening frequency.

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