Composite additive for producing calcium hydroxide with high specific surface area, its preparation method and application

Abstract

This invention relates to the field of calcium hydroxide production aids, and more specifically to a composite aid for producing high specific surface area calcium hydroxide, its preparation method, and its application. The raw materials of the composite aid, by mass parts, include 5-15 parts of a crystal regulator, 10-25 parts of a dispersant stabilizer, 3-10 parts of a reaction rate regulator, and 50-80 parts of a solvent; wherein the crystal regulator is selected from at least one of sodium citrate, glucose, and sodium pyrophosphate; the dispersant stabilizer is selected from at least one of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium dodecyl sulfonate; and the reaction rate regulator is selected from at least one of triethanolamine, diethanolmonoisopropanolamine, and glycerol. The composite aid provided by this invention is suitable for both wet and dry processes in the preparation of calcium hydroxide, effectively inhibiting particle agglomeration, precisely controlling the digestion reaction rate, and optimizing the crystal form and pore structure, resulting in a stable specific surface area of ​​45-60 m². 2 / g, which is 30%-50% higher than that of traditional processes.

Description

Technical Field

[0001] This invention relates to the field of calcium hydroxide production auxiliaries, and more specifically to a composite auxiliary for producing high specific surface area calcium hydroxide, its preparation method, and its application. Background Technology

[0002] Calcium hydroxide, commonly known as slaked lime or quicklime, is a widely used inorganic alkaline material. Calcium hydroxide possesses advantages such as strong alkalinity, good adsorption properties, and low cost, making it important in fields such as environmental desulfurization, chemical synthesis, building materials processing, and food processing. High specific surface area calcium hydroxide (specific surface area ≥ 40 m²) is particularly valuable. 2 High-specific-surface-area calcium hydroxide (HDH) possesses abundant active sites and excellent reaction and adsorption properties, making it a core raw material for high-end applications such as dry flue gas desulfurization, heavy metal wastewater and waste gas treatment, and high-performance catalyst carriers, with market demand continuing to grow. Currently, the industrial production of HDH mainly focuses on the quicklime digestion reaction, optimizing product performance by controlling the water-ash ratio, reaction temperature, stirring rate, and adding functional additives. However, existing technologies have significant shortcomings in terms of particle structure, reaction efficiency, additive functionality, and process adaptability, making it difficult to meet the dual requirements of high-end fields for product quality and large-scale production.

[0003] Existing preparation processes generally suffer from severe particle agglomeration and poor reaction uniformity. Quicklime slaking is a strongly exothermic and rapid reaction; the resulting primary calcium hydroxide particles are easily agglomerated due to van der Waals forces and electrostatic attraction, forming coarse-to-dense particles, making it difficult for the product's specific surface area to exceed 50 m². 2 / g, with a significant loss of active sites. Simultaneously, uneven moisture penetration in traditional processes leads to the rapid formation of a dense calcium hydroxide shell on the surface of quicklime, hindering sufficient contact between the internal calcium oxide and water. This results in low raw material utilization, disordered product pore size distribution, and a simple pore structure, affecting both adsorption and reaction performance, and hindering stable industrial production. Furthermore, the limited functionality of single additives and the difficulty in balancing process adaptability and economic efficiency have become key bottlenecks restricting industry upgrades. Currently, commonly used additives in the industry are mostly single-component substances such as ethylene glycol, ethanol, and sodium dodecylbenzene sulfonate, which can only achieve single effects such as dispersion or corrosion inhibition, failing to simultaneously meet the triple core requirements of inhibiting agglomeration, regulating reaction rate, and optimizing crystal growth, thus having limited effect on specific surface area improvement. Some high-efficiency additives are only suitable for wet processes, which are complex and have high drying energy consumption; additives suitable for dry, low-energy processes show far less performance improvement than wet processes, resulting in poor process flexibility, high production costs, and difficulty in achieving a balance between performance and cost, failing to meet the requirements for large-scale industrial promotion.

[0004] In summary, existing high specific surface area calcium hydroxide production technologies suffer from multiple drawbacks, including particle agglomeration, uneven reaction, inefficient and limited auxiliary agents, and poor process adaptability, failing to simultaneously guarantee product performance, production efficiency, and economic costs. Developing a multifunctional composite auxiliary agent that integrates crystal regulation, dispersion stabilization, and reaction rate adjustment, capable of significantly increasing specific surface area and optimizing pore structure through simple addition, while simultaneously being compatible with both dry and wet processes, using readily available raw materials, and being non-toxic and residue-free, has become an urgent need for promoting the high-end, green, and large-scale development of calcium hydroxide. This is of great significance for improving the technological level and application benefits in fields such as environmental desulfurization, heavy metal treatment, and catalytic materials. Summary of the Invention

[0005] To address the aforementioned technical problems, the first aspect of this invention provides a composite additive, the raw materials of which, by mass parts, comprise 5-15 parts of a crystal regulator, 10-25 parts of a dispersant stabilizer, 3-10 parts of a reaction rate regulator, and 50-80 parts of a solvent. The high specific surface area calcium hydroxide has a specific surface area greater than 40 m². 2 / g As an example of implementation, the crystal regulator includes at least one of sodium citrate, glucose, and sodium pyrophosphate.

[0006] As an example of implementation, the dispersion stabilizer includes at least one of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium dodecyl sulfonate.

[0007] As an implementable example, the reaction rate regulator includes at least one of triethanolamine, diethanolmonoisopropanolamine, and glycerol.

[0008] The composite additive provided by this invention, through the scientific compounding of crystal regulator, dispersant stabilizer, reaction rate regulator, and solvent, forms a three-in-one synergistic system. This system can precisely regulate the crystal growth of calcium hydroxide, effectively inhibit particle agglomeration, and stably control the quicklime digestion reaction rate. It effectively solves problems such as severe particle agglomeration, uneven reaction, and low raw material utilization in traditional processes, resulting in a stable specific surface area of ​​calcium hydroxide reaching 45-60 m². 2 / g, which is 30%-50% higher than traditional processes, while optimizing pore size distribution and pore volume structure, improving product purity and stability, and is compatible with both dry and wet preparation processes, reducing production energy consumption, significantly enhancing the desulfurization and heavy metal adsorption performance of calcium hydroxide, with non-toxic and residue-free raw materials, low addition amount, and simple preparation, suitable for large-scale industrial production, and can comprehensively promote the high-end and green upgrading of the high specific surface area calcium hydroxide industry.

[0009] As an example of implementation, the mass ratio of sodium citrate to glucose is 1:(0.5-2).

[0010] This invention limits the mass ratio of sodium citrate to glucose to 1:(0.5-2) to achieve a synergistic and controllable crystal regulation effect. Sodium citrate, as a strong crystal regulator, can inhibit excessive growth of calcium hydroxide crystal faces and avoid coarse grains. Glucose, as a mild crystal face guide, can modify the grain surface and reduce the tendency of agglomeration. The combination of the two at 1:(0.5-2) can ensure concentration matching and synchronous action, avoiding the imbalance of function of a single component, and stabilizing the crystal form and particle structure from the source. If the glucose ratio is less than 0.5, the relative excess of sodium citrate will lead to excessive crystal regulation, forming fine high surface energy particles, aggravating secondary agglomeration, reducing the specific surface area and increasing crystal defects. If the glucose ratio is greater than 2, its mild modification effect will dominate, weakening the crystal regulation effect, making it easy for the grains to grow coarsely, failing to achieve the target specific surface area, and also increasing the viscosity of the system, reducing reaction uniformity and raw material utilization.

[0011] As an implementable example, the polycarboxylate includes at least one of potassium polycarboxylate, ammonium polycarboxylate, calcium polycarboxylate, magnesium polycarboxylate, sodium polycarboxylate, and triethanolamine polycarboxylate.

[0012] As an implementable example, the fatty alcohol polyoxyethylene ether includes at least one of AEO-3, AEO-7, AEO-8, AEO-9, AEO-10, AEO-15, isomeric decayl alcohol polyoxyethylene ether, and isomeric tridecyl alcohol polyoxyethylene ether.

[0013] Furthermore, the mass ratio of the sodium polycarboxylate to AEO-9 is (2-1):1.

[0014] This invention specifies the mass ratio of sodium polycarboxylate and AEO-9 as (2-1):1, mainly based on the dual synergistic mechanism of electrostatic dispersion and steric hindrance, AEO... 9. An electrostatic adsorption layer can be formed on the surface of calcium hydroxide particles via ether bonds and hydroxyl groups, rapidly reducing particle surface tension and inhibiting initial agglomeration. Sodium polycarboxylate provides strong electrostatic repulsion and long-term dispersion stability. A mixture of the two in a ratio of (2-1):1 achieves optimal matching of adsorption rate, dispersion strength, and system compatibility, avoiding imbalance caused by a single component. If the sodium polycarboxylate ratio is higher than 2:1, it will lead to excessively strong electrostatic interaction and increased viscosity, interfering with AEO. 9% electrostatic adsorption and wetting penetration reduce the uniformity of the digestion reaction; if AEO If the ratio of 9 is too high and sodium polycarboxylate is insufficient, a long-lasting and stable dispersion layer cannot be formed, the particles are prone to secondary agglomeration, and the specific surface area and pore volume are difficult to meet the standards; only within the range of (2-1):1 can AEO be maximized. 9. The synergistic effect of electrostatic adsorption and sodium polycarboxylate dispersion stabilization steadily improves the specific surface area and reactivity of calcium hydroxide products.

[0015] As an implementable example, the mass ratio of triethanolamine to glycerol is (3-1):1.

[0016] This invention limits the mass ratio of triethanolamine to glycerol to (3-1):1 as a reaction rate regulator to achieve the dual effect of precise reaction rate control and synergistic moisturizing effect. Triethanolamine, as a strong alkaline reaction regulator, can stably control the exothermic rate of quicklime digestion and avoid local overheating; glycerol, as a mild moisturizer, can delay water evaporation and improve reaction uniformity. The (3-1):1 ratio of the two ensures that the intensity of their effects is matched and the rhythm is synchronized, guaranteeing a mild and controllable digestion process and orderly crystal growth. If the glycerol ratio is less than 1, the moisturizing and corrosion-inhibiting effects are insufficient, and the digestion reaction is still prone to excessively rapid exothermic reaction, leading to particle agglomeration and a decrease in specific surface area; if the glycerol ratio is greater than 3, it will excessively delay the reaction, prolong the digestion cycle, and increase the viscosity of the system, hindering the diffusion of water and additives, reducing the utilization rate of raw materials and product uniformity; only within the range of (3-1):1 can the optimal technical effect of moderate reaction rate, regular crystal form, and uniform pore size be stably achieved.

[0017] As an example of implementation, the solvent includes distilled water or deionized water.

[0018] A second aspect of this invention provides a method for preparing a composite additive, comprising the following steps: S1. Mix the crystal regulator and the reaction rate regulator, grind them until the particle size is ≤100μm, then add them to the solvent and stir at 40-60℃ and 300-500rpm until the raw materials are completely dissolved. S2. Add the dispersant and stabilizer, and stir at 50-70℃ and 400-600rpm until the system is uniform, transparent and free of precipitate to obtain the composite additive.

[0019] A third aspect of this invention provides an application of a composite additive in the preparation of high specific surface area calcium hydroxide.

[0020] As an feasible example, the high specific surface area calcium hydroxide is prepared by using quicklime and composite additives as raw materials through a dry process or a wet process.

[0021] Furthermore, the dry process includes the following steps: S1. Grind quicklime to a particle size ≤150μm and add it to the digester; S2. Atomize the composite additive into droplets with a particle size of 10-50μm and spray them into the digester for digestion reaction; S3. After the reaction is complete, pass the solution through a 325-mesh sieve and cool it to obtain calcium hydroxide with high specific surface area.

[0022] As an feasible example, in the dry process described, the mass ratio of quicklime to composite additive is 100:(0.3-0.8); the temperature of the digestion reaction is 70-90℃, the stirring speed is 300-500rpm, the reaction time is 20-40min, and the water-lime ratio is ≤0.5.

[0023] Furthermore, the wet process includes the following steps: S1. Crush quicklime to 0.5-5mm, pass it through a 200-mesh sieve, then add composite additives and water to carry out a digestion reaction; S2. After the reaction is complete, age for 1-3 hours, filter, dry at 80-100℃ until the moisture content is ≤1%, and then air-jet pulverize to a particle size D50≤5μm to obtain high specific surface area calcium hydroxide.

[0024] As an feasible example, in the wet process described, the mass ratio of quicklime to composite additive is 100:(0.5-1.2), the mass ratio of water to calcium is (1.5-3):1; the temperature of the digestion reaction is 60-80℃, the stirring speed is 400-600rpm, and the reaction time is 30-60min.

[0025] High specific surface area calcium hydroxide, with its larger specific surface area and abundant microporous structure, provides a large number of active adsorption sites, enabling it to quickly contact and capture sulfur dioxide in flue gas. At the same time, its strong alkalinity allows it to undergo an efficient acid-base neutralization reaction with sulfur dioxide, converting gaseous sulfur into stable sulfate for chemical fixation. The well-developed porous structure also prolongs the residence time of sulfur dioxide and increases the adsorption capacity. In addition, the particles are uniformly dispersed without agglomeration, ultimately achieving rapid, efficient, and deep adsorption and removal of sulfur dioxide.

[0026] Beneficial effects (I) This invention constructs a three-in-one synergistic system of "crystal regulation + dispersion stabilization + reaction rate regulation" through the scientific compounding of crystal regulators, dispersants, reaction rate regulators and solvents. This system can inhibit the agglomeration of calcium hydroxide particles from the source, so that the specific surface area of ​​the product can be stably maintained at 45-60m². 2 / g, which improves efficiency by 30%-50% compared to traditional additive-free processes, while also achieving a more uniform pore size distribution with 2-10nm micropores accounting for ≥70%, significantly increasing the number of active sites and reaction contact area, providing an excellent structural basis for applications such as efficient desulfurization and heavy metal adsorption.

[0027] (II) This invention can precisely control the reaction rate of quicklime digestion, avoid local temperature rise and disordered crystal growth caused by excessively fast reaction, effectively solve the problems of uneven moisture penetration and rapid passivation of raw material surface in traditional processes, improve calcium oxide conversion efficiency and product uniformity, make calcium hydroxide purer and more stable, with a specific surface area retention rate of ≥90% in high humidity environment, and not easily absorb moisture and agglomerate during long-term storage, greatly improving product applicability and shelf life.

[0028] (III) The composite additive provided by this invention is compatible with both wet and dry preparation processes. The water-cement ratio of the dry process can be reduced to below 0.5, and the drying energy consumption can be reduced by more than 30%. Industrial production can be achieved without complex equipment modification, effectively balancing product performance and production cost, solving the industry pain point that traditional additives cannot achieve both low energy consumption in dry process and high performance in wet process, simplifying the process flow and improving production efficiency.

[0029] (iv) The auxiliary raw materials used in this invention are all common industrial-grade chemicals, which are non-toxic, harmless, and have no harmful residues. They do not affect the purity and application safety of calcium hydroxide products and can meet the requirements of high-end fields such as food processing and environmental protection. At the same time, the polycarboxylate, fatty alcohol polyoxyethylene ether, triethanolamine, glycerol and other components work synergistically to improve dispersion, wetting and adsorption performance, thereby increasing the adsorption capacity of calcium hydroxide for sulfur dioxide by 25%-40% and the adsorption efficiency of heavy metals by 30%-45%. The desulfurization reaction time is shortened, the amount of reagent used is reduced, and the overall cost of use is significantly reduced.

[0030] (V) The composite additive provided by this invention has a simple preparation process. A uniform and stable system can be obtained by dissolving in stages and compounding by heating. It can be stored at room temperature in a sealed and light-proof manner for a shelf life of ≥6 months. It is convenient to store, transport and use. The proportion of each component is scientific and reasonable, with strong compatibility. The amount added is only 0.3%-1.2% of the mass of quicklime. The addition method is flexible. It can be directly mixed or sprayed into the solution. It is suitable for large-scale continuous production and has excellent economic, environmental and promotional value. It can comprehensively promote the high-end and green upgrading of the high specific surface area calcium hydroxide industry. Detailed Implementation

[0031] Example 1 The first aspect of this example provides a composite additive, the raw materials for which, by mass parts, include 12 parts of a crystal regulator, 15 parts of a dispersant stabilizer, 6 parts of a reaction rate regulator, and 65 parts of a solvent, deionized water.

[0032] The crystal regulator comprises 8 parts sodium citrate and 4 parts glucose by weight.

[0033] The dispersion stabilizer comprises 10 parts sodium polycarboxylate and 5 parts AEO-9 by weight.

[0034] The reaction rate regulator comprises 2 parts glycerol and 4 parts triethanolamine by mass.

[0035] The second aspect of this example provides a method for preparing a composite additive, comprising the following steps: S1. Mix the crystal regulator and the reaction rate regulator, grind them until the particle size is ≤100μm, then add them to the solvent and stir at 50℃ and 400rpm until the raw materials are completely dissolved. S2. Add the dispersant and stabilizer, and stir at 60°C and 500 rpm until the system is uniform, transparent and free of precipitate to obtain the composite additive.

[0036] The third aspect of this example provides an application of a composite additive in the preparation of high specific surface area calcium hydroxide. The method for preparing high specific surface area calcium hydroxide includes the following steps: S1. Crush quicklime to 0.5-5mm, pass it through a 200-mesh sieve, then add composite additive and water. The mass ratio of quicklime to composite additive is 100:0.8, and the mass ratio of water to calcium is 2:1. Carry out the digestion reaction at a temperature of 80℃, a stirring speed of 500rpm, and a reaction time of 45min. S2. After the reaction is complete, age at room temperature (25℃) for 2 hours, filter, dry at 90℃ until the moisture content is ≤1%, and then air-jet pulverize to a particle size D50≤5μm to obtain high specific surface area calcium hydroxide.

[0037] The high specific surface area calcium hydroxide prepared in this example has a specific surface area of ​​52 m². 2 / g, pore volume 0.28cm 3 / g, Ca(OH)2 content is 96.5wt%.

[0038] Example 2 (Suboptimal Case) The first aspect of this example provides a composite additive, the raw materials for which, by mass parts, include 10 parts of a crystal regulator, 15 parts of a dispersant stabilizer, 5 parts of a reaction rate regulator, and 70 parts of a solvent, deionized water.

[0039] The crystal regulator comprises 6 parts sodium pyrophosphate and 4 parts sodium citrate by mass.

[0040] The dispersion stabilizer comprises 7 parts AEO-9 and 8 parts sodium dodecyl sulfonate by weight.

[0041] The reaction rate regulator comprises, by mass, 2 parts glycerol and 3 parts diethanol monoisopropanolamine.

[0042] The second aspect of this example provides a method for preparing a composite additive, comprising the following steps: S1. Mix the crystal regulator and the reaction rate regulator, grind them until the particle size is ≤100μm, then add them to the solvent and stir at 50℃ and 400rpm until the raw materials are completely dissolved. S2. Add the dispersant and stabilizer, and stir at 60°C and 500 rpm until the system is uniform, transparent and free of precipitate to obtain the composite additive.

[0043] The third aspect of this example provides an application of a composite additive in the preparation of high specific surface area calcium hydroxide.

[0044] The high specific surface area calcium hydroxide is prepared by a dry process using quicklime and composite additives as raw materials. The dry process includes the following steps: S1. Grind quicklime to a particle size ≤150μm and add it to the digester; S2. The composite additive is atomized into droplets with a particle size of 10-50μm. The mass ratio of quicklime to composite additive is 100:0.5. The droplets are sprayed into a digester for digestion reaction. The digestion reaction temperature is 85℃, the stirring speed is 400rpm, the reaction time is 30min, and the water-lime ratio is 0.45. S3. After the reaction is complete, pass the solution through a 325-mesh sieve and cool it to room temperature (about 25°C) to obtain calcium hydroxide with high specific surface area.

[0045] In this example, the specific surface area of ​​the high specific surface area calcium hydroxide is 48 m². 2 / g, pore volume 0.25cm 3 / g, with a water content of 0.9%; the specific surface area and pore volume of the calcium hydroxide obtained in this example are both smaller than those in Example 1, so its adsorption effect on sulfur dioxide is relatively poor.

[0046] Example 3 The specific implementation method in this example is the same as in Example 1, except that the mass ratio of quicklime to composite additive is 100:1.

[0047] The high specific surface area calcium hydroxide prepared in this example has a specific surface area of ​​58 m². 2 / g, pore volume 0.30cm 3 / g is the optimal implementation case.

[0048] Comparative Example 1 This example provides a composite additive whose raw materials, by mass, include 10 parts crystal regulator, 15 parts dispersant stabilizer, 5 parts reaction rate regulator, and 70 parts solvent deionized water.

[0049] The crystal regulator is sodium citrate.

[0050] The dispersion stabilizer is sodium dodecyl sulfonate.

[0051] The reaction rate regulator is triethanolamine.

[0052] The second aspect of this example provides a method for preparing a composite additive, comprising the following steps: S1. Mix the crystal regulator and the reaction rate regulator, grind them until the particle size is ≤100μm, then add them to the solvent and stir at 50℃ and 400rpm until the raw materials are completely dissolved. S2. Add the dispersant and stabilizer, and stir at 60°C and 500 rpm until the system is uniform, transparent and free of precipitate to obtain the composite additive.

[0053] The third aspect of this example provides an application of a composite additive in the preparation of high specific surface area calcium hydroxide.

[0054] The high specific surface area calcium hydroxide is prepared by a dry process using quicklime and composite additives as raw materials. The dry process includes the following steps: S1. Grind quicklime to a particle size ≤150μm and add it to the digester; S2. The composite additive is atomized into droplets with a particle size of 10-50μm. The mass ratio of quicklime to composite additive is 100:0.5. The droplets are sprayed into a digester for digestion reaction. The digestion reaction temperature is 85℃, the stirring speed is 400rpm, the reaction time is 30min, and the water-lime ratio is 0.45. S3. After the reaction is complete, pass the solution through a 325-mesh sieve and cool it to room temperature (about 25°C) to obtain calcium hydroxide with high specific surface area.

[0055] In this example, the specific surface area of ​​the high specific surface area calcium hydroxide is 38 m². 2 / g, calcium hydroxide particles showed significant agglomeration, and the effect was significantly inferior to that of Example 3.

[0056] Comparative Example 2 This example provides a calcium hydroxide that is prepared without the composite additives provided in this invention. Instead, it is prepared using quicklime and water as raw materials and through a conventional wet process in the art.

[0057] In this example, the specific surface area of ​​the high specific surface area calcium hydroxide is 32 m². 2 / g, with relatively large particle size and severe agglomeration.

[0058] Sulfur dioxide adsorption experiment The calcium hydroxides prepared according to Examples 1, 3, Comparative Example 1, and Comparative Example 2 were subjected to adsorption tests of sulfur dioxide in flue gas. The test results are detailed in Table 1.

[0059] Table 1

[0060] From the perspective of the product's physicochemical properties, Example 1, using a preferred wet process and optimal component ratio, yielded a product with a specific surface area of ​​52 m². 2 / g, pore volume 0.28cm 3 / g, calcium hydroxide purity 96.5%; Example 2 uses a dry process, the product specific surface area is 48m² 2 / g, pore volume 0.25cm 3 With a moisture content of only 0.9% and a weight of / g, this invention's additive is suitable for both wet and dry processes. However, the choice of raw material blending has a certain impact on the performance of calcium hydroxide. Example 3 optimizes the additive dosage based on Example 1, increasing the specific surface area to 58m². 2 / g, pore volume 0.30cm 3 / g represents the optimal implementation case, indicating that reasonably increasing the amount of additives can further enhance the crystal regulation and dispersion stability effects, thereby maximizing performance. Comparative Example 1 uses a single-component additive formulation, resulting in a product with a specific surface area of ​​only 38m². 2 / g, with significant particle agglomeration, indicating that a single additive cannot achieve synergistic multi-functionality and its effect is far inferior to the composite system of this invention. Comparative Example 2, without any additives, produced a product with a specific surface area of ​​only 32m². 2 / g, severe particle agglomeration, proving that the composite additive of the present invention is the core factor in increasing the specific surface area of ​​calcium hydroxide and improving the particle morphology.

[0061] From the perspective of sulfur dioxide adsorption effect in flue gas, Examples 1 and 3 are significantly superior to the comparative example in terms of desulfurization efficiency, reagent dosage, and reaction time. Example 3, under conditions of higher initial sulfur dioxide concentration, reagent addition of only 400 kg / h, and reaction time of 20 min, can reduce the sulfur dioxide concentration to 50-60 mg / m³. 3 The desulfurization efficiency was optimal; in Example 1, a good desulfurization effect was achieved with a reaction time of only 15 minutes. In Comparative Example 1, with the same reagent dosage and reaction time, the outlet concentration still reached 80-90 mg / m³. 3 Comparative Example 2 required 600 kg / h of reagent and a 30-minute reaction time, yet the outlet concentration remained as high as 100-110 mg / m³. 3 Overall data shows that the high specific surface area calcium hydroxide prepared by this invention has sufficient active sites, well-developed pore structure, and rapid alkaline reaction. It can significantly reduce the amount of desulfurization agent, shorten the reaction time, and improve the desulfurization depth, fully verifying that the product performance is significantly positively correlated with the desulfurization effect, and also confirming that the composite additive of this invention has excellent industrial application value.

Claims

1. A composite additive for producing high specific surface area calcium hydroxide, characterized in that, The raw materials for preparation, by mass, include 5-15 parts crystal regulator, 10-25 parts dispersant stabilizer, 3-10 parts reaction rate regulator, and 50-80 parts solvent; The crystal regulators include at least one of sodium citrate, glucose, and sodium pyrophosphate; The dispersion stabilizer includes at least one of polycarboxylate, fatty alcohol polyoxyethylene ether, and sodium dodecyl sulfonate; The reaction rate regulators include at least one of triethanolamine, diethanolmonoisopropanolamine, and glycerol. The specific surface area of ​​the high specific surface area calcium hydroxide is greater than 40 m². 2 / g.

2. The composite additive according to claim 1, characterized in that, The polycarboxylate includes at least one of potassium polycarboxylate, ammonium polycarboxylate, calcium polycarboxylate, magnesium polycarboxylate, sodium polycarboxylate, and triethanolamine polycarboxylate. The fatty alcohol polyoxyethylene ethers include at least one of AEO-3, AEO-7, AEO-8, AEO-9, AEO-10, AEO-15, isomeric decaol polyoxyethylene ether, and isomeric tridecyl alcohol polyoxyethylene ether.

3. The composite additive according to claim 2, characterized in that, The dispersion stabilizers include sodium polycarboxylate and AEO-9.

4. The composite additive according to claim 3, characterized in that, The mass ratio of sodium polycarboxylate to AEO-9 is (2-1):

1.

5. The composite additive according to claim 1, characterized in that, The crystal regulator comprises sodium citrate and glucose, with a mass ratio of sodium citrate to glucose of 1:(0.5-2).

6. The composite additive according to claim 1, characterized in that, The reaction rate regulators include triethanolamine and glycerol, with a mass ratio of triethanolamine to glycerol of (3-1):

1.

7. A method for preparing a composite additive according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix the crystal regulator and the reaction rate regulator, grind them until the particle size is ≤100μm, then add them to the solvent and stir at 40-60℃ and 300-500rpm until the raw materials are completely dissolved. S2. Add the dispersant and stabilizer, and stir at 50-70℃ and 400-600rpm until the system is uniform, transparent and free of precipitate to obtain the composite additive.

8. The application of a composite additive according to any one of claims 1-6, characterized in that, Applications in the preparation of calcium hydroxide with high specific surface area; The high specific surface area calcium hydroxide is prepared by dry or wet process using quicklime and composite additives as raw materials.

9. The application of the composite additive according to claim 8, characterized in that, The dry process includes the following steps: S1. Grind quicklime to a particle size ≤150μm and add it to the digester; S2. Atomize the composite additive into droplets with a particle size of 10-50μm and spray them into the digester for digestion reaction; S3. After the reaction is complete, sieve and cool to obtain calcium hydroxide with high specific surface area.

10. The application of the composite additive according to claim 8, characterized in that, The wet process includes the following steps: S1. Crush quicklime to 0.5-5mm, pass it through a 200-mesh sieve, then add composite additives and water to carry out a digestion reaction; S2. After the reaction is complete, age for 1-3 hours, filter, dry at 80-100℃ until the moisture content is ≤1%, and then air-jet pulverize to a particle size D50≤5μm to obtain high specific surface area calcium hydroxide.

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