Preparation method of calcium hydroxide with high specific surface area

Abstract

The invention discloses a preparation method of calcium hydroxide with high specific surface area, and belongs to the technical field of calcium hydroxide production. The method specifically comprises the following steps: mixing lime powder and a digestion aid in a premixing tank, and feeding the mixture into a Venturi mixer I to react with steam to generate high-porosity Ca (OH) 2 / CaO mixed powder; meanwhile, tail gas washing water is pressurized and then forms an atomized solution with an auxiliary agent mixed solution in a venturi mixer II, the atomized solution is introduced into the digestion reactor according to a certain powder-liquid ratio for a secondary digestion reaction, a final product is spirally conveyed and cooled, and a calcium hydroxide product with high purity and high specific surface area is obtained. According to the invention, the lime powder and the digestion aid are premixed, the two-stage venturi mixer is adopted to realize rapid steam digestion and secondary reaction of atomized liquid, and the mass transfer is optimized in combination with the powder uniform distributor and the spiral nozzle, so that the problems of incomplete reaction and reduced specific surface are solved. The tail gas waste heat recovery and spiral cooling system realizes energy consumption optimization, and is suitable for industrial continuous production.

Description

Technical Field

[0001] The present invention belongs to the technical field of calcium hydroxide production, and particularly relates to a preparation method of high specific surface area calcium hydroxide. Background Art

[0002] Calcium hydroxide, also known as slaked lime, is an important chemical raw material. Because it has strong alkalinity and can absorb SO2, it is widely used in fields such as construction, medical treatment, and petroleum. Its most common use is as an adsorbent and flue gas desulfurization agent. In recent years, with the increasing requirements for environmental protection, the quality requirements for calcium hydroxide have also increased; due to its high specific surface area, high activity, good dispersibility, large porosity, high utilization rate and other characteristics, high specific surface area calcium hydroxide replaces ordinary calcium hydroxide in many fields. With the maturity of technology, the market for high specific surface area calcium hydroxide can be further expanded.

[0003] Currently, the processes for preparing calcium hydroxide mainly include dry process and wet process. Among them, the dry process mainly uses gas stirring or mechanical stirring to prepare calcium hydroxide. This process has the advantages of short process, low cost, high degree of automation, etc. However, since the reaction mode is a small amount of water reacting with calcium oxide, usually multiple-stage reactions and ripening are required to ensure complete reaction. During the ripening process, the reaction is uneven due to local moisture differences, resulting in a relatively low specific surface area of the prepared calcium hydroxide; the wet process mainly uses a relatively high liquid-solid ratio for reaction, and then prepares calcium hydroxide through filtration, dehydration, drying, and pulverization. This method has the characteristics of high product purity, mature process flow, and being suitable for large-scale production, and solves the problems of calcium oxide and calcium hydroxide being wrapped and uneven reaction. However, due to the long process flow, there are problems such as high equipment failure rate and high production cost.

[0004] Chinese Patent CN114538799A discloses a preparation method of ultra-high specific surface area calcium hydroxide powder with a cluster-like meristematic structure: this method includes steps such as quicklime crushing, digestion in a closed pressure-resistant container, high-pressure ripening after digestion, and rapid pressure relief and discharging. This method can produce and prepare high specific surface area calcium hydroxide. However, since the reaction pressure reaches 0.6 MPa during the reaction process and pressure reduction and discharging are required, it belongs to batch production, and the efficiency is relatively low, which is not conducive to large-scale production.

[0005] Chinese Patent CN116903271A discloses a high specific surface area calcium hydroxide production line. This method includes an operation bin group and a digestion unit, and reasonably designs the digestion system. However, because the product has fine particles and many pores, it is easy to absorb moisture and agglomerate during storage and transportation, and strict moisture-proof and packaging measures need to be taken, thereby increasing the cost and difficulty of storage and transportation.

[0006] Chinese Patent CN115340303A discloses a high specific surface area and high activity calcium hydroxide and its preparation method. In this method, a non-ionic surfactant is added during the lime digestion process to reduce the surface energy of calcium hydroxide, avoid agglomeration, and improve the dispersion of calcium hydroxide, thereby preparing calcium hydroxide with a high specific surface area and large pore size. This method uses a relatively low water-lime ratio, and it is very easy to have uneven reaction problems. Especially during industrial production, lime and water will react violently. When the water-lime ratio is too low, some lime fails to react with water to form a mixture of calcium hydroxide and calcium oxide, affecting the product quality.

[0007] Chinese Patent CN116099429A discloses a continuous mixing device for the production of high specific surface area calcium hydroxide and its usage method. Through reasonable layout design, this device can meet the production of calcium hydroxide. However, a relatively large amount of raw materials is likely to adhere to the inner wall of the device and the stirring rod. Moreover, the device structure is relatively complex, resulting in a relatively high equipment cost, and the maintenance difficulty and cost also increase accordingly. During the continuous mixing process, extremely high precision is required for controlling the flow rate and ratio of various raw materials. Once there is a deviation, the stability of the product quality will be affected, and it may also require more stringent professional skills for workers due to the complex operation. Summary of the Invention

[0008] In view of the above deficiencies, the present invention proposes a preparation method of high specific surface area calcium hydroxide to solve problems such as the batch stability of technical products for producing high specific surface area calcium hydroxide, high costs of some wet digestion products, and the lack of corresponding production equipment.

[0009] To solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A preparation method of high specific surface area calcium hydroxide, comprising the following steps:

[0011] (1) Add lime powder and digestion aids to the lime premixing tank, and at the same time start the stirrer of the lime premixing tank. After mixing them evenly, send them to Venturi mixer I to react with the water vapor entering from the steam inlet to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area;

[0012] (2) Pass tap water into the tail gas scrubber, start the booster pump to pressurize the water discharged from the tail gas scrubber, and mix it evenly with the auxiliary agent mixed solution entering from the auxiliary agent mixed solution feed port in Venturi mixer II to prepare a mixed solution; then pass it into the digestion reactor for atomization;

[0013] (3) Perform a secondary digestion reaction on the mixed powder prepared in step (1) and the atomized mixed solution prepared in step (2) according to the mass ratio to prepare high-purity and high-specific surface area calcium hydroxide;

[0014] (4) The calcium hydroxide prepared in step (3) is discharged from the discharge port of the digestion reactor, enters a screw conveyor for transportation and cooling, and then is discharged for packaging to obtain a calcium hydroxide product with a high specific surface area.

[0015] Preferably, the mesh number of the lime powder in step (1) is 100 - 800 meshes.

[0016] Preferably, the digestion aid in step (1) is one or more of ethylene glycol, propylene glycol, glycerol, butanediol, benzyl alcohol, and cyclohexanol.

[0017] Preferably, the dosage of the digestion aid in step (1) is 1% - 8% of the mass of the lime.

[0018] Preferably, the steam in step (1) is 20% - 100% of the mass of the lime powder.

[0019] Preferably, the temperature of the steam entering Venturi mixer I in step (1) is 125 - 200 °C, and the pressure is 0.3 - 1 MPa.

[0020] Preferably, the auxiliary agent mixture in step (2) is one or more of diethylene glycol, polyethylene glycol, triethanolamine, sorbitol, xylitol, and pentaerythritol.

[0021] Preferably, the auxiliary agent mixture is prepared as a mixture with ammonia water in a mass ratio of 1:(1 - 5).

[0022] Preferably, the dosage of the auxiliary agent mixture in step (2) is 5% - 20% of the mass of the washing wastewater.

[0023] Preferably, the mass ratio of the powder to the mixed solution in step (3) is 1:(0.6 - 1.5).

[0024] The technical principle of the present invention:

[0025] The traditional dry digestion process relies on mechanical stirring to achieve solid-liquid mixing. Limited by the mass transfer efficiency, it is prone to incomplete reactions and local overheating. The specific surface area of the generated calcium hydroxide particles is significantly reduced due to crystal rearrangement and agglomeration. Although the wet digestion can inhibit crystal transformation through hydrothermal conditions, the high water-cement ratio leads to a sharp increase in subsequent drying energy consumption, and overburned lime is difficult to be completely hydrated due to insufficient activity, requiring additional screening for impurity removal, and the raw material utilization rate is only 60% - 70%.

[0026] The present invention realizes the preparation of high specific surface area calcium hydroxide through process optimization and equipment innovation. First, in the lime premixing tank, a spiral ribbon agitator is used to forcefully convectively mix lime powder and digestion aids, eliminating local concentration gradients and solving the problem of out-of-control reaction rates; the mixed material enters Venturi mixer I, where it undergoes a rapid gas-solid reaction with water vapor. Based on the Knudsen diffusion effect, the mass transfer efficiency is enhanced, and the powder is dispersed using the kinetic energy of the steam to construct a reaction intermediate with a high porosity. The tail gas scrubber recovers the reaction waste heat to heat tap water, which is pressurized and mixed with the aid mixture to form a turbulent jet in Venturi mixer II. After atomization through a spiral nozzle, it enters a new digestion reactor and undergoes a secondary liquid-solid reaction with the gas-solid fluidized bed formed by a powder distributor. This reactor utilizes two-fluid atomization technology and the principle of laminar flow distribution to break through the mass transfer limitations of traditional dry digestion, avoid crystal rearrangement during the ripening process, and improve the product purity through in-situ carbonization inhibition technology. The final product undergoes a rapid temperature drop through a screw conveyor integrated with a cooling system, inhibiting crystal form transformation, obtaining calcium hydroxide products with qualified specific surface areas, and achieving the coordinated optimization of energy consumption and cost.

[0027] Compared with the prior art, the technical advantages of the present invention are as follows:

[0028] 1. The product performance is significantly improved

[0029] Through innovative two-stage reaction design and precise process control, the present invention has achieved a breakthrough improvement in the physical and chemical properties of calcium hydroxide products. The system uses the synergistic effect of ultrafine lime powder and specific polyol digestion aids. In Venturi mixer I, the preliminary digestion reaction is achieved by precisely controlling the steam parameters, effectively avoiding the common phenomenon of calcium oxide encapsulation in traditional processes. In the secondary digestion stage, through the synergistic effect of the powder distributor and spiral nozzle II, the unreacted intermediate products are fully contacted with the atomized aid mixture to ensure the thoroughness of the reaction.

[0030] 2. Process flow optimization and energy consumption reduction

[0031] The device of the present invention adopts a modular design, realizing the efficient integration of the production process. The closed-loop tail gas treatment system achieves efficient dust removal through a serrated gas distributor and a spiral nozzle. The washing wastewater is pressurized and recycled to the reaction system, with the water resource utilization rate increased by more than 30%. The innovative baffle structure realizes efficient gas-solid separation, combined with the cooling system of the screw conveyor, increasing the heat energy utilization rate by more than 25%. Compared with the traditional wet process, this method omits multiple processes such as filtration and drying, reduces the equipment investment by 30%, reduces the energy consumption by about 25%, and avoids the loss problem in the slurry treatment link, having significant economic benefits.

[0032] 3. Enhanced environmental protection performance and process adaptability

[0033] The device of the present invention adopts a fully enclosed design. The tail gas is discharged up to the standard after multi-stage purification treatment, and the dust emission is reduced by more than 80%. The range of auxiliaries is wide, and the formula can be flexibly adjusted according to different product requirements. The device can adapt to lime powder raw materials with different finenesses of 100 - 800 meshes. By adjusting the steam parameters and the proportion of auxiliaries, products with a specific surface area of 40 - 52m 2 / g series can be produced to meet the requirements of different fields such as flue gas desulfurization and fine chemicals. This excellent process adaptability gives it obvious competitive advantages in industrial production and provides reliable technical support for the large-scale production of high-value-added calcium hydroxide products. Brief Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of the device for preparing high specific surface area calcium hydroxide of the present invention.

[0035] In the drawings: 1 - lime powder premixing tank, 101 - lime powder inlet; 102 - premixing tank motor; 103 - digestion aid inlet; 104 - ultrasonic level gauge; 105 - ribbon mixer; 106 - lime powder discharge port; 107 - steam inlet; 108 - Venturi mixer I, 109 - digestion reactor feed inlet and pipeline; 2 - digestion reactor; 201 - digestion reactor exhaust port; 202 - serrated gas distributor; 203 - tail gas scrubber; 204 - corrugated plate of tail gas scrubber; 205 - spiral nozzle I; 206 - water inlet pipeline and pipeline; 207 drain port; 208 - booster pump; 209 - booster pump water inlet; 210 - booster pump water outlet; 211 - Venturi mixer II; 212 - Venturi mixer discharge port; 213 - auxiliary mixture inlet; 214 - digestion reactor water inlet and pipeline; 215 - spiral nozzle II; 216 - powder distributor; 217 - deflector; 218 - discharge port; 219 - rotary feeder; 220 - screw conveyor feed inlet; 221 - screw conveyor motor; 222 - screw conveyor cooling water inlet; 223 - screw conveyor; 224 - screw conveyor drain port; 225 - screw conveyor discharge port; 226 - digestion reactor support. Detailed Embodiments

[0036] The following further elaborates on the present invention patent in detail with reference to the drawings and examples:

[0037] The working principle of the application of the device of the present invention:

[0038] As Figure 1As described above, a device for preparing calcium hydroxide with a high specific surface area comprises a lime premixing tank 1 and a digestion reactor 2; a spiral ribbon agitator 105 is arranged in the lime premixing tank 1 and is connected to a stirring motor 102 at the top of the premixing tank 1. Lime powder enters from the lime powder inlet 101 at the top of the lime premixing tank 1, and a digestion aid is added from the digestion aid inlet 103. They are mixed under the monitoring of an ultrasonic level gauge 104. The preliminarily mixed powder material is discharged from the lime powder discharge port 106 arranged at the bottom of the lime premixing tank 1 and enters a Venturi mixer I 108.

[0039] One inlet of the Venturi mixer I 108 is communicated with the lime powder discharge port 106. Steam enters from the steam inlet 107 of the Venturi mixer I 108 and reacts with the lime powder wrapped with the digestion aid to prepare calcium hydroxide with a high specific surface area. Since the reaction time is short, there is still some unreacted calcium oxide. Under the action of the steam, the mixed powder material is transported to the digestion reactor inlet and pipeline 109 and enters the interior of the digestion reactor 2. A powder distributor 216 is arranged at the end of the digestion reactor inlet and pipeline 109. The powder material with a high flow rate rapidly drops in pressure inside the digestion reactor 2. After impacting the powder distributor 216, the powder material is evenly distributed inside the digestion reactor 2 and undergoes a secondary digestion reaction with the auxiliary agent mixed solution atomized by a spiral nozzle II 215.

[0040] A tail gas scrubber 203 is arranged at the top of the digestion reactor 2. The dust-containing gas inside is discharged from the digestion reactor exhaust port 201. Under the action of a serrated gas distributor 202 and a corrugated plate 204 of the tail gas scrubber, it is slowly and evenly distributed in the tail gas scrubber 203. Then, tap water is introduced from the water inlet pipeline port and pipeline 206. The dust-containing tail gas is sprayed under the action of a spiral nozzle I 205. After the tail gas is purified, it is discharged. The scrubbing wastewater after scrubbing is discharged to the inlet of a booster pump 209 from the drain port 207. Then, after being boosted by the booster pump 208, it is transported to a Venturi mixer II 211 and mixed evenly with the auxiliary agent mixed solution entering from the auxiliary agent mixed solution inlet 213. Then, they are transported together to the digestion reactor water inlet and pipeline 214 and atomized under the action of a spiral nozzle II 215 and undergo a digestion reaction with the powder material to prepare high-purity calcium hydroxide with a high specific surface area.

[0041] The prepared calcium hydroxide with a high specific surface area falls into the internal baffle 217 of the digestion reactor 2 under the action of gravity and then falls to the bottom of the digestion reactor 2 along the baffle 217. Since the lime reaction takes some time, most of the steam generated during the reaction process rises from the other side of the baffle 217 to the top of the digestion reactor 2, while the calcium hydroxide with a high specific surface area that has fallen to the bottom is discharged from the discharge port 218 and is evenly transported to the screw conveyor feed port 220 of the screw conveyor 223 under the action of the rotary feeder valve 219. It is evenly stirred under the action of the screw conveyor motor 221 and exchanges heat with the cold water entering from the screw conveyor cooling water inlet 222. Then the water is discharged from the screw conveyor drain port 224, and the calcium hydroxide with a high specific surface area after cooling is discharged from the screw conveyor discharge port 225. After packaging, the calcium hydroxide product with a high specific surface area is obtained.

[0042] Example 1

[0043] A preparation method of calcium hydroxide with a high specific surface area includes the following steps:

[0044] Step 1: Add 100-mesh lime powder and glycerol to the lime premixing tank. The dosage of the digestion aid is 1% of the lime. At the same time, start the stirrer of the lime premixing tank to mix the two evenly and then send them to the Venturi mixer I, where they react with the water vapor entering from the steam inlet at a temperature of 125 °C, a pressure of 0.3 MPa, and a mass of 20% of the powder to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area.

[0045] Step 2: Pass tap water into the tail gas scrubber, start the booster pump to boost the scrubbing wastewater discharged from the tail gas scrubber, and mix it evenly with the mixture of diethylene glycol: ammonia water = 1:5 with a mass of 5% of the scrubbing wastewater entering from the auxiliary agent mixing liquid inlet in the Venturi mixer II to prepare a mixed solution, and then pass it into the digestion reactor for atomization.

[0046] Step 3: The mixed powder prepared in Step 1 and the atomized mixed solution prepared in Step 2 are subjected to a secondary digestion reaction at a mass ratio of powder: mixed solution = 1:0.6 to prepare calcium hydroxide with high purity and high specific surface area.

[0047] Step 4: The calcium hydroxide prepared in Step 3 is discharged from the discharge port of the digestion reactor, enters the screw conveyor for transportation and cooling, and then is discharged for packaging to obtain the calcium hydroxide product with a high specific surface area.

[0048] Example 2

[0049] A preparation method of calcium hydroxide with a high specific surface area includes the following steps:

[0050] Step 1: Add 400-mesh lime powder and benzyl alcohol to the lime premixing tank. The dosage of the digestion aid is 5% of the lime. At the same time, start the agitator of the lime premixing tank. After mixing them evenly, send them to Venturi mixer I to react with the water vapor entering from the steam inlet at a temperature of 150 °C, a pressure of 0.5 MPa, and a water vapor quality of 100% powder mass to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area;

[0051] Step 2: Pass tap water into the tail gas scrubber. Start the booster pump to boost the scrubbing wastewater discharged from the tail gas scrubber. In Venturi mixer II, mix it evenly with the mixed solution of triethanolamine:ammonia water = 1:3 with a mass of 10% of the scrubbing wastewater entering from the auxiliary agent mixed solution inlet to prepare a mixed solution, and then pass it into the digestion reactor for atomization;

[0052] Step 3: Perform a secondary digestion reaction on the mixed powder prepared in Step 1 and the atomized mixed solution prepared in Step 2 according to the mass ratio of powder:mixed solution = 1:1.5 to prepare calcium hydroxide with high purity and high specific surface area.

[0053] Step 4: The calcium hydroxide prepared in Step 3 is discharged from the discharge port of the digestion reactor, enters the screw conveyor for transportation and cooling, and then is discharged for packaging to obtain a calcium hydroxide product with a high specific surface area.

[0054] Example 3

[0055] A preparation method of high specific surface area calcium hydroxide includes the following steps:

[0056] Step 1: Add 800-mesh lime powder and ethylene glycol to the lime premixing tank. The dosage of the digestion aid is 8% of the lime. At the same time, start the agitator of the lime premixing tank. After mixing them evenly, send them to Venturi mixer I to react with the water vapor entering from the steam inlet at a temperature of 200 °C, a pressure of 1 MPa, and a water vapor quality of 50% powder mass to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area;

[0057] Step 2: Pass tap water into the tail gas scrubber. Start the booster pump to boost the scrubbing wastewater discharged from the tail gas scrubber. In Venturi mixer II, mix it evenly with the mixed solution of polyethylene glycol:ammonia water = 1:1 with a mass of 20% of the scrubbing wastewater entering from the auxiliary agent mixed solution inlet to prepare a mixed solution, and then pass it into the digestion reactor for atomization;

[0058] Step 3: Perform a secondary digestion reaction on the mixed powder prepared in Step 1 and the atomized mixed solution prepared in Step 2 according to the mass ratio of powder:mixed solution = 1:1 to prepare calcium hydroxide with high purity and high specific surface area.

[0059] Step 4: The calcium hydroxide prepared in Step 3 is discharged from the discharge port of the digestion reactor, enters a screw conveyor for transportation and cooling, and then is discharged for packaging, thus obtaining a calcium hydroxide product with a high specific surface area.

[0060] Comparative Example 1

[0061] A method for preparing calcium hydroxide includes the following steps:

[0062] Step 1: Add 80-mesh lime powder and ethylene glycol to a lime premixing tank. The dosage of the digestion aid is 10% of the lime. At the same time, turn on the stirrer of the lime premixing tank to mix the two evenly and then send them to Venturi mixer I, where they react with water vapor entering from the steam inlet at a temperature of 110°C, a pressure of 0.25 MPa, and a mass of water vapor 110% of the powder mass to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area;

[0063] Step 2: Pass tap water into the tail gas scrubber, turn on the booster pump to boost the scrubbing wastewater discharged from the tail gas scrubber, and in Venturi mixer II, mix it evenly with a mixed solution of polyethylene glycol: ammonia water = 1:6 with a mass of 4% of the scrubbing wastewater entering from the auxiliary agent mixed solution inlet to prepare a mixed solution, and then pass it into the digestion reactor for atomization;

[0064] Step 3: The mixed powder prepared in Step 1 and the atomized mixed solution prepared in Step 2 are subjected to a secondary digestion reaction at a mass ratio of powder: mixed solution = 1:1.6 to prepare calcium hydroxide with high purity and high specific surface area.

[0065] Step 4: The calcium hydroxide prepared in Step 3 is discharged from the discharge port of the digestion reactor, enters a screw conveyor for transportation and cooling, and then is discharged for packaging to obtain a calcium hydroxide product.

[0066] Comparative Example 2

[0067] A method for preparing high specific surface area calcium hydroxide is basically the same as that in Example 3, except that in Step 1, adding ethylene glycol to the lime premixing tank is changed to adding ethanol.

[0068] Comparative Example 3

[0069] A method for preparing high specific surface area calcium hydroxide is basically the same as that in Example 3, except that in Step 2, adding a mixed solution of polyethylene glycol: ammonia water = 1:1 is changed to adding tap water.

[0070] The specific surface area of the calcium hydroxide product with high specific surface area is tested according to GB / T 19587-2017 "Determination of Specific Surface Area of Solid Materials by Gas Adsorption - BET Method", and the pore volume is tested according to GB / T 21650.2-2008 "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Intrusion Method and Gas Adsorption Method - Part 2: Analysis of Mesopores and Macropores by Gas Adsorption Method". The test data are as follows in the table:

[0071]

[0072]

[0073] As can be seen from the above table:

[0074] The specific surface area and pore volume of Examples 1, 2, and 3 are significantly improved compared with Comparative Example 1. The specific surface area of Example 1 is 40.26 m 2 / g, which is about 37.5% higher than 29.28 m 2 / g of Comparative Example 1. The pore volume increases from 0.146 cm 3 / g to 0.208 cm 3 / g, with an increase of about 42.5%; the specific surface area of Example 2 is 48.16 m 2 / g, which is about 64.5% higher than 29.28 m 2 / g of Comparative Example 1. The pore volume increases from 0.146 cm 3 / g to 0.253 cm 3 / g, with an increase of 73.3%; the specific surface area of Example 3 is 52.33 m 2 / g, which is about 80.4% higher than 29.28 m 2 / g of Comparative Example 1. The pore volume increases from 0.146 cm 3 / g to 0.289 cm 3 / g, with an increase of 98%, almost doubling.

[0075] In Comparative Example 1, due to the too coarse lime powder (80 mesh) and the deviation of the additive ratio from the scope of the present invention, the reaction is insufficient, resulting in insufficient pore development. In the examples, by precisely controlling the powder fineness, additive dosage and steam conditions, a "powder dispersion - steam activation - pore growth" path is formed, significantly increasing the porosity between calcium hydroxide crystals, improving the specific surface area and pore volume, providing high-performance materials for applications such as adsorption and catalysis, and highlighting the core advantages of the patented process in optimizing the product functionality.

[0076] The specific surface area and pore volume of Examples 1, 2, and 3 are significantly improved compared with Comparative Example 2. The specific surface area of Example 1 is 40.26 m 2 / g, which is about 53.5% higher than 26.23 m 2 / g of Comparative Example 2. The pore volume increases from 0.132 cm3 Increase / g to 0.208 cm 3 / g, with an increase of 57.6%; the specific surface area of Example 2 is 48.16 m 2 / g, compared with 26.23 m of Comparative Example 2 2 / g, an increase of about 83.6%, and the pore volume increases from 0.132 cm 3 / g to 0.253 cm 3 / g, with an increase of 91.7%; the specific surface area of Example 3 is 52.33 m 2 / g, compared with 26.23 m of Comparative Example 2 2 / g, an increase of nearly 100%, and the pore volume increases from 0.132 cm 3 / g to 0.289 cm 3 / g, with an increase of 119%, almost doubling.

[0077] In Comparative Example 2, due to the weak polarity and fast volatilization of ethanol, the pore development could not be effectively promoted. In the examples, by selecting polyhydroxy polar additives such as glycerol, benzyl alcohol, and ethylene glycol, and using their hydrogen bond adsorption and interfacial activation effects, a "additive-induced pore growth" mechanism was constructed, resulting in a rich microporous structure formed between calcium hydroxide crystals, significantly improving the specific surface area and pore volume, verifying the decisive influence of the additive molecular structure on the product performance, and highlighting the key role of the patented additive system in the directional regulation of material functionality.

[0078] The specific surface area and pore volume of Examples 1, 2, and 3 were significantly improved compared with Comparative Example 3: the specific surface area of Example 1 is 40.26 m 2 / g, compared with 18.96 m of Comparative Example 3 2 / g, an increase of about 112.3%, and the pore volume increases from 0.118 cm 3 / g to 0.208 cm 3 / g, with an increase of 76.3%; the specific surface area of Example 2 is 48.16 m 2 / g, compared with 18.96 m of Comparative Example 3 2 / g, an increase of about 154%, and the pore volume increases from 0.118 cm 3 / g to 0.253 cm 3 / g, with an increase of 114.4%; the specific surface area of Example 3 is 52.33 m 2 / g, compared with 18.96 m of Comparative Example 3 2 / g, an increase of about 176%, and the pore volume increases from 0.118 cm 3 / g to 0.289 cm 3 / g, with an increase of 144.9%, almost 2.5 times the original value.

[0079] In Comparative Example 3, due to the lack of a composite additive, the reaction interface could not be activated solely by tap water, resulting in severely restricted pore development. In the examples, polyhydroxy additives such as glycerol, benzyl alcohol, and ethylene glycol were introduced and compounded with ammonia water. By utilizing the interfacial adsorption, dispersion lubrication, and alkaline catalysis of the additives, a "directed pore growth" mechanism was constructed, forming a dense microporous network between calcium hydroxide crystals, significantly enhancing the specific surface area and pore volume, verifying the decisive influence of the composite additive system on the reaction efficiency and product performance, and highlighting the core advantage of the patent in optimizing the material structure through chemical regulation.

[0080] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of high specific surface area calcium hydroxide, characterized in that, It includes the following steps: (1) Add lime powder and digestion aid to the lime premixing tank, and at the same time start the agitator of the lime premixing tank. After the two are evenly mixed, they are sent to Venturi mixer I to react with the water vapor entering from the steam inlet to prepare a mixed powder of calcium hydroxide and calcium oxide with high porosity and high specific surface area; (2) Pass water into the tail gas scrubber, start the booster pump to pressurize the water discharged from the tail gas scrubber, and mix it evenly with the auxiliary agent mixed solution entering from the auxiliary agent mixed solution feed port in Venturi mixer II to prepare a mixed solution; then it is passed into the digestion reactor for atomization; (3) The mixed powder prepared in step (1) and the atomized mixed solution prepared in step (2) are subjected to a secondary digestion reaction according to the mass ratio to prepare calcium hydroxide with high purity and high specific surface area; (4) The calcium hydroxide prepared in step (3) is discharged from the discharge port of the digestion reactor, enters the screw conveyor for transportation and cooling, and then is discharged for packaging to obtain a calcium hydroxide product with a high specific surface area.

2. The preparation method of a high specific surface area calcium hydroxide according to claim 1, characterized in that, In step (1), the mesh number of the lime powder is 100 - 800 mesh.

3. The preparation method of a high specific surface area calcium hydroxide according to claim 1, characterized in that, The digestion aid described in step (1) is one or more of ethylene glycol, propylene glycol, glycerol, butanediol, benzyl alcohol, and cyclohexanol.

4. The preparation method of a high specific surface area calcium hydroxide according to claim 3, characterized in that, The dosage of the digestion aid described in step (1) is 1% - 8% of the lime mass.

5. The preparation method of a high specific surface area calcium hydroxide according to claim 1, characterized in that, The water vapor described in step (1) is 20% - 100% of the mass of the lime powder.

6. The preparation method of high specific surface calcium hydroxide according to claim 1, characterized in that, The temperature of the water vapor entering Venturi mixer I in step (1) is 125 - 200 °C, and the pressure is 0.3 - 1 MPa.

7. A preparation method of high specific surface area calcium hydroxide according to claim 1, characterized in that, The auxiliary agent mixed solution described in step (2) is one or more of diethylene glycol, polyethylene glycol, triethanolamine, sorbitol, xylitol, and pentaerythritol.

8. The preparation method of a high specific surface area calcium hydroxide according to claim 7, characterized in that, The auxiliary agent mixed solution is a mixed solution prepared with ammonia water according to a mass ratio of 1:(1 - 5).

9. The preparation method of high specific surface area calcium hydroxide according to claim 8, characterized in that, The dosage of the auxiliary agent mixed solution described in step (2) is 5% - 20% of the mass of the washing wastewater.

10. The preparation method of a high specific surface area calcium hydroxide according to claim 1, characterized in that, In step (3), the mass ratio of the powder to the mixed solution is 1:(0.6 - 1.5).

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