Process for producing calcium hydroxide with high specific surface area by dry method

Abstract

The invention discloses a production process of calcium hydroxide with a high specific surface area by a dry method, and belongs to the technical field of preparation of calcium hydroxide, the production process of the calcium hydroxide with the high specific surface area by the dry method comprises the following steps: preparing quicklime powder, preparing a perlite composite material, preparing a mixture, digesting, drying, grading and removing impurities. The preparation of the perlite composite material comprises modification and compounding, and the compounding method comprises the following steps: adding modified perlite, a polycarboxylate superplasticizer and stearic acid diethanolamide into water, controlling the temperature at 55-65 DEG C, stirring for 15-25 minutes, then adding hydrochloric acid and trimethylolpropane, stirring for 8-12 minutes, filtering, washing and drying to obtain the perlite composite material. The digestion comprises primary digestion and secondary digestion; the specific surface area, the purity and the desulfurization efficiency of the calcium hydroxide are improved under the condition of not additionally introducing new impurities.

Description

Technical Field

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

[0002] Calcium hydroxide is used as a common desulfurizer because of its more efficient acid removal performance, wide temperature adaptability, and easy treatment of by-products. When calcium hydroxide is used as a desulfurizer, it reacts with sulfur dioxide in flue gas to form calcium sulfite, and is further oxidized to calcium sulfate by introducing air. In this process, the specific surface area, purity, porosity, surface adherents, etc. of calcium hydroxide are important factors affecting the sulfur dioxide removal efficiency.

[0003] In industry, calcium hydroxide is mostly directly prepared by the hydration digestion of quicklime. Quicklime is generally prepared by calcining and decomposing limestone, and its main component is calcium oxide, but it often contains various impurities such as quartz, iron oxide, aluminum, magnesium, potassium and their compounds.

[0004] The process for preparing calcium hydroxide from quicklime is divided into dry digestion and wet digestion. The dry digestion process is an earlier powder-making process in industrial applications. It has a short digestion time, less water consumption, and large heat release, and can effectively solve the problems of large water consumption, much heat loss, high cost, and serious pollution in the wet process. However, it is prone to incomplete reaction, leaving some quicklime residues, and the obtained calcium hydroxide product has a small specific surface area and many impurities.

[0005] CN117510101A discloses a method for dry-preparing calcium hydroxide with a high specific surface area. This application improves the activity, specific surface area, and dispersibility of calcium hydroxide by preparing highly active lime, adding promoters and dispersants; among them, the promoters are one or several combinations of methanol, ethanol, propanol, isopropanol, n-butanol, etc., and the dispersants are one or several combinations of sodium carboxymethyl cellulose, sodium sulfonate, sodium polyacrylate, and polyacrylamide.

[0006] CN117865514A discloses a method for dry-preparing calcium hydroxide with a high specific surface area at a low water-cement ratio. During the lime digestion process, by adding additives such as trithiocyanuric acid and calcium lignosulfonate, the water-cement ratio required for the digestion process is reduced, and the specific surface area of calcium hydroxide is increased.

[0007] As described above, the prior art has shown that during the dry digestion of quicklime to prepare calcium hydroxide, the specific surface area of calcium hydroxide can be increased by adding additives such as promoters and dispersants, but there are also the following problems: (1) The added organic matter additives are difficult to remove and remain in the product, adsorbed on the surface of calcium hydroxide particles; (2) The calcium oxide digestion reaction is incomplete; (3)The prepared calcium hydroxide has a high impurity content; These problems have all affected the desulfurization efficiency of calcium hydroxide as a desulfurizing agent in flue gas treatment. Therefore, providing a production process for dry-process calcium hydroxide with a high specific surface area to increase the specific surface area of calcium hydroxide without introducing new impurities additionally, improve the purity of calcium hydroxide, and enable calcium hydroxide to have a high desulfurization efficiency is an urgent problem to be solved in the existing technology. Summary of the Invention

[0008] In view of the deficiencies existing in the prior art, the present invention provides a production process for dry-process calcium hydroxide with a high specific surface area, which can increase the specific surface area of calcium hydroxide without introducing new impurities additionally, improve the purity of calcium hydroxide, and improve the desulfurization efficiency of calcium hydroxide.

[0009] To solve the above technical problems, the technical solutions adopted by the present invention are as follows: A production process for dry-process calcium hydroxide with a high specific surface area includes the following steps: preparing quicklime powder, preparing perlite composite material, preparing a mixture, digestion, drying, and grading and impurity removal; The method for preparing the quicklime powder is to crush limestone, calcine it at 830 - 880 °C for 70 - 90 min, pulverize it, and sieve it through a 1.5 - 2 mm sieve to remove impurities to obtain quicklime powder.

[0010] The preparation of the perlite composite material includes modification and compounding; The method for modification is to add expanded perlite into water, and at the same time add γ-glycidoxypropyltrimethoxysilane, control the temperature at 75 - 85 °C at a rotation speed of 380 - 420 rpm, stir for 8 - 12 min. After stirring, filter, wash, and dry to obtain modified perlite; The expanded perlite is 70 - 100 mesh expanded perlite, and the mass ratio of the expanded perlite, water, and γ-glycidoxypropyltrimethoxysilane is 20:450 - 550:0.8 - 1.2.

[0011] The method for compounding is to add the modified perlite, polycarboxylate superplasticizer, and stearic acid diethanolamide into water, control the temperature at 55 - 65 °C, stir for 15 - 25 min, then add hydrochloric acid and trimethylolpropane, stir for 8 - 12 min, filter, wash, and dry to obtain the perlite composite material; The polycarboxylate superplasticizer is LCX-9 polycarboxylate superplasticizer; The concentration of the hydrochloric acid is 36.5 - 37.0 wt%; The mass ratio of the modified perlite, water, polycarboxylate superplasticizer, stearic acid diethanolamide, hydrochloric acid, and trimethylolpropane is 20:450 - 550:0.8 - 1.2:0.7 - 0.9:4.5 - 5.5:0.15 - 0.25.

[0012] The method for preparing the mixed material is to mix quicklime powder and perlite composite material evenly according to a mass ratio of 100:7-9 to prepare the mixed material.

[0013] The digestion includes primary digestion and secondary digestion; The method for primary digestion is to atomize water at 70-80°C and spray it on the surface of the mixed material under the stirring state at a rotation speed of 600-800 rpm, control the digestion temperature at 85-95°C, and the digestion time is 8-10 min. After the primary digestion is completed, primary digested calcium hydroxide is obtained; The mass ratio of the mixed material to water is 10:2-3.

[0014] The method for secondary digestion is to add expanded perlite after saturated water absorption to the primary digested calcium hydroxide, stir and mix evenly, then raise the temperature to 103-106°C, and continue to stir and digest at a rotation speed of 350-450 rpm for 18-22 min. After the digestion is completed, sieve through a 20-25 mesh sieve to remove impurities to obtain primary calcium hydroxide; The expanded perlite is 100-120 mesh expanded perlite with a water absorption rate greater than 800%; The mass ratio of the expanded perlite after saturated water absorption to the primary digested calcium hydroxide is 28-32:100.

[0015] The drying method is to dry the primary calcium hydroxide at a temperature of 108-112°C for 1.8-2.2 h to obtain calcium hydroxide powder.

[0016] The classification and impurity removal method is to perform air classification and impurity removal on the calcium hydroxide powder at a rotation speed of 950-1050 rpm to obtain calcium hydroxide with a high specific surface area.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The production process of dry-process calcium hydroxide with a high specific surface area of the present invention can increase the specific surface area of calcium hydroxide, do not introduce new impurities additionally, improve the purity of calcium hydroxide, improve the desulfurization efficiency of calcium hydroxide, and the specific surface area of the prepared calcium hydroxide is 53.3-54.5 m 2 / g, the purity is 96.8-97.7%, and the breakthrough sulfur capacity is 119.6-124.3 mg / g. Specific Embodiments

[0018] In order to have a clearer understanding of the technical features, purposes, and effects of the present invention, the specific embodiments of the present invention are now described.

[0019] Example 1 A production process of dry-process calcium hydroxide with a high specific surface area includes the following steps: (1) Preparation of quicklime powder Crush the limestone, calcine it at 830 °C for 90 min, pulverize it and sieve it through a 1.5 mm sieve to remove impurities to obtain quicklime powder.

[0020] (2) Preparation of perlite composite A. Modification Add 70-mesh expanded perlite into water, and at the same time add γ-glycidoxypropyltrimethoxysilane, control the temperature at 75 °C, stir at 380 rpm for 12 min. After stirring, filter, wash and dry to obtain modified perlite; The mass ratio of the expanded perlite, water and γ-glycidoxypropyltrimethoxysilane is 20:450:0.8.

[0021] B. Composite Add the modified perlite, polycarboxylate superplasticizer and stearic acid diethanolamide into water, control the temperature at 55 °C, stir at 280 rpm for 25 min, then add hydrochloric acid and trimethylolpropane, stir at 450 rpm for 12 min, filter, wash and dry to obtain perlite composite.

[0022] The polycarboxylate superplasticizer is LCX-9 polycarboxylate superplasticizer; The concentration of the hydrochloric acid is 36.5 wt%; The mass ratio of the modified perlite, water, polycarboxylate superplasticizer, stearic acid diethanolamide, hydrochloric acid and trimethylolpropane is 20:450:0.8:0.7:4.5:0.15.

[0023] (3) Preparation of mixture Mix the quicklime powder and perlite composite evenly according to the mass ratio of 100:7 to prepare a mixture.

[0024] (4) Digestion a. Primary digestion Add the mixture into the digester, control the stirring speed of the digester at 600 rpm, atomize the water at 70 °C and spray it on the surface of the mixture under stirring, control the digestion temperature at 85 °C, and the digestion time is 10 min. After the primary digestion, obtain primary digested calcium hydroxide; The mass ratio of the mixture and water is 10:2.

[0025] b. Secondary digestion Add the saturated water-absorbed expanded perlite into the primary digested calcium hydroxide, stir and mix evenly, then raise the temperature to 103 °C, continue to digest for 22 min, control the stirring speed of the digester at 350 rpm, and remove impurities with a 20-mesh sieve after digestion to obtain primary calcium hydroxide; The expanded perlite is 100-mesh expanded perlite with a water absorption rate greater than 800%. The mass ratio of the expanded perlite after saturated water absorption to calcium hydroxide monohydrate is 28:100.

[0026] (5) Drying The primary calcium hydroxide is dried at 108 °C for 2.2 h to obtain calcium hydroxide powder.

[0027] (6) Classification and impurity removal The calcium hydroxide powder is placed in an air classifier, and the rotation speed is adjusted to 950 rpm for classification and impurity removal to obtain calcium hydroxide with a high specific surface area.

[0028] Example 2 A production process for dry-process calcium hydroxide with a high specific surface area includes the following steps: (1) Preparation of quicklime powder The limestone is crushed, calcined at 850 °C for 80 min, pulverized, and screened through a 2-mm sieve to remove impurities to obtain quicklime powder.

[0029] (2) Preparation of perlite composite material A. Modification 80-mesh expanded perlite is added to water, and γ-glycidoxypropyltrimethoxysilane is added simultaneously. The temperature is controlled at 80 °C, and stirring is carried out at a rotation speed of 400 rpm for 10 min. After stirring, filtration, washing, and drying are carried out to obtain modified perlite; The mass ratio of the expanded perlite, water, and γ-glycidoxypropyltrimethoxysilane is 20:500:1.

[0030] B. Composite The modified perlite, polycarboxylate superplasticizer, and stearic acid diethanolamide are added to water. The temperature is controlled at 60 °C, and stirring is carried out at a rotation speed of 300 rpm for 20 min. Then hydrochloric acid and trimethylolpropane are added, and stirring is carried out at a rotation speed of 500 rpm for 10 min. Filtration, washing, and drying are carried out to obtain the perlite composite material.

[0031] The polycarboxylate superplasticizer is LCX-9 polycarboxylate superplasticizer; The concentration of the hydrochloric acid is 36.7 wt%; The mass ratio of the modified perlite, water, polycarboxylate superplasticizer, stearic acid diethanolamide, hydrochloric acid, and trimethylolpropane is 20:500:1:0.8:5:0.2.

[0032] (3) Preparation of the mixture The quicklime powder and the perlite composite material are uniformly mixed according to a mass ratio of 100:8 to prepare the mixture.

[0033] (4) Digestion a. Primary digestion Add the mixture into the digester, control the stirring speed of the digester at 700 rpm, atomize water at 75 °C and spray it on the surface of the mixture under stirring, control the digestion temperature at 90 °C, and the digestion time is 8 min. After the primary digestion is completed, primary digested calcium hydroxide is obtained; The mass ratio of the mixture to water is 10:2.5.

[0034] b. Secondary digestion Add the saturated water-absorbed expanded perlite into the primary digested calcium hydroxide, stir and mix evenly, then raise the temperature to 105 °C, continue digestion for 20 min, control the stirring speed of the digester at 400 rpm, and remove impurities with a 25-mesh sieve after digestion to obtain primary calcium hydroxide; The expanded perlite is 120-mesh expanded perlite with a water absorption rate greater than 800%; The mass ratio of the saturated water-absorbed expanded perlite to the primary digested calcium hydroxide is 30:100.

[0035] (5) Drying Dry the primary calcium hydroxide at 110 °C for 2 h to obtain calcium hydroxide powder.

[0036] (6) Classification and impurity removal Place the calcium hydroxide powder in an air classifier, adjust the rotation speed to 1000 rpm for classification and impurity removal to obtain calcium hydroxide with a high specific surface area.

[0037] Example 3 A production process of dry-process calcium hydroxide with a high specific surface area includes the following steps: (1) Preparation of quicklime powder Crush limestone, calcine it at 880 °C for 70 min, pulverize it and sieve it through a 2-mm sieve to remove impurities to obtain quicklime powder. [[ID=3,5]]

[0038] (2) Preparation of perlite composite material A. Modification Add 100-mesh expanded perlite into water, and at the same time add γ-glycidoxypropyltrimethoxysilane, control the temperature at 85 °C, stir at 420 rpm for 8 min, and after stirring, filter, wash and dry to obtain modified perlite; The mass ratio of the expanded perlite, water and γ-glycidoxypropyltrimethoxysilane is 20:550:1.2.

[0039] B. Composite Add modified perlite, polycarboxylate superplasticizer and stearic acid diethanolamide into water, control the temperature at 65°C, stir at 320 rpm for 15 min, then add hydrochloric acid and trimethylolpropane, stir at 550 rpm for 8 min, filter, wash and dry to obtain perlite composite material.

[0040] The polycarboxylate superplasticizer is LCX-9 polycarboxylate superplasticizer; The concentration of the hydrochloric acid is 37.0 wt%; The mass ratio of the modified perlite, water, polycarboxylate superplasticizer, stearic acid diethanolamide, hydrochloric acid and trimethylolpropane is 20:550:1.2:0.9:5.5:0.25.

[0041] (3)Prepare the mixture Mix quicklime powder and perlite composite material evenly according to the mass ratio of 100:9 to prepare the mixture.

[0042] (4)Slake a、Primary slaking Add the mixture into the slaker, control the stirring speed of the slaker at 800 rpm, atomize the water at 80°C and spray it on the surface of the mixture under stirring, control the slaking temperature at 95°C, and the slaking time is 8 min. After the primary slaking, primary slaked calcium hydroxide is obtained; The mass ratio of the mixture and water is 10:3.

[0043] b、Secondary slaking Add the expanded perlite after saturated water absorption into the primary slaked calcium hydroxide, stir and mix evenly, then raise the temperature to 106°C, continue to slake for 18 min, control the stirring speed of the slaker at 450 rpm, and remove impurities with a 25-mesh sieve after slaking to obtain primary calcium hydroxide; The expanded perlite is 120-mesh expanded perlite, and the water absorption rate is greater than 800%; The mass ratio of the expanded perlite after saturated water absorption and the primary slaked calcium hydroxide is 32:100.

[0044] (5)Dry Dry the primary calcium hydroxide at 112°C for 1.8 h to obtain calcium hydroxide powder.

[0045] (6)Classify and remove impurities Place the calcium hydroxide powder in an air classifier, adjust the rotation speed to 1050 rpm for classification and impurity removal to obtain calcium hydroxide with a high specific surface area.

[0046] Comparative Example 1 Comparative Example 1 adopted the production process of dry high specific surface area calcium hydroxide described in Example 2, the difference being that the step of preparing the perlite composite material was omitted, and the step of preparing the mixture was changed to: mixing quicklime powder, ethylene glycol and sodium carboxymethyl cellulose evenly according to a mass ratio of 100:0.4:0.35 to prepare the mixture.

[0047] Comparative Example 2 Comparative Example 2 adopted the production process of dry high specific surface area calcium hydroxide described in Example 2, the difference being that the step of preparing the perlite composite material was omitted, and the step of preparing the mixture was changed to: mixing quicklime powder, 80-mesh expanded perlite, polycarboxylate superplasticizer and stearic acid diethanolamide evenly according to a mass ratio of 100:7:0.4:0.35 to prepare the mixture.

[0048] Comparative Example 3 Comparative Example 3 adopted the production process of dry high specific surface area calcium hydroxide described in Example 2, the difference being that the step of preparing the perlite composite material was omitted, and the step of preparing the mixture was changed to: mixing quicklime powder, polycarboxylate superplasticizer and stearic acid diethanolamide evenly according to a mass ratio of 100:0.4:0.35 to prepare the mixture.

[0049] Comparative Example 4 Comparative Example 4 adopted the production process of dry high specific surface area calcium hydroxide described in Example 2, the difference being that the digestion step was changed to: adding the mixture into the digester, controlling the stirring speed of the digester at 700 rpm, atomizing water at 75°C and spraying it on the surface of the mixture under stirring, controlling the digestion temperature at 90°C, with a digestion time of 28 min, and removing impurities with a 1-mm sieve after digestion to obtain primary calcium hydroxide; The mass ratio of the mixture to water was 10:2.5.

[0050] Test Example  1 The high specific surface area calcium hydroxide prepared in Examples 1-3 and Comparative Examples 1-4 was tested using a specific surface area analyzer (BET), and the test results are as follows: Table 1 Specific surface areas of calcium hydroxide in Examples and Comparative Examples

[0051] As can be seen from Table 1, in Comparative Example 2, the preparation of the perlite composite material was omitted, and expanded perlite, polycarboxylate superplasticizer, diethanolamide stearate and quicklime powder were simply mixed directly; in Comparative Example 3, the preparation of the perlite composite material was omitted, and polycarboxylate superplasticizer, diethanolamide stearate and quicklime powder were simply mixed directly; the specific surface areas of the calcium hydroxide prepared in Comparative Examples 2-3 were significantly lower than that of Example 2, indicating that preparing the perlite composite material and mixing the perlite composite material with quicklime powder can effectively increase the specific surface area of calcium hydroxide.

[0052] The specific surface area of calcium hydroxide in Comparative Example 4 was significantly lower than that of Example 2, indicating that the secondary digestion step can increase the specific surface area of calcium hydroxide.

[0053] The surface of the perlite composite material has abundant polar groups with strong water affinity such as carboxyl groups, hydroxyl groups, polyoxyalkyl groups, etc. The carboxyl groups can react with calcium ions to form complexes, reduce the calcium ion concentration, delay the crystallization rate of calcium hydroxide and make its particle size smaller, increasing its specific surface area. The strong polar groups such as hydroxyl groups and polyoxyalkyl groups have strong water affinity. Through surface actions such as wetting and lubrication, the dispersion and fluidity of the calcium hydroxide generated by digestion are improved, the frictional resistance is reduced, its aggregation and caking are prevented, the dispersibility of calcium hydroxide particles is improved, and its specific surface area is increased.

[0054] In the secondary digestion step, the saturated water-absorbed expanded perlite evaporates water vapor at high temperature, and the water vapor reacts with some unreacted quicklime again to make the digestion reaction of quicklime more complete; moreover, the water vapor evaporated by the water-absorbed perlite can increase the porosity of the calcium hydroxide generated by digestion and increase the specific surface area of calcium hydroxide.

[0055] Test Example 2 The purity of the high specific surface area calcium hydroxide prepared in Examples 1-3 and Comparative Examples 1-4 was tested in accordance with HG / T 4120-2009, and the test results are as follows: Table 2 Purity of calcium hydroxide in Examples and Comparative Examples

[0056] As can be seen from the test results in Table 2, the purity of calcium hydroxide in Comparative Examples 1-4 was lower than that of Example 2, indicating that the perlite composite material and the secondary digestion step can increase the purity of calcium hydroxide.

[0057] In the classification and impurity removal step of the present invention, the specific gravities of the dried perlite composite material, expanded perlite and calcium hydroxide differ greatly, and the perlite composite material and expanded perlite can be easily removed by air classification without introducing new impurities into the prepared high specific surface area calcium hydroxide.

[0058] In the step of preparing the perlite composite material of the present invention, a polycarboxylate water reducing agent, diethanolamide stearate and expanded perlite are connected together by γ-glycidoxypropyltrimethoxysilane. Trimethylolpropane can crosslink the polycarboxylate water reducing agent and diethanolamide stearate on the surface of perlite, improving the binding firmness of the polycarboxylate water reducing agent, diethanolamide stearate and perlite, and preventing the polycarboxylate water reducing agent and diethanolamide stearate from falling off during the digestion reaction. The hydrophilicity of the perlite composite material itself slows down the rate of calcium oxide reacting with water to generate calcium hydroxide crystals, making the calcium hydroxide formed on the surface of quicklime easy to peel off from the surface of quicklime, improving the digestion conversion rate. After digestion is completed, the impurities carried in the quicklime are dispersed and can be removed in the classification and impurity removal step, improving the purity of calcium hydroxide.

[0059] After the first digestion is completed, the reaction system contains small particles of quicklime wrapped with calcium hydroxide. In the second digestion step, the temperature of the reaction system is increased. The water absorbed by the expanded perlite evaporates to form water vapor at high temperature. The water vapor can promote the peeling of the calcium hydroxide generated on the surface of the small particles of quicklime and react with the inner core quicklime, promoting the reaction to be more complete. After digestion is completed, the impurities carried in the quicklime are dispersed and can be removed in the classification and impurity removal step, improving the purity of calcium hydroxide.

[0060] Test Example 3 The sulfur capacity of the high specific surface area calcium hydroxide prepared in Examples 1-3 and Comparative Examples 1-4 was tested. The test method is as follows: A U-shaped glass tube with a branch pipe having a length of 300 mm, an inner diameter of 9 mm, and an outer diameter of 12 mm was used as the fixed bed for the adsorbent. 1 g of calcium hydroxide was weighed and filled into the U-shaped glass tube. The upper and lower ends of the calcium hydroxide were fixed with quartz wool and glass beads. After the adsorbent was loaded into the tube, the gas flow rate was set. After the flow rate remained unchanged, the experiment was started, and a sulfur dioxide gas detector was used to measure the outlet concentration.

[0061] When the sulfur dioxide outlet concentration is set to a certain concentration, the sulfur capacity per unit mass of the desulfurizer from the start of desulfurization to the time when the sulfur dioxide outlet concentration reaches this value is the breakthrough sulfur capacity, and the time to reach this specific concentration is the breakthrough time. When the outlet concentration reaches 200 ppm, it is regarded as breakthrough. The calculation formula for the breakthrough sulfur capacity is as follows:

[0062] q--breakthrough sulfur capacity, mg / g; c--volume fraction of sulfur dioxide in the raw gas, %; Q--flow rate of the raw gas, mL / min; M--molar amount of sulfur dioxide, 64 g / mol; t--breakthrough time, min; V m --standard state molar volume, 22.4 L / mol; M A --dosage of the desulfurizer, g.

[0063] The feed gas consists of nitrogen, oxygen, and sulfur dioxide. The concentration of sulfur dioxide is 600 ppm, the concentration of oxygen is 10%, and nitrogen is the balance gas.

[0064] Table 3 Penetration sulfur capacity of calcium hydroxide in examples and comparative examples

[0065] As can be seen from Table 3, the penetration sulfur capacity of calcium hydroxide in Comparative Example 1 and Comparative Example 2 is significantly lower than that in Example 2. The penetration sulfur capacity of calcium hydroxide in Comparative Example 1 and Comparative Example 2 decreased by 33.5% and 24.0% respectively compared with Example 2. Combining with Table 1, it can be known that the specific surface area of calcium hydroxide in Comparative Example 1 and Comparative Example 2 decreased by 25.7% and 15.2% respectively compared with Example 2. The decrease rate of the penetration sulfur capacity is significantly higher than the decrease rate of the specific surface area. Additives remained in the calcium hydroxide prepared in Comparative Example 1 and Comparative Example 2. The additives adhered to the surface of calcium hydroxide, affecting the reaction between sulfur dioxide and calcium hydroxide, reducing the penetration sulfur capacity value of calcium hydroxide, and affecting the desulfurization efficiency of calcium hydroxide.

[0066] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A production process for dry-process high specific surface area calcium hydroxide, characterized in that, The production process of the dry-process high specific surface area calcium hydroxide includes the following steps: preparing quicklime powder, preparing perlite composite materials, preparing a mixture, digestion, drying, and grading and impurity removal; The preparation of the perlite composite materials includes modification and compounding; The method of modification is to add expanded perlite into water, and at the same time add γ-glycidyl ether oxypropyltrimethoxysilane, control the temperature at 75-85°C, stir for 8-12 minutes. After the stirring ends, filter, wash, and dry to obtain modified perlite; The method of compounding is to add the modified perlite, polycarboxylate superplasticizer, and stearic acid diethanolamide into water, control the temperature at 55-65°C, stir for 15-25 minutes, then add hydrochloric acid and trimethylolpropane, stir for 8-12 minutes, filter, wash, and dry to obtain perlite composite materials.

2. The production process of a dry-process high specific surface area calcium hydroxide according to claim 1, characterized in that, The method of preparing the mixture is to mix the quicklime powder and the perlite composite materials evenly to prepare a mixture.

3. The production process of dry high specific surface area calcium hydroxide according to claim 2, characterized in that, The mass ratio of the quicklime powder to the perlite composite materials is 100:7-9.

4. The production process of a dry-process high specific surface area calcium hydroxide according to claim 1, characterized in that, The digestion includes primary digestion and secondary digestion; The method of primary digestion is to atomize water at 70-80°C and spray it on the surface of the mixture under stirring, control the digestion temperature at 85-95°C, and the digestion time is 8-10 minutes. After the primary digestion ends, primary digestion calcium hydroxide is obtained; The method of secondary digestion is to add the expanded perlite saturated with water into the primary digestion calcium hydroxide, stir and mix evenly, then raise the temperature to 103-106°C, continue to stir and digest for 18-22 minutes. After the digestion ends, sieve to remove impurities to obtain primary calcium hydroxide.

5. The production process of a dry-process high specific surface area calcium hydroxide according to claim 1, characterized in that, In the modification step, the mass ratio of the expanded perlite, water, and γ-glycidyl ether oxypropyltrimethoxysilane is 20:450-550:0.8-1.

2.

6. The production process of a dry-process high specific surface area calcium hydroxide according to claim 1, characterized in that, In the compounding step, the mass ratio of the modified perlite, water, polycarboxylate superplasticizer, stearic acid diethanolamide, hydrochloric acid, and trimethylolpropane is 20:450-550:0.8-1.2:0.7-0.9:4.5-5.5:0.15-0.

25.

7. The production process of a dry-process high specific surface area calcium hydroxide according to claim 1, characterized in that, The polycarboxylate superplasticizer is LCX-9 polycarboxylate superplasticizer, and the concentration of the hydrochloric acid is 36.5-37.0wt%.

8. The production process of dry high specific surface area calcium hydroxide according to claim 4, characterized in that, In the primary digestion step, the mass ratio of the mixture to water is 10:2-3.

9. The production process of dry-process high specific surface area calcium hydroxide according to claim 4, characterized in that, In the secondary digestion step, the expanded perlite is 100-120 mesh expanded perlite with a water absorption rate greater than 800%; the mass ratio of the expanded perlite saturated with water to the primary digestion calcium hydroxide is 28-32:100.

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