Preparation process of calcium hydroxide with high dispersibility and high specific surface area

Abstract

The invention belongs to the field of new materials, and particularly discloses a high-dispersity high-specific-surface-area calcium hydroxide preparation process which comprises the following steps: S1, adjusting an additive and deionized water to prepare a digestion mixed solution; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is carried out in the mixing process; s2, the quick lime and the digestion mixed solution enter a digestion machine to be subjected to a digestion reaction, and calcium hydroxide slurry is obtained; s3, the calcium hydroxide slurry passes through an aging barrel, aging is conducted for 12-36 h under stirring, and the obtained refined calcium hydroxide slurry is pressed into a filter cake through a filter press; s4, primarily powdering the filter cake, drying, scattering into powder, and packaging to obtain calcium hydroxide with high dispersity and high specific surface area; according to the method, the existing quick lime raw material is used, the hydroxypropyl methylcellulose and the methacrylic acid are used as additives, the calcium hydroxide prepared after digestion and aging has the high specific surface area of 45 m < 2 > / mL or above, the raw materials are easy to obtain, the preparation condition is mild, the preparation cost is low, and the method is suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the field of new materials and specifically discloses a preparation process of calcium hydroxide with high dispersibility and high specific surface area. Background Art

[0002] Calcium hydroxide is an important inorganic compound and is widely used in environmental protection, construction, agriculture and other fields. However, the dispersibility of calcium hydroxide is poor, and precipitation and agglomeration often occur, which affects its application effect. The dispersibility of calcium hydroxide is affected by many factors, mainly including the following aspects: 1. Particle size: The particle size of calcium hydroxide has an important influence on its dispersibility. The smaller the particle, the larger the specific surface area and the better the dispersibility. 2. Surface properties: The surface properties of calcium hydroxide will also affect its dispersibility. Factors such as surface charge and surface energy will affect the interaction between calcium hydroxide particles, thereby affecting its dispersibility. 3. Dispersion medium: The properties of the dispersion medium also affect the dispersibility of calcium hydroxide. The properties of the medium, pH value, temperature and other factors will affect the dispersibility of calcium hydroxide. In view of the above influencing factors, the following methods can be adopted to improve the dispersibility of calcium hydroxide: 1. Select an appropriate dispersion medium: Selecting a suitable dispersion medium can improve the dispersibility of calcium hydroxide. Generally speaking, factors such as the polarity, pH value, and temperature of the medium should be compatible with calcium hydroxide. 2. Controlling particle size and surface properties: By controlling the particle size and surface properties of calcium hydroxide, its dispersibility can be improved. For example, the use of nanotechnology to prepare calcium hydroxide can reduce the particle size and increase the specific surface area, thereby improving dispersibility. 3. Introducing dispersants: Introducing dispersants can effectively improve the dispersibility of calcium hydroxide. Dispersants can reduce the interaction between calcium hydroxide particles, making it easier to disperse in the medium.

[0003] Especially in the field of environmental protection, experimental data show that when the specific surface area increases from 7.1m 2 / g increased to 41.55m 2 / g, this high specific surface area and high activity calcium hydroxide has a sulfur dioxide removal effect 3-5 times that of traditional calcium hydroxide prepared by digestion. Figure 1 shown.

[0004] Prior art, CN202311536258.9 discloses a method for preparing highly active and highly dispersed calcium hydroxide, comprising the following steps: mixing potassium chloride and calcium carbonate powder evenly before calcination; calcining the calcium carbonate powder in a high-temperature calcining furnace after mixing to obtain quicklime; adjusting additives and tap water to prepare a digestion mixture; the additive is a combination of one or more of triethanolamine, sodium polyacrylate, and glacial acetic acid; placing quicklime and the digestion mixture into a digestion machine for digestion reaction to obtain calcium hydroxide slurry; aging the calcium hydroxide slurry, The obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press; after the filter cake is preliminarily pulverized, it is dried, broken into powder, and packaged to obtain calcium hydroxide particles. After testing, the specific surface area is 28m2 / g. However, in the above invention, the quicklime needs to be mixed with potassium chloride and calcium carbonate powder and then calcined, which has high requirements on raw materials and cannot be prepared using existing quicklime raw materials, which limits its application. In addition, its specific surface area does not exceed 41m2 / g, which is not very excellent, limiting its application in the field of environmental protection, including sulfur dioxide removal. Summary of the invention

[0005] In order to solve the above problems, the present invention discloses a process for preparing calcium hydroxide with high dispersibility and high specific surface area.

[0006] The technical solution of the present invention is as follows:

[0007] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0008] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0009] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0010] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 12-36 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake through a filter press;

[0011] S4: After the filter cake is preliminarily pulverized, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide.

[0012] Furthermore, in the above-mentioned process for preparing highly dispersible and high specific surface area calcium hydroxide, in step S1, the mass ratio of the additive to deionized water is 1:1000-10000.

[0013] Furthermore, in the above-mentioned process for preparing highly dispersible and high specific surface area calcium hydroxide, in step S1, the mass ratio of the hypromellose to methacrylic acid is 1:2-5.

[0014] Furthermore, in the above-mentioned process for preparing highly dispersible and high specific surface area calcium hydroxide, in step S2, the solid-liquid ratio of quicklime to the digestion mixture is 1:10-15 g / mL.

[0015] Furthermore, in the above-mentioned process for preparing calcium hydroxide with high dispersibility and high specific surface area, the hydroxypropyl methylcellulose in step S1 is modified hydroxypropyl methylcellulose, which comprises the following modification steps:

[0016] 1) Add the raw material of hydroxypropyl methylcellulose to the oxalic acid solution, stir and react at 80-90°C for 15-25 minutes, wash, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 2;

[0017] 2) Add raw material 2 to alkali solution, then introduce inert gas into the alkali solution, stir and react for 30-60 minutes, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 3;

[0018] 3) According to the mass fraction, 100 parts of raw material 3 are placed in a kneader, the system is evacuated to maintain a vacuum degree of -0.2 to -0.05 MPa, heated to a temperature of 65-85°C, and then 3-5 parts of propylene oxide are added to knead and react for 35-50 minutes, and then 1-2 parts of methyl chloride and 3-5 parts of isopropanol are added, the temperature is kept constant, and the reaction is continued for 60-80 minutes; after the reaction, the product is placed in an excess ethanol solution, the pH is adjusted to neutral with glacial acetic acid, the product is filtered and washed, and after low-temperature vacuum drying to constant weight, it is crushed through a 20-50 mesh sieve to obtain modified hydroxypropyl methylcellulose.

[0019] Furthermore, in the above-mentioned process for preparing highly dispersible and high specific surface area calcium hydroxide, in the step 1), the solid-liquid ratio of the hydroxypropyl methylcellulose raw material to the oxalic acid solution is 1:40-100 g / mL, and the concentration of the oxalic acid is 5-8 wt%.

[0020] Furthermore, in the above-mentioned process for preparing highly dispersible and high specific surface area calcium hydroxide, the alkali solution in step 2) is a 1-2M sodium hydroxide solution, the solid-liquid ratio of the raw material 2 to the alkali solution is 1:80-120 g / mL, and the inert gas is nitrogen.

[0021] The invention also discloses calcium hydroxide with high dispersibility and high specific surface area, which is prepared by any one of the above-mentioned preparation processes.

[0022] The invention also discloses application of the high-dispersibility and high-specific-surface-area calcium hydroxide or its preparation process in the field of environmental protection.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The invention discloses a calcium hydroxide with high dispersibility and high specific surface area. The calcium hydroxide prepared by using existing quicklime raw materials, using hydroxypropyl methylcellulose and methacrylic acid as additives, and digesting and aging the calcium hydroxide has a surface area of ​​45 m 2 / mL or more high specific surface area; further, the applicant found that after the hydroxypropyl methylcellulose was subjected to acid-base alternation treatment and modified with propylene oxide, the obtained calcium hydroxide can reach 55m 2 / mL or more specific surface area is more suitable as an environmentally friendly adsorption raw material, especially for use in the adsorption of sulfur dioxide. Compared with the existing technical solutions, the raw materials are easy to obtain, the preparation conditions are mild, the preparation cost is low, and it is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The removal effect of sulfur dioxide by high specific surface area and high activity calcium hydroxide in the prior art is compared with that by traditional digestion-prepared calcium hydroxide;

[0026] Figure 2 is the specific surface area of ​​calcium hydroxide powder m 2 / g comparison;

[0027] Figure 3 Comparison of zeta potential (mv) of calcium hydroxide powder. DETAILED DESCRIPTION

[0028] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0029] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0030] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0031] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 12-36 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake through a filter press;

[0032] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0033] In step S1, the mass ratio of the additive to deionized water is 1:1000-10000;

[0034] In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:2-5;

[0035] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:10-15 g / mL;

[0036] Furthermore, the hypromellose in step S1 is modified hypromellose, which includes the following modification steps:

[0037] 1) Add the raw material of hydroxypropyl methylcellulose to the oxalic acid solution, stir and react at 80-90°C for 15-25 minutes, wash, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 2;

[0038] 2) Add raw material 2 to alkali solution, then introduce inert gas into the alkali solution, stir and react for 30-60 minutes, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 3;

[0039] 3) According to the mass fraction, 100 parts of raw material 3 are placed in a kneader, the system is evacuated to maintain a vacuum degree of -0.2 to -0.05 MPa, heated to a temperature of 65-85°C, and then 3-5 parts of propylene oxide are added to knead and react for 35-50 minutes, and then 1-2 parts of methyl chloride and 3-5 parts of isopropanol are added, the temperature is kept constant, and the reaction is continued for 60-80 minutes; after the reaction, the product is placed in an excess ethanol solution, the pH is adjusted to neutral with glacial acetic acid, the product is filtered and washed, and low-temperature vacuum drying is performed to constant weight, and then crushed through a 20-50 mesh sieve to obtain modified hydroxypropyl methylcellulose;

[0040] In the step 1), the solid-liquid ratio of the hydroxypropyl methylcellulose raw material to the oxalic acid solution is 1:40-100 g / mL, and the concentration of the oxalic acid is 5-8 wt %;

[0041] In the step 2), the alkali solution is a 1-2M sodium hydroxide solution, the solid-liquid ratio of the raw material 2 to the alkali solution is 1:80-120 g / mL, and the inert gas is nitrogen.

[0042] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The reagents or instruments used in the examples of the present invention without indicating the manufacturer are all conventional reagent products that can be obtained through commercial purchase.

[0044] Example 1

[0045] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0046] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0047] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0048] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 12 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0049] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0050] In step S1, the mass ratio of the additive to deionized water is 1:1000;

[0051] In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:2;

[0052] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:10 g / mL.

[0053] Example 2

[0054] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0055] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0056] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0057] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 24 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0058] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0059] In step S1, the mass ratio of the additive to deionized water is 1:5000;

[0060] In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:4;

[0061] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:12 g / mL.

[0062] Example 3

[0063] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0064] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0065] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0066] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 36 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0067] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0068] In step S1, the mass ratio of the additive to deionized water is 1:10000;

[0069] In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:5;

[0070] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:15 g / mL.

[0071] Example 4

[0072] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0073] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0074] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0075] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 24 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0076] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0077] In step S1, the mass ratio of the additive to deionized water is 1:5000;

[0078] In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:4;

[0079] In the step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:12 g / mL;

[0080] Furthermore, the hypromellose in step S1 is modified hypromellose, which includes the following modification steps:

[0081] 1) Add the raw material of hydroxypropyl methylcellulose to the oxalic acid solution, stir and react at 85°C for 20 minutes, wash, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 2;

[0082] 2) Add raw material 2 to alkali solution, then introduce inert gas into the alkali solution, stir and react for 45 minutes, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 3;

[0083] 3) According to the mass fraction, 100 parts of raw material 3 are placed in a kneader, the system is evacuated to maintain a vacuum degree of -0.2 to -0.05 MPa, heated to a temperature of 75°C, and then 4 parts of propylene oxide are added to knead and react for 40 minutes, and then 1.5 parts of methyl chloride and 4 parts of isopropanol are added, the temperature is kept constant, and the reaction is continued for 70 minutes; after the reaction, the product is placed in an excess ethanol solution, the pH is adjusted to neutral with glacial acetic acid, the product is filtered and washed, and then low-temperature vacuum drying is performed to constant weight and then crushed through a 20-50 mesh sieve to obtain modified hydroxypropyl methylcellulose;

[0084] In the step 1), the solid-liquid ratio of the hydroxypropyl methylcellulose raw material to the oxalic acid solution is 1:60 g / mL, and the concentration of the oxalic acid is 6 wt%;

[0085] In the step 2), the alkali solution is a 1.5M sodium hydroxide solution, the solid-liquid ratio of the raw material 2 to the alkali solution is 1:100 g / mL, and the inert gas is nitrogen.

[0086] Comparative Example 1

[0087] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0088] S1: preparing a digestion mixture by adjusting an additive and deionized water; wherein the additive is hypromellose and ultrasonic treatment is performed during the mixing process;

[0089] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0090] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 24 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0091] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0092] In step S1, the mass ratio of the additive to deionized water is 1:5000;

[0093] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:12 g / mL.

[0094] The difference from Example 2 is that this example does not contain methacrylic acid.

[0095] Comparative Example 2

[0096] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0097] S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is methacrylic acid, and ultrasonic treatment is performed during the mixing process;

[0098] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0099] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 124 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0100] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0101] In step S1, the mass ratio of the additive to deionized water is 1:5000;

[0102] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:12 g / mL.

[0103] The difference from Example 2 is that this example does not contain hypromellose.

[0104] Comparative Example 3

[0105] A process for preparing highly dispersible and high specific surface area calcium hydroxide comprises the following steps:

[0106] S1: Digestion mixture prepared with deionized water;

[0107] S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry;

[0108] S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 24 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake by a filter press;

[0109] S4: After the filter cake is preliminarily powdered, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide;

[0110] In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:12 g / mL.

[0111] The difference from Example 2 is that this example does not contain additives.

[0112] Test Case

[0113] The calcium hydroxide powders prepared in Examples 1-4 and Comparative Examples 1-3 were measured using a JW-TB400 specific surface area and pore size analyzer to determine the specific surface area m of the powder material. 2 / g, the zeta potential (mv) of the powder material was measured using a Truth Optical Zeta Potential Analyzer. The results are as follows Figure 2-3 And as shown in Table 1.

[0114] Table 1: Calcium hydroxide powder performance test

[0115]

[0116]

[0117] The significance of Zeta potential lies in the fact that its value is related to the stability of colloidal dispersion. Zeta potential is a measure of the strength of mutual repulsion or attraction between particles. The smaller the molecule or dispersed particle, the higher the absolute value of Zeta potential (positive or negative), and the more stable the system, that is, the dissolution or dispersion can resist aggregation. Conversely, the lower the Zeta potential (positive or negative), the more it tends to coagulate or aggregate, that is, the attraction exceeds the repulsion, the dispersion is destroyed and coagulation or aggregation occurs. The approximate relationship between Zeta potential and system stability is shown in Table 2 below.

[0118] Table 2: Approximate relationship between Zeta potential and system stability

[0119] Zeta potential [mV] Colloidal stability 0 to ±5 Rapid condensation or coagulation ±10 to ±30 Beginning to become unstable ±30 to ±40 Average stability ±40 to ±60 Better stability More than ±61 Excellent stability

[0120] From Table 1 and Figure 2 and 3 It can be seen from the data that the calcium hydroxide prepared by the method described in the present invention, using the existing quicklime raw materials, using hydroxypropyl methylcellulose and methacrylic acid as additives, has a 45m 2 / mL or more high specific surface area; from the comparison of the data of Comparative Examples 1-3 and Example 2, it can be seen that the use of either hydroxypropyl methylcellulose or methacrylic acid as an additive alone cannot make the specific surface area of ​​calcium hydroxide reach 35m 2From the test data of Example 2 and Example 4, it can be seen that after the modification of hydroxypropyl methylcellulose, the specific surface area of ​​calcium hydroxide can be increased by more than 20%, which has an unexpectedly good effect and can be applied to the environmental protection treatment of sulfur dioxide.

[0121] It can be seen from the above embodiments that the present invention discloses a highly dispersible and high specific surface area calcium hydroxide, which uses existing quicklime raw materials, uses hydroxypropyl methylcellulose and methacrylic acid as additives, and the calcium hydroxide obtained after digestion and aging has a high specific surface area of ​​more than 45m2 / mL; further, the applicant found that after the hydroxypropyl methylcellulose is subjected to alternating acid and alkali treatment and modified by adding propylene oxide, the obtained calcium hydroxide can reach a specific surface area of ​​more than 55m2 / mL, which is more suitable as an environmentally friendly adsorption raw material, especially for use in the adsorption of sulfur dioxide. Compared with the existing technical solutions, the raw materials are easy to obtain, the preparation conditions are mild, the preparation cost is low, and it is suitable for large-scale industrial production.

[0122] The description of the limited preferred embodiments of the invention is relatively specific and detailed, but it should not be understood as limiting the scope of the invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the invention, which all belong to the protection scope of the invention.

Claims

1. A process for preparing highly dispersible and high specific surface area calcium hydroxide, characterized in that: The following steps are involved: S1: preparing a digestion mixture by adjusting an additive and deionized water; the additive is hydroxypropyl methylcellulose and methacrylic acid, and ultrasonic treatment is performed during the mixing process; S2: quicklime and digestion mixture are put into a digestion machine for digestion reaction to obtain calcium hydroxide slurry; S3: The calcium hydroxide slurry is passed through an aging barrel and aged for 12-36 hours under stirring, and the obtained refined calcium hydroxide slurry is then pressed into a filter cake through a filter press; S4: After the filter cake is preliminarily pulverized, it is dried, broken into powder, and packaged to obtain highly dispersible and high specific surface area calcium hydroxide.

2. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 1, characterized in that: In the step S1, the mass ratio of the additive to the deionized water is 1:1000-10000.

3. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 1, characterized in that: In the step S1, the mass ratio of the hypromellose to methacrylic acid is 1:2-5.

4. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 1, characterized in that: In step S2, the solid-to-liquid ratio of quicklime to the digestion mixture is 1:10-15 g / mL.

5. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 1, characterized in that: The hypromellose in step S1 is modified hypromellose, which includes the following modification steps: 1) Add the raw material of hydroxypropyl methylcellulose to the oxalic acid solution, stir and react at 80-90°C for 15-25 minutes, wash, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 2; 2) Add raw material 2 to alkali solution, then introduce inert gas into the alkali solution, stir and react for 30-60 minutes, filter and dry the residue under low temperature vacuum to constant weight, crush and pass through a 50-100 mesh sieve to obtain raw material 3; 3) According to the mass fraction, 100 parts of raw material 3 are placed in a kneader, the system is evacuated to maintain a vacuum degree of -0.2 to -0.05 MPa, heated to a temperature of 65-85°C, and then 3-5 parts of propylene oxide are added to knead and react for 35-50 minutes, and then 1-2 parts of methyl chloride and 3-5 parts of isopropanol are added, the temperature is kept constant, and the reaction is continued for 60-80 minutes; after the reaction, the product is placed in an excess ethanol solution, the pH is adjusted to neutral with glacial acetic acid, the product is filtered and washed, and after low-temperature vacuum drying to constant weight, it is crushed through a 20-50 mesh sieve to obtain modified hydroxypropyl methylcellulose.

6. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 5, characterized in that: In the step 1), the solid-liquid ratio of the hydroxypropyl methylcellulose raw material to the oxalic acid solution is 1:40-100 g / mL, and the concentration of the oxalic acid is 5-8 wt %.

7. A process for preparing highly dispersible and high specific surface area calcium hydroxide according to claim 5, characterized in that: In the step 2), the alkali solution is a 1-2M sodium hydroxide solution, the solid-liquid ratio of the raw material 2 to the alkali solution is 1:80-120 g / mL, and the inert gas is nitrogen.

8. A highly dispersible and high specific surface area calcium hydroxide, characterized in that: Prepared by the preparation process described in any one of claims 1 to 7.

9. Use of the preparation process according to any one of claims 1 to 7 in the field of environmental protection.

10. Use of the highly dispersible and high specific surface area calcium hydroxide as claimed in claim 8 in the field of environmental protection.

Images