Method and device for preparing calcium hydroxide with high specific surface area and high purity

Abstract

The invention discloses a preparation method and device of calcium hydroxide with high specific surface area and high purity, and the method comprises the following steps: weighing crushed and ground quick lime, feeding into a first-stage digestion reactor, adding calcium nitride, water and a surfactant into the first-stage digestion reactor, and stirring to complete a first-stage digestion reaction; transferring materials which are not completely reacted in the primary digestion reaction to a secondary digestion reactor, adding calcium nitride, water and a surfactant into the secondary digestion reactor, and stirring to complete a secondary digestion reaction; transferring materials which are not completely reacted in the second-stage digestion reaction to a third-stage digestion reactor, and adding calcium nitride, water and a surfactant into the third-stage digestion reactor to complete a third-stage digestion reaction; and feeding calcium hydroxide obtained in the third-stage digestion reaction into a powder concentrator for screening, and then feeding the screened calcium hydroxide into a stock bin to obtain the high-purity calcium hydroxide with the high specific surface area.

Description

Technical Field

[0001] The invention belongs to the field of calcium hydroxide preparation, and particularly relates to a method and a device for preparing high-specific surface and high-purity calcium hydroxide. Background Art

[0002] Calcium hydroxide, commonly known as slaked lime or quicklime, is a commonly used alkaline compound that is widely used in construction, chemical industry, agriculture, water treatment and other fields. Calcium hydroxide can be prepared by a variety of methods, such as quicklime hydration method, calcium carbonate thermal decomposition method, electrolysis method, etc.

[0003] Specific surface area refers to the total surface area of ​​a material per unit mass or unit volume, and the unit is usually expressed in m2 / g or m2 / cm3. The calcium hydroxide prepared by the above method usually has a certain specific surface area, but the specific surface area is small. Calcium hydroxide with a high specific surface area is widely used in the fields of catalysts, adsorbents, and drug carriers. The following is the significance of the specific surface area of ​​calcium hydroxide in different applications:

[0004] When calcium hydroxide is used as a catalyst: the increase in specific surface area means an increase in active sites. Calcium hydroxide with a high specific surface area provides more active sites and enhances catalytic activity. This is particularly important in catalytic reactions, such as gas purification and organic synthesis. At the same time, materials with a high specific surface area usually have a porous structure, which can shorten the diffusion path of reactants and products and increase the reaction rate.

[0005] When calcium hydroxide is used as an adsorbent: Calcium hydroxide with a high specific surface area has a larger surface area, which can adsorb more gas or liquid molecules and improve the adsorption efficiency. This has a significant effect in the fields of air purification and water treatment. In addition, the porous structure can provide different pore sizes, thereby achieving selective adsorption and improving the separation effect.

[0006] When calcium hydroxide is used as a drug carrier: the drug loading capacity increases, and calcium hydroxide with a high specific surface area can load more drug molecules and increase the drug loading capacity. In addition, the porous structure can achieve the slow release of drugs, improve the controlled release performance of drugs, and prolong the drug effect time.

[0007] When calcium hydroxide is used in agriculture: calcium hydroxide with a high specific surface area can better react with acidic substances in the soil, neutralize soil acidity, increase soil pH, and improve soil structure. The porous structure can achieve slow release of fertilizers and improve fertilizer utilization efficiency.

[0008] When calcium hydroxide is used in environmental management: calcium hydroxide with a high specific surface area can absorb heavy metal ions in water, such as lead and cadmium, and is used for water treatment and soil remediation. Calcium hydroxide with a high specific surface area can absorb and neutralize acidic gases in waste gas, such as SO2 and NO xEtc., for exhaust gas purification.

[0009] Therefore, calcium hydroxide with a high specific surface area has broad application prospects in various application fields, and the preparation of calcium hydroxide with a high specific surface area is of great significance. Summary of the invention

[0010] In order to overcome the deficiencies in the prior art, the present invention provides a method and device for preparing high-specific surface area and high-purity calcium hydroxide.

[0011] To achieve the above object, the present invention provides a method for preparing high-specific surface area and high-purity calcium hydroxide, comprising the following steps:

[0012] The crushed and ground quicklime is weighed and then fed into a primary digestion reactor, and calcium nitride, water and a surfactant are added into the primary digestion reactor and stirred to complete a primary digestion reaction; wherein, in the primary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 10 parts, and the mass fraction of water is 5 to 6 parts;

[0013] The unreacted materials in the primary digestion reaction are transferred to a secondary digestion reactor, and calcium nitride, water and a surfactant are added to the secondary digestion reactor, and stirred to complete the secondary digestion reaction; wherein, in the secondary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 6 to 9 parts;

[0014] The unreacted materials in the secondary digestion reaction are transferred to a tertiary digestion reactor, and calcium nitride, water and a surfactant are added to the tertiary digestion reactor to complete the tertiary digestion reaction; wherein, in the tertiary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 12 parts to 15 parts;

[0015] The calcium hydroxide obtained from the tertiary digestion reaction is sent to the powder selector for screening and then sent to the silo.

[0016] Preferably, it also includes:

[0017] The ammonia gas obtained in the tertiary digestion reaction is passed through a spray device to form ammonia water, which is then transported to a reaction device, and an excess of carbon dioxide is introduced into the reaction device to synthesize ammonium bicarbonate.

[0018] Preferably, the digestion reaction time of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction is 30 minutes to 60 minutes, respectively.

[0019] Preferably, the digestion reaction temperatures of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are respectively 40°C to 45°C.

[0020] Preferably, the stirring rates of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are respectively 10 r / min to 15 r / min.

[0021] Preferably, the surfactant includes any one of polyethylene glycol, isopropyl alcohol, pentaerythritol, sodium alkylbenzene sulfonate, and dodecyl betaine.

[0022] Preferably, the amount of surfactant added in the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction is 2% to 5% of the total mass of the reactants, respectively.

[0023] Preferably, the size of the quicklime after crushing and grinding is below 3 mm.

[0024] To achieve the above object, the present invention also provides a calcium hydroxide preparation device for preparing calcium hydroxide using the method; the calcium hydroxide preparation device comprises: a primary digestion reactor, a secondary digestion reactor and a tertiary digestion reactor;

[0025] The primary digestion reactor is used to: add quicklime, calcium nitride, water and surfactant, and stir to complete the primary digestion reaction;

[0026] The secondary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the primary digestion reaction, and stir to complete the secondary digestion reaction;

[0027] The tertiary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the secondary digestion reaction, and stir to complete the tertiary digestion reaction.

[0028] Preferably, it also includes: a spraying device and a reaction device, wherein the spraying device is used to spray the ammonia gas obtained in the tertiary digestion reaction to form ammonia water; and the reaction device is used to introduce ammonia water and excess carbon dioxide to synthesize ammonium bicarbonate.

[0029] In the technical scheme of the present invention, quicklime reacts with water in various digestion reactors to prepare calcium hydroxide. At the same time, calcium nitride reacts violently with water to generate calcium hydroxide and ammonia. The bubbles formed by the ammonia form abundant pores on the surface of the prepared calcium hydroxide, so that the specific surface area of ​​the obtained calcium hydroxide is greater than 40m 2 / g. Furthermore, in the present invention, both reactions can produce calcium hydroxide, and the only byproduct ammonia is a gas, which is easy to separate from the calcium hydroxide. Therefore, the method for preparing calcium hydroxide of the present invention not only significantly improves the specific surface area of ​​calcium hydroxide, but also does not produce excess impurities compared to other methods for preparing calcium hydroxide with high specific surface area, and the calcium hydroxide has high purity, which is greater than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a reaction flow chart of the method for preparing high-specific surface area and high-purity calcium hydroxide. DETAILED DESCRIPTION

[0031] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods and drawings, but the present invention is not limited thereto.

[0032] Please refer to Figure 1 To achieve the above object, the present invention provides a method for preparing high-specific surface area and high-purity calcium hydroxide, comprising the following steps:

[0033] S1, weighing the crushed and ground quicklime, and sending it into a primary digestion reactor, and adding calcium nitride, water and a surfactant into the primary digestion reactor, stirring to complete the primary digestion reaction; wherein, in the primary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 10 parts, and the mass fraction of water is 5 to 6 parts;

[0034] S2, transferring the unreacted materials in the primary digestion reaction to a secondary digestion reactor, and adding calcium nitride, water and a surfactant to the secondary digestion reactor, stirring to complete the secondary digestion reaction; wherein, in the secondary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 6 to 9 parts;

[0035] S3, transferring the unreacted materials in the secondary digestion reaction to a tertiary digestion reactor, and adding calcium nitride, water and a surfactant to the tertiary digestion reactor to complete the tertiary digestion reaction; wherein, in the tertiary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 12 parts to 15 parts;

[0036] S4, the calcium hydroxide obtained from the three-stage digestion reaction is sent to the powder selector for screening and then sent to the silo. Specifically, in each stage of the digestion reaction, the digestion reaction equation of quicklime and water is as follows:

[0037] CaO+H2O=Ca(OH)2;

[0038] In each level of digestion reaction, the reaction equation of calcium nitride and water is as follows:

[0039] Ca3N2+6H2O=3Ca(OH)2+2NH3↑;

[0040] In the technical scheme of the present invention, quicklime reacts with water in various digestion reactors to prepare calcium hydroxide. At the same time, calcium nitride reacts violently with water to generate calcium hydroxide and ammonia. The bubbles formed by the ammonia form abundant pores on the surface of the prepared calcium hydroxide, so that the specific surface area of ​​the obtained calcium hydroxide is greater than 40m 2 / g. Furthermore, in the present invention, both reactions can produce calcium hydroxide, and the only byproduct ammonia is a gas, which is easy to separate from the calcium hydroxide. Therefore, the method for preparing calcium hydroxide of the present invention not only significantly improves the specific surface area of ​​calcium hydroxide, but also does not produce excess impurities compared to other methods for preparing calcium hydroxide with high specific surface area, and the calcium hydroxide has high purity, which is greater than 95%.

[0041] Preferably, the method further comprises:

[0042] S5, the ammonia gas obtained in the tertiary digestion reaction is passed through a spray device to form ammonia water, which is then transported to a reaction device, and excess carbon dioxide is introduced into the reaction device to synthesize ammonium bicarbonate.

[0043] Specifically, a gas phase outlet is provided at the top of the three-stage digestion reactor, and after the ammonia is discharged through the gas phase outlet, it passes through a spray device. The spray device uses water to recover the ammonia gas and a part of the reaction heat to achieve energy recovery. The formed ammonia water enters the reaction device.

[0044] The reaction equation in the reaction device is:

[0045] NH3·H2O+CO2=NH4HCO3;

[0046] Preferably, the digestion reaction time of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction is 30 minutes to 60 minutes, respectively.

[0047] Preferably, the digestion reaction temperatures of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are respectively 40°C to 45°C.

[0048] Preferably, the stirring rates of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are respectively 10 r / min to 15 r / min.

[0049] Preferably, the surfactant includes any one of polyethylene glycol, isopropyl alcohol, pentaerythritol, sodium alkylbenzene sulfonate, and dodecyl betaine. Specifically, the surfactant includes but is not limited to: polyethylene glycol, isopropyl alcohol, pentaerythritol, sodium alkylbenzene sulfonate, and dodecyl betaine.

[0050] Preferably, the amount of surfactant added in the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction is 2% to 5% of the total mass of the reactants, respectively.

[0051] Preferably, the size of the quicklime after crushing and grinding is below 3 mm.

[0052] To achieve the above object, the present invention also provides a calcium hydroxide preparation device for preparing calcium hydroxide using the method; the calcium hydroxide preparation device comprises: a primary digestion reactor, a secondary digestion reactor and a tertiary digestion reactor;

[0053] The primary digestion reactor is used to: add quicklime, calcium nitride, water and surfactant, and stir to complete the primary digestion reaction;

[0054] The secondary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the primary digestion reaction, and stir to complete the secondary digestion reaction;

[0055] The tertiary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the secondary digestion reaction, and stir to complete the tertiary digestion reaction.

[0056] Preferably, the calcium hydroxide preparation device further comprises: a spraying device and a reaction device, wherein the spraying device is used to spray the ammonia gas obtained in the tertiary digestion reaction to form ammonia water; and the reaction device is used to introduce ammonia water and excess carbon dioxide to synthesize ammonium bicarbonate.

[0057] Embodiment 1:

[0058] In the primary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:10:5, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is polyethylene glycol, and the amount of surfactant added is 2% of the total mass of the reactants; in the secondary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:6, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is polyethylene glycol, and the amount of surfactant added is 2% of the total mass of the reactants; in the tertiary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:12, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is polyethylene glycol, and the amount of surfactant added is 4% of the total mass of the reactants.

[0059] The final product obtained after the third-stage digestion has a specific surface area of ​​52 m 2 / g, with a purity of 99%.

[0060] Embodiment 2:

[0061] In the primary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:10:5, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is dodecyl betaine, and the amount of surfactant added is 2% of the total mass of the reactants; in the secondary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:6, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is dodecyl betaine, and the amount of surfactant added is 2% of the total mass of the reactants; in the tertiary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:15, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is dodecyl betaine, and the amount of surfactant added is 2% of the total mass of the reactants.

[0062] The final product obtained after the third-stage digestion has a specific surface area of ​​calcium hydroxide of 50m 2 / g, with a purity of 99%.

[0063] Embodiment 3:

[0064] In the primary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:10:5, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is sodium alkylbenzene sulfonate, and the added amount of the surfactant is 2% of the total mass of the reactants; in the secondary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:6, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is sodium alkylbenzene sulfonate, and the added amount of the surfactant is 2% of the total mass of the reactants; in the tertiary digestion reactor, the mass ratio of calcium nitride:calcium oxide:water is 1:12:12, the digestion reaction is 30 minutes, the digestion temperature is 40°C, the added surfactant is sodium alkylbenzene sulfonate, and the added amount of the surfactant is 5% of the total mass of the reactants.

[0065] The final product obtained after the third-stage digestion has a specific surface area of ​​56 m 2 / g, with a purity of 99%.

Claims

1. A method for preparing high-specific surface and high-purity calcium hydroxide, characterized in that: The following steps are involved: The crushed and ground quicklime is weighed and then fed into a primary digestion reactor, and calcium nitride, water and a surfactant are added into the primary digestion reactor and stirred to complete a primary digestion reaction; wherein, in the primary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 10 parts, and the mass fraction of water is 5 to 6 parts; The unreacted materials in the primary digestion reaction are transferred to a secondary digestion reactor, and calcium nitride, water and a surfactant are added to the secondary digestion reactor, and stirred to complete the secondary digestion reaction; wherein, in the secondary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 6 to 9 parts; The unreacted materials in the secondary digestion reaction are transferred to a tertiary digestion reactor, and calcium nitride, water and a surfactant are added to the tertiary digestion reactor to complete the tertiary digestion reaction; wherein, in the tertiary digestion reaction, the mass fraction of calcium nitride is 1 part, the mass fraction of calcium oxide is 12 parts, and the mass fraction of water is 12 parts to 15 parts; The calcium hydroxide obtained from the tertiary digestion reaction is sent to the powder selector for screening and then sent to the silo.

2. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 1, wherein Also includes: The ammonia gas obtained in the tertiary digestion reaction is passed through a spray device to form ammonia water, which is then transported to a reaction device, and an excess of carbon dioxide is introduced into the reaction device to synthesize ammonium bicarbonate.

3. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 1, wherein The digestion reaction times of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are 30 minutes to 60 minutes, respectively.

4. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 1, wherein: The digestion reaction temperatures of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are 40°C to 45°C, respectively.

5. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 1, wherein The stirring rates of the primary digestion reaction, the secondary digestion reaction, and the tertiary digestion reaction are 10 r / min to 15 r / min, respectively.

6. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 1, wherein: The surfactant includes any one of polyethylene glycol, isopropyl alcohol, pentaerythritol, sodium alkylbenzene sulfonate, and dodecyl betaine.

7. The method for preparing high-specific surface high-purity calcium hydroxide according to claim 6, wherein: The added amounts of surfactants in the primary digestion reaction, the secondary digestion reaction and the tertiary digestion reaction are 2% to 5% of the total mass of the reactants respectively.

8. The method for preparing high-specific surface high-purity calcium hydroxide according to any one of claims 1 to 7, characterized in that, The size of the quicklime after crushing and grinding is less than 3mm.

9. A calcium hydroxide preparation device, characterized in that, Used to prepare calcium hydroxide using the method according to any one of claims 1 to 8; the calcium hydroxide preparation device comprises: a primary digestion reactor, a secondary digestion reactor and a tertiary digestion reactor; The primary digestion reactor is used to: add quicklime, calcium nitride, water and surfactant, and stir to complete the primary digestion reaction; The secondary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the primary digestion reaction, and stir to complete the secondary digestion reaction; The tertiary digestion reactor is used to add calcium nitride, water, a surfactant, and materials that have not reacted completely in the secondary digestion reaction, and stir to complete the tertiary digestion reaction.

10. The calcium hydroxide preparation device according to claim 9, wherein Also includes: A spraying device and a reaction device, wherein the spraying device is used to spray the ammonia gas obtained in the tertiary digestion reaction to form ammonia water; and the reaction device is used to introduce ammonia water and excess carbon dioxide to synthesize ammonium bicarbonate.

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