Method for preparing high-fluidity calcium hydroxide powder by using solid-phase surface modification method

Abstract

A method for preparing high-fluidity calcium hydroxide powder by using a solid-phase surface modification method belongs to the technical field of calcium hydroxide preparation, and is characterized by comprising the following steps: burdening according to a mass ratio, weighing calcium hydroxide powder, potassium sulfate, nonylphenol polyoxyethylene ether OP-4 and zinc acetate, adding grinding balls, putting into a ball-milling tank, and uniformly stirring; and mixing the materials in a rapid ball mill, and screening to obtain an undersize powder material, namely the high-fluidity calcium hydroxide powder. The method is simple in technological process, wide in reagent source, small in adding amount and low in cost. The solid-phase surface modification method does not need additional drying treatment, can be used for real-time modification treatment on a calcium hydroxide powder production line, and is beneficial to industrial production.

Description

Technical Field

[0001] A method for preparing calcium hydroxide powder with high fluidity by using a solid-phase surface modification method belongs to the technical field of calcium hydroxide preparation. Background Art

[0002] Calcium hydroxide powder, as a chemical assistant, has wide applications in fields such as food, paint, coating, rust inhibitor, and flue gas desulfurization and denitrification assistant. Industrially, calcium hydroxide powder is generally first obtained by high-temperature decomposition of heavy calcium carbonate to produce quicklime - calcium oxide, then the quicklime - calcium oxide is digested to prepare calcium hydroxide powder, and finally the final product - calcium hydroxide powder is obtained after screening. When the particle size of calcium hydroxide powder becomes smaller during screening and processing, it is easy to get stuck and form an arch bridge, resulting in poor fluidity, which is not conducive to the continuous progress of production and also does not meet the fluidity requirements of subsequent application scenarios.

[0003] In application fields, such as in applications like dry powder desulfurization, denitrification agent, and powder injection of scavengers, fluidity performance is extremely important. When using alkaline calcium hydroxide powder to deal with applications such as industrial tail gas and leakage of polluting gases, the fluidity of calcium hydroxide powder can significantly improve its application effect. For example, when used as an industrial flue gas desulfurization agent, good fluidity of calcium hydroxide powder can increase the conveying rate of the powdered desulfurization agent, effectively improve the desulfurization efficiency, and at the same time reduce the frequency of problems such as blockage of flue gas pipelines.

[0004] Generally speaking, the larger the particle size of the powder, the better the fluidity, but a large particle size is likely to cause a sharp decrease in the specific surface area, which is not conducive to improving the efficiency of chemical reactions such as desulfurization. Chinese invention patent 202210827993.4 discloses a method for preparing calcium hydroxide with good fluidity by adding an organic surfactant and an alkali metal compound during the digestion process of quicklime - calcium oxide. Chinese invention patent 202010310295.8 discloses a method for preparing calcium hydroxide with good fluidity by adding a dispersant, a surfactant, and a dispersive hydrophobic moisture-proof additive during the digestion process of quicklime - calcium oxide. Therefore, a technical solution for modifying the already digested calcium hydroxide by a solid-phase modification method to improve the fluidity of calcium hydroxide powder without a significant reduction in the specific surface area has not been reported. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing calcium hydroxide powder with high fluidity by using a solid-phase surface modification method, which is characterized by including the following steps: Step 1: Weigh calcium hydroxide powder, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate according to the mass ratio, so that the mass ratio of calcium hydroxide, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate is 100:1.50:0.50:1 or 100:1.50:0.50:3.00. Add grinding balls with a diameter of 10 mm, and make the mass ratio of the grinding balls to calcium hydroxide 2:1; Step 2: Put the materials obtained by mixing in Step 1 into a ball mill tank, mix the materials in a high-speed ball mill for 10 minutes, screen the grinding balls and materials with a 200-mesh standard sieve, and finally take the powdery materials under the sieve as the prepared high-fluidity calcium hydroxide powder.

[0006] Among them, potassium sulfate and zinc acetate are both chemical additives without crystal water. The grinding balls have the same diameter, and the purpose of the ball milling process is to mix the materials.

[0007] The beneficial effects of the present invention are as follows: 1. The process flow of the present invention is simple, the reagents are widely sourced, the addition amount is small, the cost is low, which is conducive to industrial production; 2. In the process of the present invention, no solvents such as water are added, and the solid-phase modification method does not require additional drying treatment, and the fluidity of the powder is greatly improved; 3. The process of the present invention is applicable to the current calcium hydroxide production process, can be used for real-time modification treatment on the production line, is conducive to reducing the cost of calcium hydroxide powder, and thus is conducive to industrial production. Description of the Drawings

[0008] Figure 1 It is a scanning electron microscope photograph of the high-fluidity calcium hydroxide powder prepared in Example 1.

[0009] Figure 2 It is a scanning electron microscope photograph of the high-fluidity calcium hydroxide powder prepared in Example 2.

[0010] Figure 3 It is a scanning electron microscope photograph of the calcium hydroxide powder prepared in Comparative Example 1. Detailed Embodiments

[0011] To characterize the changes in the powder properties of calcium hydroxide powder before and after modification, the oil absorption value, specific surface area, and angle of repose of the powder were measured, and the morphology photographs of the calcium hydroxide powder were taken by a scanning electron microscope.

[0012] Weigh 5.00 g of the prepared sample and place it on a clean flat glass plate. Gradually add glycerol dropwise to the sample powder while continuously rolling the powder with a glass rod to ensure thorough mixing of the sample and glycerol. When all the powder can evenly adhere to the glass rod, the oil absorption is completed. After comparing and calculating the mass of the adsorbed glycerol with the mass of the powder, the oil absorption value can be obtained.

[0013] A fully automatic specific surface area and pore size analyzer was used to measure the specific surface area of calcium hydroxide powder.

[0014] The angle of repose of the calcium hydroxide sample was measured using an angle of repose measuring instrument to reflect its fluidity. Weigh 150 mL of calcium hydroxide powder, block the funnel opening of the angle of repose measuring instrument with a thin sheet, then pour the powder into the funnel, remove the thin sheet, gently stir the powder in the funnel to make it fall naturally, and let it fall into the placed receiving disk. After all the powder in the funnel has fallen into the disk (with a fixed radius), wait for two minutes, measure the height from the top of the powder to the bottom of the disk at this time, and calculate through the angular relationship between the height and the radius of the disk to obtain the angle of repose of the calcium hydroxide powder. The angle of repose reflects the stability of granular materials in a static state. The smaller the angle of repose, the better the fluidity of the calcium hydroxide powder. Example 1

[0015] Step 1: Weigh calcium hydroxide powder, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate according to the mass ratio, so that the mass ratio of calcium hydroxide, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate is 100:1.50:0.50:3.00. Add grinding balls with a diameter of 10 mm, and make the mass ratio of the grinding balls to calcium hydroxide 2:1. Step 2: Put the material obtained by mixing in Step 1 into a ball mill tank, mix the materials in a high-speed ball mill for 10 minutes, screen the grinding balls and powder with a 200-mesh standard sieve, and finally take the powdery material under the sieve as the prepared high-fluidity calcium hydroxide powder.

[0016] The scanning electron microscope photograph of the high-fluidity calcium hydroxide powder prepared in Step 2 is as Figure 1 shown. There are second-phase small particle precipitates attached to the surface of the calcium hydroxide powder, and the edges of the particles are blunt and no longer sharp. The high-fluidity calcium hydroxide powder prepared in Step 2 was tested. The oil absorption value per 100 g of calcium hydroxide powder is 49.10 g, the BET specific surface area is 14.709 m² / g, and the angle of repose is 55.01 degrees, with good fluidity. Example 2

[0017] Step 1: Weigh the calcium hydroxide powder, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate according to the mass ratio, so that the mass ratio of calcium hydroxide, potassium sulfate, nonylphenol polyoxyethylene ether OP-4, and zinc acetate is 100:1.50:0.50:1.00. Add grinding balls with a diameter of 10 mm, so that the mass ratio of the grinding balls to calcium hydroxide is 2:1; Step 2: Put the material obtained by mixing in Step 1 into a ball mill tank, mix the materials in a high-speed ball mill for 10 minutes, screen the grinding balls and powder materials with a 200-mesh standard sieve, and finally take the powdery material under the sieve, which is the prepared high-fluidity calcium hydroxide powder.

[0018] The scanning electron microscope photograph of the high-fluidity calcium hydroxide powder prepared in Step 2 is as Figure 2 shown. There are a small amount of second-phase small particle precipitates attached to the surface of the calcium hydroxide powder, and the edges of the particles are blunt and no longer sharp. The high-fluidity calcium hydroxide powder prepared in Step 2 is tested. The oil absorption value of every 100 grams of calcium hydroxide powder is 44.49 grams, the BET specific surface area is 11.505 square meters per gram, and the angle of repose is 57.95 degrees, indicating good fluidity. Comparative Example 1

[0019] Step 1: Weigh the calcium hydroxide powder according to the mass ratio, add grinding balls with a diameter of 10 mm, so that the mass ratio of the grinding balls to calcium hydroxide is 2:1; Step 2: Put the material obtained by mixing in Step 1 into a ball mill tank, mix the materials in a high-speed ball mill for 10 minutes, screen the grinding balls and powder materials with a 200-mesh standard sieve, and finally take the powdery material under the sieve, which is the prepared calcium hydroxide powder.

[0020] The scanning electron microscope photograph of the calcium hydroxide powder prepared in Step 2 is as Figure 3 shown. There is no adsorption of second-phase small particles on the surface of the calcium hydroxide powder, and the edges of the particles are sharp. The calcium hydroxide powder prepared in Step 2 is tested. The oil absorption value of every 100 grams of calcium hydroxide powder is 43.57 grams, the BET specific surface area is 15.817 square meters per gram, and the angle of repose is 60.57 degrees, indicating poor fluidity. Comparative Example 2

[0021] Step 1: Weigh the calcium hydroxide powder, potassium sulfate, and nonylphenol polyoxyethylene ether OP-4 according to the mass ratio, so that the mass ratio of calcium hydroxide, potassium sulfate, and nonylphenol polyoxyethylene ether OP-4 is 100:1.50:0.50. Add grinding balls with a diameter of 10 mm, so that the mass ratio of the grinding balls to calcium hydroxide is 2:1; Step 2: Put the material obtained by mixing in Step 1 into a ball mill tank, mix the materials in a high-speed ball mill for 10 minutes, screen the grinding balls and powder materials with a 200-mesh standard sieve, and finally take the powdery material under the sieve as the prepared high-flowability calcium hydroxide powder.

[0022] Test the calcium hydroxide powder prepared in Step 2. The oil absorption value of every 100 grams of calcium hydroxide powder is 44.33 grams, and the angle of repose is 59.31 degrees, with poor fluidity.

Claims

1. A method for preparing high-fluidity calcium hydroxide powder using a solid phase surface modification method, characterized in that The following steps are involved: Step 1, mixing ingredients according to the mass ratio, weighing calcium hydroxide powder, potassium sulfate, nonylphenol polyoxyethylene ether, and zinc acetate, so that the mass ratio of calcium hydroxide, potassium sulfate, nonylphenol polyoxyethylene ether, and zinc acetate is 100:1.50:0.50:1 or 100:1.50:0.50:3.00, wherein potassium sulfate and zinc acetate are chemical additives without crystal water, adding grinding balls with a diameter of 10 mm, and making the mass ratio of grinding balls to calcium hydroxide powder be 2:1; Step 2: Put the material mixed in step 1 into a ball mill, mix it in a fast ball mill for 10 minutes, sieve the grinding balls and materials with a 200-mesh standard sieve, and finally take the powdered material under the sieve to obtain the prepared high-fluidity calcium hydroxide powder.

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