Method for producing active lime by calcining limestone

Abstract

The invention discloses a method for producing active lime by calcining limestone, which comprises the following steps of: crushing limestone raw ore, cleaning to remove mud, and removing magnetic components by using a magnet to obtain limestone powder with the particle size of less than 3mm; then adding limestone powder into a 1-2 mol / L sodium hydroxide solution with the weight 3-5 times that of the limestone powder, carrying out ultrasonic oscillation treatment, filtering to obtain a solid I, washing to be neutral, stirring and dispersing in a dispersion liquid, carrying out microwave irradiation under the condition of an alternating magnetic field, and filtering to obtain a solid II, so as to obtain pretreated limestone powder; freezing the pretreated limestone powder under a static magnetic field condition to obtain frozen limestone powder; and finally, mixing and calcining the pretreated limestone powder and carbon dioxide adsorption balls with the particle size of 10-15mm, and separating to remove the carbon dioxide adsorption balls, thereby obtaining the active lime. The obtained active lime is high in calcium oxide content, few in impurities, high in activity degree and good in stability.

Description

Technical Field

[0001] The present invention relates to a method for producing active lime by calcining limestone, belonging to the technical field of lime production. Background Art

[0002] The production process of lime (i.e., quicklime) is essentially a process of thermal decomposition of calcium carbonate (CaCO3). Lime has a wide range of applications in the fields of metallurgy, construction, chemical industry, environment, agriculture, etc. Activity is an important index to characterize the quality of lime.

[0003] Active lime, also known as lightly burned lime or softly burned lime, has remarkable characteristics such as large specific surface area, small bulk density, high porosity, and fine crystal grains. As a desulfurizer with rich resources, wide sources, and low cost, active lime is widely used in the steelmaking industry. Applying active lime to the steelmaking process can accelerate slag formation and melting, shorten the smelting time, and also achieve better desulfurization and dephosphorization effects.

[0004] Traditionally, lime is usually produced by calcining limestone with coal or coal gas as fuel. During the calcination process, a large amount of pollutants are emitted, causing serious air pollution. On the other hand, there is a contradiction between the decomposition rate of limestone and the activity of lime: when the calcination temperature is high, the decomposition rate of limestone is fast, but the activity of lime is low, and even porcelainization may occur on the surface of limestone, resulting in loss of activity; when the calcination temperature is low, it is possible to increase the activity of lime, but the decomposition rate of limestone is slow, the calcination time is long, and underburning may also occur, which will also reduce the activity of lime. Moreover, the specific components of limestone produced from different ore sources are different. Accordingly, impurities will inevitably be introduced into the calcined lime, affecting the use performance of lime. Generally, the activity of lime obtained by most existing process methods is less than 360 ml, and it is usually calcined at a temperature of 950 - 1150 °C, consuming a large amount of energy and being prone to overburning.

[0005] In addition, the stability of active lime during storage is poor, resulting in a decrease in activity and poor desulfurization efficiency. Therefore, it is very necessary to improve the method for producing active lime by calcining limestone.

[0006] Patent CN100361917C discloses a method for obtaining highly active lime by vacuum calcining limestone. The specific steps are as follows: Crush the limestone and load it into a material tank, then hoist the material tank into the vacuum chamber of a vacuum electric furnace; While starting the vacuum system to evacuate and controlling the pressure in the vacuum chamber within the range of 100 - 1000 Pa, power on for heating and control the calcination temperature within the range of 750 - 900 °C by the electric furnace temperature measurement and control cabinet; When the pressure in the vacuum chamber drops to less than 100 Pa, stop supplying power for heating the vacuum electric furnace. When the temperature drops below 700 °C, close the vacuum system and restore the pressure in the vacuum chamber to normal pressure; Take out the lime in the material tank and quickly cool it to obtain highly active lime with an activity of 380 - 450 ml. This patented technology solves the contradiction between the lime activity and the limestone decomposition rate and the problem of lime being polluted by fuel or furnace gas. Because limestone decomposes rapidly in a vacuum, with a low calcination temperature and a short calcination time, the obtained lime has the advantages of high activity and strong reactivity. However, the vacuum production cost is relatively high, which limits its popularization and application. Summary of the Invention

[0007] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a method for producing active lime by calcining limestone, so as to improve the activity and stability of active lime.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for producing active lime by calcining limestone, the specific steps are as follows:

[0010] (1) First, crush the raw limestone ore and wash it to remove mud, and remove magnetic components with a magnet to obtain limestone powder with a particle size of less than 3 mm;

[0011] (2) Then add the limestone powder to a 1 - 2 mol / L sodium hydroxide solution with a weight 3 - 5 times that of the limestone powder, perform ultrasonic oscillation treatment, filter to obtain solid I, wash it with water until neutral, then stir and disperse it in a dispersion liquid, and perform microwave irradiation under the condition of an alternating magnetic field, filter to obtain solid II to obtain pretreated limestone powder;

[0012] (3) Perform freezing treatment on the pretreated limestone powder under the condition of a static magnetic field to obtain frozen limestone powder;

[0013] (4) Finally, mix and calcine the pretreated limestone powder with carbon dioxide adsorption balls with a particle size of 10 - 15 mm, separate and recover the carbon dioxide adsorption balls to obtain active lime;

[0014] Wherein, the dispersion liquid is obtained by ultrasonic dispersing tributylmethylammonium tetrafluoroborate, 1 - hydroxyethyl - 3 - methylimidazole tetrafluoroborate, triethanolamine, and polyacrylamide in water;

[0015] The carbon dioxide adsorption spheres are prepared from tetraethyl orthosilicate, lithium nitrate, and cerium nitrate as raw materials.

[0016] Preferably, in the dispersion liquid, the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3-5:3-5:4-6:4-6:100; during preparation, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300-400 W for 15-20 minutes.

[0017] Preferably, the carbon dioxide adsorption spheres are prepared by the following method: Stir and mix tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol to obtain an alcohol solution, then add polyethylene glycol 2000 to the alcohol solution, stir and mix well, heat to 180-190 °C, keep warm and stir for 2-3 hours, heat to 235-245 °C, keep warm and stir for 1-2 hours, centrifuge to obtain the precipitate, form it into a spherical shape, degrease at 700-750 °C for 1-2 hours, and calcine at 900-950 °C for 1-2 hours to obtain the product.

[0018] More preferably, the molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8-1.9:0.1-0.2, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8-10:2-3.

[0019] Preferably, in step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300-400 W for 30-40 minutes.

[0020] Preferably, in step (2), the mass ratio of solid I to the dispersion liquid is 1:3-5.

[0021] Preferably, in step (2), the alternating magnetic field conditions are: magnetic field strength 3-5 mT, frequency 30-40 Hz.

[0022] Preferably, in step (2), the microwave irradiation conditions are: microwave irradiation at 300-400 W for 2-3 minutes.

[0023] Preferably, in step (3), the static magnetic field strength is 30-40 mT.

[0024] Preferably, in step (3), the freezing treatment conditions are: standing at -40 °C for 30-40 minutes.

[0025] Preferably, in step (4), the mass ratio of pretreated limestone powder to the carbon dioxide adsorption spheres is 1:0.2-0.3.

[0026] Preferably, in step (4), the calcination conditions are as follows: first, heat up to 500 - 550 °C at a rate of 20 - 25 °C / min and calcine for 1 hour, then heat up to 700 - 750 °C at a rate of 3 - 5 °C / min and calcine for 2 - 3 hours.

[0027] Advantages of the present invention:

[0028] The present invention provides a method for producing active lime by calcining limestone. First, the original limestone ore is crushed and washed to remove mud, and magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm. Then, the limestone powder is added to a 1 - 2 mol / L sodium hydroxide solution with a weight 3 - 5 times that of the limestone powder, and ultrasonic oscillation treatment is carried out. The solid I is filtered out, washed until neutral, and then stirred and dispersed in a dispersion liquid. Microwave irradiation is carried out under the condition of an alternating magnetic field, and the solid II is filtered out to obtain pretreated limestone powder. The pretreated limestone powder is subjected to freezing treatment under the condition of a static magnetic field to obtain frozen limestone powder. Finally, the pretreated limestone powder is mixed and calcined with carbon dioxide adsorption balls with a particle size of 10 - 15 mm, and the carbon dioxide adsorption balls are separated to obtain active lime. The active lime obtained by the present invention has a high calcium oxide content, few impurities, high activity, and good stability.

[0029] In the present invention, impurities in limestone are removed by magnetic separation, alkali solution soaking, and ultrasonic oscillation treatment, which helps to increase the calcium oxide content in active lime. In the present invention, tetrabutylmethylammonium tetrafluoroborate, 1 - hydroxyethyl - 3 - methylimidazole tetrafluoroborate, triethanolamine, and polyacrylamide are ultrasonically dispersed in water to obtain a dispersion liquid. The limestone powder treated with the alkali solution is dispersed in this dispersion liquid, and microwave irradiation is carried out under the condition of an alternating magnetic field, so that the components of the dispersion liquid enter the interior of the lime powder, reducing the calcination difficulty. Calcium carbonate decomposition can be achieved at a lower calcination temperature, increasing the activity of active lime and improving the stability of active lime.

[0030] The pretreated limestone powder is subjected to freezing treatment under the condition of a static magnetic field, further reducing the calcination difficulty. Calcium carbonate decomposition can be achieved at a lower calcination temperature, increasing the activity of active lime and improving the stability of active lime.

[0031] During calcination, the pretreated limestone powder is mixed and calcined with carbon dioxide adsorption balls. The carbon dioxide adsorption balls are prepared from tetraethyl orthosilicate, lithium nitrate, and cerium nitrate as raw materials, have a good adsorption effect on carbon dioxide, promote the progress of calcium carbonate decomposition, increase the activity of active lime, and improve the stability of active lime. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with embodiments. It should be noted that the following description is only for explaining the present invention and does not limit its content.

[0033] Example 1:

[0034] A method for producing active lime by calcining limestone, the specific steps are as follows:

[0035] (1) First, crush and wash the raw limestone to remove mud, and use a magnet to remove magnetic components to obtain limestone powder with a particle size of less than 3 mm;

[0036] (2) Then add the limestone powder to 1 mol / L sodium hydroxide solution with a weight three times that of the limestone powder, perform ultrasonic oscillation treatment, filter to obtain solid I, wash it with water until neutral, then stir and disperse it in the dispersion liquid, and perform microwave irradiation under the condition of an alternating magnetic field, filter to obtain solid II, and obtain pretreated limestone powder;

[0037] (3) Freeze the pretreated limestone powder under the condition of a static magnetic field to obtain frozen limestone powder;

[0038] (4) Finally, mix and calcine the pretreated limestone powder with carbon dioxide adsorption balls with a particle size of 10 mm, and sieve to separate and recover the carbon dioxide adsorption balls to obtain active lime;

[0039] Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3:3:4:4:100; when preparing, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300 W for 15 minutes.

[0040] The carbon dioxide adsorption balls are prepared by the following method: Stir and mix tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol to obtain an alcohol solution, then add polyethylene glycol 2000 to the alcohol solution, stir and mix well, heat to 180 °C, keep stirring for 2 hours, heat to 235 °C, keep stirring for 1 hour, centrifuge to obtain a precipitate, form it into a spherical shape, degrease at 700 °C for 1 hour, and calcine at 900 °C for 1 hour to obtain.

[0041] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8:0.1, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8:2.

[0042] In step (2), the process conditions of the ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300 W for 30 minutes;

[0043] The mass ratio of solid I to the dispersion liquid is 1:3;

[0044] The alternating magnetic field conditions are: magnetic field strength 3 mT, frequency 30 Hz;

[0045] The microwave irradiation conditions are as follows: microwave irradiation at 300 W for 2 minutes.

[0046] In step (3), the static magnetic field strength is 30 mT;

[0047] The freezing treatment conditions are as follows: standing for 30 minutes at -40 °C.

[0048] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.2;

[0049] The calcination conditions are as follows: first heating to 500 °C at a rate of 20 °C / min and calcining for 1 hour, then heating to 700 °C at a rate of 3 °C / min and calcining for 2 hours.

[0050] Example 2:

[0051] A method for producing activated lime by calcining limestone, the specific steps are as follows:

[0052] (1) First, the original limestone ore is crushed, washed to remove mud, and the magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm;

[0053] (2) Then, the limestone powder is added to a 2 mol / L sodium hydroxide solution with a weight 5 times that of the limestone powder, and ultrasonic oscillation treatment is carried out. The solid I is filtered out, washed to neutrality, and then stirred and dispersed in a dispersion liquid. Microwave irradiation is carried out under an alternating magnetic field condition, and the solid II is filtered out to obtain pretreated limestone powder;

[0054] (3) The pretreated limestone powder is subjected to freezing treatment under a static magnetic field condition to obtain frozen limestone powder;

[0055] (4) Finally, the pretreated limestone powder is mixed and calcined with carbon dioxide adsorption balls with a particle size of 15 mm, and the carbon dioxide adsorption balls are recovered by sieving separation to obtain activated lime;

[0056] Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 5:5:6:6:100; during preparation, the ultrasonic dispersion conditions are as follows: ultrasonic dispersion at 400 W for 20 minutes.

[0057] The carbon dioxide adsorption spheres are prepared by the following method: tetraethyl orthosilicate, lithium nitrate, cerium nitrate and benzyl alcohol are stirred and mixed evenly to obtain an alcohol solution. Then, polyethylene glycol 2000 is added to the alcohol solution, stirred and mixed evenly, heated to 190 °C, kept warm and stirred for 3 hours, heated to 245 °C, kept warm and stirred for 2 hours, centrifuged to obtain a precipitate, formed into spheres, degummed at 750 °C for 2 hours, and calcined at 950 °C for 2 hours to obtain the product.

[0058] The molar ratio of tetraethyl orthosilicate, lithium nitrate and cerium nitrate is 1:1.9:0.2, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol and polyethylene glycol 2000 is 1:10:3.

[0059] In step (2), the process conditions of ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 400 W for 40 minutes;

[0060] The mass ratio of solid I to the dispersion liquid is 1:5;

[0061] The conditions of the alternating magnetic field are: magnetic field strength 5 mT, frequency 40 Hz;

[0062] The conditions of microwave irradiation are: microwave irradiation at 400 W for 3 minutes.

[0063] In step (3), the static magnetic field strength is 40 mT;

[0064] The conditions of the freezing treatment are: standing at -40 °C for 40 minutes.

[0065] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption spheres is 1:0.3;

[0066] The calcination conditions are: first heating to 550 °C at a rate of 25 °C / min and calcining for 1 hour, then heating to 750 °C at a rate of 5 °C / min and calcining for 3 hours.

[0067] Example 3:

[0068] A method for producing activated lime by calcining limestone, the specific steps are as follows:

[0069] (1) First, the raw limestone ore is crushed and washed to remove mud, and the magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm;

[0070] (2) Then, the limestone powder is added to a 2 mol / L sodium hydroxide solution with 3 times its weight, subjected to ultrasonic oscillation treatment, filtered to obtain solid I, washed with water until neutral, then stirred and dispersed in a dispersion liquid, and microwave irradiated under the conditions of an alternating magnetic field, and filtered to obtain solid II to obtain pretreated limestone powder;

[0071] (3) The pretreated limestone powder is subjected to freezing treatment under static magnetic field conditions to obtain frozen limestone powder;

[0072] (4) Finally, mix the pretreated limestone powder with the carbon dioxide adsorption spheres with a particle size of 10 mm, calcine them, and separate and recover the carbon dioxide adsorption spheres by sieving to obtain active lime;

[0073] Among them, the dispersion liquid is obtained by ultrasonically dispersing tetrabutylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tetrabutylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 5:3:6:4:100; during preparation, the ultrasonic dispersion conditions are: ultrasonic dispersion at 400 W for 15 minutes.

[0074] The carbon dioxide adsorption spheres are prepared by the following method: Stir and mix tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol to obtain an alcohol solution. Then, add polyethylene glycol 2000 to the alcohol solution, stir and mix well, heat to 190 °C, keep stirring for 2 hours, heat to 245 °C, keep stirring for 1 hour, centrifuge to obtain the precipitate, form it into a spherical shape, degrease at 750 °C for 1 hour, and calcine at 950 °C for 1 hour to obtain the product.

[0075] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.9:0.1, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:10:2.

[0076] In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 400 W for 30 minutes;

[0077] The mass ratio of solid I to the dispersion liquid is 1:5;

[0078] The alternating magnetic field conditions are: magnetic field strength 3 mT, frequency 40 Hz;

[0079] The microwave irradiation conditions are: microwave irradiation at 300 W for 3 minutes.

[0080] In step (3), the static magnetic field strength is 30 mT;

[0081] The freezing treatment conditions are: standing at -40 °C for 40 minutes.

[0082] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption spheres is 1:0.2;

[0083] The calcination conditions are: first heat up to 500 °C at a rate of 25 °C / min and calcine for 1 hour, then heat up to 700 °C at a rate of 5 °C / min and calcine for 3 hours.

[0084] Example 4:

[0085] A method for producing active lime by calcining limestone, the specific steps are as follows:

[0086] (1) First, crush and wash the raw limestone to remove mud, and use a magnet to remove magnetic components to obtain limestone powder with a particle size of less than 3 mm;

[0087] (2) Then add the limestone powder to a 1.5 mol / L sodium hydroxide solution with a weight 4 times that of the limestone powder, perform ultrasonic oscillation treatment, filter to obtain solid I, wash it with water until neutral, then stir and disperse it in the dispersion liquid, and perform microwave irradiation under the condition of an alternating magnetic field, filter to obtain solid II, and obtain pretreated limestone powder;

[0088] (3) Freeze the pretreated limestone powder under the condition of a static magnetic field to obtain frozen limestone powder;

[0089] (4) Finally, mix and calcine the pretreated limestone powder with carbon dioxide adsorption balls with a particle size of 12 mm, and sieve to separate and recover the carbon dioxide adsorption balls to obtain active lime;

[0090] Among them, the dispersion liquid is obtained by ultrasonically dispersing tetrabutylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tetrabutylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 4:4:5:5:100; when preparing, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300 W for 18 minutes.

[0091] The carbon dioxide adsorption balls are prepared by the following method: Stir and mix tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol to obtain an alcohol solution, then add polyethylene glycol 2000 to the alcohol solution, stir and mix evenly, heat to 185 °C, keep stirring for 2 hours, heat to 240 °C, keep stirring for 1 hour, centrifuge to obtain a precipitate, form it into a spherical shape, degrease at 720 °C for 2 hours, and calcine at 930 °C for 1 hour to obtain the product.

[0092] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8:0.15, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:9:2.5.

[0093] In step (2), the process conditions of the ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 400 W for 35 minutes;

[0094] The mass ratio of solid I to the dispersion liquid is 1:4;

[0095] The alternating magnetic field conditions are: magnetic field strength 4 mT, frequency 35 Hz;

[0096] The microwave irradiation conditions are as follows: microwave irradiation at 400 W for 2 minutes.

[0097] In step (3), the static magnetic field strength is 40 mT;

[0098] The freezing treatment conditions are as follows: standing for 35 minutes at -40°C.

[0099] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.25;

[0100] The calcination conditions are as follows: first heating to 520°C at a rate of 22°C / min and calcining for 1 hour, then heating to 720°C at a rate of 4°C / min and calcining for 2 hours.

[0101] Comparative Example 1

[0102] A method for producing active lime by calcining limestone, the specific steps are as follows:

[0103] (1) First, the raw limestone ore is crushed, washed to remove mud, and the magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm;

[0104] (2) Then, the limestone powder is added to a 1 mol / L sodium hydroxide solution with a weight three times that of the limestone powder, and ultrasonic oscillation treatment is carried out. The solid I is filtered out, washed to neutrality, and then stirred and dispersed in a dispersion liquid, followed by microwave irradiation. The solid II is filtered out to obtain the pretreated limestone powder;

[0105] (3) The pretreated limestone powder is subjected to freezing treatment under a static magnetic field condition to obtain frozen limestone powder;

[0106] (4) Finally, the pretreated limestone powder is mixed and calcined with carbon dioxide adsorption balls with a particle size of 10 mm, and the carbon dioxide adsorption balls are recovered by sieving separation to obtain active lime;

[0107] Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3:3:4:4:100; during preparation, the ultrasonic dispersion conditions are as follows: ultrasonic dispersion at 300 W for 15 minutes.

[0108] The carbon dioxide adsorption spheres are prepared by the following method: tetraethyl orthosilicate, lithium nitrate, cerium nitrate and benzyl alcohol are stirred and mixed evenly to obtain an alcohol solution. Then, polyethylene glycol 2000 is added to the alcohol solution, stirred and mixed evenly, heated to 180 °C, kept warm and stirred for 2 hours, heated to 235 °C, kept warm and stirred for 1 hour, centrifuged to obtain a precipitate, formed into spheres, degummed at 700 °C for 1 hour, and calcined at 900 °C for 1 hour to obtain the product.

[0109] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8:0.1, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8:2.

[0110] In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300 W for 30 minutes;

[0111] The mass ratio of solid I to the dispersion liquid is 1:3;

[0112] The microwave irradiation conditions are: microwave irradiation at 300 W for 2 minutes.

[0113] In step (3), the static magnetic field strength is 30 mT;

[0114] The freezing treatment conditions are: standing at -40 °C for 30 minutes.

[0115] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption spheres is 1:0.2;

[0116] The calcination conditions are: first heating to 500 °C at a rate of 20 °C / min and calcining for 1 hour, then heating to 700 °C at a rate of 3 °C / min and calcining for 2 hours.

[0117] Comparative Example 2

[0118] A method for producing active lime by calcining limestone, the specific steps are as follows:

[0119] (1) First, the raw limestone ore is crushed and washed to remove mud, and the magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm;

[0120] (2) Then, the limestone powder is added to 1 mol / L sodium hydroxide solution with 3 times its weight, subjected to ultrasonic oscillation treatment, filtered to obtain solid I, washed to neutral, then stirred and dispersed in the dispersion liquid, and microwave irradiated under an alternating magnetic field condition, filtered to obtain solid II to obtain the pretreated limestone powder;

[0121] (3) The pretreated limestone powder is treated under a static magnetic field condition to obtain frozen limestone powder;

[0122] (4) Finally, the pretreated limestone powder is mixed with carbon dioxide adsorption balls with a particle size of 10 mm and calcined. The carbon dioxide adsorption balls are recovered by sieving to obtain activated lime;

[0123] Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3:3:4:4:100; during preparation, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300 W for 15 minutes.

[0124] The carbon dioxide adsorption balls are prepared by the following method: tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol are stirred and mixed evenly to obtain an alcohol solution. Then, polyethylene glycol 2000 is added to the alcohol solution, stirred and mixed evenly, heated to 180 °C, kept stirring for 2 hours, heated to 235 °C, kept stirring for 1 hour, the precipitate is taken by centrifugation, formed into a spherical shape, degummed at 700 °C for 1 hour, and calcined at 900 °C for 1 hour to obtain the product.

[0125] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8:0.1, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8:2.

[0126] In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300 W for 30 minutes;

[0127] The mass ratio of solid I to the dispersion liquid is 1:3;

[0128] The conditions of the alternating magnetic field are: magnetic field intensity 3 mT, frequency 30 Hz;

[0129] The conditions of microwave irradiation are: microwave irradiation at 300 W for 2 minutes.

[0130] In step (3), the static magnetic field intensity is 30 mT; stand still for 30 minutes.

[0131] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.2;

[0132] The calcination conditions are: first, heat up to 500 °C at a rate of 20 °C / min and calcine for 1 hour, then heat up to 700 °C at a rate of 3 °C / min and calcine for 2 hours.

[0133] Comparative Example 3

[0134] A method for producing activated lime by calcining limestone, the specific steps are as follows:

[0135] (1) First, crush the original limestone ore and wash it to remove mud, and use a magnet to remove magnetic components to obtain limestone powder with a particle size of less than 3 mm;

[0136] (2) Then, add the limestone powder to a 1 mol / L sodium hydroxide solution with a weight three times that of the limestone powder, perform ultrasonic oscillation treatment, filter to obtain solid I, wash it with water until neutral, then stir and disperse it in the dispersion liquid, and perform microwave irradiation under the condition of an alternating magnetic field, filter to obtain solid II, and obtain pretreated limestone powder;

[0137] (3) Freeze the pretreated limestone powder under the condition of a static magnetic field to obtain frozen limestone powder;

[0138] (4) Finally, mix the pretreated limestone powder with carbon dioxide adsorption balls with a particle size of 10 mm and calcine them, and separate and recover the carbon dioxide adsorption balls by sieving to obtain active lime;

[0139] Among them, the dispersion liquid is obtained by ultrasonically dispersing tetrabutylmethylammonium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tetrabutylmethylammonium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3:4:4:100; during preparation, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300 W for 15 minutes.

[0140] The carbon dioxide adsorption balls are prepared by the following method: Stir and mix tetraethyl orthosilicate, lithium nitrate, cerium nitrate, and benzyl alcohol to obtain an alcohol solution, then add polyethylene glycol 2000 to the alcohol solution, stir and mix well, heat to 180 °C, keep stirring for 2 hours, heat to 235 °C, keep stirring for 1 hour, centrifuge to obtain a precipitate, form it into a spherical shape, degum at 700 °C for 1 hour, and calcine at 900 °C for 1 hour to obtain them.

[0141] The molar ratio of tetraethyl orthosilicate, lithium nitrate, and cerium nitrate is 1:1.8:0.1, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8:2.

[0142] In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300 W for 30 minutes;

[0143] The mass ratio of solid I to the dispersion liquid is 1:3;

[0144] The conditions for the alternating magnetic field are: magnetic field strength 3 mT, frequency 30 Hz;

[0145] The conditions for microwave irradiation are: microwave irradiation at 300 W for 2 minutes.

[0146] In step (3), the static magnetic field strength is 30 mT;

[0147] The freezing treatment conditions are: standing still for 30 minutes at -40°C.

[0148] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.2;

[0149] The calcination conditions are: first heating up to 500°C at a rate of 20°C / min and calcining for 1 hour, then heating up to 700°C at a rate of 3°C / min and calcining for 2 hours.

[0150] Comparative Example 4

[0151] A method for producing activated lime by calcining limestone, the specific steps are as follows:

[0152] (1) First, crush and wash the raw limestone ore to remove mud, and use a magnet to remove magnetic components to obtain limestone powder with a particle size of less than 3 mm;

[0153] (2) Then add the limestone powder to 1 mol / L sodium hydroxide solution with a weight three times that of the limestone powder, perform ultrasonic oscillation treatment, filter to obtain solid I, wash it with water until neutral, then stir and disperse it in the dispersion liquid, and perform microwave irradiation under the condition of an alternating magnetic field, filter to obtain solid II, and obtain the pretreated limestone powder;

[0154] (3) Perform freezing treatment on the pretreated limestone powder under the condition of a static magnetic field to obtain frozen limestone powder;

[0155] (4) Finally, mix and calcine the pretreated limestone powder with carbon dioxide adsorption balls with a particle size of 10 mm, and separate and recycle the carbon dioxide adsorption balls by sieving to obtain activated lime;

[0156] Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide (non-ionic, molecular weight 2 million, purchased from Guangzhou Musen Technology Co., Ltd.) in water; the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3:3:4:4:100; when preparing, the ultrasonic dispersion conditions are: ultrasonic dispersion at 300 W for 15 minutes.

[0157] The carbon dioxide adsorption balls are prepared by the following method: stir and mix tetraethyl orthosilicate, lithium nitrate, and benzyl alcohol to obtain an alcohol solution, then add polyethylene glycol 2000 to the alcohol solution, stir and mix evenly, heat to 180°C, keep stirring for 2 hours, heat to 235°C, keep stirring for 1 hour, centrifuge to obtain a precipitate, form it into a spherical shape, degrease at 700°C for 1 hour, and calcine at 900°C for 1 hour to obtain.

[0158] The molar ratio of tetraethyl orthosilicate to lithium nitrate is 1:1.8, and the mass ratio of tetraethyl orthosilicate, benzyl alcohol, and polyethylene glycol 2000 is 1:8:2.

[0159] In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300 W for 30 minutes;

[0160] The mass ratio of solid I to the dispersion liquid is 1:3;

[0161] The conditions for the alternating magnetic field are: magnetic field strength 3 mT, frequency 30 Hz;

[0162] The conditions for microwave irradiation are: microwave irradiation at 300 W for 2 minutes.

[0163] In step (3), the static magnetic field strength is 30 mT;

[0164] The conditions for the freezing treatment are: standing for 30 minutes at -40 °C.

[0165] In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.2;

[0166] The calcination conditions are: first heating to 500 °C at a rate of 20 °C / min and calcining for 1 hour, then heating to 700 °C at a rate of 3 °C / min and calcining for 2 hours.

[0167] Test Examples

[0168] The calcium oxide content, activity, and stability of the active lime obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were respectively tested. The results are shown in Table 1.

[0169] Activity: 50 g of lime was rapidly stirred and digested in 2 L of water at 40 °C, and phenolphthalein reagent was used as an indicator. The calcium hydroxide generated during the digestion of the lime was neutralized with a 4 mol / L hydrochloric acid solution (just changing from red to colorless). The consumption of the hydrochloric acid solution at 10 minutes was recorded, and the activity of the lime was expressed as the number of milliliters of hydrochloric acid consumed in 10 minutes.

[0170] Stability: Standing at room temperature for 30 days, and the activity was tested again.

[0171] Table 1. Performance Test of Active Lime

[0172]

[0173] As can be seen from Table 1, the active lime obtained in Examples 1 to 4 has a high calcium oxide content, few impurities, high activity, and good stability.

[0174] In Comparative Example 1, the alternating magnetic field condition was omitted; in Comparative Example 2, the freezing treatment was omitted; in Comparative Example 3, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate was omitted during the preparation of the dispersion; in Comparative Example 4, cerium nitrate was omitted during the preparation of the carbon dioxide adsorption spheres. The calcium oxide content of the activated lime was significantly decreased, and the activity and stability were also significantly deteriorated. This shows that the appropriate pretreatment of the present invention helps to reduce product impurities and improve product quality, and the specific dispersion treatment and carbon dioxide adsorption spheres contribute to the progress of the calcium carbonate decomposition reaction, improve the activity of the activated lime, and improve the stability.

[0175] Although the specific implementation manners of the present invention have been described above, they are not limitations on the protection scope of the present invention. Based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A method for producing active lime by calcining limestone, characterized in that, The specific steps are as follows: (1) First, the original limestone ore is crushed and washed to remove mud, and magnetic components are removed by a magnet to obtain limestone powder with a particle size of less than 3 mm; (2) Then, the limestone powder is added to a 1-2 mol / L sodium hydroxide solution with a weight 3-5 times that of the limestone powder, and ultrasonic oscillation treatment is carried out. The solid I is filtered, washed with water until neutral, and then stirred and dispersed in the dispersion liquid. Microwave irradiation is carried out under the condition of an alternating magnetic field. The solid II is filtered to obtain pretreated limestone powder; (3) The pretreated limestone powder is subjected to a freezing treatment under a static magnetic field condition to obtain frozen limestone powder; (4) Finally, the pretreated limestone powder is mixed and calcined with carbon dioxide adsorption balls with a particle size of 10-15 mm, and the carbon dioxide adsorption balls are separated and recovered to obtain active lime; Among them, the dispersion liquid is obtained by ultrasonically dispersing tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, and polyacrylamide in water; The carbon dioxide adsorption balls are prepared from tetraethyl orthosilicate, lithium nitrate, and cerium nitrate as raw materials.

2. The method according to claim 1, characterized in that, In the dispersion liquid, the mass ratio of tributylmethylammonium tetrafluoroborate, 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate, triethanolamine, polyacrylamide, and water is 3-5:3-5:4-6:4-6:100; when preparing, the ultrasonic dispersion condition is: ultrasonic dispersion at 300-400 W for 15-20 minutes.

3. The method according to claim 1, characterized in that The carbon dioxide adsorption balls are prepared by the following method: tetraethyl orthosilicate, lithium nitrate, cerium nitrate and benzyl alcohol are stirred and mixed evenly to obtain an alcohol solution. Then, polyethylene glycol 2000 is added to the alcohol solution, stirred and mixed evenly, heated to 180-190 °C, kept warm and stirred for 2-3 hours, heated to 235-245 °C, kept warm and stirred for 1-2 hours, centrifuged to obtain a precipitate, formed into a spherical shape, degummed at 700-750 °C for 1-2 hours, and calcined at 900-950 °C for 1-2 hours to obtain.

4. The method according to claim 1, wherein In step (2), the process conditions for ultrasonic oscillation treatment are: ultrasonic oscillation treatment at 300-400 W for 30-40 minutes.

5. The method according to claim 1, characterized in that, In step (2), the mass ratio of solid I to the dispersion liquid is 1:3-5.

6. The method according to claim 1, wherein In step (2), the alternating magnetic field condition is: magnetic field strength 3-5 mT, frequency 30-40 Hz.

7. The method according to claim 1, characterized in that In step (2), the microwave irradiation condition is: microwave irradiation at 300-400 W for 2-3 minutes.

8. The method according to claim 1, characterized in that, In step (3), the static magnetic field strength is 30-40 mT.

9. The method according to claim 1, wherein In step (3), the freezing treatment condition is: standing at -40 °C for 30-40 minutes.

10. The method according to claim 1, wherein In step (4), the mass ratio of the pretreated limestone powder to the carbon dioxide adsorption balls is 1:0.2-0.3; The calcination condition is: first heating to 500-550 °C at a rate of 20-25 °C / min and calcining for 1 hour, then heating to 700-750 °C at a rate of 3-5 °C / min and calcining for 2-3 hours.

Images