Calcium-based dry desulfurizer for industrial silicon smelting flue gas and preparation method thereof

Abstract

The application provides a calcium-based dry desulfurizer for industrial silicon smelting flue gas and a preparation method, and the method comprises the following steps: adding propylene carbonate, alcohol, alcohol amine and sodium-based additives into water, heating to completely dissolve and fully mix, to obtain a hot digestion solution; adding crushed active lime containing magnesium oxide into the hot digestion solution, and performing a digestion reaction in an ultrasonic reactor to obtain an intermediate product; and vacuum drying the intermediate product to obtain a calcium-based desulfurizer. Experimental verification shows that the specific surface area, sulfur capacity and chlorine capacity of the calcium-based desulfurizer prepared by the method are all much larger than those of calcium-based desulfurizers prepared by other methods, and the calcium-based desulfurizer has good adsorption capacity and sulfur capacity and chlorine capacity. The calcium-based desulfurizer can be widely applied to the desulfurization treatment of industrial silicon flue gas with low water content.

Description

Technical Field

[0001] This invention relates to the field of dry desulfurization agents for industrial silicon smelting flue gas, and in particular to a calcium-based dry desulfurization agent for industrial silicon smelting flue gas and its preparation method. Background Technology

[0002] The industrial silicon production process involves adding high-purity silica, a carbonaceous reducing agent (petroleum coke or coal), and a loosening agent (wood or coke) in a specific ratio to a submerged arc furnace. Anhydrous calcium chloride is also added to help lower the melting temperature, reduce energy consumption, and improve the purity and quality of elemental silicon. These raw materials are mixed together in the submerged arc furnace and smelted at high temperatures through electrode discharge. The silicon-containing minerals in the silica are reduced by the carbonaceous reducing agent to obtain liquid elemental silicon; the remaining silicon-containing substances enter the flue gas along with dust. Therefore, the main components of the flue gas are N2, O2, CO2, HCl, SO2, and NO. X And a small amount of water vapor, including: SO2 and NO X It mainly comes from coal, coke and petroleum coke, while HCl comes from anhydrous calcium chloride.

[0003] The flue gas enters a waste heat boiler for heat exchange, and after desulfurization, denitrification, and dust removal, it is discharged through a chimney. Currently, the desulfurization processes used are divided into wet desulfurization and dry desulfurization. Due to the disadvantages of wet desulfurization, such as severe equipment corrosion, large initial investment, large flue gas temperature drop, and the generation of large amounts of acidic wastewater and waste residue that are difficult to treat, newly built desulfurization facilities in recent years have mainly adopted dry desulfurization. Dry desulfurization mainly uses the sodium bicarbonate process (referred to as "SDS desulfurization"), which generally requires grinding in a mill to achieve a good desulfurization effect; its theoretical sulfur capacity is low, and when the concentration of HCl and CO2 in the flue gas is too high, it has a significant impact on sodium bicarbonate desulfurization; at the same time, the desulfurization byproducts are all water-soluble substances (a mixture of sodium sulfate, sodium carbonate, and sodium chloride), which are not conducive to recycling.

[0004] Compared to the sodium bicarbonate process, calcium-based desulfurizers for desulfurizing industrial silicon submerged arc furnace flue gas offer advantages such as high theoretical sulfur capacity and easy recovery of desulfurization byproducts, making them the preferred choice for this purpose. However, due to the low water content of industrial silicon submerged arc furnace flue gas, traditional calcium-based desulfurizers exhibit poor deacidification performance under low water conditions, resulting in low sulfur capacity and calcium utilization. Furthermore, the HCl content in the industrial silicon submerged arc furnace flue gas significantly impacts the desulfurization effect of traditional calcium-based desulfurizers. Summary of the Invention

[0005] In view of this, the present invention provides a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas and a preparation method thereof, in order to solve the above-mentioned technical problems.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, the method comprising:

[0007] Propylene carbonate, alcohol, alkanolamine and sodium-based additives are added to water and heated until completely dissolved and thoroughly mixed to obtain a hot digestive solution;

[0008] Crushed quicklime is added to the hot digestion liquid and digested in an ultrasonic reactor to obtain an intermediate product; the quicklime contains magnesium oxide.

[0009] The intermediate product was dried under vacuum to obtain a calcium-based desulfurizer.

[0010] According to a preferred embodiment of the present invention, the alcohol is one or more of ethanol, propylene glycol or glycerol, the alcohol amine is one or more of triethanolamine, diethanolamine, propanolamine or butanolamine, and the sodium-based adjuvant is one or more of sodium tripolyphosphate, sodium dodecyl sulfate, sodium chloride or sodium carbonate.

[0011] According to a preferred embodiment of the present invention, the active lime contains >80% calcium oxide and <10% magnesium oxide; the temperature of the hot digestion liquid is 30-60°C.

[0012] According to a preferred embodiment of the present invention, before adding the crushed quicklime to the hot digestion liquid, the method further includes:

[0013] Dolomite and limestone are mixed and then lightly burned to obtain active lime.

[0014] According to a preferred embodiment of the present invention, the components are as follows by weight: 85-93 parts of quicklime; 1-2 parts of propylene carbonate; 5-10 parts of alcohol; 0.1-1 parts of alkanolamine; and 1-2 parts of additives.

[0015] According to a preferred embodiment of the present invention, the digestion reaction temperature is 70-90°C, and the time is 1-9 hours; the mass ratio of the hot digestion liquid to the active lime is 0.6-1.5.

[0016] According to a preferred embodiment of the present invention, the particle size of the activated lime is 0.1 mm to 10 mm, and the activity of the activated lime is greater than 300 ml based on 4 mol / L hydrochloric acid.

[0017] According to a preferred embodiment of the present invention, the digestion reactor is a closed ultrasonic reactor with a power of 200-1500w.

[0018] According to a preferred embodiment of the present invention, the vacuum drying process involves a vacuum degree of -0.08 MPa, a temperature of 60°C to 120°C, and a time of 1 to 3 hours.

[0019] To solve the above-mentioned technical problems, a second aspect of the present invention provides a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, which is prepared by any one of the above-described methods for preparing calcium-based dry desulfurizing agents for industrial silicon smelting flue gas.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] 1. In the digestive fluid used in this invention, the carboxyl functional groups of propylene carbonate, the hydroxyl groups of alcohols, and the amino and hydroxyl groups of amines can interact to form hydrogen bonds. The resulting network structure material can serve as a dispersant and stabilizer for nanomaterials, thereby preventing the aggregation of nano-calcium hydroxide.

[0022] 2. The propylene carbonate used in this invention has a strong adsorption capacity for carbon dioxide, and its ester functional groups can react with H+. + Rapid reaction can improve the absorption pathways of HCl, CO2, and SO2. Furthermore, sodium-based additives, adhering to the interior and surface of the pores, can reduce the diffusion resistance of HCl, CO2, and SO2, thereby increasing their saturated adsorption capacity.

[0023] 3. The active lime in this invention contains a certain amount of magnesium oxide. Therefore, the calcium-based desulfurizer prepared contains magnesium hydroxide, which has a skeletal structure function and can prevent byproducts such as calcium sulfate, calcium chloride, and calcium carbonate from clogging the pore structure.

[0024] 4. The hot digestion solution prepared in this invention, compared with the room temperature digestion solution, can, on the one hand, ensure uniform mixing of the components, and on the other hand, improve the activation properties of each component. Although increasing the temperature accelerates the digestion rate of calcium oxide, it also accelerates the penetration of the component solutions into the particles to form bonds, thereby slowing down the digestion reaction rate of calcium hydroxide.

[0025] 5. The use of an ultrasonic reactor in this invention facilitates the formation of nano-calcium hydroxide. The ultrasonic action helps to further reduce the particle size of the active lime before the reaction and also helps to inhibit the crystallization of calcium hydroxide, thus avoiding the formation of large particles.

[0026] 6. The negative pressure environment of vacuum drying in this invention helps calcium-based desulfurizer form a more complete pore structure, avoiding pore collapse caused by high-temperature drying at normal pressure. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, provided in Embodiment 1 of the present invention.

[0029] Figure 2 This is a schematic flowchart of a method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, provided in Embodiment 2 of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0032] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0033] Example 1

[0034] Embodiment 1 of the present invention provides a method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, such as... Figure 1 As shown, the method includes:

[0035] S1. Add propylene carbonate, alcohol, alkanolamine and sodium-based additives to water and heat until completely dissolved and thoroughly mixed to obtain a hot digestion solution;

[0036] In this embodiment, propylene carbonate (molecular formula: C4H6O3) has a strong adsorption capacity for CO2, and its ester functional groups can react with H2O. + The rapid reaction increases the absorption pathways of calcium-based desulfurizers for HCl, CO2, and SO2.

[0037] Sodium-based additives adhere to the interior and surface of the pores, reducing the diffusion resistance of calcium-based desulfurizers to HCl, CO2, and SO2, and increasing their saturated adsorption capacity. Optionally, the sodium-based additive may be one or more of sodium tripolyphosphate, sodium dodecyl sulfate, sodium chloride, or sodium carbonate.

[0038] The alcohol may be one or more of ethanol, propylene glycol or glycerol, and the alcoholamine may be one or more of triethanolamine, diethanolamine, propanolamine or butanolamine.

[0039] The carboxyl functional groups of propylene carbonate, the hydroxyl groups of alcohols, and the amino and hydroxyl groups of alkanolamines in the digestion solution prepared in this step can interact to form hydrogen bonds. The resulting network structure material can act as a dispersant and stabilizer for nanomaterials, thereby preventing the aggregation of nano-calcium hydroxide.

[0040] The heating temperature is consistent with the temperature of the hot digestion solution. For example, propylene carbonate, alcohol, alkanolamine, and sodium-based additives can be heated in a water bath to 30–60°C to ensure that the temperature of the resulting hot digestion solution is 30–60°C. This step of preparing the hot digestion solution by heating can, on the one hand, ensure uniform mixing of the components of the digestion solution, and on the other hand, improve the activation performance of each component. Although increasing the temperature will accelerate the digestion rate of calcium oxide, it will also accelerate the penetration of the digestion solution components into the particles to form bonds, thereby slowing down the digestion reaction rate of calcium hydroxide.

[0041] S2. Add the crushed active lime to the hot digestion liquid and carry out the digestion reaction in an ultrasonic reactor to obtain an intermediate product.

[0042] Preferably, the mass ratio of the hot digestion liquid to the quicklime is 0.6-1.5, that is, the mass of the digestion liquid is 0.6 to 1.5 times the mass of the quicklime.

[0043] The components, by weight, are: 85-93 parts of quicklime; 1-2 parts of propylene carbonate; 5-10 parts of alcohol; 0.1-1 parts of alkanolamine; and 1-2 parts of sodium-based additives.

[0044] In this embodiment, the activated lime contains a certain amount of magnesium oxide. Therefore, the magnesium hydroxide in the prepared calcium-based desulfurizer has a skeletal structural function, which can prevent byproducts such as calcium sulfate, calcium chloride, and calcium carbonate from clogging the pore structure. In a preferred embodiment, the activated lime can be obtained by lightly calcining a mixture of dolomite and limestone, wherein the activated lime contains >80% calcium oxide and <10% magnesium oxide.

[0045] To improve the reaction efficiency, the particle size D90 of the activated lime is 0.1 mm to 10 mm, preferably 0.1 mm to 5 mm, and more preferably 0.1 mm to 2 mm. The activity of the activated lime is required to be greater than 300 ml (based on 4 mol / L hydrochloric acid). Therefore, in a preferred example, before this step, dolomite and limestone can be mixed and lightly calcined to obtain activated lime; the activated lime is then crushed and sieved to obtain activated lime with a particle size between 0.1 mm and 2 mm.

[0046] In this embodiment, since the active lime contains a certain amount of magnesium oxide, its reaction with water is relatively mild and the heat release is relatively small. Therefore, it is necessary to maintain a certain digestion reaction temperature to allow the digestion reaction to occur. Preferably, the digestion reaction temperature is 70-90°C, and the time is 1-9 hours.

[0047] This invention utilizes an ultrasonic reactor to facilitate the formation of nano-calcium hydroxide. The ultrasonic action further reduces the particle size of the pre-reaction quicklime and also helps inhibit calcium hydroxide crystallization, preventing the formation of large particles. Preferably, the ultrasonic reactor is a closed-type ultrasonic reactor with a power of 200-1500W, which prevents rapid loss of water vapor, thus avoiding incomplete digestion of the material. The higher digestion temperature helps water vapor penetrate into the interior of the calcium oxide or magnesium oxide particles, ensuring a thorough digestion reaction.

[0048] S3. The intermediate product is dried under vacuum to obtain a calcium-based desulfurizer.

[0049] Specifically, the negative pressure environment of the vacuum dryer helps the desulfurizing agent form a more complete pore structure, avoiding pore collapse caused by high-temperature drying at normal pressure. Preferably, the vacuum degree of the vacuum drying is -0.08 MPa, the temperature is 60℃-120℃, and the time is 1-3 hours.

[0050] Furthermore, the vacuum-dried calcium-based desulfurizer can be ground and crushed for subsequent use.

[0051] Example 2

[0052] Embodiment 2 of the present invention provides a method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, such as... Figure 2 As shown, the method includes:

[0053] S201. Glycerin, propylene carbonate, sodium dodecyl sulfate and propanolamine are added to water in a mass ratio of 7:2:2:1 and heated in a water bath to 60°C to dissolve them completely and mix thoroughly to obtain a hot digestive solution.

[0054] S202. The active lime is crushed and sieved to obtain sieved active lime.

[0055] The active lime contains >86% calcium oxide and <5% magnesium oxide. The particle size of the sieved active lime is between 0.1 mm and 2 mm.

[0056] S203. The sieved material is added to a closed ultrasonic reactor containing hot digestion liquid to carry out the digestion reaction.

[0057] The digestion reaction was carried out at a temperature of 75°C for 6 hours.

[0058] S204. The reacted material is transferred to a vacuum dryer for drying to obtain a calcium-based desulfurizer.

[0059] S205. Grind and crush the dried sample.

[0060] The following simulates the composition of industrial silicon flue gas and uses a fixed-bed reactor to test the performance of sodium bicarbonate, ordinary calcium hydroxide, high specific surface area calcium hydroxide, and the calcium-based desulfurizer prepared in Example 2 of this invention.

[0061] Test method: SO2 concentration was detected using the MGA6 Plus flue gas analyzer from MRU, Germany.

[0062] Test conditions: Temperature 220℃, flue gas humidity 1%, O2 content 19%, CO2 content 3%, HCl concentration 200mg / Nm³ 3 SO2 concentration 800 mg / Nm 3 NO concentration 200 mg / Nm 3 Reaction space velocity 9000 h -1 The concentration of SO2 in the sulfur-containing flue gas was measured before and after treatment with the aforementioned desulfurizing agent. When the SO2 concentration reached 30 mg / m³, the concentration was determined. 3 The test was stopped at the designated time, the test duration was calculated, the increased sulfur and chlorine content in the desulfurization byproducts was analyzed, and the sulfur and chlorine capacities were calculated. The results are shown in Table 1.

[0063] Table 1 Performance test results of each desulfurizing agent

[0064]

[0065] As shown in Table 1, the calcium-based desulfurizer prepared using the method provided in this invention for preparing calcium-based dry desulfurizers for industrial silicon smelting flue gas has a significantly larger specific surface area, sulfur capacity, and chlorine capacity than the calcium-based desulfurizers prepared by the other three methods, exhibiting excellent adsorption capacity and sulfur and chlorine capacity. It can be widely applied to desulfurization treatment of industrial silicon flue gas with low water content.

[0066] Example 3

[0067] Embodiment 3 of the present invention provides a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, which is prepared by any of the above-described methods for preparing calcium-based dry desulfurizing agents for industrial silicon smelting flue gas.

[0068] Compared with the prior art, the present invention has at least the following beneficial effects:

[0069] 1. In the digestive fluid used in this invention, the carboxyl functional groups of propylene carbonate, the hydroxyl groups of alcohols, and the amino and hydroxyl groups of amines can interact to form hydrogen bonds. The resulting network structure material can serve as a dispersant and stabilizer for nanomaterials, thereby preventing the aggregation of nano-calcium hydroxide.

[0070] 2. The propylene carbonate used in this invention has a strong adsorption capacity for carbon dioxide, and its ester functional groups can react with H+. + Rapid reaction can improve the absorption pathways of HCl, CO2, and SO2. Furthermore, sodium-based additives, adhering to the interior and surface of the pores, can reduce the diffusion resistance of HCl, CO2, and SO2, thereby increasing their saturated adsorption capacity.

[0071] 3. The active lime in this invention contains a certain amount of magnesium oxide. Therefore, the calcium-based desulfurizer prepared contains magnesium hydroxide, which has a skeletal structure function and can prevent byproducts such as calcium sulfate, calcium chloride, and calcium carbonate from clogging the pore structure.

[0072] 4. The hot digestion solution prepared in this invention, compared with the room temperature digestion solution, can, on the one hand, ensure uniform mixing of the components, and on the other hand, improve the activation properties of each component. Although increasing the temperature accelerates the digestion rate of calcium oxide, it also accelerates the penetration of the component solutions into the particles to form bonds, thereby slowing down the digestion reaction rate of calcium hydroxide.

[0073] 5. The use of an ultrasonic reactor in this invention facilitates the formation of nano-calcium hydroxide. The ultrasonic action helps to further reduce the particle size of the active lime before the reaction and also helps to inhibit the crystallization of calcium hydroxide, thus avoiding the formation of large particles.

[0074] 6. The negative pressure environment of vacuum drying in this invention helps calcium-based desulfurizer form a more complete pore structure, avoiding pore collapse caused by high-temperature drying at normal pressure.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, characterized in that, The method includes: Propylene carbonate, alcohol, alkanolamine and sodium-based additives are added to water and heated until completely dissolved and thoroughly mixed to obtain a hot digestive solution; Crushed quicklime is added to the hot digestion liquid and digested in an ultrasonic reactor to obtain an intermediate product; the quicklime contains magnesium oxide. The intermediate product was dried under vacuum to obtain a calcium-based desulfurizer.

2. The method according to claim 1, characterized in that, The alcohol is one or more of ethanol, propylene glycol, or glycerol; the amine is one or more of triethanolamine, diethanolamine, propanolamine, or butanolamine; and the sodium-based additive is one or more of sodium tripolyphosphate, sodium dodecyl sulfate, sodium chloride, or sodium carbonate.

3. The method according to claim 1, characterized in that, The active lime contains >80% calcium oxide and <10% magnesium oxide; the temperature of the hot digestion liquid is 30~60℃.

4. The method according to claim 1, characterized in that, Before adding the crushed quicklime to the hot digestion liquid, the method further includes: Dolomite and limestone are mixed and then lightly burned to obtain active lime.

5. The method according to claim 1, characterized in that, The components, by weight, are: 85-93 parts quicklime; 1-2 parts propylene carbonate; 5-10 parts alcohol; 0.1-1 parts alkanolamine; and 1-2 parts additives.

6. The method according to claim 1, characterized in that, The digestion reaction temperature is 70~90℃, and the time is 1-9h; the mass ratio of the hot digestion liquid to the active lime is 0.6-1.

5.

7. The method according to claim 1, characterized in that, The particle size of the activated lime is 0.1 mm to 10 mm, and the activity of the activated lime is greater than 300 ml based on 4 mol / L hydrochloric acid.

8. The method according to claim 1, characterized in that, The ultrasonic reactor is a closed ultrasonic reactor with a power of 200-1500w.

9. The method according to claim 1, characterized in that, The vacuum drying process involves a vacuum level of -0.08 MPa, a temperature of 60℃-120℃, and a time of 1-3 hours.

10. A calcium-based dry desulfurizing agent for industrial silicon smelting flue gas, characterized in that, It is prepared using the method described in any one of claims 1-9 for preparing calcium-based dry desulfurizing agent for industrial silicon smelting flue gas.

Images