Preparation method of high-activity calcium-based desulfurizer and application thereof

Abstract

The application discloses a preparation method of high-activity calcium-based desulfurizer and application thereof, and belongs to the technical field of industrial solid waste recycling. In view of the problems of single desulfurization active center, low desulfurization efficiency and high preparation cost of the calcium-based desulfurizer at present, the limestone, blast furnace slag and phosphorus iron slag are fully ground, then are calcined, and then a dispersion liquid containing an additive is added to carry out digestion reaction, so that the high-activity calcium-based desulfurizer is obtained through drying. The preparation method of the calcium-based dry desulfurizer can not only greatly reduce the safety risk of enterprise blast furnace slag and phosphorus iron slag solid waste stacking and the later treatment cost, but also can change waste into treasure, introduce additional desulfurization active center into the calcium-based desulfurizer, and improve the desulfurization efficiency.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste recycling technology, specifically relating to a method for preparing a highly active calcium-based desulfurizing agent and its application. Background Technology

[0002] Blast furnace slag, the slag discharged during the ironmaking process in a blast furnace, is a type of industrial solid waste. Blast furnace slag can be classified into steelmaking pig iron slag, foundry pig iron slag, and manganese iron ore slag, among others. The main chemical components of blast furnace slag are calcium oxide, magnesium oxide, silicon dioxide, aluminum oxide, and manganese oxide, while special pig iron slags also contain titanium dioxide and vanadium pentoxide. Phosphorus iron slag is a waste product generated during the smelting of phosphate iron ore. Its main components are iron oxide, phosphorus oxide, and small amounts of silicates. The iron oxide content is as high as 60% or more.

[0003] Sulfur dioxide (SO2) is the most common, simplest, and most irritating sulfur oxide, and one of the major air pollutants. Its main sources are the combustion of sulfur-containing fossil fuels such as coal and oil, as well as the incomplete combustion of waste such as household garbage. Sulfur dioxide is listed as a Group 3 carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization. Sulfur dioxide is readily soluble in water, forming sulfurous acid. Further oxidation of sulfurous acid rapidly and efficiently produces sulfuric acid, a major component of acid rain, which can lead to various respiratory diseases and cancers. To effectively control sulfur dioxide emissions, my country has adopted methods such as "using low-sulfur fuels," "fuel desulfurization," "fuel process desulfurization," and "flue gas desulfurization." Among these, "flue gas desulfurization" is currently the most important and effective treatment method.

[0004] Based on the morphological characteristics of desulfurizing agents and products, flue gas desulfurization is generally classified into wet, dry, and semi-dry methods. There are many types of flue gas desulfurizing agents, and their desulfurization principle involves an acid-base chemical reaction between the agent and sulfur dioxide. Their advantages include simple systems, low investment costs, small footprint, and the reaction products being in dry powder form. In the field of flue gas desulfurization, calcium-based desulfurizing agents are widely used due to their wide availability, low price, and the ease of storage, transportation, and reuse of desulfurization products. However, ordinary calcium hydroxide has a low specific surface area, small pore volume and pore size, and a single desulfurization active center. As the desulfurization reaction proceeds, the pores of calcium hydroxide become blocked by desulfurization products such as calcium sulfite and calcium sulfate, preventing other sulfur dioxide molecules from continuing to contact and react with the calcium hydroxide surface, significantly reducing desulfurization efficiency. Summary of the Invention

[0005] To address the problems of low desulfurization efficiency and high preparation cost of current calcium-based desulfurizers due to their single desulfurization active center, this invention provides a method for preparing a highly active calcium-based desulfurizer and its application.

[0006] To achieve the above objectives, the present invention employs the following technical solutions: A highly active calcium-based desulfurizing agent, wherein the specific surface area of ​​the highly active calcium-based desulfurizing agent is 40.28 m². 2 / g~48.28m 2 / g, pore size 7.62nm~9.58nm; pore volume 0.153cm³ 3 / g~0.168cm 3 / g, sulfur dioxide removal rate is 94.16%~97.72%.

[0007] A method for preparing a highly active calcium-based desulfurizing agent includes the following steps: Step (a): Limestone, blast furnace slag and ferrophosphate slag are added to a ball mill and ground thoroughly to obtain a mixed powder, which is then added to a muffle furnace for calcination to obtain a mixture. Step (b): Add the additive to water and stir quickly to disperse it evenly to obtain a dispersion. Step (c) involves adding the dispersion obtained in step (b) to the mixture obtained in step (a), then adding it to a digestion reactor for digestion, and finally drying it to obtain a highly active calcium-based desulfurizer.

[0008] Furthermore, the amounts of limestone, blast furnace slag, ferrophosphate slag, and additives used in steps (a) and (b) are as follows, by weight: limestone 20-50 parts; blast furnace slag 5-20 parts; ferrophosphate slag 10-30 parts; additives 1-5 parts.

[0009] Furthermore, the additive is one or more of sodium tripolyphosphate, sodium pyrophosphate, sodium dodecyl sulfate, sodium methacrylate, or sodium styrene sulfonate.

[0010] Furthermore, the particle size of the mixed powder in step (a) must be less than 150 mesh.

[0011] Furthermore, in step (a), the temperature for calcination in the muffle furnace is 500℃~900℃, and the calcination time is 4 hours~8 hours.

[0012] Furthermore, in step (c), the mixture is added to a digestion reactor for digestion, specifically using a jacketed stirred digester with a stirring speed of 1200 rpm to 1500 rpm.

[0013] Furthermore, in step (c), the drying temperature is 150℃~200℃, and the drying time is 1~5 h.

[0014] The application of a highly active calcium-based desulfurizing agent in flue gas desulfurization is characterized by: the flue gas desulfurization scenario being SO2 < 1200 mg / Nm³. 3 The flue gas temperature is 25~230℃.

[0015] Compared with the prior art, the present invention has the following advantages: (1) This invention significantly reduces the safety risks of solid waste disposal of blast furnace slag and ferrophosphate slag by adding roasted and ground blast furnace slag and ferrophosphate slag during lime digestion, avoids subsequent processing procedures, and effectively reduces costs. The iron oxide, manganese oxide, and other oxides produced after roasting blast furnace slag and ferrophosphate slag provide additional desulfurization active sites for calcium-based desulfurizers, which helps to improve the desulfurization efficiency of calcium-based desulfurizers.

[0016] (2) Adding special functional additives during the digestion reaction promotes the dispersion of calcium hydroxide particles and blast furnace slag and iron phosphate slag roasted particles, thereby improving the stability of the powder structure. The hydrophilic side chains on the surface of the added additive molecules have a strong steric hindrance effect, which increases the specific surface area of ​​the calcium-based desulfurizer and improves the pore size and pore volume, thus further improving the removal efficiency of SO2 from flue gas by the calcium-based desulfurizer. Detailed Implementation

[0017] To gain a deeper understanding of this invention, we will provide a comprehensive and detailed description. However, this invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a full understanding of the disclosure of this invention.

[0018] Example 1

[0019] Weigh 380 g of quicklime and 95 g of blast furnace slag, mix and grind to 200 mesh, place in a muffle furnace, and calcine at 500℃ for 5 h. Add 19.5 g of sodium tripolyphosphate (an auxiliary agent) to 168 g of tap water, and ultrasonically disperse for 10 minutes. Add the quicklime and dispersion to a digestion reactor. The initial temperature of the digestion reactor is 25℃. Start stirring at 1200 rpm and digest for 15 minutes. Dry the digested material at 150℃ for 1 h. A highly active calcium-based desulfurizer with a specific surface area of ​​40.28 m² is obtained. 2 / g, pore size 8.44 nm, pore volume 0.168 cm³ 3 / g, sulfur dioxide removal rate 98.73%.

[0020] Example 2

[0021] Weigh 380 g of quicklime and 55 g of ferrophosphate slag, mix and grind to 200 mesh, place in a muffle furnace, and calcine at 600℃ for 4 h. Add 24.5 g of sodium pyrophosphate additive to 168 g of tap water, and ultrasonically disperse for 10 minutes. Add the quicklime and dispersion to a digestion reactor. The initial temperature of the digestion reactor is 25℃. Start stirring at 1300 rpm and digest for 15 minutes. Dry the digested material at 170℃ for 2 h. A highly active calcium-based desulfurizer with a specific surface area of ​​42.29 m² is obtained. 2 / g, pore size 8.35 nm, pore volume 0.153 cm³ 3 / g, sulfur dioxide removal rate 97.16%.

[0022] Example 3

[0023] Weigh 380 g of quicklime, 65 g of blast furnace slag, and 55 g of ferrophosphate slag, mix and grind to 300 mesh, place in a muffle furnace, and calcine at 650℃ for 4.5 h. Add 12.0 g of sodium pyrophosphate and 15.8 g of sodium dodecyl sulfate to 190 g of tap water, and ultrasonically disperse for 10 minutes. Add the quicklime and dispersion to a digestion reactor. The initial temperature of the digestion reactor is 25℃. Start stirring at 1300 rpm and digest for 15 minutes. Dry the digested material at 200℃ for 3 h. A highly active calcium-based desulfurizer with a specific surface area of ​​45.48 m² is obtained. 2 / g, pore size 9.12 nm, pore volume 0.167 cm³ 3 / g, sulfur dioxide removal rate 98.89%.

[0024] Example 4

[0025] Weigh 420 g of quicklime, 39 g of blast furnace slag, and 78 g of ferrophosphate slag, mix and grind to 280 mesh, place in a muffle furnace, and calcine at 800℃ for 5 h. Add 29.5 g of sodium styrene sulfonate as an auxiliary agent to 170 g of tap water, and ultrasonically disperse for 10 minutes. Add the quicklime and dispersion to a digestion reactor. The initial temperature of the digestion reactor is 25℃. Start stirring at 1500 rpm and digest for 25 minutes. Dry the digested material at 200℃ for 1 h. A highly active calcium-based desulfurizer with a specific surface area of ​​48.28 m² is obtained. 2 / g, pore size 9.58 nm, pore volume 0.165 cm³ 3 / g, sulfur dioxide removal rate 97.72%.

[0026] Example 5

[0027] Weigh 520 g of quicklime, 120 g of blast furnace slag, and 45 g of ferrophosphate slag, mix and grind to 200 mesh, place in a muffle furnace, and calcine at 900℃ for 7 h. Add 19.5 g of sodium dodecyl sulfate and 21.8 g of sodium methacrylate to 140 g of tap water, and ultrasonically disperse for 20 minutes. Add the quicklime and dispersion to a digestion reactor. The initial temperature of the digestion reactor is 25℃. Start stirring at 1450 rpm and digest for 10 minutes. Dry the digested material at 180℃ for 2 h. A highly active calcium-based desulfurizer with a specific surface area of ​​43.73 m² is obtained. 2 / g, pore size 7.62 nm, pore volume 0.153 cm³ 3 / g, sulfur dioxide removal rate 99.28%.

[0028] Comparative Example 1 Weigh 560 g of quicklime, grind it to 200 mesh, place it in a muffle furnace, calcine it at 900℃ for 7 h, add 165 g of tap water, add the quicklime and dispersion to the digestion reactor, the initial temperature of the digestion reactor is 25 ℃, start stirring, the speed is 1400 r / min, and after digestion for 15 minutes, calcium hydroxide powder is obtained.

[0029] The target product, calcium hydroxide powder, has a specific surface area of ​​29.17 m². 2 / g, pore size 4.64 nm, pore volume 0.034 cm³ 3 / g, sulfur dioxide removal rate 62.5%.

[0030] The calcium-based dry desulfurizing agent preparation method adopted in this invention can not only greatly reduce the safety risks and subsequent treatment costs of blast furnace slag and ferrophosphate slag solid waste stockpiling in enterprises, but also turn waste into treasure by introducing additional desulfurization active centers into the calcium-based desulfurizing agent, thereby improving desulfurization efficiency.

[0031] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A highly active calcium-based desulfurizing agent, characterized in that, By weight, the raw materials for its preparation include 20-50 parts limestone; 5-20 parts blast furnace slag; 10-30 parts ferrophosphate slag; and 1-5 parts additives. The additive is one or more of sodium tripolyphosphate, sodium pyrophosphate, sodium dodecyl sulfate, sodium methacrylate, or sodium styrene sulfonate.

2. The highly active calcium-based desulfurizer according to claim 1, characterized in that: The specific surface area of ​​the highly active calcium-based desulfurizer is 40.28 m². 2 / g~48.28m 2 / g, pore size 7.62nm~9.58nm; pore volume 0.153cm³ 3 / g~0.168cm 3 / g, sulfur dioxide removal rate is 94.16%~97.72%.

3. A method for preparing a highly active calcium-based desulfurizing agent, characterized in that: Prepared using the following steps: Step (a): Limestone, blast furnace slag and ferrophosphate slag are added to a ball mill and ground thoroughly to obtain a mixed powder, which is then added to a muffle furnace for calcination to obtain a mixture. Step (b): Add the additive to water and stir quickly to disperse it evenly to obtain a dispersion. Step (c): Add the dispersion obtained in step (b) to the mixture obtained in step (a), then add it to the digestion reactor for digestion reaction, and then dry it to obtain a highly active calcium-based desulfurizer; The particle size of the mixed powder in step (a) must be less than 150 mesh; the temperature of adding the powder to the muffle furnace for calcination in step (a) is 500℃~900℃, and the calcination time is 4 hours~8 hours. In step (c), the contents are added to a digestion reactor for digestion, specifically a jacketed stirred digester with a stirring speed of 1200 rpm to 1500 rpm; in step (c), the drying temperature is 150℃ to 200℃ and the drying time is 1 to 5 hours. The additive is one or more of sodium tripolyphosphate, sodium pyrophosphate, sodium dodecyl sulfate, sodium methacrylate, or sodium styrene sulfonate.

4. The preparation method of the highly active calcium-based desulfurizer according to claim 3, characterized in that: The amounts of limestone, blast furnace slag, ferrophosphate slag, and additives used in steps (a) and (b) are as follows by weight: limestone 20-50 parts; blast furnace slag 5-20 parts; ferrophosphate slag 10-30 parts; additives 1-5 parts.

5. The application of a highly active calcium-based desulfurizer as described in any one of claims 1 to 2 in flue gas desulfurization, characterized in that: Flue gas desulfurization scenario: SO2 < 1200 mg / Nm 3 The flue gas temperature is 25~230℃.