A detoxifying protective agent for blast furnace gas hydrolysis liquid and its preparation method

Abstract

The present invention discloses a liquid detoxification protective agent for blast furnace gas hydrolysis and its preparation method. This protective agent addresses the short service life and rapid activity loss of organic sulfur hydrolysis catalysts in ultra-low blast furnace gas emission processes, addressing the complex composition and high impurity content of blast furnace gas. The liquid-phase detoxification protective agent is developed. The detoxification protective agent uses a water-soluble metal complex as an active ingredient, along with additives and stabilizers. It exhibits strong deacidification activity, effectively removing acid gases and anhydride gases from blast furnace gas, and improving the stability and lifespan of the hydrolysis catalyst.

Description

Technical Field

[0001] The present invention relates to the field of blast furnace gas purification in the steel industry, and in particular to a blast furnace gas hydrolysis liquid detoxification protective agent and a preparation method thereof. Background Art

[0002] Blast furnace gas (BFG) is a combustible byproduct of the blast furnace smelting process. Its primary components are CO, CO₂, N₂, H₂, and hydrocarbons, along with small amounts of HCl, H₂S, organic sulfur (primarily COS), and dust. BFG gas has a low calorific value and a high gas volume. Purification of BFG gas addresses two key issues: dust removal and desulfurization.

[0003] Dry dust removal technology offers numerous advantages, including water conservation, environmental protection, high dust removal efficiency, reduced production costs, and the ability to utilize sensible heat from coal gas for power generation. Consequently, it is widely adopted in blast furnace dust removal systems at major steel companies. Compared to wet dust removal, dry dust removal technology cannot absorb acidic gases such as HCl, HF, HBr, and HCN from blast furnace gas, leading to acid corrosion in piping systems, TRTs, and hot blast furnaces. Within two months to a year of adopting dry dust removal, steel companies such as Baotou Steel, Jinan Steel, Taiyuan Iron and Steel, and Wuhan Iron and Steel all experienced severe pipeline corrosion, gas leaks, TRT scaling, and damage to refractory bricks in their hot blast furnaces.

[0004] In addition to being used as fuel for the hot blast furnaces within the blast furnace system, a large amount of surplus gas is also used as fuel for TRT power generation, boiler steam power generation, coking ovens, heating furnaces, soaking pits, and steel rolling heating furnaces. Currently, blast furnace gas desulfurization mostly uses end-of-pipe treatment to remove SO2 from flue gas, which has disadvantages such as dispersed user sites, repeated investment, high operating costs, and difficult treatment. Front-end comprehensive treatment desulfurization has become a hot topic, and the COS content in blast furnace gas is as high as 250mg / Nm 3Therefore, the removal of COS is the focus and difficulty of the process. There are generally two options for the removal of COS: hydrolysis and hydrogenolysis. Hydrogenolysis is the conversion of COS into H2S through a hydrogenation process, and then the use of conventional metal oxides to remove H2S to achieve the purpose of COS removal. The chemical reaction equation for COS hydrogenation is: COS+H2=H2S+CO, which is usually carried out at 350-400°C, which increases energy consumption and high operating costs; the reaction needs to be carried out under the action of Co-Mo or Fe-Mo presulfurized catalysts. When the catalyst is used in oxygen-containing blast furnace gas, desulfurization is inevitable, resulting in unsustainable activity. Due to the above two shortcomings, the hydrogenation process cannot be used for blast furnace gas COS removal. The hydrolysis process is that COS reacts with H2O under the action of a catalyst to convert it into H2S. The reaction equation is: COS+H2O=H2S+CO2. Its advantage is that the reaction can be carried out at low temperature. At 60℃, more than 90% of COS can be converted into H2S. Although increasing the temperature can improve the conversion rate to a certain extent, this reaction is controlled by thermodynamics. The higher the temperature, the lower the equilibrium conversion rate. The single COS conversion rate generally does not exceed 95%. In order to improve the removal rate of COS, it is necessary to adopt a multi-stage hydrolysis method to remove the hydrogen sulfide produced by the first hydrolysis. After breaking the hydrolysis equilibrium, it enters the second hydrolysis and re-establishes a new equilibrium. This process is repeated until COS is reduced to less than 0.1 mg / Nm 3 The active ingredient of the hydrolysis catalyst is alkaline and is afraid of acidic gases and anhydride gases, so deacidification is required before hydrolysis.

[0005] Jiujiang Wire & Rod, Qinhuangdao Hongxing, Shanxi Hongda, and other steel mills use a process called "bag dust removal - dry dechlorination - medium-temperature hydrolysis to remove organic sulfur - TRT turbine power generation - iron oxide to remove inorganic sulfur" to control HCl and sulfide emissions at the source, thus avoiding acid corrosion. This process has some issues. Fixed-bed dechlorinators use metal oxides and hydroxides as active ingredients, resulting in low chlorine penetration capacity. The medium-temperature hydrolysis catalyst is easily deactivated by chlorine poisoning, resulting in a short operating cycle. Field sampling and analysis revealed that the hydrolysis catalyst contains chloride, bromide, fluoride, hydrocyanate, nitrate, nitrite, sulfate, and sulfite. The primary cause of hydrolysis agent deactivation is acid poisoning, indicating that fixed-bed dechlorinators cannot effectively remove acidic gases and anhydride gases from the gas phase.

[0006] In the article "Discussion on the Evaluation of Dechlorination Effectiveness of Soda-Spray Towers for Blast Furnace Dry Gas," the article reports that despite installing a soda-spray tower after bag-type dust removal, corrosion and cracking of the gas and hot air ducts continued to occur. The article evaluated the dechlorination effectiveness of the soda-spray tower by measuring the chlorine content in the gas before and after the soda-spray tower. The results showed that the dry dust removal-soda-spray tower process removes 10% to 70% of the chlorine from the gas, posing a risk of corrosion to equipment in downstream processes. Patent CN104774654B discloses a method for using a dechlorinating agent for blast furnace gas. The agent is prepared using industrial limestone, commercial sodium carbonate, and potassium hydroxide as raw materials. Under the evaluation conditions of a blast furnace gas flow rate of 5 L / min and an HCl concentration of 1000 ppm, the chlorine content ranges from 5.85% to 5.91%. Patent CN114392643B discloses a method for preparing a dechlorinating agent for blast furnace gas. The dechlorinating agent is prepared from blast furnace slag, steel slag, fly ash, desulfurization ash, calcium hydroxide, and an organic binder. The main active ingredient is calcium hydroxide, and the chlorine capacity is between 22.9% and 34.5%. Carbon dioxide readily reacts with calcium hydroxide to form calcium carbonate, which competes with hydrogen chloride for adsorption during the reaction between hydrogen chloride and calcium hydroxide. Furthermore, the carbon dioxide content in coal gas is much higher than the amount of acidic gases, resulting in low hydrogen chloride removal accuracy. Furthermore, the calcium carbonate formed by the reaction of carbon dioxide and calcium hydroxide easily clogs the pores of the dechlorinating agent, hindering the continued reaction of acidic gases with calcium hydroxide and causing a significant decrease in chlorine capacity. In the laboratory's chlorine capacity evaluation system, the national standard GB / T38108-2019 (Test method for chlorine capacity of alkaline earth metal high-temperature dechlorinating agents) requires that the gas phase composition be hydrogen chloride and nitrogen, and the hydrogen chloride content be 20-25g / cubic meter, which is much higher than the hydrogen chloride content in blast furnace gas. Therefore, the impact of carbon dioxide on chlorine capacity is easily overlooked.

[0007] In view of this, a blast furnace gas hydrolysis liquid detoxification protective agent is developed to remove acidic and anhydride gases in the gas phase, which can not only protect the pipeline system and TRT power generation equipment, but also comprehensively purify the blast furnace gas at the front end to reduce environmental protection investment, making the comprehensive utilization of blast furnace gas more economical and green. Summary of the Invention

[0008] The present invention aims to solve the corrosion and purification problems encountered in the comprehensive utilization of blast furnace gas. To achieve the above object, the present invention provides a blast furnace gas hydrolysis liquid detoxification protective agent and a preparation method thereof, the technical solution adopted is:

[0009] The active ingredient is a metal complex; the auxiliary agents are triethanolamine and N-methyldiethanolamine in a mass ratio of 2:1; the stabilizer is N,N-dimethylformamide; the metal complex is a calcium, iron, and magnesium complex solution; the mass ratio of the metal complex solution, auxiliary agent, and stabilizer is 80:15:5; and the preparation method is as follows:

[0010] S1: Place the eggshells in a muffle furnace, calcine them at 800-900°C in an oxygen atmosphere for 0.5-2 hours, air-quench, and crush them to 200 mesh to obtain calcium powder; slowly add the calcium powder into cold water, stir and mix until evenly mixed to obtain calcium slurry; the mass ratio of calcium powder to water is 1:3;

[0011] S2: Add ethanol to water, stir and mix, then add fulvic acid and fulvic acid, stir and dissolve, and filter to obtain an organic solution; the organic solution has an ethanol mass concentration of 10%, a fulvic acid mass concentration of 30%, and a fulvic acid mass concentration of 20%; add ferric hydroxide and magnesium hydroxide powders to the organic solution in a certain proportion, heat to 50-60°C, condense and reflux, stir and react for 1-2 hours, and cool to obtain an iron-magnesium complex solution; the mass ratio of the organic solution, ferric hydroxide, and magnesium hydroxide is 10:2:1;

[0012] S3: mixing the calcium slurry and the iron-magnesium complex solution in a certain mass ratio, heating to 45-55°C, condensing and refluxing, stirring and reacting for 1-2 hours, filtering to obtain an aqueous solution of the calcium, iron and magnesium complex; washing the filter cake with water, using the washing liquid to prepare the organic solution described in S2, and recycling the filter residue to the calcium slurry described in S1; the mass ratio of the calcium slurry to the iron-magnesium complex solution is 1.2:1;

[0013] S4: adding a stabilizer to the calcium, iron and magnesium complex solution, mixing well, then adding an auxiliary agent, mixing well, to obtain a liquid detoxification protective agent.

[0014] The eggshells are derived from discarded chicken eggshells and duck eggshells from food processing plants and hatcheries.

[0015] The pH value of the liquid detoxifying protective agent is 7-8.

[0016] The role of the ethanol is as follows: in the organic solution, ethanol acts as a co-solvent for dissolving fulvic acid and fulvic acid in water, thereby improving the solubility of fulvic acid and fulvic acid in water, increasing the stability and permeability of the organic solution, making the complex reaction more rapid and the organic matter reaction more complete; when the liquid phase detoxification protective agent is sprayed into the pipeline before the bag dust collector, the boiling point of ethanol is lower than the temperature of blast furnace gas and it can be instantly vaporized, driving the organic phase with a high boiling point to disperse and atomize.

[0017] The detoxification protective agent is sprayed into the blast furnace gas pipeline in liquid phase, quickly atomized and fully mixed with the gas phase, and uses the pipeline as a fluidized bed to capture acidic gas and acid anhydride gas in the gas phase and react with them to form salts; unreacted complexes are adsorbed on dust particles and intercepted by bag dust collectors to form a fixed bed deacidification layer, and the blast furnace gas passes through the bed layer to achieve deacidification again.

[0018] The liquid phase detoxification protective agent is added to the pipeline before the bag dust collector, and then quickly atomized and adsorbed on the blast furnace gas dust. The ultrafine dust particles provide a large contact area for the detoxification catalyst. The acid gas and anhydride gas in the blast furnace gas react with the calcium, magnesium and iron organic complexes in the dust to generate stable chlorine compounds that are adsorbed on the dust, and the poisons are removed through the bag dust collector.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention provides a liquid detoxification protective agent for blast furnace gas hydrolysis and a preparation method thereof. Compared with solid dechlorinating agents, the liquid deacidifying agent, which contains water-soluble complexes of calcium, iron, and magnesium as active substances, contacts blast furnace gas more fully in an atomized form, allowing the metal complex to react more thoroughly with acidic gases and acid anhydride gases. Furthermore, the metal complex has excellent deacidification activity and high deacidification accuracy.

[0021] 2. The present invention provides a detoxifying protective agent for blast furnace gas hydrolysis liquid and a preparation method thereof. Triethanolamine and N-methyldiethanolamine are used as auxiliary agents. Their first function is to directly react with acidic gases to form amide salts. Their second function is to decompose ammonia at a temperature of 80°C or higher. Ammonia and acidic gases can also react to form solid ammonium salts. Their third function is that they have a high boiling point and are not easily completely vaporized and pass through the bag filter. Instead, they capture the acidic gases in the gas phase in the form of mist and adsorb them on the dust before entering the bag filter. This increases the contact time between the acidic gases and the dust, stimulating oxides such as calcium oxide, iron oxide, zinc oxide, sodium oxide, potassium oxide, and magnesium oxide in the dust to directly react with the acidic gases.

[0022] 3. The present invention provides a blast furnace gas hydrolysis liquid detoxification protective agent and its preparation method. The eggshell is roasted to remove organic matter inside the eggshell, converting the eggshell into calcium oxide with a rich pore structure. The eggshell is brittled by quenching. The porous eggshell powder is conducive to pulping with water and is easy to react with organic matter. Iron hydroxide and magnesium hydroxide powders are first reacted and complexed with an excess of organic acid solution, which is conducive to improving the utilization rate of iron and magnesium metals. A large amount of calcium slurry is then added to react and complex with the remaining organic solution. The organic acid can be fully utilized, and the excess calcium slurry is filtered and recovered without wasting resources. The organic acid solution contains fulvic acid and fulvic acid, which can form stable water-soluble metal complexes with iron, magnesium, and calcium. Ethanol enhances the stability and permeability of the solution, making the complex reaction more rapid and the organic matter reaction more complete. Finally, triethanolamine and N-methyldiethanolamine are added to the metal complex solution to enhance the deacidification activity of the metal complex. The addition of water-miscible N,N-dimethylformamide helps stabilize the metal complex and auxiliary agent in the aqueous solution.

[0023] 4. The present invention provides a detoxifying and protective agent for blast furnace gas hydrolysis liquids and a preparation method thereof. The invention combines high- and low-boiling-point liquids. The additives triethanolamine and N-methyldiethanolamine have high boiling points, high viscosity, and are difficult to vaporize. They can be adsorbed in a bag filter dust collector in liquid form for long periods of time, continuously absorbing toxic acidic substances and anhydride gases. Ethanol, with its low boiling point, serves as a dispersant. When the liquid-phase detoxifying and protective agent is sprayed into the pipeline before the bag filter dust collector, the ethanol, with its boiling point lower than the blast furnace gas temperature, instantly vaporizes, driving the high-boiling-point additives and active ingredients to rapidly disperse and atomize, allowing the active ingredients to fully contact and react with the acidic and anhydride gases.

[0024] 5. The present invention provides a blast furnace gas hydrolysis liquid detoxification protective agent and a preparation method thereof, which uses eggshells, which are abundant, environmentally friendly, renewable and low-cost biomass materials, and humic acid extracts such as fulvic acid and fulvic acid as main raw materials, and prepares them into an organic complex liquid through a simple and controllable preparation process, thereby realizing the comprehensive resource utilization of discarded biomass eggshells, not only reducing the waste of biomass resources, but also achieving dual environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a simplified flow chart for the evaluation of the blast furnace gas deacidification side stream experiment.

[0026] Figure 1 1 is the feed pump, 2 is the inlet sampling tube, 3 is the nozzle, 4 is the drainage pipe with heating and insulation, 5 is the small bag dust collector, 6 is the outlet sampling tube, and 7 is the air pump. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The present invention provides a method for preparing a detoxifying protective agent for blast furnace gas hydrolysis liquid, comprising the following steps:

[0029] S1: Place the eggshells in a muffle furnace and roast them at 800-900°C in an oxygen atmosphere for 0.5-2 hours. Air-quench and crush to 200 mesh to obtain calcium powder. Slowly add the calcium powder to cold water, stir and mix thoroughly to obtain a calcium slurry. The mass ratio of calcium powder to water is 1:3. If the mass ratio of calcium powder to water is too high, there will be problems. First, the calcium slurry is prone to overheating and boiling. Second, the calcium slurry is viscous and easily agglomerates when reacting with the iron-magnesium complex solution, resulting in precipitation of the iron-magnesium active component in the iron-magnesium complex solution. Conversely, if the mass ratio of calcium powder to water is too low, the concentration of the active component, the complexed calcium, will be directly reduced, affecting the deacidification activity.

[0030] S2 adds ethanol to water, stirs and mixes, then adds fulvic acid and fulvic acid, stirs and dissolves, and filters to obtain an organic solution; the ethanol mass concentration of the organic solution is 10%, the fulvic acid mass concentration is 30%, and the fulvic acid mass concentration is 20%; iron hydroxide and magnesium hydroxide powders are added to the organic solution in a certain proportion, heated to 50-60°C, condensed and refluxed, stirred to react for 1-2 hours, and cooled to obtain an iron-magnesium complex liquid; the mass ratio of the organic solution, iron hydroxide, and magnesium hydroxide is 10:2:1.

[0031] S3: Mix the calcium slurry and the iron-magnesium complex solution in a certain mass ratio, heat to 45-55°C, condense and reflux, stir and react for 1-2 hours, and filter to obtain an aqueous solution of calcium, iron and magnesium complex; wash the filter cake with water, and use the washing liquid to prepare the organic solution described in S2; the filter residue is recovered to the calcium slurry described in S1; the mass ratio of the calcium slurry to the iron-magnesium complex solution is 1.2:1.

[0032] S4: adding a stabilizer to the calcium, iron and magnesium complex solution, mixing well, then adding an auxiliary agent, mixing well, to obtain a liquid detoxification protective agent.

[0033] Specifically, in step S1, the mass ratio of calcium powder to water is 1:3. If the mass ratio of calcium powder to water is too high, there will be problems: first, the calcium slurry is prone to overheating and boiling; second, the calcium slurry is viscous and easily agglomerates when reacting with the iron-magnesium complex solution, resulting in precipitation of the iron-magnesium active component in the iron-magnesium complex solution; conversely, if the mass ratio of calcium powder to water is too low, it will directly lead to a low concentration of the effective component complex calcium, affecting the deacidification activity.

[0034] In step S2, the mass concentration of fulvic acid in the organic solution is 30%, the mass concentration of fulvic acid is 20%, and the mass concentration of ethanol is 10%. If the organic acid content in the organic solution is low, there will be problems: the complex reaction between the organic acid and the metal is incomplete, and the metal complex is unstable and easy to precipitate; on the contrary, if the organic acid content is high, the organic acid is easy to precipitate in the ethanol solution.

[0035] In step S2, the reaction temperature of the organic solution with the ferric hydroxide and magnesium hydroxide powders is 45-55°C, and in step S3, the reaction temperature of the calcium slurry with the iron-magnesium complex solution is 50-60°C. If the reaction temperature is low, the metal complex generated by the reaction of the organic solution and the metal object is likely to agglomerate to form a colloid, affecting its use; if the reaction temperature is high, ethanol is likely to volatilize and the reaction phase is likely to precipitate.

[0036] In step S3, the mass ratio of the calcium slurry to the iron-magnesium complex liquid is 1.2:1. If the mass ratio is too high, the pH of the reaction liquid phase will be too high, the amount of organic acid will be insufficient, and the product will contain a large amount of hydroxide precipitation, resulting in low activity and clogging of the nozzle during use.

[0037] The following describes a blast furnace gas hydrolysis liquid detoxification protective agent and a preparation method thereof provided by the present invention in conjunction with specific embodiments and comparative examples. Example 1

[0038] S1: Place the eggshells in a muffle furnace, roast them at 900°C in an oxygen atmosphere for 0.5h, air-quench, and crush them into 200 mesh to obtain calcium powder; slowly add the calcium powder into cold water at a liquid-solid mass ratio of 3:1, stir and beat, and mix well to obtain a calcium slurry.

[0039] S2: Add ethanol to water and stir to mix. Then add fulvic acid and fulvic acid, stir to dissolve, and filter to obtain an organic solution. The mass concentration of fulvic acid in the solution is determined to be 30%, the mass concentration of fulvic acid is 20%, and the mass concentration of ethanol is 10%. Iron hydroxide and magnesium hydroxide are added to the organic solution in a mass ratio of 10:2:1. Heat to 45°C, reflux under condensation, stir, and react for 2 hours. Cool to obtain an iron-magnesium complex solution.

[0040] S3: Mix calcium slurry and iron-magnesium complex solution at a mass ratio of 1.2:1, heat to 60°C, reflux under condensation, and react with stirring for 1 hour. Filter to obtain an aqueous solution of calcium, iron, and magnesium complex. Wash the filter cake with water, use the washing liquid to prepare the organic solution, and recycle the filter residue into the calcium slurry.

[0041] S4 Weigh 80 parts of the complex solution, add 5 parts of stabilizer N,N-dimethylformamide, mix well, then add 10 parts of triethanolamine and 5 parts of N-methyldiethanolamine, mix well, and obtain liquid detoxification protective agent A.

[0042] Comparative Example 1

[0043] This comparative example provides a liquid detoxifying protective agent B. In the preparation process S2 of the agent, deionized water is used instead of 40% ethanol aqueous solution to prepare the organic solution. The other preparation processes are the same as those in Example 1.

[0044] The differences between liquid detoxification protective agents A and B are as follows: 1. The concentrations of fulvic acid and fulvic acid in the organic solution S2 during the preparation process of liquid detoxification protective agent B are relatively low, with mass concentrations of 22.4% and 17.6%, respectively; 2. The mass of the filter cake S3 during the preparation process of liquid detoxification protective agent B is greater than that of A, indicating that the reaction between the calcium slurry and the iron-magnesium complex liquid is not complete, resulting in a low content of effective deacidification active components and poor activity; 3. During use, liquid detoxification protective agent A is easy to atomize, while liquid detoxification protective agent B is in the form of liquid droplets, which are easy to adhere to the wall of the pipe and have poor deacidification accuracy. Example 2

[0045] S1: Place the eggshells in a muffle furnace, roast them at 800°C in an oxygen atmosphere for 2 hours, air-quench, and crush them into 200 mesh to obtain calcium powder; slowly add the calcium powder into cold water at a liquid-solid mass ratio of 3:1, stir and beat, and mix well to obtain a calcium slurry.

[0046] S2: Add ethanol to water and stir to mix. Then add fulvic acid and fulvic acid, stir to dissolve, and filter to obtain an organic solution. The mass concentration of fulvic acid in the solution is determined to be 30%, the mass concentration of fulvic acid is 20%, and the mass concentration of ethanol is 10%. Add ferric hydroxide and magnesium hydroxide to the organic solution in a mass ratio of 10:2:1. Heat to 55°C, reflux under condensation, stir, and react for 1 hour. Cool to obtain an iron-magnesium complex solution.

[0047] S3: Mix calcium slurry and iron-magnesium complex solution in a mass ratio of 1.2:1, heat to 50°C, reflux under condensation, and react with stirring for 2 hours. Filter to obtain an aqueous solution of calcium, iron, and magnesium complex. Wash the filter cake with water, use the washing liquid to prepare the organic solution, and recycle the filter residue to the calcium slurry.

[0048] S4 weighed 80 parts of the complex solution, added 5 parts of the stabilizer N,N-dimethylformamide, mixed evenly, then added 10 parts of the auxiliary agents triethanolamine and 5 parts of N-methyldiethanolamine, mixed evenly, to obtain a liquid detoxification protective agent C.

[0049] Comparative Example 2

[0050] This comparative example provides a liquid detoxifying protective agent D. In the preparation process S4 of the agent, 80 parts of the complex solution are weighed, 5 parts of the stabilizer N,N-dimethylformamide are added, and the mixture is mixed evenly. Then, 15 parts of deionized water are added instead of the auxiliary agents triethanolamine and N-methyldiethanolamine, and the mixture is mixed evenly. The other preparation processes are the same as those in Example 2.

[0051] The differences between liquid detoxification protective agents C and D are as follows: when in use, liquid detoxification protective agent C is in mist form and has a good deacidification effect, while contrast agent D is sprayed into the pipeline liquid phase and quickly atomized, and then vaporizes and precipitates metal complexes that adhere to the inner wall of the pipeline and the surface of dust, continuously capturing reduced deacidification activity and easily causing pipeline blockage.

[0052] In order to further compare the removal effects of liquid detoxifiers A, B, C, D, sodium hydroxide solution and organic amine solution on acid gas and anhydride gas in blast furnace gas, a side stream experiment was conducted by draining blast furnace gas from the pipeline between gravity dust collector and bag dust collector as raw gas. Figure 1 As shown, on the main blast furnace gas pipeline with gravity dust removal and bag dust removal, a hole is opened to guide the blast furnace gas into the heat-insulated drainage pipe 4. The drainage pipe is equipped with inlet and outlet sampling pipes 2 / 6, a feed pump 1, a nozzle 3, a small bag dust collector 5, and an air pump 7. The specific steps are as follows:

[0053] The blast furnace gas enters the drainage pipe, and the temperature of the pipe and the small bag dust collector is adjusted to 120℃, with a gas volume of 50L / min. Samples are taken at the inlet and outlet to analyze the acid gas and anhydride gas content in the blast furnace gas. After the two are balanced, the detoxification protective agent is fed into the heat-insulated drainage pipe through the feed pump and nozzle at 1mL / min. After running smoothly for 1 hour, the acid gas and anhydride gas content at the inlet and outlet are measured every 30 minutes. The average value is taken for 3 measurements, and the stability is measured continuously. 24 hours is a cycle. After 24 hours, stop spraying the detoxification protective agent and detect the total concentration C of the acid gas and anhydride gas at the outlet. t The removal rate y is calculated according to the following formula:

[0054] y=[(C0-C t ) / C0]×100%

[0055] Where, C0, C t Respectively, the total concentrations of inlet and outlet acid gases and acid anhydride gases, in mg / m 3 .

[0056] The removal rates of acid gas and anhydride gas in blast furnace gas by detoxification protective agents A, B, C, D, sodium hydroxide solution and triethanolamine are shown in Table 1.

[0057] Table 1. Comparison of the effects of detoxification protective agents on deacidification of blast furnace gas

[0058] Serial number <![CDATA[C0]]> y stability A 86.6 99 24h no congestion B 85.8 62 3h pipe blockage C 87.2 99 24h no congestion D 86.4 74 24h no congestion Sodium hydroxide 86.5 43 1.5h Nozzle and pipe blockage triethanolamine 86.5 52 2h pipe blockage

[0059] Table 1 shows that detoxifying agents A and C have high removal rates for acidic and anhydride gases and exhibit no clogging. Detoxifying agents B and D have poor removal rates for these gases, with Detoxifying agent D exhibiting poor continuous operation. Sodium hydroxide and organic amine solutions have the lowest removal rates and are prone to clogging. Analysis of the clogging causes reveals that detoxifying agent B and the organic amine solution lack ethanol, making them less active and less likely to vaporize. This leads to a liquid phase within the pipeline, where it absorbs and accumulates dust in the gas phase, causing clogging. Sodium hydroxide solution is an aqueous solution, and at temperatures above the boiling point of water, the water evaporates rapidly, leading to sodium hydroxide crystallization on the nozzle and causing clogging. Further analysis of the purified gas composition at the outlet revealed that the organic amine solution only removes acidic gases such as hydrogen chloride and hydrocyanic acid from the gas phase, while having a low removal rate for anhydride gases such as nitrogen dioxide and sulfur dioxide.

[0060] After 24 hours, stop spraying the detoxification agent and detect the total concentration of acid gas and anhydride gas at the outlet. t The changes over time are shown in Table 2.

[0061] Table 2 Total concentration C of acid gas and anhydride gas t Changes over time t

[0062] <![CDATA[tC t ]]> 25 26 27 28 29 30 31 32 33 34 35 36 A 0.8 0.8 0.8 0.9 1.1 2.3 4.5 8.4 15.7 30.2 50.9 80.1 B 36.0 37.6 40.2 45.9 51.3 60.3 80.2 84.2 84.6 84.7 84.3 84.5 C 0.8 0.8 0.9 0.9 1.2 3.1 4.0 8.7 14.8 29.3 55.7 83.4 D 23.8 40.6 60.4 83.7 84.9 85.1 85.6 84.3 84.9 86.0 84.7 85.2 Sodium hydroxide solution 84.1 85.7 84.2 85.4 85.3 84.9 83.8 85.1 84.2 85.3 85.6 84.4 Triethanolamine solution 42.3 44.9 49.8 60.1 78.4 84.6 85.2 85.3 85.4 84.9 84.8 85.7

[0063] As can be seen from Table 2, after stopping the spraying of the detoxifying protective agent, detoxifying protective agents A and C can continue to efficiently remove acid gases and anhydride gases for 4 hours. After 4 hours, the removal rate gradually decreases until it loses activity, indicating that unreacted calcium, iron, and magnesium complexes are adsorbed on the dust particles to form a fixed bed deacidification layer, and the blast furnace gas passes through the bed layer to achieve deacidification again. Under the same conditions, after stopping the spraying of detoxifying protective agents B, D, and triethanolamine solution, the activity of removing acid gases and anhydride gases continues to decline. Protective agent B is mainly due to the lack of ethanol as an atomizing agent, and the dispersion of metal complexes in the bag dust collector bed is not high, resulting in low activity. Protective agent D is mainly due to the lack of the high-boiling-point auxiliary alcohol amine component, and its ability to capture acid gases and anhydride gases is low, resulting in low activity. Triethanolamine has good deacidification activity for 24-28 hours, but its low removal rate of anhydride gas leads to poor overall activity. For sodium hydroxide solution, the deacidification activity is lost immediately after the spraying is stopped. The main reason is that sodium hydroxide loses water and easily crystallizes, making it difficult to directly react with acidic gas and acid anhydride gas.

Claims

1. A method for preparing a blast furnace gas hydrolysis liquid detoxification protective agent, characterized in that: The active ingredient is a metal complex solution; the auxiliary agents are triethanolamine and N-methyldiethanolamine in a mass ratio of 2:1; the stabilizer is N,N-dimethylformamide; the mass ratio of the metal complex solution, auxiliary agent, and stabilizer is 80:15:5; the metal complex is a calcium, iron, and magnesium complex; and the preparation method is as follows: S1: Place the eggshells in a muffle furnace, calcine them at 800-900°C in an oxygen atmosphere for 0.5-2 hours, air-quench, and crush them to 200 mesh to obtain calcium powder; slowly add the calcium powder into cold water, stir and mix until evenly mixed to obtain calcium slurry; the mass ratio of calcium powder to water is 1:3; S2: Add ethanol to water, stir and mix, then add fulvic acid and fulvic acid, stir and dissolve, and filter to obtain an organic solution; the organic solution has an ethanol mass concentration of 10%, a fulvic acid mass concentration of 30%, and a fulvic acid mass concentration of 20%; add ferric hydroxide and magnesium hydroxide powders to the organic solution in a certain proportion, heat to 50-60°C, condense and reflux, stir and react for 1-2 hours, and cool to obtain an iron-magnesium complex solution; the mass ratio of the organic solution, ferric hydroxide, and magnesium hydroxide is 10:2:1; S3: mixing the calcium slurry and the iron-magnesium complex solution in a certain mass ratio, heating to 45-55°C, condensing and refluxing, stirring and reacting for 1-2 hours, filtering to obtain an aqueous solution of the calcium, iron and magnesium complex; washing the filter cake with water, using the washing liquid to prepare the organic solution described in S2, and recycling the filter residue to the calcium slurry described in S1; the mass ratio of the calcium slurry to the iron-magnesium complex solution is 1.2:1; S4: adding a stabilizer to the calcium, iron and magnesium complex solution, mixing well, then adding an auxiliary agent, mixing well, to obtain a liquid detoxification protective agent.

2. The method for preparing a blast furnace gas hydrolysis liquid detoxification protective agent according to claim 1, wherein: The pH value of the liquid detoxifying protective agent is 7-8.

3. The method for preparing a blast furnace gas hydrolysis liquid detoxification protective agent according to claim 1, wherein: The role of the ethanol described in S2 is: in the organic solution, ethanol acts as a co-solvent for dissolving fulvic acid and fulvic acid in water, thereby increasing the solubility of fulvic acid and fulvic acid in water, increasing the stability and permeability of the organic solution, making the complexation reaction more rapid and the organic matter reaction more complete; when the liquid phase detoxification protective agent is sprayed into the pipeline before the bag dust collector, the boiling point of ethanol is lower than the temperature of blast furnace gas and it can be vaporized instantly, driving the organic phase with a high boiling point to disperse and atomize.

4. The method for preparing a blast furnace gas hydrolysis liquid detoxification protective agent according to claim 1, wherein: The liquid detoxification protective agent is added to the pipeline before the bag dust collector, quickly atomizes and captures the poisonous acidic gas and acid anhydride gas in the blast furnace gas, reacts with calcium, iron and magnesium complexes to produce metal salts, and is filtered and intercepted by the bag dust collector; the unreacted calcium, iron and magnesium complexes are adsorbed on the dust particles to form a fixed bed deacidification layer, and the blast furnace gas passes through the bed layer to achieve deacidification again.

Images