Composite iron-aluminum oxide powder based on red mud, hydrolytic agent and preparation method of hydrolytic agent

Abstract

The invention provides composite iron-aluminum oxide powder based on red mud, a hydrolytic agent and a preparation method of the composite iron-aluminum oxide powder and the hydrolytic agent, and belongs to the technical field of solid waste treatment.The preparation method comprises the following steps that the red mud is ground and then cleaned, and pretreated red mud is obtained; digesting the pretreated red mud by using an acid solution, and filtering to obtain slurry containing Fe < 3 + > and Al < 3 + >; adding a surfactant into the slurry, stirring and dispersing, dropwise adding alkali liquor into the slurry, standing and precipitating after the stirring reaction is completed, and filtering to obtain a filter cake; drying, grinding and roasting the filter cake to obtain a roasted material; and modifying the roasted material by adopting potassium salt to obtain the composite iron-aluminum oxide powder. The red mud generated in the Al2O3 production process is adopted to prepare the blast furnace gas COS hydrolytic agent for fine desulfurization of the blast furnace gas, so that industrial solid waste is recycled as a green resource, the waste is treated by waste, the harm of the red mud to the environment is reduced, and the method is an effective way for reducing the cost and improving the efficiency of enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, and in particular to a composite iron-aluminum oxide powder based on red mud, a hydrolyzing agent and a preparation method thereof. Background Art

[0002] Red mud is an industrial solid waste discharged when the aluminum industry extracts Al2O3. It is called red mud because it contains a large amount of iron oxide and looks similar to red soil. According to the different Al2O3 production processes, red mud can be divided into sintering red mud, Bayer red mud and combined red mud. Its main components are Al2O3, Fe2O3, SiO2, CaO, etc. According to the characteristics of bauxite, process conditions and technical levels, about 1.0 to 1.8 tons of red mud are discharged for every ton of alumina produced. According to statistics, the total amount of red mud in the world has exceeded 4 billion tons at least, and it is increasing at a rate of 175.5 million tons per year. As the largest producer of Al2O3, my country has a cumulative stockpile of about 400 million tons of red mud. At present, the global comprehensive utilization rate of red mud is about 15%, while that of my country is only 5%. Red mud is an insoluble residue with strong alkaline corrosiveness and heavy metal dissolution risks. Excessive storage of red mud not only wastes land resources, but also, due to its highly alkaline nature, the chemical components of red mud will seep into the soil and groundwater, seriously polluting the surrounding ecological environment. Therefore, low-cost, large-scale disposal and high-value utilization of red mud are global problems that need to be solved urgently.

[0003] Blast furnace gas is a byproduct of the ironmaking process. As the combustible gas with the largest output in steel enterprises, most of it is used for combustion for heating and power generation after dust removal and purification. The main components of blast furnace gas are CO, CO2, H2, hydrocarbons and sulfides, among which the total sulfur content (COS, H2S) is 100~200 mg / m 3 The proportion of COS in COS is between 20% and 70%, while organic sulfur COS accounts for about 70%. COS is a weakly polar gas and is much more difficult to remove than H2S. Therefore, in the process of blast furnace gas purification, COS removal is the core of gas desulfurization. The main methods for removing COS gas are catalytic hydrolysis, amine absorption, adsorption, hydrogenation reduction, oxidation, etc. Among them, catalytic hydrolysis has become the most promising COS removal method due to its mild reaction conditions, high conversion rate and low cost. COS hydrolysis catalysts are usually prepared with Al2O3, Fe2O3, TiO2 and activated carbon as carriers, and alkali metals or alkaline earth metals as active components. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a composite iron-aluminum oxide powder based on red mud, a hydrolyzing agent and a preparation method thereof, aiming to solve the technical problems that red mud storage harms the environment and organic sulfur COS in blast furnace gas is difficult to remove.

[0005] In a first aspect, the present invention provides a method for preparing a composite iron-aluminum oxide powder based on red mud, comprising the following steps: S1, grinding the red mud and then washing it to obtain pretreated red mud; S2, using acid to digest and filter the pretreated red mud to obtain Fe 3+ and Al 3+ of slurry; S3, adding a surfactant to the slurry, stirring and dispersing, then dropping an alkali solution thereinto, stirring and reacting, allowing the mixture to settle, and filtering to obtain a filter cake; S4, drying, grinding and roasting the filter cake to obtain a roasting material; S5. Modify the calcined material with potassium salt to obtain composite iron-aluminum oxide powder.

[0006] In some embodiments, the acid solution in step S2 is sulfuric acid produced by desulfurization of steel smelting tail gas.

[0007] In some embodiments, in step S3, the amount of surfactant added is 5% to 30% of the mass of the slurry; The surfactant includes one or more of polyethylene glycol, hexamethyltetraimide, sodium dodecyl sulfonate, polyvinyl alcohol, triblock polyethylene oxide, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate; The conditions for stirring and dispersing the surfactant are: stirring in a 60~100℃ water bath for 2~6h.

[0008] In some embodiments, the alkali solution in step S3 includes one or more of sodium hydroxide, ammonia water, urea, sodium carbonate, ammonium carbonate and ammonium bicarbonate; The concentration of alkali solution is 0.5~2mol / L. The pH value of the slurry is adjusted to 8~13 with alkali solution to make the Fe 3+ and Al 3+ Complete precipitation.

[0009] In some embodiments, in step S4, the filter cake is dried at a temperature of 80-120° C. for a drying time of 8-24 h; and the calcination temperature is 300-700° C. for a calcination time of 5-12 h.

[0010] In some embodiments, the step S5 of modifying the roasting material with potassium salt comprises the following steps: The potassium salt is dissolved in water, and composite iron-aluminum oxide powder is added thereto, and the reaction is carried out at a stirring rate of 200-800 r / min for 4-12 hours. The slurry after the reaction is placed in an oven at 60-120° C. and dried for 8-24 hours. The obtained solid is then ground and calcined in an oxygen atmosphere at a temperature of 300-700° C. for 5-12 hours to obtain composite iron-aluminum oxide powder modified by the potassium salt; The potassium salt includes one or more of K2CO3, KOH, KNO3, K2O, KCl, K2C2O4, K3C6H5O7, and KC2H3O2, and the loading amount of the potassium salt in the composite iron-aluminum oxide powder is 5-40wt%.

[0011] In a second aspect, an embodiment of the present application provides a red mud-based composite iron-aluminum oxide powder, which is prepared by the above-mentioned method for preparing the red mud-based composite iron-aluminum oxide powder.

[0012] In a third aspect, the embodiment of the present application provides a composite iron-aluminum oxide hydrolyzer based on red mud, comprising 75-90 parts of composite iron-aluminum oxide powder, 5-15 parts of pore-forming agent, 3-15 parts of adhesive, 5-40 parts of active agent and water; The pore-forming agent includes one or more of starch, sawdust, biomass, polyvinyl alcohol, ammonium bicarbonate, and carbon powder; The adhesive comprises one or more of sesbania powder, silica sol, glycerin, starch, polyethylene oxide, calcium oxide and clay; The active auxiliary agent includes one or more of CuO, NaOH, K3PO4, zinc chloride, basic zinc carbonate, sodium carbonate, potassium carbonate, and ammonium bicarbonate.

[0013] In a fourth aspect, the present application provides a method for preparing a composite iron-aluminum oxide hydrolyzing agent based on red mud, comprising the following steps: Mix the composite iron-aluminum oxide with the pore-forming agent, adhesive, active agent and water, and stir evenly; then extrude it into shape, and then place it in a cool place for 24 to 36 hours; Then dry at 60~120℃ for 6~24h; Finally, the mixture is calcined in an oxygen atmosphere at a temperature of 100-300°C for 4-10 hours, or calcined in an oxygen atmosphere at a temperature of 300-700°C for 6-12 hours, and a hydrolyzing agent is obtained after cooling.

[0014] In a fifth aspect, an embodiment of the present application provides a use of a composite iron-aluminum oxide hydrolyzing agent based on red mud for catalytic hydrolysis of COS (carbonyl sulfide) in blast furnace gas.

[0015] Different from the existing technical solutions, the beneficial effects of this application include: 1. In the use of raw materials for blast furnace gas COS hydrolyzer, the present application utilizes red mud produced in the Al2O3 industry to replace traditional aluminum sulfate and ferrous sulfate sources, and the crude sulfuric acid obtained after desulfurization of steel smelting tail gas is used to digest the red mud to prepare composite iron-aluminum oxide powder as a raw material for the hydrolyzer, thereby realizing the resource utilization of Al2O3 industrial solid waste and the reduction of steel metallurgical tail gas emissions; on the other hand, the surfactant added in the synthesis process of the present application will combine with Al ions and Fe ions to form a chelate, thereby being able to regulate the generation of active γ-Al2O3 and Fe2O3, increase the specific surface area of ​​the composite iron-aluminum oxide powder, promote the absorption and hydrolysis reaction of COS, and thus improve the hydrolysis performance of the hydrolyzer on COS.

[0016] 2. This application uses red mud produced in the Al2O3 production process to prepare blast furnace gas COS hydrolyzing agent for blast furnace gas desulfurization, so that industrial solid waste can be recycled as a green resource, waste can be treated with waste, and the harm caused by red mud to the environment can be reduced. It is an effective way for enterprises to reduce costs and increase efficiency.

[0017] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a process flow chart for preparing the hydrolyzing agent in the examples of this application. DETAILED DESCRIPTION

[0020] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0022] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] Considering that COS is weakly acidic, while red mud is strongly alkaline and contains a variety of components such as Al2O3 and Fe2O3 that are beneficial to the adsorption and reaction of COS, these Fe and Al elements in red mud can be used to prepare blast furnace gas COS hydrolyzing agent, which can reduce the environmental hazards caused by red mud storage, and make high-value use of solid waste resources, reduce the production cost of desulfurization in the steel industry, comply with the national policy orientation of solid waste resource utilization, and achieve waste treatment with waste.

[0027] In order to solve the technical problems of environmental harm caused by red mud storage and difficulty in removing organic sulfur COS in blast furnace gas, the present application provides a composite iron-aluminum oxide powder, a hydrolyzing agent and a preparation method thereof based on red mud. Specifically, the present application uses red mud produced in the production process of Al2O3 to prepare blast furnace gas COS hydrolyzing agent for blast furnace gas fine desulfurization, so that industrial solid waste is recycled as a green resource, waste is treated with waste, and the harm caused by red mud to the environment is reduced. It is an effective way for enterprises to reduce costs and increase efficiency.

[0028] like Figure 1 As shown, in the first aspect, the embodiment of the present application provides a method for preparing composite iron-aluminum oxide powder based on red mud, comprising the following steps: S1, grinding the red mud and then washing it to obtain pretreated red mud; S2, using acid to digest and filter the pretreated red mud to obtain Fe 3+ and Al 3+ of slurry; S3, adding a surfactant to the slurry, stirring and dispersing, then dropping an alkali solution thereinto, stirring and reacting, allowing the mixture to settle, and filtering to obtain a filter cake; S4, drying, grinding and roasting the filter cake to obtain a roasting material; S5. Modify the calcined material with potassium salt, load the potassium salt on the calcined material, and obtain composite iron-aluminum oxide powder.

[0029] In the technical solution of the embodiment of the present application, the red mud is first ground into fine powder, and then clean water is used to remove impurities such as fluoride, alkali, chloride, dust, etc.; then the acid produced after desulfurization is used to digest the pretreated red mud. The main components of the red mud are Al2O3, Fe2O3, SiO2, CaO, Na2O and TiO2, etc. The role of the acid digestion is mainly to use sulfuric acid to dissolve these oxides in the red mud into metal ions for the subsequent co-precipitation method to prepare composite iron-aluminum oxide powder.

[0030] Adding surfactants to the slurry, on the one hand, surfactants can combine with metal ions to form a colloidal protective layer, and the steric hindrance effect of its long molecular chain can hinder the colloid particles from approaching in space, reduce the cohesive force between the colloid particles, and reduce the strength of agglomeration; on the other hand, surfactants also serve as ordered molecular templates for crystal synthesis. 3+ Metal ions form micelles, and during the coprecipitation stage of adding alkali solution, Al 3+ With OH - The generated Al(OH)3 nuclei are combined with surfactants and arranged in a specific orientation under their induction, and finally highly active γ-Al2O3 is formed by controlling the calcination temperature.

[0031] Potassium salt is an alkali metal element with unique electron donor properties, surface alkalinity and electrostatic adsorption characteristics. Adding potassium salt as an active component can improve the weak alkaline center on the surface of the composite iron-aluminum oxide powder and enhance the hydrolysis activity of the composite iron-aluminum oxide powder.

[0032] In some embodiments, the acid solution in step S2 is sulfuric acid produced by desulfurization of steel smelting tail gas.

[0033] In some embodiments, in step S3, the amount of surfactant added is 5% to 30% of the mass of the slurry; The amount of surfactant added is 5% to 30% of the mass of the slurry, and the surfactant includes one or more of polyethylene glycol, hexamethyltetraimide, sodium dodecyl sulfonate, polyvinyl alcohol, triblock polyethylene oxide, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate; The conditions for stirring and dispersing the surfactant are: stirring in a 60~100℃ water bath for 2~6h.

[0034] In the technical solution of the embodiment of the present application, the addition amount of the surfactant ranges from 5% to 30%. If the addition amount is too little, the surfactant cannot combine with the metal ions to form a colloidal protective layer, will not hinder the colloid particles from approaching in space, reduce the cohesive force between the colloid particles, and reduce the strength of the agglomeration; if the addition amount is too much, the micelles formed on the surface will be unstable, which is not conducive to the formation of fine particle precipitation.

[0035] In some embodiments, the alkali solution in step S3 includes one or more of sodium hydroxide, ammonia water, urea, sodium carbonate, ammonium carbonate and ammonium bicarbonate, and the concentration of the alkali solution is 0.5-2 mol / L. The alkali solution is used to adjust the pH of the slurry to 8-13, so that the Fe 3+ and Al 3+ Complete precipitation.

[0036] In some embodiments, in step S4, the filter cake is dried at a temperature of 80-120° C. for a drying time of 8-24 h; and the calcination temperature is 300-700° C. for a calcination time of 5-12 h.

[0037] In some embodiments, the step S5 of modifying the roasting material with potassium salt comprises the following steps: The potassium salt is dissolved in water, and composite iron-aluminum oxide powder is added thereto, and the reaction is carried out at a stirring rate of 200-800 r / min for 4-12 hours. The slurry after the reaction is placed in an oven at 60-120° C. and dried for 8-24 hours. The obtained solid is then ground and calcined in an oxygen atmosphere at a temperature of 300-700° C. for 5-12 hours to obtain composite iron-aluminum oxide powder modified by the potassium salt; The potassium salt includes one or more of K2CO3, KOH, KNO3, K2O, KCl, K2C2O4, K3C6H5O7, and KC2H3O2, and the loading amount of the potassium salt in the composite iron-aluminum oxide powder is 5-40wt%.

[0038] In a second aspect, an embodiment of the present application provides a red mud-based composite iron-aluminum oxide powder, which is prepared by the above-mentioned method for preparing the red mud-based composite iron-aluminum oxide powder.

[0039] In a third aspect, the embodiment of the present application provides a composite iron-aluminum oxide hydrolyzer based on red mud, comprising 75-90 parts of composite iron-aluminum oxide powder, 5-15 parts of pore-forming agent, 3-15 parts of adhesive, 5-40 parts of active agent and water; The pore-forming agent includes one or more of starch, sawdust, biomass, polyvinyl alcohol, ammonium bicarbonate, and carbon powder; The adhesive comprises one or more of sesbania powder, silica sol, glycerin, starch, polyethylene oxide, calcium oxide and clay; The active auxiliary agent includes one or more of CuO, NaOH, K3PO4, zinc chloride, basic zinc carbonate, sodium carbonate, potassium carbonate, and ammonium bicarbonate.

[0040] In a fourth aspect, the present application provides a method for preparing a composite iron-aluminum oxide hydrolyzing agent based on red mud, comprising the following steps: Mix the composite iron-aluminum oxide, pore-forming agent, adhesive, active agent and water, and stir evenly; Then it is extruded into shape and placed in a cool place for 24 to 36 hours; then dried at 60 to 120 degrees Celsius for 6 to 24 hours; Finally, the mixture is calcined in an oxygen atmosphere at a temperature of 100-300°C for 4-10 hours, or calcined in an oxygen atmosphere at a temperature of 300-700°C for 6-12 hours, and a hydrolyzing agent is obtained after cooling.

[0041] In a fifth aspect, an embodiment of the present application provides a use of a composite iron-aluminum oxide hydrolyzing agent based on red mud for catalytic hydrolysis of carbonyl sulfide in blast furnace gas.

[0042] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0043] 1. Preparation method Example 1 1. Collect the red mud produced by Al2O3 industry and put it into 105 o The red mud was dried in a C oven for 24 h and then ball-milled in a planetary ball mill for 3 h to break the large particles in the red mud into fine powder.

[0044] 2. Pour the ground red mud powder into clean water and stir and wash for 2 h to remove excess impurities, then filter and wash to obtain pretreated red mud.

[0045] 3. Weigh 2 kg of cleaned pretreated red mud and put it into a reactor containing 4000 mL of water, and slowly add crude sulfuric acid obtained by desulfurization of steel smelting tail gas. o C for 4 h to allow the reaction to fully and completely dissolve. The slurry was then poured into a filter for vacuum filtration to obtain a solution containing Fe and Al elements at the bottom, while insoluble silica and other insolubles were filtered out.

[0046] 4. Dissolve 200 g of triblock polyethylene oxide in the above 2000 mL filtrate and stir for 3 h to completely dissolve it. Slowly add 0.5 mol / L alkali solution at 60 o C and stirred to allow it to react fully, and the pH of the solution was adjusted to 10 until the Al and Fe in the solution were completely precipitated, followed by stirring and aging at room temperature for 24 h, and standing for precipitation for 24 h to obtain a mixed precipitate of Al(OH)3 and Fe(OH)3.

[0047] 5. After filtering, the suspension was washed three times with a mixed aqueous solution of ethanol and water in a ratio of 1:1. The filter cake was placed on a 100 o C oven for 12 h to dry the moisture, then grind the filter cake into powder and o C calcined for 4 h, 500 o C for 4 h.

[0048] 6. Weigh 100 g K2CO3 and dissolve it in water. Stir until it is completely dissolved. Then slowly add 1 kg of composite iron-aluminum oxide powder and react for 12 h at a stirring rate of 600 r / min. Place the slurry after the reaction at 100 o C oven for 24 h to dry the water, and the obtained solid was ground and then heated at 500 o C for 6 h. Then, K-modified composite iron-aluminum oxide powder was obtained.

[0049] 7. The K-modified composite iron-aluminum oxide powder is blended with a pore-forming agent, a binder, an active agent and water in a ratio of 80:5:4:10:1, and sent into a high-power mixer for stirring and mixing. The mixing time is 30 minutes.

[0050] 8. The mixed material is extruded through a screw extruder. The extruded sample is placed in a cool place at room temperature for 24 hours and then placed in 100 o C oven for 24 h and then in an oxygen atmosphere at 500 o C calcined for 6 h.

[0051] Example 2 The difference between Example 2 and Example 1 is that the amount of surfactant added is 500g, and the other steps are the same as Example 1.

[0052] Example 3 The difference between Example 3 and Example 1 is that the amount of surfactant added is 100 g, and the other steps are the same as Example 1.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no surfactant is added, and the other steps are the same as those of Example 1.

[0054] Comparative Example 2 The difference between Example 4 and Example 1 is that the raw material used is not red mud but crude Al2O3 produced by the Al2O3 plant, the amount of surfactant added is still 200g, and the other steps are the same as those in Example 1. The specific steps are as follows: 1. Place the crude Al2O3 produced by the Al2O3 factory into 105 o C oven for 24 h, and then the red mud was placed in a planetary ball mill for 3 h to break the large particles in Al2O3 into fine powder.

[0055] 2. Pour the ground Al2O3 powder into clean water and stir and wash for 2 h to remove excess impurities, then filter and wash to obtain pretreated Al2O3.

[0056] 3. Weigh 2 kg of cleaned pretreated Al2O3 and put it into a reactor containing 4000 mL of water. Slowly add crude sulfuric acid obtained by desulfurization of steel smelting tail gas at 90 °C. o C for 4 h to allow the reaction to fully and completely dissolve. The slurry was then poured into a filter for vacuum filtration to obtain a solution containing Al elements at the bottom, while insoluble silica and other insolubles were filtered out.

[0057] 4. Dissolve 200 g of triblock polyethylene oxide in the above 2000 mL filtrate and stir for 3 h to completely dissolve it. Slowly add 0.5 mol / L alkali solution at 60 o C and stirred to allow it to react fully, and the pH of the solution was adjusted to 10 until the Al in the solution was completely precipitated, followed by stirring and aging at room temperature for 24 h, and standing for precipitation for 24 h to obtain Al(OH)3 precipitate.

[0058] 5. After filtering, the suspension was washed three times with a mixed aqueous solution of ethanol and water in a ratio of 1:1. The filter cake was placed on a 100 o C oven for 12 h to dry the moisture, then grind the filter cake into powder and o C calcined for 4 h, 500o C for 4 h.

[0059] 6. Weigh 100 g K2CO3 and dissolve it in water. Stir until it is completely dissolved. Then slowly add 1 kg aluminum oxide powder and react for 12 h at a stirring rate of 600 r / min. o C oven for 24 h to dry the water, and the obtained solid was ground and then heated at 500 o C for 6 h to obtain K-modified aluminum oxide powder.

[0060] 7. The potassium salt-modified aluminum oxide powder is blended with a pore-forming agent, a binder, an active agent and water in a ratio of 80:5:4:10:1, and sent into a high-power mixer for stirring and mixing for 30 minutes.

[0061] 8. The mixed material is extruded through a screw extruder. The extruded sample is placed in a cool place at room temperature for 24 hours and then placed in 100 o C oven for 24 h and then in an oxygen atmosphere at 500 o C calcined for 6 h.

[0062] 2. Test Method The COS hydrolysis activity of the hydrolyzing agents prepared in Examples 1 to 3 and Comparative Example 1 and the commercial hydrolyzing agent was evaluated. Specific evaluation steps: 1 mL of the hydrolyzing agent was weighed and loaded into the middle of the adsorption column of the quartz tube (0.8 cm inner diameter) of the fixed bed tube furnace, and 300 mg / Nm 3 The activity test was carried out in a mixed atmosphere with COS and N2 as the balance gas. The total flow rate of the experimental gas was 50 mL / min and the reaction space velocity was 3000 h -1 Open the gas valve switch, adjust the gas to the specified concentration according to the working conditions, keep the gas flow stable, and set the reaction temperature to 60 o C. After passing through the mass flow meter, the N2 gas passes through the water saturator, and the temperature is adjusted to control the relative humidity, ensuring that the relative humidity of the reaction atmosphere is 3%. After the conditions are stable, the mixed gas containing a certain concentration of carbonyl sulfide passes through the adsorption column, and the outlet concentration is monitored online using an SP-6802 gas chromatograph. The time interval for measuring the outlet tail gas content is 30 minutes, and the outlet tail gas is absorbed by alkaline solution. When the outlet concentration of carbonyl sulfide reaches 10% of the inlet concentration, it is considered that COS has penetrated. Continue to detect until the outlet concentration reaches 90% of the inlet concentration, which is considered to be adsorption saturation of COS and stop measuring.

[0063] III. Analysis of test results of various embodiments and comparative examples The hydrolyzing agents prepared in Examples 1 to 3 and Comparative Example 1 and the commercial hydrolyzing agent were tested for COS hydrolysis activity. The test results are shown in Table 1 below.

[0064] Table 1 Test results of hydrolysis activity of COS hydrolyzing agent in various examples and comparative examples

[0065] As can be seen from Table 1, the hydrolyzing agent prepared by the method of the present application has a good COS hydrolysis effect, which is comparable to the COS hydrolysis rate of the commercial hydrolyzing agent. Without the addition of a surfactant, the COS hydrolysis activity of the hydrolyzing agent is greatly reduced. The hydrolyzing agent prepared in Comparative Example 2 does not contain Fe element, and the COS hydrolysis effect is reduced compared with Example 1, indicating that the presence of Fe-Al composite oxide can promote the adsorption and hydrolysis of COS.

[0066] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing composite iron-aluminum oxide powder based on red mud, characterized in that: The steps include: S1, grinding the red mud and then washing it to obtain pretreated red mud; S2, using acid to digest and filter the pretreated red mud to obtain Fe 3+ and Al 3+ of slurry; S3, adding a surfactant to the slurry, stirring and dispersing, and then dropping an alkali solution therein, stirring and reacting, allowing the slurry to settle, and filtering to obtain a filter cake; S4, drying, grinding and roasting the filter cake to obtain a roasting material; S5. Modify the calcined material with potassium salt to obtain composite iron-aluminum oxide powder.

2. The method for preparing composite iron-aluminum oxide powder based on red mud according to claim 1, characterized in that: The acid solution in step S2 is sulfuric acid obtained by desulfurization of steel smelting tail gas.

3. The method for preparing composite iron-aluminum oxide powder based on red mud according to claim 1, characterized in that: In step S3, the amount of the surfactant added is 5% to 30% of the mass of the slurry; The surfactant includes one or more of polyethylene glycol, hexamethyltetraimide, sodium dodecyl sulfonate, polyvinyl alcohol, triblock polyethylene oxide, hexadecyltrimethylammonium bromide, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate; The conditions for stirring and dispersing the surfactant are: stirring in a 60-100° C. water bath for 2-6 hours.

4. The method for preparing composite iron-aluminum oxide powder based on red mud according to claim 1, characterized in that: The alkali solution in step S3 includes one or more of sodium hydroxide, ammonia water, urea, sodium carbonate, ammonium carbonate and ammonium bicarbonate; The concentration of the alkali solution is 0.5-2 mol / L, and the pH of the slurry is adjusted to 8-13 by using the alkali solution, so that the Fe 3+ and Al 3+ Complete precipitation.

5. The method for preparing composite iron-aluminum oxide powder based on red mud according to claim 1, characterized in that: In the step S4, the filter cake is dried at a temperature of 80-120° C. for 8-24 hours; the calcination temperature is 300-700° C. for 5-12 hours.

6. The method for preparing composite iron-aluminum oxide powder based on red mud according to claim 1, characterized in that: The step S5 uses potassium salt to modify the roasting material, including the following steps: The potassium salt is dissolved in water, and composite iron-aluminum oxide powder is added thereto, and the reaction is carried out at a stirring rate of 200-800 r / min for 4-12 hours. The slurry after the reaction is placed in an oven at 60-120° C. and dried for 8-24 hours. The obtained solid is then ground and calcined in an oxygen atmosphere at a temperature of 300-700° C. for 5-12 hours to obtain composite iron-aluminum oxide powder modified by the potassium salt; The potassium salt includes one or more of K2CO3, KOH, KNO3, K2O, KCl, K2C2O4, K3C6H5O7, and KC2H3O2, and the loading amount of the potassium salt in the composite iron-aluminum oxide powder is 5-40wt%.

7. A composite iron-aluminum oxide powder based on red mud, characterized in that: The composite iron-aluminum oxide powder is prepared by the method for preparing the red mud-based composite iron-aluminum oxide powder according to any one of claims 1 to 6.

8. A composite iron-aluminum oxide hydrolyzing agent based on red mud, characterized in that: The invention comprises, by weight, 75 to 90 parts of the composite iron-aluminum oxide powder according to claim 7, 5 to 15 parts of a pore former, 3 to 15 parts of a binder, 5 to 40 parts of an active agent and water; The pore-forming agent includes one or more of starch, sawdust, biomass, polyvinyl alcohol, ammonium bicarbonate, and carbon powder; The adhesive comprises one or more of sesbania powder, silica sol, glycerin, starch, polyethylene oxide, calcium oxide and clay; The active auxiliary agent includes one or more of CuO, NaOH, K3PO4, zinc chloride, basic zinc carbonate, sodium carbonate, potassium carbonate, and ammonium bicarbonate.

9. The method for preparing a composite iron-aluminum oxide hydrolyzing agent based on red mud according to claim 8, characterized in that: The steps include: Mix the composite iron-aluminum oxide, pore-forming agent, adhesive, active agent and water, and stir evenly; Then it is extruded into shape and placed in a cool place for 24 to 36 hours; then dried at 60 to 120 degrees Celsius for 6 to 24 hours; Finally, the mixture is calcined in an oxygen atmosphere at a temperature of 100-300°C for 4-10 hours, or calcined in an oxygen atmosphere at a temperature of 300-700°C for 6-12 hours, and a hydrolyzing agent is obtained after cooling.

10. The use of a composite iron-aluminum oxide hydrolyzing agent based on red mud according to claim 8, characterized in that: Used for catalytic hydrolysis of carbonyl sulfide in blast furnace gas.

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