Red-mud-based mercury and sulfur removal material, preparation thereof and application of red-mud-based mercury and sulfur removal material in synchronous removal of mercury and sulfur dioxide in flue gas

Abstract

The invention belongs to the field of waste gas treatment, and particularly relates to a preparation method of a red mud-based mercury and sulfur removal material, which comprises the following steps: aging and modifying a solution containing red mud, carbonate, a selenium source, an additive and an auxiliary agent, and then carrying out solid-liquid separation to obtain the red mud-based mercury and sulfur removal material, the auxiliary agent comprises at least one of ferric chloride, ferrous sulfate and polyferric sulfate. The invention also comprises the red mud-based mercury and sulfur removal material prepared by the preparation method and application of the red mud-based mercury and sulfur removal material in mercury removal and sulfur removal. The carbonate, the selenium source, the additive and the assistant are creatively combined to modify the red mud, so that the characteristics of the red mud can be fully utilized, the network structure and active sites of the adsorption material are synergistically endowed and optimized, and the exposure characteristics of the active sites are improved; further, the synchronous removal effect of the prepared red mud-based material on sulfur dioxide and mercury is improved.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection and comprehensive utilization of resources, and specifically relates to a red mud-based composite material for purifying flue gas and a preparation method and application thereof. Background Art

[0002] Red mud is an alkaline solid waste generated during the production of alumina. The accumulated amount of red mud in the world has exceeded 4 billion tons, which has caused serious pollution to the natural environment and waste of resources. Red mud is easy to cause dust pollution, reduce visibility, damage the ecological environment, and cause air pollution. The alkaline elements in red mud lead to soil salinization, which is not conducive to plant growth and difficult to reclaim. The high alkalinity and high fluoride content of red mud leaching liquid can pollute groundwater and affect the ecological structure. The stacking of red mud poses a risk of dam collapse, threatens safety, seriously wastes land resources, and causes environmental and economic losses. The comprehensive utilization of red mud is a difficult problem that the alumina industry urgently needs to solve, and it is of great significance to realize the comprehensive utilization of red mud resources. Red mud has small particle size, large porosity, good dispersion performance, high specific surface area, high iron oxide content, and high flocculation. Therefore, red mud particles have a certain adsorption capacity for heavy metal ions and can be used as a potential adsorption material in the field of pollutant control. In addition, the high alkalinity of red mud has the potential to be used as an alkaline neutralizer, which can be used in processes such as flue gas desulfurization.

[0003] Pollutant control in flue gas is another prominent environmental problem facing today's society. Sulfur dioxide emitted into the air easily reacts chemically with water vapor, oxygen, etc. to form acidic substances such as sulfuric acid, leading to the production of acid rain. Acid rain is extremely destructive to soil and water ecosystems, and can change the acid-base balance of the soil and affect crop growth; sulfur dioxide can harm the human respiratory system after inhalation; sulfur dioxide is further converted into fine particulate matter (PM2.5), thereby exacerbating smog weather. Mercury and its compounds are highly toxic, highly corrosive, highly volatile, bioaccumulative, and easy to migrate and diffuse. After mercury enters the atmosphere, it enters the soil and water through sedimentation or precipitation cycles, and is converted into methylmercury by microorganisms, affecting the survival of fish, birds and mammals and endangering the ecosystem; methylmercury damages the central nervous system, leading to nerve damage, mental retardation, and memory loss; gaseous mercury damages the kidneys and lungs, and long-term exposure increases the risk of cancer.

[0004] However, most of the existing red mud-based treatment materials are developed for single mercury vapor or sulfur dioxide, and there are few technologies that can simultaneously treat sulfur dioxide and mercury vapor in flue gas in a gentle and efficient manner. For example, a Chinese patent document with publication number CN118179245A discloses a method for preparing an alkaline absorbent for simultaneously removing SO3 and mercury from coal-fired flue gas, wherein alkali slag, carbide slag and red mud are mixed and immersed in a halide salt solution, stirred and mixed evenly, and then dried and calcined. After completion, the mixture is cooled to room temperature to obtain a calcined product, which is then ground to obtain the product. This technology is used for the coordinated treatment of the simultaneous removal of SO3 and mercury heavy metals, but it is difficult to adapt to the simultaneous removal of SO2 and mercury. In addition, the removal process needs to be carried out at a higher temperature, and the simultaneous removal effect at low temperatures is not ideal. For another example, the Chinese patent document with publication number CN108722143A discloses a dry purification device and process that can achieve ultra-low flue gas emissions. This technology can remove SO2, NOx, mercury, etc., but requires the use of special equipment and the technology is not universal.

[0005] In summary, the existing technology still lacks the ability to efficiently utilize the characteristics of red mud and obtain red mud-based treatment materials that can efficiently and simultaneously remove mercury and sulfur dioxide under mild conditions. Summary of the invention

[0006] In order to change the problem of red mud accumulation and the difficulty of existing red mud-based treatment materials in removing sulfur dioxide and mercury from flue gas in a gentle and efficient manner, the present invention innovatively provides a method for preparing a red mud-based mercury-removing sulfur material, aiming to make full use of the characteristics of red mud to prepare a treatment material that can simultaneously and efficiently remove sulfur dioxide and mercury from flue gas.

[0007] The second object of the present invention is to provide a red mud-based mercury-removing sulfur material obtained by the preparation method and its application in adsorbing sulfur dioxide and mercury vapor in flue gas.

[0008] Existing red mud-based materials can achieve good results in the adsorption and removal of sulfur dioxide or mercury vapor alone, but when sulfur dioxide and mercury vapor are adsorbed simultaneously, they will compete for adsorption sites, thereby interfering with the simultaneous removal of sulfur dioxide and mercury vapor. Especially under mild adsorption conditions, the impact of this mutual competition and interference will be further amplified. In view of this problem, the present invention has been studied in depth and provides the following improvement scheme:

[0009] A method for preparing a red mud-based mercury-removing sulfur material, comprising aging and modifying a solution containing red mud, carbonate, selenium source, additives and auxiliary agents, and then performing solid-liquid separation to obtain the red mud-based mercury-removing sulfur material;

[0010] The auxiliary agent includes at least one of ferric chloride, ferrous sulfate and polymerized ferric sulfate.

[0011] In view of the problem that it is difficult to simultaneously adsorb mercury and sulfur dioxide due to the physical and chemical characteristics of red mud, the present invention innovatively uses the carbonate, selenium source, additives and auxiliary agents to modify the red mud, so that the characteristics of red mud can be fully utilized, the network structure and active sites of the adsorption material can be synergistically given and optimized, and the exposure characteristics of the active sites can be improved, thereby improving the simultaneous removal effect of sulfur dioxide and mercury by the obtained red mud-based material. The research of the present invention shows that the prepared material can be suitable for the simultaneous removal of sulfur dioxide and mercury in different adsorption scenarios such as solid phase method and liquid phase method, and even under relatively low temperature and low alkali conditions, a good simultaneous removal effect of sulfur dioxide and mercury can still be obtained. Not only that, it also has an excellent material utilization advantage, can achieve efficient disposal of red mud, and can effectively reduce material costs.

[0012] In the present invention, the red mud may be red mud waste known in the industry, for example, it may be derived from at least one of the Bayer process, sintering process and combined process red mud in alkaline alumina production.

[0013] In the present invention, the carbonate includes at least one of sodium bicarbonate, calcium bicarbonate, sodium carbonate, calcium carbonate, and magnesium carbonate. The present invention's research shows that, unlike other alkaline components, the present invention uses the carbonate, which, in combination with other components, can further synergistically optimize the microstructure and active sites of the prepared material, and can further help improve the prepared red mud-based material's simultaneous removal effect on sulfur dioxide and mercury.

[0014] In the present invention, the selenium source includes at least one of selenium dioxide, selenite and selenate.

[0015] In the present invention, the additive includes at least one of thiosulfate and GSH.

[0016] In the present invention, the additive is 0.5 to 1.5 times the weight of the selenium source.

[0017] In the present invention, the above-mentioned material components can be mixed based on any steps. For example, in one practicable manner of the present invention, red mud and carbonate are mixed in advance to obtain a mixture A; a selenium source and an additive are dispersed in a solution to obtain an activated mother solution; the mixture A, the activated mother solution and an auxiliary agent are then mixed, aged and modified, and then solid-liquid separation is performed to obtain a red mud-based mercury-removing sulfur material.

[0018] In the present invention, fine selenium powder seeds with a selenium particle size of more than 400 meshes are also added to the activation mother solution. Under the preferred process, the efficiency and effect of simultaneous removal of sulfur dioxide and mercury in the prepared material can be further optimized.

[0019] Preferably, the amount of fine selenium powder seed crystals used is 1%-20% by weight of the selenium source, and further can be 4-15%.

[0020] In the present invention, the combined control of the auxiliary agents and auxiliary agent types can adapt to the physical and chemical characteristics of red mud, and can be combined with other processes and components to help synergistically impart and construct the three-dimensional structure and sites of the prepared materials, thereby helping to improve the simultaneous removal effect of red mud-based materials in sulfur dioxide and mercury.

[0021] In the present invention, the weight ratio of red mud to carbonate is 75-95:5-25, and can further be 80-92:8-20;

[0022] The selenium source is 1-10wt.% of the weight of the red mud, and can further be 2-6wt.%;

[0023] The additive is 0.2-8% by weight of the red mud, preferably 1-6%;

[0024] Preferably, the aging and modification time is more than 0.5 h, and can further be 1 to 2 h.

[0025] The present invention also includes the step of granulating the red mud-based mercury-removing sulfur material to obtain a granular red mud-based mercury-removing sulfur material.

[0026] The invention also provides a red mud-based mercury-removing sulfur material prepared by the preparation method.

[0027] The research of the present invention shows that the preparation method can give the prepared material special physical and chemical characteristics, and the product with the characteristics can obtain excellent simultaneous removal effect of sulfur dioxide and mercury under mild conditions.

[0028] The present invention also provides an application of the red mud-based mercury-removing sulfur material for synchronously removing sulfur dioxide and mercury from flue gas.

[0029] In the present invention, the red mud-based mercury-removing sulfur material of the present invention can be used as an adsorbent to remove sulfur dioxide and mercury from flue gas based on conventional adsorption methods. For example, the removal method is dry adsorption or wet adsorption.

[0030] In the present invention, the temperature in the removal stage is 20-200° C. The process of the present invention can achieve efficient and simultaneous removal of sulfur dioxide and mercury under mild conditions.

[0031] Principles and advantages

[0032] Taking full advantage of the characteristics of red mud materials, such as small particle size, large porosity, good dispersion performance, high specific surface area, high iron oxide content, and high flocculation, the active ingredients are organically combined with the red mud materials through simple modification. Due to the high flocculation and high dispersion characteristics of red mud materials, a very small amount of active ingredients can be evenly distributed on the red mud base. The adsorption, flocculation, acid-base neutralization and other abilities of red mud are fully improved through modification. The red mud-based composite material has abundant adsorption sites, and these sites are fully exposed during the modification process, increasing the contact probability with pollutants; the base and carbonate groups in the red mud-based composite material can react with sulfur dioxide and water in the flue gas to fix and remove sulfur dioxide. When the red mud-based composite material enters the slurry, the high alkalinity of red mud has the potential to be used as an alkaline neutralizer, which can effectively reduce the amount of alkali in the desulfurization system. The selenium active sites, oxygen sites, and metal sites in the red mud-based composite material work synergistically to fix mercury into stable selenium-oxymercury compounds.

[0033] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0034] (1) At the same time, it can alleviate the environmental problems caused by the large-scale accumulation of solid waste red mud and the emission of flue gas pollutants, treat waste with waste, turn waste into treasure, and achieve green and sustainable development.

[0035] (2) The process is simple and does not require fine synthesis, which is conducive to large-scale production and has a wide range of applications. It can be applied to various types of red mud.

[0036] (3) Low cost, using red mud, which is almost free and in huge stock, as the base material.

[0037] (4) It is environmentally friendly and has no secondary pollution. It avoids the environmental problems in the fine synthesis process using chemical raw materials and reagents, and has huge environmental benefits.

[0038] (5) It can reduce the amount of alkali used in the desulfurization system and reduce the overall cost of flue gas purification.

[0039] (6) The flue gas pollutant purification efficiency is high and deep removal can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of powder composite material spraying in the flue;

[0041] Figure 2 Schematic diagram of the application of granular composite materials in a fixed bed. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below through specific examples, which are not intended to limit the scope of protection.

[0043] The preparation method of the red mud-based composite material is as follows:

[0044] (1) Dry the red mud at room temperature, then add carbonate additives, mix well and dry at 90-150℃, and then grind the mixture.

[0045] (2) Prepare a solution of selenium substances, add an appropriate amount of solid additives, and then add a small amount of fine selenium powder with a mesh size of 400 or above as a seed crystal. Stir at high speed to form an activated mother solution.

[0046] (3) The activated mother liquor is diluted and added to the red mud mixture, and then a small amount of ferric chloride is added for aging and modification to form a slurry, which is stirred for 1 to 3 hours. After aging, the modified red mud-based material is obtained by dehydration and drying.

[0047] (4) The powdered red mud-based composite material can be obtained by direct grinding and crushing; or a certain proportion of water glass and CaO can be added to the mixture after appropriate crushing, and then mixed evenly, and an appropriate amount of water can be sprayed into the mixture, and then granulated in an extruder to obtain a granular red mud-based composite material.

[0048] The raw material red mud comes from the Bayer process, sintering process and combined process red mud in the production of alkaline alumina.

[0049] The selenium substances include at least one of selenium dioxide, selenite and selenate.

[0050] The mass fraction ratio of red mud to carbonate is 75-95:5-25; the solid additive is a mixture of sodium thiosulfate and GSH in a mass ratio of 1-4:1; the amount of fine selenium powder seed added is 1%-10% of the mass of selenium in selenium-based substances; the amount of ferric chloride added is 0.2-3% of the mass of the red mud mixture.

[0051] The solid additive is a mixture of sodium thiosulfate and GSH in a mass ratio of 2:1, and the amount of fine selenium powder seed added is 4%-7% of the mass of selenium in the selenium-based substance.

[0052] For Bayer process and combined process red mud, when the granular powder red mud-based composite material is balled and granulated, the mass fractions of modified red mud-based material, water glass, CaO and water are 87-97:0.5-4:0-6:0.5-6; CaO is no longer added to the sintered red mud.

[0053] The particle size is less than 8 mm.

[0054] For red mud with CaO content higher than 8%, no additional CaO is added.

[0055] In the present invention, the test method of the treated material can be conventional, for example, the powder composite material is injected into the flue before the flue gas dust removal device or the wet desulfurization device (such as Figure 1As shown in the figure, the powder composite material fully contacts the pollutants in the flue gas in the flue or the device cavity, and the mercury and sulfur dioxide in the flue gas are fixedly removed; the powder composite material enters the desulfurization slurry of the wet desulfurization device with the flue gas, and the powder composite material contacts the pollutants in the flue gas in three phases of gas, liquid and solid, and strengthens the fixed removal of mercury and sulfur dioxide in the flue gas; the granular composite material is filled into the box, and the box is arranged and installed in the fixed bed (as shown in the figure). Figure 2 As shown in the figure, the particle composite material and the pollutants in the flue gas fully contact with each other in the bed body, thereby fixing and removing the mercury and sulfur dioxide in the flue gas.

[0056] Preferably, the flue gas dust removal device includes an electrostatic precipitator, a bag filter, a wet dust collector, etc.

[0057] Preferably, the application temperature of the powder composite material in the flue, flue gas dust removal device, and wet desulfurization device is 25-190°C, the application temperature of the particle composite material in the fixed bed is 25-150°C, and the injection amount of the powder composite material in the flue is 0.03-12g / m 3 .

[0058] Industrial flue gas pollutants come from non-ferrous smelting, coal-fired power plants, catalyst production, cement production, petrochemicals, waste disposal, natural gas and other industries.

[0059] Example 1

[0060] 8g of Bayer red mud with a CaO content of 14% was dried at room temperature, and then 2g of carbonate (sodium carbonate) was added, mixed and dried at 100°C, and ground; 0.16g of SeO2 was dissolved in water to prepare a solution, 0.1g of sodium thiosulfate and 0.1g of GSH were added, and then 0.02g of fine selenium powder above 400 mesh was added as a seed crystal, and the activated mother liquor was obtained by high-speed stirring; the activated mother liquor was diluted and added to the red mud mixture, and then 0.16g of ferric chloride was added for aging and modification to form a mud slurry, which was stirred for 1h, dehydrated after aging, dried at 105°C for 6h, ground and crushed, and passed through a 200-mesh sieve to obtain a powdered red mud-based composite material.

[0061] 20 mg of powdered red mud-based composite material was weighed and placed in a simulated fixed bed reactor. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller, and a quantitative amount of elemental mercury was generated through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury analyzer were used to measure sulfur dioxide and mercury in real time. The total gas flow rate was 1 L / min, the initial sulfur dioxide concentration was 30 ppm, and the initial mercury concentration was 50 ± 1 μg / m 3 In the temperature range of 100-190℃, the sulfur dioxide removal rate is higher than 80%, and the mercury removal efficiency is higher than 99%, indicating that the red mud-based composite materials have a significant effect in removing pollutants from flue gas in a wide temperature range.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that the red mud before modification in Example 1 is directly used as the treating agent, and the other operations, parameters and tests are the same as in Example 1. For example, 20 mg of the red mud before modification in Example 1 is weighed and placed in a simulated fixed bed reactor, a quantitative amount of sulfur dioxide is generated through a sulfur dioxide standard gas cylinder and a flow controller, a quantitative amount of elemental mercury is produced through a mercury permeation tube, and a flue gas analyzer and a VM-3000 mercury meter are used to perform real-time measurement of sulfur dioxide and mercury. The total gas flow rate is 1 L / min, the initial sulfur dioxide concentration is 30 ppm, and the initial mercury concentration is 50±1 μg / m3. At 125°C, the sulfur dioxide removal rate is 18%, and the mercury removal efficiency is 5.4%, indicating that the unmodified red mud has almost no removal effect on pollutants in the flue gas.

[0064] Comparative Example 2

[0065] Compared with Example 1, the only difference is that the carbonate is replaced by an equal amount of sodium hydroxide, and the other operations and parameters are the same as those of Example 1. When the flue gas temperature is 150°C, the sulfur dioxide removal rate is only 42%, and the mercury removal efficiency is 87%.

[0066] Comparative Example 3

[0067] Compared with Example 1, the only difference is that ferric chloride is not added, and other operations and parameters are the same as Example 1. When the flue gas temperature is 150°C, the sulfur dioxide removal efficiency is 70%, and the mercury removal efficiency is 72%.

[0068] Comparative Example 4

[0069] Compared with Example 1, the only difference is that aluminum sulfate is used in equal amount to replace the ferric chloride, and other operations and parameters are the same as Example 1. When the flue gas temperature is 150°C, the sulfur dioxide removal efficiency is 65%, and the mercury removal efficiency is 71%.

[0070] Example 2

[0071] Compared with Example 1, the only difference is that no selenium source and seed crystal are added, and other operations and parameters are the same as Example 1. When the flue gas temperature is 150°C, the sulfur dioxide removal efficiency is 77%, and the mercury removal efficiency is 83%.

[0072] Example 3

[0073] 9.2 g of the powdered red mud-based composite material obtained in Example 1 was mixed with 0.3 g of water glass, and 0.5 mL of water was added dropwise to wet and mix, and the mixture was added to an extruder for molding and granulation to obtain a granular red mud-based composite material with a size of 4 mm.

[0074] The granular red mud-based composite material was filled in a simulated fixed bed reactor with a filling height of 4 cm. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller, and a quantitative amount of elemental mercury was produced through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury analyzer were used to measure sulfur dioxide and mercury in real time. The total gas flow rate was 2 L / min, the initial sulfur dioxide concentration was 100 ppm, and the initial mercury concentration was 400 ± 2 μg / m 3 At 125℃, the sulfur dioxide removal rate is higher than 75%, and the mercury removal efficiency is higher than 99.5%.

[0075] Example 4

[0076] 9g of sintered red mud with a CaO content of 17% was dried at room temperature, and then 1g of carbonate (calcium carbonate) was added, mixed and dried at 110°C, and ground; 0.52g of sodium selenite was dissolved in water to prepare a solution, 0.3g of sodium thiosulfate and 0.15g of GSH were added, and then 0.06g of fine selenium powder above 400 mesh was added as a seed crystal, and the activated mother liquor was obtained by high-speed stirring; the activated mother liquor was diluted and added to the red mud mixture, and then 0.2g of ferric chloride was added for aging and modification to form a mud, which was stirred for 1h, dehydrated after aging, dried at 95°C for 12h, ground and crushed, and passed through a 200-mesh sieve to obtain a powdered red mud-based composite material.

[0077] 20 mg of powdered red mud-based composite material was weighed and placed in a simulated fixed bed reactor. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller, and a quantitative amount of elemental mercury was generated through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury analyzer were used to measure sulfur dioxide and mercury in real time. The total gas flow rate was 1 L / min, the initial sulfur dioxide concentration was 50 ppm, and the initial mercury concentration was 200 ± 2 μg / m 3 In the temperature range of 100-175℃, the sulfur dioxide removal rate is higher than 70%, and the mercury removal efficiency is higher than 98%.

[0078] The powdered red mud-based composite material was sprayed into the flue of the simulated pilot platform. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller. A quantitative amount of elemental mercury was produced through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury analyzer were used to measure sulfur dioxide and mercury in real time. The initial sulfur dioxide concentration was 50 ppm and the initial mercury concentration was 40 ± 1 μg / m 3 The spraying amount of powdered red mud-based composite material is 0.6g / m 3 At 100℃, the sulfur dioxide removal rate is higher than 90%, and the mercury removal efficiency is higher than 99%.

[0079] Example 5

[0080] 9.2g of Bayer red mud with a CaO content of 5% was dried at room temperature, and then 0.8g of carbonate (sodium carbonate) was added, mixed and dried at 110°C, and ground; 0.45g of SeO2 was dissolved in water to prepare a solution, 0.3g of sodium thiosulfate and 0.15g of GSH were added, and then 0.02g of fine selenium powder above 400 mesh was added as a seed crystal, and an activated mother liquor was obtained by high-speed stirring; the activated mother liquor was diluted and added to the red mud mixture, and then 0.5g of ferric chloride was added for aging and modification to form a mud slurry, which was stirred for 1h, dehydrated after aging, dried at 95°C for 12h, ground and crushed, and passed through a 200-mesh sieve to obtain a powdered red mud-based composite material.

[0081] 9 g of powdered red mud-based composite material, 0.2 g of water glass, and 0.4 g of CaO were mixed according to mass fractions, and 0.4 mL of water was added dropwise to wet and mix, and the mixture was added to an extruder for molding and granulation to obtain granular red mud-based composite materials with a size of 3 mm.

[0082] The granular red mud-based composite material was filled in a simulated fixed bed reactor with a filling height of 6 cm. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller, and a quantitative amount of elemental mercury was produced through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury meter were used to measure sulfur dioxide and mercury in real time. The total gas flow rate was 1 L / min, the initial sulfur dioxide concentration was 100 ppm, and the initial mercury concentration was 1200 ± 2 μg / m 3 At 125℃, the sulfur dioxide removal rate is higher than 80%, and the mercury removal efficiency is higher than 98%.

[0083] Example 6

[0084] The red mud-based composite material powder material was produced in batches according to the proportion of Example 2, and the powder material was sprayed into the air inlet of the pilot simulated wet desulfurization tower. A quantitative amount of sulfur dioxide was generated through a sulfur dioxide standard gas cylinder and a flow controller, and a quantitative amount of elemental mercury was generated through a mercury permeation tube. A flue gas analyzer and a VM-3000 mercury meter were used to measure sulfur dioxide and mercury in real time. The initial sulfur dioxide concentration was 200 ppm, and the initial mercury concentration was 200±1 μg / m 3 The spraying amount of powdered red mud-based composite material is 1g / m 3 , measuring the outlet of the desulfurization tower, the sulfur dioxide removal rate is higher than 99%, and the mercury removal efficiency is higher than 99.5%.

[0085] When the alkali dosage in the simulated wet desulfurization tower was reduced to 70%, the sulfur dioxide removal rate was 82% when the red mud-based composite material powder was not sprayed, and the sulfur dioxide removal rate was higher than 99% when the powder was sprayed, indicating that the spraying of red mud-based composite materials can reduce the use of alkali in the wet desulfurization tower to a certain extent.

[0086] Example 7

[0087] A field test was conducted in a certain enterprise, and the smoke volume was 3600m 3 / h, the concentration of sulfur dioxide is 30 PPM,

[0088] The concentration of mercury is 100-200 μg / m 3 , about 0.6 m 3 The granular red mud-based composite material is filled into the drawers of the fixed bed (such as Figure 2 As shown in the figure), the temperature of the fixed bed is 45-50°C, the removal rate of sulfur dioxide is 79%, and the removal rate of mercury is more than 98%.

[0089] The above embodiments are intended to illustrate the present invention rather than to limit the present invention. Any solution that is simply modified from the present invention falls within the protection scope of the present invention.

Claims

1. A method for preparing a red mud-based mercury-removing sulfur material, characterized in that: A solution containing red mud, carbonate, selenium source, additives and auxiliary agents is aged and modified, followed by solid-liquid separation to obtain a red mud-based mercury-removing sulfur material; The auxiliary agent includes at least one of ferric chloride, ferrous sulfate and polymerized ferric sulfate.

2. The method for preparing the red mud-based mercury-removing sulfur material according to claim 1, characterized in that: The red mud is derived from at least one of the red muds of the Bayer process, the sintering process and the combined process in the production of alkaline alumina.

3. The method for preparing the red mud-based mercury-removing sulfur material according to claim 1, characterized in that: The carbonate includes at least one of sodium bicarbonate, calcium bicarbonate, sodium carbonate, calcium carbonate and magnesium carbonate.

4. The method for preparing the red mud-based mercury-removing sulfur material according to claim 1, characterized in that: The selenium source includes at least one of selenium dioxide, selenite and selenate; Preferably, the additive comprises at least one of thiosulfate and GSH; Preferably, the additive is 0.5 to 1.5 times the weight of the selenium source.

5. The method for preparing the red mud-based mercury-removing sulfur material according to any one of claims 1 to 4, characterized in that: The red mud and carbonate are mixed in advance to obtain a mixture A; a selenium source and an additive are dispersed in a solution to obtain an activated mother solution; the mixture A, the activated mother solution and an auxiliary agent are then mixed, aged and modified, and then solid-liquid separation is performed to obtain a red mud-based mercury-removing sulfur material.

6. The method for preparing the red mud-based mercury-removing sulfur material according to claim 5, characterized in that: The activation mother solution is further added with fine selenium powder seeds with a selenium particle size of more than 400 meshes; Preferably, the amount of fine selenium powder seed crystals used is 1%-20% by weight of the selenium source.

7. The method for preparing the red mud-based mercury-removing sulfur material according to any one of claims 1 to 6, characterized in that: The weight ratio of red mud to carbonate is 75-95:5-25; The selenium source is 1-10wt.% of the weight of red mud; The additive is 0.2-8% of the weight of red mud; Preferably, the aging and modification time is more than 0.5 h.

8. The method for preparing the red mud-based mercury-removing sulfur material according to claim 1, characterized in that: The method also includes the step of granulating the red mud-based mercury-removing sulfur material to obtain granular red mud-based mercury-removing sulfur material.

9. A red mud-based mercury-removing sulfur material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the red mud-based mercury-removing sulfur material prepared by the preparation method according to any one of claims 1 to 8 for the simultaneous removal of sulfur dioxide and mercury from flue gas; Preferably, the removal method is dry adsorption or wet adsorption; Preferably, the temperature in the removal stage is 20-200°C.

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