Device and method for removing pollutants through ozone oxidation

Abstract

The invention belongs to the field of red mud, sulfur dioxide and nitrogen oxide treatment, and relates to a device and a method for removing pollutants through ozone oxidation. The device comprises a flue gas inlet pipeline, a heat exchange device, a pre-dedusting device, a red mud liquid inlet pipe, an ozone machine, a conveyor, a desulfurization and denitrification unit tower and a red mud recycling device, the interior of the desulfurization and denitrification unit tower is sequentially divided into a red mud discharge area, a mixing area, a dust removal and desulfurization area, a denitrification area and a flue gas discharge area from bottom to top; a red mud liquid inlet pipe is connected with the upper portion of the denitration area, a red mud conveyor pipe, an ozone conveying pipe and a red mud liquid return pipe are all connected with a conveyor, the red mud discharging area is provided with a red mud discharging pipe, the red mud discharging pipe is connected with the bottom of the red mud recycling device, and the smoke discharging area is provided with a first smoke discharging pipe. The integrated liquid phase synchronous desulfurization and denitrification reactor is adopted, SO2 and NO are efficiently removed, meanwhile, dust is synchronously removed, the occupied area of the device and the technology is saved, and the flue gas pollutant treatment economical efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of red mud and sulfur dioxide and nitrogen oxide treatment, specifically, it relates to an apparatus and method for ozone oxidation to remove pollutants. Background Technology

[0002] my country's alumina production is substantial, generating large quantities of red mud annually. As a hazardous waste, red mud, when left in stockpiles for extended periods, causes soil alkalization due to its alkaline nature and pollutes groundwater. Furthermore, my country's industrial processes also produce significant amounts of waste gas containing particulate matter, SO2, and NO, severely impacting the atmospheric environment. Therefore, the proper treatment of waste red mud and gaseous pollutants during production is an essential environmental protection requirement.

[0003] The treatment of particulate matter in flue gas commonly employs processes such as cyclone dust collection, bag filter dust collection, electrostatic precipitator, and electrostatic-bag filter dust collection to ensure that flue gas emissions meet standards and that particulate matter concentration is less than 10 mg / m³. 3 To meet the demands of flue gas desulfurization and denitrification, a two-stage dust removal process is often employed to ensure efficient removal of particulate matter. This also ensures that particulate matter does not negatively impact SO2 and NO removal during the subsequent desulfurization and denitrification processes. However, this results in a large footprint, high cost, and complex operation for dust removal processes. Therefore, reducing the number of dust removal process units is an effective way to improve the economy and operability of flue gas treatment.

[0004] For the treatment of SO2 and NO in flue gas, conventional wet flue gas desulfurization combined with selective catalytic reduction (SCR) denitrification technology has a large footprint, complex processes, and high temperature requirements. For example, CN117205738A discloses a flue gas desulfurization and denitrification system and method. This invention proposes a treatment device consisting of an oxidation reaction tower, an alkaline absorption tower, an acid storage tank, an alkaline storage tank, and an activated carbon box. However, the oxidation reaction tower and alkaline absorption tower require the addition of packing material, which is costly due to the packing material and the acid and alkali solutions. The oxidation and alkali absorption require a large amount of equipment, increasing the process's footprint and complexity. CN109718653B discloses a flue gas desulfurization and denitrification device and method. This method uses a flue gas scrubbing and denitrification structure to inject chlorine dioxide into the flue gas to oxidize NO, followed by alkaline absorption. However, in this process, chlorine dioxide simultaneously contacts both NO and SO2. The oxidation of SO2 increases the amount of chlorine dioxide used, leading to increased ineffective usage and chlorine residue issues.

[0005] Alkaline absorption saves space and avoids temperature limitations. Red mud contains a large amount of alkaline substances such as calcium oxide and sodium oxide, making it suitable for resource utilization as an alkaline absorbent. Through liquid-phase desulfurization and denitrification, it achieves resource-based treatment of gaseous pollutants from waste. However, this process suffers from low NO solubility and competition between SO2 and particulate matter during NO oxidation, leading to decreased oxidant efficiency and insufficient NO removal. Ozone is often added as an oxidant to oxidize NO and enhance the red mud's NO absorption capacity. However, ozone itself has low utilization, resulting in high ozone consumption, significant ineffective utilization, and limited improvement in NO removal rate. Furthermore, the spraying method in this process has poor gas-liquid two-phase contact efficiency. To ensure treatment effectiveness, the alkaline absorbent is often circulated during spraying, increasing the cost and complexity of the process. For example, CN109675425B discloses a system and method for integrated desulfurization and denitrification treatment and resource utilization of flue gas using red mud. The invention includes two independent parts, a desulfurization spray tower and a denitrification spray tower, which perform desulfurization and denitrification separately. Although it avoids the ineffective consumption of ozone caused by ozone oxidation of SO2, the addition of equipment leads to the problem of increased cost due to increased floor space and mechanical equipment.

[0006] As shown above, ozone oxidation desulfurization and denitrification is a method that oxidizes SO2 and NO in flue gas after dust removal with an oxidant and then treats them using alkaline solution absorption. In this process, alkaline solution and oxidant are the main reagent sources, directly affecting the operating cost. Furthermore, in this technology, the oxidation of SO2 and particulate matter in the flue gas by the oxidant increases the ineffective use of the oxidant, resulting in increased oxidant consumption and decreased NO removal efficiency.

[0007] Therefore, while ensuring the removal rate of pollutants, how to effectively utilize oxidants and simplify the scale of equipment are problems that urgently need to be solved in this field. Summary of the Invention

[0008] To address the problems of high reagent costs, large ozone usage but low effective utilization rate, and low NO removal efficiency in current ozone oxidation pollutant removal processes, this invention provides an ozone oxidation pollutant removal device and method. It utilizes hazardous waste red mud, optimizes reactor structure and design, enhances ozone effective utilization while reducing usage, improves the efficiency of integrated reactor in removing particulate matter, SO2, NO, and other pollutants from flue gas, and recycles byproducts.

[0009] To achieve the above objectives, a first aspect of the present invention provides an ozone oxidation device for removing pollutants, the device comprising: a flue gas inlet pipe, a heat exchange device, a pre-dust removal device, a red mud inlet pipe, an ozone generator, a conveyor, a desulfurization and denitrification unit tower, and a red mud recycling device;

[0010] The desulfurization and denitrification unit tower is divided into red mud discharge zone, mixing zone, dust removal and desulfurization zone, denitrification zone and flue gas discharge zone from bottom to top;

[0011] The flue gas inlet pipe is connected in sequence to a heat exchange device and a pre-dust removal device, and then extends into the mixing zone. An aeration device is installed on the pipe extending into the mixing zone.

[0012] The red mud inlet pipe is connected to the upper part of the denitrification zone. A red mud conveyor pipe is also installed on the red mud inlet pipe. An ozone generator is equipped with an ozone conveyor pipe. A red mud slurry return pipe is installed in the mixing zone. The red mud conveyor pipe, the ozone conveyor pipe, and the red mud slurry return pipe are all connected to the conveyor. The conveyor is located at the junction of the dust removal and desulfurization zone and the denitrification zone.

[0013] The red mud discharge area is equipped with a red mud discharge pipe, which is connected to the bottom of the red mud recycling device. The flue gas discharge area is equipped with a No. 1 flue gas pipe, which is connected to a heat exchange device.

[0014] A second aspect of the present invention provides a method for removing pollutants by ozone oxidation, using the aforementioned ozone oxidation apparatus, comprising the following steps:

[0015] S1: The flue gas to be treated enters the device through the flue gas inlet pipe. After the temperature is reduced by the heat exchange device, the flue gas to be treated is cooled and then enters the pre-dust removal device for pre-dust removal treatment to obtain the pre-dust-removed flue gas.

[0016] S2: Red mud slurry is continuously transported to the desulfurization and denitrification unit tower through the red mud inlet pipe and conveyor. Oxygen source generates ozone-containing gas through an ozone generator. The ozone-containing gas is continuously transported to the desulfurization and denitrification unit tower through the conveyor. The red mud slurry entering the desulfurization and denitrification unit tower through the conveyor comes from the red mud conveyor pipe and the red mud slurry return pipe.

[0017] S3: After pre-dust removal treatment, the flue gas enters the mixing zone and reacts with the red mud slurry in the desulfurization and denitrification unit tower. Dust removal and desulfurization are carried out in the dust removal and desulfurization zone, and ozone denitrification reaction is carried out in the denitrification zone after contacting ozone-containing gas.

[0018] S4: The gas generated in step S3 is discharged from the top of the flue gas discharge zone through the No. 1 flue pipe, and exchanges heat with the flue gas to be treated through the heat exchange device. The red mud slurry after the reaction in step S3 is discharged from the bottom of the red mud discharge zone and transported to the red mud recycling device.

[0019] The present invention has the following advantages:

[0020] (1) An integrated liquid phase synchronous desulfurization and denitrification reactor is adopted, with zoning and internal component control to enhance treatment efficiency and effect, and to treat flue gas in a coordinated manner. It can efficiently remove SO2 and NO while simultaneously removing dust, saving the footprint of the equipment and process, and improving the economic efficiency of flue gas pollutant treatment.

[0021] (2) Optimize the process and equipment structure to enhance ozone utilization, improve treatment effect, reduce ozone usage, and increase ozone utilization.

[0022] (3) While co-treating pollution with waste pollutant red mud, the resource utilization of hazardous waste is used to prepare building materials.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0024] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of a pollutant removal device according to a specific embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the internal partitioning of the desulfurization and denitrification unit tower in a pollutant removal device according to a specific embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the construction of the denitrification zone inside the desulfurization and denitrification unit tower in a pollutant removal device according to a specific embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the flue gas flow direction inside the desulfurization and denitrification unit tower of a pollutant removal device according to a specific embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram showing the flow direction of red mud inside the desulfurization and denitrification unit tower of a pollutant removal device according to a specific embodiment of the present invention.

[0030] Figure 6 This is a schematic diagram showing the flow direction of ozone micro-nano bubbles generated by the conveyor inside the desulfurization and denitrification unit tower in a specific embodiment of the pollutant removal device of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 1. Flue gas inlet pipe; 2. Heat exchanger; 3. Pre-dust removal device; 4. No. 1 exhaust pipe; 5. Red mud inlet pipe; 6. Red mud conveyor pipe; 7. Ozone generator; 8. Ozone conveying pipe; 9. Conveyor; 10. Red mud slurry return pipe; 11. Desulfurization and denitrification unit tower; 12. Aeration device; 13. No. 1 air inlet pipe; 14. Red mud discharge pipe; 15. Material recovery pipe; 16. Heating device; 17. Heating pipeline; 18. Red mud recycling; 19. No. 2 air inlet pipe; 20. No. 2 exhaust pipe; 21. Flue gas discharge pipeline; 22. Flue gas flow meter.

[0033] A1: Red mud discharge zone; A2: Mixing zone; A3: Dust removal and desulfurization zone; A4: Denitrification zone; A5: Flue gas discharge zone.

[0034] B1: First guide vane, B2: Second guide vane, B2-1: First arc, B3: Third guide vane, B3-1: Second arc. Detailed Implementation

[0035] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0036] To achieve the above objectives, a first aspect of the present invention provides an ozone oxidation device for removing pollutants, the device comprising: a flue gas inlet pipe 1, a heat exchange device 2, a pre-dust removal device 3, a red mud inlet pipe 5, an ozone generator 7, a conveyor 9, a desulfurization and denitrification unit tower 11, and a red mud recycling device 18.

[0037] The desulfurization and denitrification unit tower 11 is divided into red mud discharge zone A1, mixing zone A2, dust removal and desulfurization zone A3, denitrification zone A4 and flue gas discharge zone A5 from bottom to top;

[0038] The flue gas inlet pipe 1 is connected in sequence to the heat exchange device 2 and the pre-dust removal device 3, and then extends into the mixing zone A2. An aeration device 12 is installed on the pipe extending into the mixing zone A2.

[0039] The red mud inlet pipe 5 is connected to the upper part of the denitrification zone A4. The red mud inlet pipe 5 is also equipped with a red mud conveyor pipe 6. The ozone generator 7 is equipped with an ozone conveyor pipe 8. The mixing zone A2 is equipped with a red mud slurry return pipe 10. The red mud conveyor pipe 6, the ozone conveyor pipe 8 and the red mud slurry return pipe 10 are all connected to the conveyor 9. The conveyor (9) is located at the junction of the dust removal and desulfurization zone (A3) and the denitrification zone (A4).

[0040] The red mud discharge zone A1 is equipped with a red mud discharge pipe 14, which is connected to the bottom of the red mud recycling device 18. The flue gas discharge zone A5 is equipped with a No. 1 flue pipe 4, which is connected to the heat exchange device 2.

[0041] According to the present invention, preferably, the conveyor 9 is a micro-nano bubble generator, wherein at least one swirling structure and multiple breaking structures are distributed inside the micro-nano bubble generator. Preferably, the number of swirling structures is 1 to 5, more preferably 3 to 4, and the number of breaking structures is 12 to 36, more preferably 15 to 20.

[0042] According to the present invention, preferably, the number of conveyors 9 is 2 to 8, more preferably 3 to 6.

[0043] According to the present invention, preferably, the red mud slurry return pipe 10, the red mud conveyor pipe 6 and the ozone conveyor pipe 8 are combined and then connected to the conveyor 9.

[0044] According to the present invention, the desulfurization and denitrification unit tower is designed with a dust removal and desulfurization zone and a denitrification zone. The two functional zones can be divided by the height of the two zones and the height of the conveyor. Preferably, the height ratio of the dust removal and desulfurization zone A3 to the denitrification zone A4 is 1:1 to 4, and more preferably 1:2 to 3.

[0045] According to the present invention, preferably, the denitrification zone A4 is provided with a guide plate to improve the contact efficiency between the pre-dust removal flue gas, the red mud slurry, and the micro-nano bubbles; the guide plate includes at least a first guide plate B1, the first guide plate B1 is a first conical surface, the axis of the first conical surface is arranged in the vertical direction, the center height of the first conical surface is consistent with the horizontal height of the outlet of the conveyor 9, and the angle between the generatrix of the first conical surface and the horizontal direction is 20° to 45°;

[0046] Preferably, the guide plate further includes a second guide plate B2, which is an inverted cone. The longitudinal profile of the cone includes a pair of first arcs B2-1 symmetrically arranged with respect to the axis of the cone and a base tangent to the pair of first arcs. The center of each first arc is located on the extension line of the outlet of the conveyor 9, and the intersection of the pair of first arcs or the intersection of their extension lines is also located on the extension line of the outlet of the conveyor 9. The arc of the first arc is 100° to 160°.

[0047] More preferably, the guide plate further includes a third guide plate B3, which is a second conical surface. The second conical surface is attached to the inner wall of the denitrification zone A4, and its axis is set in the horizontal direction. The longitudinal profile of the second conical surface includes a pair of second arcs B3-1 symmetrically arranged with respect to the axis of the second conical surface. The distance between the vertex of the second conical surface and the top of the second guide plate B2 is equal to the distance between it and the bottom of the red mud inlet pipe 5. The arc of the second arc is 60° to 80°.

[0048] The first guide plate B1 has two main functions: (1) When the flue gas moving upward from the bottom is guided by the lower part of the guide plate, it is gathered and concentrated into the surrounding channel of the reaction tower and moves upward, forcing the flue gas to approach the outlet of the conveyor 9, completing the forced mixing with ozone micro-nano bubbles, and being carried by the ozone micro-nano bubbles with high impact force and high flow rate into the second guide plate; (2) The height center of the first guide plate corresponds to the outlet of the conveyor 9. The ozone micro-nano bubbles with high impact force and high flow rate emitted by the conveyor carry the flue gas and the red mud slurry moving downward from the top of the device tower through the guiding effect of the upper part of the first guide plate and are transported into the second guide plate.

[0049] The functions of the second guide plate B2 are: (1) to provide an arc-shaped space to enhance the mixing effect of flue gas and red mud slurry carried by ozone micro-nano bubbles at the outlet of conveyor 9. The arc-shaped space is narrower than the upper and lower parts of the second type of guide plate, which can increase the mixing fluid outlet of the mixed fluid containing ozone micro-nano bubbles at the second type of guide plate to carry the red mud and flue gas in the reaction tower. When leaving the second type of guide plate, the mixed fluid can be further fully mixed and optimized under the condition that the flow field space suddenly increases; (2) the outer part of the inner circle of the upper part of the second type of guide plate can guide the red mud slurry moving from top to bottom at the top of the reaction tower, concentrate the red mud slurry around the reaction tower and move downward, so that the red mud slurry is closer to the outlet of conveyor 9, which facilitates the red mud slurry containing ozone micro-nano bubbles to carry the red mud slurry entering through the red mud inlet pipe 5 into the arc cavity of the second type of guide plate for enhanced contact.

[0050] The function of the third guide plate B3 is as follows: (1) The red mud slurry entering from the top moves downward around the reaction tower after the combined action of the upper part of the third guide plate and the upper part of the second guide plate, bringing the red mud slurry closer to the outlet of the conveyor 9; (2) When the micro-nano bubbles and flue gas in the mixed liquid after the enhanced mixing inside the second guide plate move upward, they are evenly distributed through the lower part of the third guide plate, so that the gas moves closer to the center at the top of the reaction tower, improving the contact efficiency with the red mud slurry in the denitrification zone A4, and at the same time enhancing the discharge of flue gas from the top center outlet of the reaction tower.

[0051] In this invention, the denitrification zone inside the desulfurization and denitrification unit tower is equipped with a flow guide baffle to improve the contact efficiency between the pre-dust removal flue gas, red mud slurry, and micro-nano bubbles.

[0052] According to the present invention, preferably, the pre-dust removal device 3 is at least one of gravity dust removal device, cyclone dust removal device, bag dust removal device, electrostatic dust removal device and electrostatic bag dust removal device.

[0053] According to the present invention, preferably, the device further includes a heating device 16, the heating device 16 being provided with a heating pipeline 17, the heating pipeline 17 being connected to the lower part of the red mud recycling device 18.

[0054] Preferably, the No. 1 exhaust pipe 4 is connected to the heat exchange device 2 and then splits into two branches. One branch is connected to the lower part of the red mud recycling device 18 through the No. 2 air inlet pipe 19, and the other branch is connected to the outside as the flue gas exhaust pipeline 21. A flue gas flow meter 22 is installed on the pipeline.

[0055] According to the present invention, preferably, the red mud recycling 18 is provided with a material recycling pipe 15 at the bottom and a No. 2 exhaust pipe 20 at the top, and the No. 2 exhaust pipe 20 is connected to the flue gas inlet pipe 1.

[0056] A second aspect of the present invention provides a method for removing pollutants by ozone oxidation, using the aforementioned ozone oxidation apparatus, comprising the following steps:

[0057] S1: The flue gas to be treated enters the device through the flue gas inlet pipe 1, and after the temperature is reduced by the heat exchange device 2, the flue gas to be treated after cooling is obtained. It then enters the pre-dust removal device 3 for pre-dust removal treatment, and the flue gas after pre-dust removal treatment is obtained.

[0058] S2: Red mud slurry is continuously transported to the desulfurization and denitrification unit tower 11 through red mud inlet pipe 5 and conveyor 9. Oxygen source generates ozone-containing gas through ozone generator 7, and the ozone-containing gas is continuously transported to the desulfurization and denitrification unit tower 11 through conveyor 9. The red mud slurry entering the desulfurization and denitrification unit tower 11 through conveyor 9 comes from red mud conveyor pipe 6 and red mud slurry return pipe 10.

[0059] S3: After pre-dust removal treatment, the flue gas enters the mixing zone A2 and reacts with the red mud slurry in the desulfurization and denitrification unit tower. Dust removal and desulfurization are carried out in the dust removal and desulfurization zone A3, and ozone denitrification reaction is carried out in the denitrification zone A4 with ozone-containing gas.

[0060] S4: The gas generated in step S3 is discharged from the top of flue gas discharge zone A5 through flue gas pipe No. 1 4, and exchanges heat with the flue gas to be treated through heat exchange device 2. The red mud slurry after the reaction in step S3 is discharged from the bottom of red mud discharge zone A1 and transported to red mud recycling 18.

[0061] According to the present invention, preferably, in step S1, the temperature of the cooled flue gas to be treated is 80-200°C, more preferably 100-120°C.

[0062] Preferably, the particulate matter concentration in the flue gas after the pre-dust removal treatment is 10–200 mg / m³. 3 Preferably 10–70 mg / m³ 3 .

[0063] According to the present invention, preferably, in step S2, the red mud slurry is selected from at least one of Bayer process red mud, sintered red mud and composite red mud; the red mud content in the red mud slurry is 1 to 15 wt%, preferably 8 to 12 wt%.

[0064] Preferably, the flow rate of the red mud slurry in the red mud inlet pipe 5 is 0.1–1 m³. 3 / h, preferably 0.4~0.6m 3 / h.

[0065] Preferably, the flow rate of the red mud slurry entering the desulfurization and denitrification unit tower 11 via the conveyor 9 is 1-6 m³ / s. 3 / h; wherein, the flow rate of the red mud slurry in the red mud conveyor pipe 6 is 0.01~1m³. 3 / h; the flow rate of the red mud slurry in the red mud slurry return pipe 10 is 0.1~5m³ / h. 3 / h.

[0066] According to the present invention, preferably, in step S2, the oxygen source is at least one of air, oxygen, and oxygen-containing industrial waste gas (oxygen content higher than 8%).

[0067] Preferably, the ozone generator produces ozone-containing gas at a rate of 100-400 g / h, more preferably 150-250 g / h, and the ozone concentration in the ozone-containing gas is 30-150 g / m³. 3 Preferably 60-90 mg / m³ 3 .

[0068] Preferably, the flow rate ratio of ozone to red mud slurry in the conveyor 9 is (0.2-1.2):1.

[0069] According to the present invention, preferably, in step S3, the flow rate of the flue gas after pre-dust removal is 50-600 m³ / h. 3 / h, preferably 200-300m 3 / h.

[0070] Preferably, the residence time of the flue gas after pre-dust removal in the desulfurization and denitrification unit tower 11 is 5 to 60 seconds, more preferably 20 to 40 seconds.

[0071] Preferably, the ratio of flue gas to red mud slurry treated in the desulfurization and denitrification unit tower is in the range of 200 to 800:1, more preferably 400 to 600:1;

[0072] Preferably, the hydraulic residence time of the red mud slurry in the desulfurization and denitrification unit tower 11 is 1 to 6 hours, and more preferably 3 to 4 hours.

[0073] According to the present invention, preferably, the gas generated in step S3 includes flue gas after oxidation and absorption and ozone-containing gas after reaction.

[0074] According to the present invention, preferably, the method further includes step S5: the red mud slurry after the reaction in step S3 is doped with additives and calcined in the red mud recycling device 18 to prepare building materials through resource utilization.

[0075] According to the present invention, preferably, after the flue gas discharged from the top of the flue gas discharge zone A5 exchanges heat with the flue gas to be discharged through the heat exchange device 2, a portion of it enters the red mud recycling device 18 to provide an oxygen source and supply heat energy. The ratio of the flue gas entering the red mud recycling device 18 to the flue gas discharged from the top of the flue gas discharge zone A5 is 1:10 to 1:50; preferably 1:22 to 1:28.

[0076] According to the present invention, preferably, the mixing ratio of the reacted red mud slurry to the additive is 1:0.8 to 1:2; more preferably, it is 1:1.1 to 1:1.5; the additive includes fly ash and at least one of the following components: coal gangue, desulfurization ash, cement, lime, gypsum, sand, graphite, clay, sludge, bentonite and steel slag.

[0077] Preferably, the calcination conditions include: a temperature of 1000–1350°C, more preferably 1150–1250°C, and a time of 0.5–5 h, more preferably 1.5–2.5 h.

[0078] According to the present invention, preferably, the flue gas generated by calcination is mixed with the flue gas to be treated.

[0079] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0080] Example 1

[0081] This embodiment employs a device for ozone oxidation to remove pollutants enhanced by micro-nano bubbles, such as... Figures 1-3 As shown, the device includes: flue gas inlet pipe 1, heat exchange device 2, pre-dust removal device 3, red mud inlet pipe 5, ozone generator 7, 4 micro-nano bubble generators, desulfurization and denitrification unit tower 11, and red mud recycling device 18; the micro-nano bubble generator has 3 swirl structures and 18 breaking structures distributed inside.

[0082] The desulfurization and denitrification unit tower 11 is divided into red mud discharge zone A1, mixing zone A2, dust removal and desulfurization zone A3, denitrification zone A4 and flue gas discharge zone A5 from bottom to top; the denitrification zone A4 is equipped with 3 sets of guide baffles, and the height ratio of the dust removal and desulfurization zone A3 to the denitrification zone A4 is 1:2.

[0083] The flue gas inlet pipe 1 is connected in sequence to the heat exchange device 2 and the pre-dust removal device 3, and then extends into the mixing zone A2. An aeration device 12 is installed on the pipe extending into the mixing zone A2.

[0084] The red mud inlet pipe 5 is connected to the upper part of the denitrification zone A4. The red mud inlet pipe 5 is also equipped with a red mud conveyor pipe 6. The ozone generator 7 is equipped with an ozone conveyor pipe 8. The mixing zone A2 is equipped with a red mud slurry return pipe 10. The red mud slurry return pipe 10, the red mud conveyor pipe 6 and the ozone conveyor pipe 8 are connected together and then connected to the micro-nano bubble generator. The micro-nano bubble generator is located at the junction of the dust removal and desulfurization zone A3 and the denitrification zone A4.

[0085] The red mud discharge area A1 is equipped with a red mud discharge pipe 14, which is connected to the bottom of the red mud recycling device 18. The flue gas discharge area A5 is equipped with a No. 1 exhaust pipe 4, which is connected to the heat exchange device 2 and then splits into two branches. One branch is connected to the lower part of the red mud recycling device 18 through the No. 2 air inlet pipe, and the other branch is connected to the outside. The bottom of the red mud recycling device 18 is equipped with a material recovery pipe 15, and the top is equipped with a No. 2 exhaust pipe 20, which merges with the flue gas inlet pipe 1.

[0086] The denitrification zone A4 is equipped with guide plates, and each conveyor 9 corresponds to three sets of guide plates: a first guide plate B1, a second guide plate B2, and a third guide plate B3. The first guide plate B1 is a first conical surface, the axis of which is set vertically, the center height of which is consistent with the horizontal height of the conveyor 9 outlet, and the angle between the generatrix of the first conical surface and the horizontal direction is 35°. The second guide plate B2 is an inverted cone, the longitudinal profile of which includes a pair of first arcs B2-1 symmetrically arranged with respect to the axis of the cone and a base tangent to the pair of first arcs, the center of each first arc being... All are located on the extension line of the outlet of conveyor 9, and the intersection of a pair of first arcs or the intersection of their extension lines are also located on the extension line of the outlet of conveyor 9. The arc of the first arc is 120°. The third guide plate B3 is a second conical surface. The second conical surface is attached to the inner wall of the denitrification zone (A4). The axis is set in the horizontal direction. The longitudinal profile of the second conical surface includes a pair of second arcs B3-1 symmetrically arranged with respect to the axis of the second conical surface. The distance between the vertex of the second conical surface and the top of the second guide plate B2 is equal to the distance between it and the bottom of the red mud inlet pipe 5. The arc of the second arc is 70°.

[0087] The red mud treated was Bayer process red mud, whose main components included: CaO 25.4%, Fe2O3 22.3%, SiO2 15.2%, Al2O3 13.2%, Na2O 9.3%, and other components. The flue gas composition was: particulate matter 1733 mg / m³. 3 SO2 867 mg / m³ 3 NO 455mg / m 3CO2 12.3%, temperature 220℃.

[0088] A method for removing pollutants by ozone oxidation enhanced by micro-nano bubbles includes the following steps:

[0089] S1: Pre-dust removal

[0090] The treated flue gas is conveyed to flue gas inlet pipe 1. The exhaust flue gas from desulfurization and denitrification unit tower 11 enters heat exchange device 2. After heat exchange, the temperature of the treated flue gas decreases from 220℃ to 111℃, and the exhaust flue gas temperature increases from 56℃ to 92℃. The treated flue gas after heat exchange enters pre-dust removal device 3. Pre-dust removal device 3 adopts electrostatic precipitator and bag filter technology. After pre-dust removal, the particulate matter concentration in the treated flue gas decreases from 1733 mg / m³. 3 Reduced to 56 mg / m 3 .

[0091] S2: Ingredients

[0092] Ozone gas is generated by an ozone generator 7 using air as the oxygen source. The ozone gas generation rate is 220 g / h, and the ozone concentration is 80 g / m³. 3 The generated ozone gas enters the micro-nano bubble generator through ozone delivery pipe 8. Water is added to the Bayer process red mud residue to form a red mud slurry, improving the fluidity of the red mud. The red mud residue accounts for approximately 11% of the red mud slurry. The red mud slurry flows at a flow rate of 2.5m... 3 A flow rate of / h enters the micro / nano bubble generator, of which 0.05m 3 / h comes from red mud slurry conveyor pipe 6, with a length of 2.45m. 3 / h comes from the red mud slurry return pipe 10, in addition to 0.45m 3 / h of red mud slurry enters the red mud slurry inlet pipe 5, and the red mud slurry and ozone-containing gas enter the desulfurization and denitrification unit tower 11 respectively.

[0093] S3: Oxidation absorption

[0094] The flue gas after pre-dust removal is at 250m 3A flow rate of [flow rate] / h is delivered to the bottom of the desulfurization and denitrification unit tower 11 through inlet pipe 13. The dispersion of the treated flue gas within the tower is enhanced by aeration device 12. The treated flue gas undergoes enhanced mixing with red mud slurry in mixing zone A2 at the bottom of the tower. Particulate matter and SO2 are removed from the treated flue gas via red mud absorption in dust removal and desulfurization zone A3. As the treated flue gas rises within the tower, it comes into contact with ozone-containing micro-nano bubbles generated by a micro-nano bubble generator in denitrification zone A4. Forced mixing via the first guide plate B1, second guide plate B2, and third guide plate B3 improves the ozone oxidation efficiency and utilization rate of NO. Further NO removal from the flue gas occurs via red mud absorption. A schematic diagram of the fluid flow direction inside the desulfurization and denitrification unit tower 11 is shown below. Figure 4 , Figure 5 and Figure 6 As shown, the red mud slurry inside the desulfurization and denitrification unit tower exhibits a downward movement direction, as... Figure 5 As shown, the treated flue gas generally moves from bottom to top, as... Figure 4 As shown, the two achieve overall countercurrent flow, and within the denitrification zone, the micro-nano bubble ozone generated by the conveyor exhibits local crossflow with the red mud slurry and the treated flue gas, which enhances the treatment effect of the flue gas, improves the ozone utilization rate, and increases the absorption efficiency of the red mud slurry.

[0095] S4: Separation

[0096] After the flue gas treated in the desulfurization and denitrification unit tower 11 reacts with red mud slurry and ozone micro-nano bubbles, the nearly saturated red mud slurry is discharged from the lower red mud discharge pipe 14. After solid-liquid separation, the leachate returns to the front end to mix with red mud to prepare red mud slurry. The leachate residue is transported to the red mud recycling device 18. The flue gas composition after the reaction is 7 mg / m³ of particulate matter. 3 SO2 4.6 mg / m³ 3 NO 14.7 mg / m³ 3 The flue gas contains 8.2% CO2 and is 56°C. It is discharged through the No. 1 exhaust pipe 4 at the top and enters the heat exchange device 2 to exchange heat with the flue gas being processed. After heat exchange, the temperature rises from 56°C to 92°C. Subsequently, part of it is transported through the No. 2 intake pipe 19 to the red mud recycling device 18 as an oxygen source for calcination to prepare building materials. The excess flue gas is discharged from the system through the flue gas exhaust pipeline 21 after the flow rate is regulated by the flue gas flow meter 22.

[0097] S5: Resource Recycling

[0098] The red mud entering the red mud recycling device 18 is mixed with additives fly ash, cement, clay and graphite in a ratio of 1:1.3. Then, it is calcined at 1200°C for 2 hours by the heating device 16. The resulting building material is obtained through the material recycling pipe 15. The compressive strength of the obtained building material is 17.5 MPa. The flue gas generated by combustion is transported to the flue gas inlet pipe 1 through the No. 2 flue pipe 20 and mixed with the treated flue gas for treatment.

[0099] Example 2

[0100] The apparatus used in this embodiment is the same as in Example 1. The red mud processed is Bayer process red mud, whose main components include: CaO 21.8%, Fe2O3 20.5%, SiO2 17.4%, Al2O3 15.8%, Na2O 8.2%, and other components. The composition of the flue gas processed is: particulate matter 1862 mg / m³. 3 SO2 823mg / m 3 NO 427mg / m 3 CO2 15.1%, temperature 236℃.

[0101] A method for removing pollutants by ozone oxidation enhanced by micro-nano bubbles includes the following steps:

[0102] S1: Dust Removal

[0103] The treated flue gas is conveyed to flue gas inlet pipe 1. The exhaust flue gas from desulfurization and denitrification unit tower 11 enters heat exchange device 2. After heat exchange, the temperature of the treated flue gas decreases from 236℃ to 118℃, and the exhaust flue gas temperature increases from 62℃ to 96℃. The treated flue gas after heat exchange enters pre-dust removal device 3, which adopts electrostatic precipitator (ESP) technology. After pre-dust removal, the particulate matter concentration in the treated flue gas decreases from 1862 mg / m³. 3 Reduced to 63 mg / m 3 .

[0104] S2: Ingredients

[0105] Ozone gas is generated by an ozone generator 7 using air as the oxygen source. The ozone gas generation rate is 90 g / h, and the ozone concentration is 90 g / m³. 3 The generated ozone gas enters the micro-nano bubble generator through ozone delivery pipe 8. Water is added to the Bayer process red mud residue to form a red mud slurry, improving the fluidity of the red mud. The red mud residue accounts for approximately 12% of the red mud slurry. The red mud slurry flows at a flow rate of 2.5m... 3 A flow rate of / h enters the micro / nano bubble generator, of which 0.05m 3 / h comes from red mud slurry conveyor pipe 6, with a length of 2.45m. 3 / h comes from the red mud slurry return pipe 10, in addition to 0.5m 3 / h of red mud slurry enters the red mud slurry inlet pipe 5, and the red mud slurry and ozone-containing gas enter the desulfurization and denitrification unit tower 11 respectively.

[0106] S3: Oxidation absorption

[0107] The flue gas after pre-dust removal is at 265m 3 A flow rate of [flow rate] / h is delivered to the bottom of the desulfurization and denitrification unit tower 11 through inlet pipe 13. The dispersion of the treated flue gas within the tower is enhanced by aeration device 12. The treated flue gas undergoes enhanced mixing with red mud slurry in mixing zone A2 at the bottom of the tower. In dust removal and desulfurization zone A3, particulate matter and SO2 are removed from the treated flue gas through red mud absorption. As the treated flue gas rises within the desulfurization and denitrification unit tower 11, it comes into contact with ozone-containing micro-nano bubbles generated by a micro-nano bubble generator in denitrification zone A4. Forced mixing by the first guide plate B1, the second guide plate B2, and the third guide plate B3 improves the ozone oxidation efficiency for NO and the utilization rate of ozone. Further NO removal from the flue gas occurs through red mud absorption. A schematic diagram of the fluid flow direction inside the desulfurization and denitrification unit tower 11 is shown below. Figure 4 , Figure 5 and Figure 6 As shown, the red mud slurry inside the desulfurization and denitrification unit tower exhibits a downward movement direction, as... Figure 5 As shown, the treated flue gas generally moves from bottom to top, as... Figure 4 As shown, the two achieve overall countercurrent flow, and in the denitrification zone, the micro-nano bubble ozone generated by the conveyor exhibits local crossflow with the red mud slurry and the treated flue gas, which enhances the treatment effect of the flue gas, improves the ozone utilization rate, and increases the absorption efficiency of the red mud slurry.

[0108] S4: Separation

[0109] 11. After the flue gas treated in the desulfurization and denitrification unit tower reacts with red mud slurry and ozone micro-nano bubbles, the nearly saturated red mud slurry is discharged from the lower red mud discharge pipe 14. After solid-liquid separation, the leachate returns to the front end to mix with red mud to prepare red mud slurry. The leachate residue is transported to the red mud recycling device 18. After the reaction, the flue gas composition is 8 mg / m³ of particulate matter. 3 SO2 3.9 mg / m³ 3 NO 15.0 mg / m 3 The CO2 content is 9.2%, the temperature is 62℃, and the flue gas is discharged through the No. 1 exhaust pipe 4 at the top and enters the heat exchange device 2 to exchange heat with the flue gas being treated. Then, it is transported through the No. 2 intake pipe 19 to the red mud recycling device 18 as an oxygen source for calcination to prepare ceramsite materials.

[0110] S5: Resource Recycling

[0111] The red mud entering the red mud recycling device 18 is mixed with additives fly ash, bentonite, sludge, graphite and lime in a ratio of 1:1.4 and shaped into spherical particles. Then, it is calcined at 1250°C for 2.2 hours by the heating device 16. The resulting ceramsite material is obtained through the material recovery pipe 15. The compressive strength of the obtained ceramsite material is 9.7 MPa. The flue gas generated by combustion is transported to the flue gas inlet pipe 1 through the No. 2 exhaust pipe 20 and mixed with the treated flue gas for treatment.

[0112] Example 3

[0113] The apparatus used in this embodiment is the same as in Example 1. The red mud processed is Bayer process red mud, whose main components include: CaO 22.2%, Fe2O3 19.8%, SiO2 17.3%, Al2O3 16.2%, Na2O 8.4%, K2O 0.6%, and other components. The composition of the flue gas processed is: particulate matter 1965 mg / m³. 3 SO2 896mg / m³ 3 NO 537mg / m 3 CO2 10.7%, temperature 208℃.

[0114] A method for removing pollutants by ozone oxidation enhanced by micro-nano bubbles includes the following steps:

[0115] S1: Dust Removal

[0116] The treated flue gas is conveyed to flue gas inlet pipe 1. The exhaust flue gas from the desulfurization and denitrification unit tower 11 enters heat exchange device 2. After heat exchange, the temperature of the treated flue gas decreases from 208℃ to 106℃, and the exhaust flue gas temperature increases from 53℃ to 82℃. The treated flue gas after heat exchange enters pre-dust removal device 3, which adopts electrostatic precipitator (ESP) technology. After pre-dust removal, the particulate matter concentration in the treated flue gas decreases from 1965 mg / m³. 3 Reduced to 51 mg / m 3 .

[0117] S2: Ingredients

[0118] Ozone gas is generated by an ozone generator 7 using air as the oxygen source. The ozone gas generation rate is 90 g / h, and the ozone concentration is 90 g / m³. 3 The generated ozone gas enters the micro-nano bubble generator through ozone delivery pipe 8. Water is added to the Bayer process red mud residue to form a red mud slurry, improving the fluidity of the red mud. The red mud residue accounts for approximately 9% of the red mud slurry, which flows at a flow rate of 2.5m... 3 A flow rate of / h enters the micro / nano bubble generator, of which 0.05m 3 / h comes from red mud slurry conveyor pipe 6, with a length of 2.45m. 3 / h comes from the 10. Red mud slurry return pipe, in addition to 0.45m 3 / h of red mud slurry enters the red mud slurry inlet pipe 5, and the red mud slurry and ozone-containing gas enter the desulfurization and denitrification unit tower 11 respectively.

[0119] S3: Oxidation absorption

[0120] The flue gas after pre-dust removal is at 265m 3 A flow rate of [flow rate] / h is delivered to the bottom of the desulfurization and denitrification unit tower 11 through inlet pipe 13. The dispersion of the treated flue gas within the tower is enhanced by aeration device 12. The treated flue gas undergoes enhanced mixing with red mud slurry in mixing zone A2 at the bottom of the tower. In dust removal and desulfurization zone A3, particulate matter and SO2 are removed from the treated flue gas through red mud absorption. As the treated flue gas rises within the desulfurization and denitrification unit tower 11, it comes into contact with ozone-containing micro-nano bubbles generated by a micro-nano bubble generator in denitrification zone A4. Forced mixing by the first guide plate B1, the second guide plate B2, and the third guide plate B3 improves the ozone oxidation efficiency for NO and the utilization rate of ozone. Further NO removal from the flue gas occurs through red mud absorption. A schematic diagram of the fluid flow direction inside the desulfurization and denitrification unit tower 11 is shown below. Figure 4 , Figure 5 and Figure 6 As shown, the red mud slurry inside the desulfurization and denitrification unit tower exhibits a downward movement direction, as... Figure 5 As shown, the treated flue gas generally moves from bottom to top, as... Figure 4 As shown, the two achieve overall countercurrent flow, and in the denitrification zone, the micro-nano bubble ozone generated by the conveyor exhibits local crossflow with the red mud slurry and the treated flue gas, which enhances the treatment effect of the flue gas, improves the ozone utilization rate, and increases the absorption efficiency of the red mud slurry.

[0121] S4: Separation

[0122] After the flue gas treated in the desulfurization and denitrification unit tower 11 reacts with red mud slurry and ozone micro-nano bubbles, the nearly saturated red mud slurry is discharged from the lower red mud discharge pipe 14. After solid-liquid separation, the leachate returns to the front end to mix with red mud to prepare red mud slurry. The leachate residue is transported to the red mud recycling device 18. The flue gas composition after the reaction is 8 mg / m³ of particulate matter. 3 SO2 4.9 mg / m³ 3 NO 16.5 mg / m 3 The CO2 content is 7.5%, the temperature is 53℃, and the flue gas is discharged through the No. 1 exhaust pipe 4 at the top and enters the heat exchange device 2 to exchange heat with the flue gas being treated. Then, it is transported through the No. 2 intake pipe 19 to the red mud recycling device 18 as an oxygen source for calcination to prepare building materials.

[0123] S5: Resource Recycling

[0124] The red mud entering the red mud recycling device 18 is mixed with additives fly ash, lime, cement, sand, steel slag and coal gangue in a ratio of 1:1.5 and shaped into spherical particles. Then, it is calcined at 1225°C for 2.5 hours by the heating device 16. The resulting building material is obtained through the material recycling pipe 15. The compressive strength of the obtained building material is 18.5 MPa. The flue gas generated by combustion is transported to the flue gas inlet pipe 1 through the No. 2 exhaust pipe 20 and mixed with the treated flue gas for treatment.

[0125] Keeping the operating conditions in Example 1 unchanged, the temperature of the flue gas after heat exchange was adjusted. The ozone concentration, flue gas dust removal efficiency, flue gas desulfurization efficiency and flue gas denitrification efficiency in No. 1 exhaust pipe corresponding to different flue gas temperatures after heat exchange are shown in Examples A1-A11 of Table 1.

[0126] Keeping the operating conditions in Example 1 unchanged, the particulate matter content in the flue gas after pre-dust removal was adjusted. The ozone concentration, flue gas dust removal efficiency, flue gas desulfurization efficiency and flue gas denitrification efficiency in No. 1 flue gas pipe corresponding to different particulate matter contents in the flue gas after pre-dust removal are shown in Examples A12-A23 of Table 1.

[0127] Table 1

[0128]

[0129]

[0130] Comparing the results of A1-A11 and Example 1, it can be seen that the flue gas temperature after heat exchange affects the ozone concentration in the flue gas inside Exhaust Pipe No. 1. This ozone in the flue gas originates from incompletely reacted ozone within the desulfurization and denitrification unit tower. Ozone significantly affects the denitrification efficiency of the flue gas. When the flue gas temperature after heat exchange is 100–120°C, the denitrification efficiency of the process unit is higher than 95%. When the flue gas temperature after heat exchange is lower than 100°C, the ozone concentration in the flue gas at Exhaust Pipe No. 1 increases, indicating that the ozone reactivity decreases with decreasing temperature, reducing the oxidation efficiency for NO and resulting in a denitrification efficiency below 95%. When the flue gas temperature after heat exchange is higher than 120°C, the ozone concentration in the flue gas at Exhaust Pipe No. 1 is zero, but the denitrification efficiency is still lower than 95%. This is because the higher flue gas temperature reduces ozone stability, leading to ozone decomposition and ineffective consumption, resulting in decreased oxidation efficiency for NO and thus reduced denitrification efficiency.

[0131] Comparing the results of A12-A23 and Example 1, it can be seen that the particulate matter concentration in the flue gas after pre-dust removal affects the dust removal efficiency of the treated flue gas. The pre-dust removal unit removes some particulate matter, but it consumes a relatively high amount of energy. Under the same energy consumption process conditions, the more particulate matter removed by the pre-dust removal unit, the higher the energy consumption. Maintaining some particulate matter in the flue gas after pre-dust removal can be achieved through simultaneous removal by the desulfurization and denitrification unit, reducing process energy consumption. However, the emission of the treated flue gas must meet the requirement that particulate matter concentration is less than 10 mg / m³. 3 The emission limit is set when the particulate matter concentration in the pre-dust removal flue gas is below 70 mg / m³. 3 At the same time, the desulfurization and denitrification unit towers can synergistically remove particulate matter, achieving a dust removal efficiency of over 99.5%, resulting in a particulate matter concentration in the treated flue gas emissions below 10 mg / m³. 3 .

[0132] Keeping the operating conditions of Example 1 unchanged, the concentration of red mud slurry was adjusted. The ozone concentration, flue gas desulfurization efficiency and flue gas denitrification efficiency in No. 1 flue gas pipe corresponding to different red mud slurry concentrations are shown in Examples B1-B8 of Table 2.

[0133] Keeping the operating conditions of Example 1 unchanged, the ozone gas generation rate was adjusted. The ozone concentration, flue gas desulfurization efficiency, and flue gas denitrification efficiency in Exhaust Pipe No. 1 corresponding to different ozone gas generation rates are shown in Examples B9-B17 of Table 2. In order to ensure that the gas volume entering the conveyor remains constant during this process, the ozone gas concentration is adjusted accordingly with the change in the ozone gas generation rate to keep the gas volume entering the conveyor basically constant (error < 2.5%).

[0134] Keeping the operating conditions of Example 1 unchanged, the ozone concentration was adjusted. The ozone concentration, flue gas desulfurization efficiency and flue gas denitrification efficiency in No. 1 flue gas pipe corresponding to different ozone concentrations are shown in Examples B18-B26 of Table 2.

[0135] Table 2

[0136]

[0137]

[0138] Comparing the results of B1-B8 and Example 1, it can be seen that the concentration of red mud in the slurry affects the ozone concentration in the No. 1 flue gas pipe, as well as the desulfurization and denitrification efficiency of the process. When the red mud slurry concentration is 8-12%, the desulfurization efficiency can be maintained above 99% and the denitrification efficiency above 95%. When the red mud slurry concentration is above 12%, the desulfurization efficiency will increase, but the red mud components will consume ozone, reducing the efficiency of ozone catalytic oxidation of NO, resulting in a denitrification efficiency below 95%. When the red mud slurry concentration is below 8%, the alkaline absorption capacity decreases, and both the desulfurization and denitrification efficiencies decrease, with the desulfurization efficiency below 99% and the denitrification efficiency below 95%.

[0139] Comparing the results of B9-B17 and Example 1, it can be seen that the ozone generation rate affects the ozone concentration in flue gas duct No. 1, as well as the desulfurization and denitrification efficiency of the process. When the ozone generation rate is in the range of 150-250 g / h, the desulfurization efficiency is higher than 99% while maintaining the denitrification efficiency above 95%, and the ozone concentration in flue gas duct No. 1 is kept below 15 mg / m³. 3 This method avoids excessive ozone release, reduces the environmental impact and equipment corrosion caused by ozone, and decreases ozone usage, thus improving process economy. When the ozone-generating gas velocity exceeds 250 g / h, the ozone concentration in exhaust pipe No. 1 exceeds 15 mg / m³. 3 This increases the corrosiveness of the equipment and poses a pollution risk to the environment. When the ozone production rate is below 150g / h, there is insufficient ozone, the denitrification efficiency decreases to below 95%, and the process treatment effect declines.

[0140] Comparing the results of B18-B26 and Example 1, it can be seen that ozone concentration affects the denitrification efficiency of the process. When the ozone concentration is 60-90 g / m³, the efficiency is significantly affected. 3 Within the specified range, the process achieves high denitrification efficiency, maintaining above 96%. However, when the ozone concentration exceeds 90 g / m³... 3 When less gas enters the conveyor, the ozone gas contact efficiency between the first and second guide plates in the denitrification zone of the desulfurization and denitrification unit tower decreases, and the ozone mass transfer rate slows down, resulting in a decrease in NO oxidation efficiency and thus a decrease in the denitrification efficiency of the process. When the ozone concentration is below 60 g / m³, the process becomes less efficient. 3 When a large amount of gas enters the conveyor, it is difficult for the conveyor to generate micro-nano bubbles. The size of ozone bubbles in the denitrification zone increases, which leads to a decrease in ozone contact efficiency and mass transfer rate, thereby reducing NO oxidation efficiency and the denitrification efficiency of the process.

[0141] Keeping the operating conditions of Example 2 unchanged, the flow rate of red mud slurry was adjusted. The flue gas dust removal efficiency, flue gas desulfurization efficiency and flue gas denitrification efficiency corresponding to different red mud slurry flow rates are shown in Examples C1-C7 of Table 3.

[0142] Keeping the operating conditions of Example 2 unchanged, the flue gas flow rate was adjusted, and the flue gas dust removal efficiency, flue gas desulfurization efficiency and flue gas denitrification efficiency corresponding to different flue gas flow rates are shown in Examples C8-C17 of Table 3.

[0143] Table 3

[0144]

[0145]

[0146] The red mud slurry flow rate is the total amount of fresh red mud slurry entering the desulfurization and denitrification unit tower, including the red mud slurry conveyor pipe and the red mud slurry inlet pipe. The results show that the red mud slurry flow rate and the flue gas flow rate affect the dust removal efficiency, desulfurization efficiency and denitrification efficiency in the process. At the same time, the ratio of the two will also affect the process efficiency in removing pollutants.

[0147] Comparing C1-C7 with Example 2, it can be found that when the red mud slurry flow rate is between 0.4-0.6 m³ / h... 3 Within the range of [flow rate] / h, the process exhibits good pollutant treatment efficiency, with dust removal efficiency exceeding 99.5%, desulfurization efficiency exceeding 99.5%, and denitrification efficiency exceeding 95.5%. This is achieved when the red mud slurry flow rate is below 0.4 m³ / h. 3 When the flow rate is less than 0.6 m³ / h, the alkali solution is insufficient, reducing the absorption capacity for SO2 and NO, especially the denitrification efficiency, which drops below 95%. 3 When the amount of red mud is too high, it will consume ozone and reduce the ozone's oxidation efficiency for NO, resulting in a denitrification efficiency of less than 95.5%.

[0148] Comparing C8-C17 and Example 2, it can be found that when the flue gas flow rate is 200-300 m³ / h... 3 Within the range of [flow rate] / h, the process exhibits good pollutant treatment efficiency, with dust removal efficiency exceeding 99.5%, desulfurization efficiency exceeding 99.5%, and denitrification efficiency exceeding 95.5%. This is particularly effective when the flue gas flow rate exceeds 300 m³ / h. 3 At a flow rate of [number] m³ / h, due to the large flue gas volume and the unchanged absorption capacity of the red mud slurry, the process's pollutant removal efficiency decreases, with dust removal efficiency below 99.5%, desulfurization efficiency below 99.5%, and denitrification efficiency below 95.5%. This effect also occurs when the flue gas flow rate is below 200 m³ / h. 3 At a rate of / h, the red mud slurry content is relatively high, which will consume ozone and reduce the ozone oxidation efficiency of NO, thereby reducing the denitrification efficiency to below 95.5%.

[0149] Comparing C1-C17 with Example 2 reveals that, in addition to the red mud slurry flow rate and flue gas flow rate, the ratio of flue gas flow rate to red mud slurry flow rate also affects the process operation. A suitable ratio enables the red mud slurry to efficiently absorb pollutants. When the ratio of flue gas flow rate to red mud slurry flow rate is within the range of 400-600:1, the process operation is excellent, ensuring a dust removal efficiency higher than 99.5%, a desulfurization efficiency higher than 99.5%, and a denitrification efficiency higher than 96%. An excessively high ratio of flue gas flow rate to red mud slurry flow rate will result in limited red mud slurry treatment effect and reduced flue gas treatment efficiency. Conversely, an excessively low ratio will result in excessive red mud slurry, causing ozone waste, reducing the ozone oxidation efficiency of NO, and leading to a decrease in denitrification efficiency.

[0150] Keeping the operating conditions of Example 2 unchanged, the number of conveyors connected to the desulfurization and denitrification unit tower was adjusted. The ozone concentration in No. 1 flue gas pipe, the average size of the bubble at the conveyor outlet, the flue gas desulfurization efficiency and the flue gas denitrification efficiency corresponding to different numbers of conveyors are shown in Examples D1-D4 of Table 4.

[0151] Keeping the operating conditions of Example 2 unchanged, the number of swirl structures inside each conveyor connected to the desulfurization and denitrification unit tower was adjusted. The ozone concentration in the No. 1 flue gas exhaust pipe, the average bubble size at the conveyor outlet, the flue gas desulfurization efficiency, and the flue gas denitrification efficiency corresponding to different numbers of swirl structures are shown in Examples D4-D7 of Table 4.

[0152] Keeping the operating conditions of Example 2 unchanged, the number of internal crushing structures in each conveyor connected to the desulfurization and denitrification unit tower was adjusted. The ozone concentration in No. 1 flue gas pipe, the average size of the bubble at the conveyor outlet, the flue gas desulfurization efficiency and the flue gas denitrification efficiency corresponding to different numbers of crusher structures are shown in Examples D8-D13 of Table 4.

[0153] Table 4

[0154]

[0155] A comparison of results D1-D3 with Example 2 reveals that the number of conveyors connected to the desulfurization and denitrification unit tower affects the ozone concentration and denitrification efficiency at flue gas outlet No. 1. When the number of conveyors is 4, the device and process treatment effect are optimal. The angular spacing between the conveyors in the reaction tower is consistent. With 4 conveyors, the fluid at the conveyor outlets interferes with each other less, while ensuring sufficient mixing in the reactor. At this time, the mixing efficiency and contact efficiency of the micro-nano bubbles at the outlet of the conveyor inside the second guide plate with the red mud slurry and the treated flue gas are high, thereby obtaining a high denitrification efficiency, which is higher than 96%. When the number of conveyors is less than 4 (e.g., 2 conveyors), the mixing of liquid and gas in the reaction tower is uneven, and the mixing effect in areas without conveyors is poor, resulting in a decrease in flue gas denitrification efficiency to 92.1%. When the number of conveyors is greater than 4 (e.g., 6 or 8), the angle between adjacent conveyors decreases, and the liquid swirling process at the outlet of adjacent conveyors overlaps and interferes, resulting in a worse fluid mixing effect in the reaction tower. As a result, although the number of conveyors increases, the denitrification efficiency decreases to below 95%.

[0156] A comparison of results D4-D7 with Example 2 reveals that the number of rotating structures inside the conveyor affects the ozone concentration at exhaust port 1, the average bubble size at the conveyor outlet, and the denitrification efficiency. When the number of rotating structures inside the conveyor is 3, the device and process achieve the best NO removal effect. When the number of rotating structures is less than 3, the average bubble size at the conveyor outlet increases significantly, indicating insufficient centrifugal force in the internal flow field of the conveyor. The increased bubble size leads to a decrease in ozone mass transfer efficiency, thus reducing the denitrification efficiency. When the number of rotating structures is greater than 3, the ozone concentration at exhaust port 1 drops to 0, indicating that the excessively rapid swirling flow field inside the conveyor accelerates ozone decomposition, leading to increased ineffective ozone consumption and thus reducing the denitrification efficiency.

[0157] A comparison of results D8-D13 with Example 2 reveals that the number of breakable structures inside the conveyor affects the ozone concentration at flue gas outlet No. 1, the average size of bubbles at the conveyor outlet, and the denitrification efficiency. The device and process achieve the best NO treatment effect when the number of breakable structures is 18. When the number of breakable structures is less than 15, the ozone bubble breakage effect inside the conveyor is insufficient, resulting in a larger average bubble size at the conveyor outlet. This leads to lower contact efficiency and mass transfer efficiency of ozone inside the desulfurization and denitrification unit, thus reducing the denitrification efficiency. When the number of breakable structures exceeds 21, the frequency of bubble collisions inside the conveyor increases, accelerating ozone decomposition and increasing ineffective ozone consumption, further reducing the denitrification efficiency.

[0158] Keeping the operating conditions of Example 3 unchanged, and keeping the tower height and internal volume of the desulfurization and denitrification unit tower unchanged, the height ratio of the dust removal and desulfurization zone to the denitrification zone is adjusted by regulating the height of the conveyor and guide plate in the desulfurization and denitrification unit tower. The ozone concentration, flue gas desulfurization efficiency and flue gas denitrification efficiency in No. 1 exhaust pipe corresponding to different height ratios are shown in Examples E1-E4 of Table 5.

[0159] Table 5

[0160]

[0161] Comparing Examples E1-E4 with Example 3, it can be found that a suitable ratio of dust removal / desulfurization zone to denitrification zone inside the desulfurization and denitrification unit tower can effectively improve the removal efficiency of SO2 and NO by the device and process. The ratio of the dust removal / desulfurization zone to the denitrification zone determines the contact time for SO2 absorption by the red mud slurry and NO oxidation by ozone inside the desulfurization and dust removal unit tower. When the height ratio of the dust removal / desulfurization zone to the denitrification zone is 1:2, the device and process of the present invention achieve better removal efficiency for SO2 and NO. When the ratio is 1:1 to 1:2, the contact time between SO2 and red mud slurry is prolonged, and the desulfurization efficiency is slightly increased. However, the contact oxidation time between ozone and NO in the flue gas is shortened, resulting in a decrease in NO oxidation efficiency and a significant decrease in denitrification efficiency. When the ratio is 1:2 to 1:3, the dust removal and desulfurization zone is shortened, and particulate matter and SO2 in the dust removal and desulfurization zone are difficult to be completely absorbed by the red mud. Some particulate matter and SO2 in the treated flue gas come into contact with ozone in the denitrification zone, leading to ozone consumption and reducing the efficiency of ozone oxidation of NO. This results in increased ozone consumption, which is consistent with the decrease in ozone concentration in the No. 1 flue gas outlet. Furthermore, the denitrification efficiency of the device and process decreases.

[0162] Keeping the operating conditions of Example 1 unchanged, the ratio of red mud residue to additives in the material preparation unit was adjusted. The compressive strength results of building materials corresponding to different additive addition ratios are shown in Examples F1-F5 in Table 6.

[0163] Keeping the operating conditions of Example 1 unchanged, the calcination temperature in the material preparation unit was adjusted, and the compressive strength results of the building materials corresponding to different calcination temperatures are shown in Examples F6-F1 in Table 6.

[0164] Keeping the operating conditions of Example 1 unchanged, the calcination time in the material preparation unit was adjusted, and the compressive strength results of the building materials corresponding to different calcination times are shown in Examples F12-F18 in Table 6.

[0165] Table 6

[0166]

[0167] Comparing Examples F1-F5 with Example 1, it can be found that the ratio of red mud to additives affects the compressive strength of the obtained building materials. When the ratio of red mud slag to additives is in the range of 1:1.1 to 1:1.5, the compressive strength of the obtained building materials is relatively high, exceeding 15 MPa. When the ratio of red mud slag to additives is in the range of 1:0.8 to 1:1, the additives are too few, the adhesion of the building materials deteriorates, and the compressive strength of the final fired building materials decreases. When the ratio of red mud slag to additives is in the range of 1:1.5 to 1:2, the proportion of red mud slag is too small, the compressive strength of the building materials decreases slightly to less than 15 MPa, and the amount of additives increases, resulting in higher costs for the obtained building materials.

[0168] Comparing Examples F6-F11 with Example 1, it can be found that the calcination temperature affects the compressive strength of the obtained building materials. When the calcination temperature is between 1150-1250℃, the obtained building materials have better compressive strength, which is higher than 15.5MPa. When the calcination temperature is lower than 1150℃, the mineral phase transformation is incomplete, resulting in lower compressive strength. When the calcination temperature is higher than 1250℃, the material undergoes partial aging at high temperature, which leads to a decrease in compressive strength.

[0169] Comparing Examples F12-F18 with Example 1, it can be found that the calcination time affects the compressive strength of the obtained building materials. When the calcination time is 1.5-2.5h, the compressive strength of the obtained building materials is relatively high, exceeding 15.5MPa. When the calcination time is less than 1.5h, the calcination time is too short, the internal sintering of the building materials is incomplete, and the compressive strength decreases. When the calcination time is more than 2.5h, the internal aging phenomenon of the building materials is aggravated, leading to a decrease in compressive strength.

[0170] Keeping the operating conditions of Example 1 unchanged, the number of guide plates inside the desulfurization and denitrification unit tower was adjusted. The results of dust removal efficiency, desulfurization efficiency and denitrification efficiency corresponding to different guide plate combinations are shown in Examples G1-G7 in Table 7.

[0171] Table 7

[0172]

[0173]

[0174] Comparing Examples G1-G7 with Example 1, it can be found that the first, second, and third guide plates inside the desulfurization and denitrification unit tower can improve the removal efficiency of particulate matter, SO2, and NO by the device and process of the present invention, mainly affecting the denitrification efficiency. When the first, second, and third guide plates are used simultaneously, the device and process of the present invention achieve higher processing effects. At this time, the flue gas, red mud slurry, and micro / nano bubbles processed inside the desulfurization and denitrification unit tower can achieve forced and efficient mixing. Figure 4 , Figure 5 and Figure 6 As shown.

[0175] Comparing Example 1 and Example G7, it can be found that the internal guide plate of the desulfurization and denitrification unit tower used in this invention can improve the mass transfer efficiency and improve the denitrification efficiency by about 20%.

[0176] Keeping the operating conditions of Example 3 unchanged, the effects of different ozone production on desulfurization efficiency and denitrification efficiency were compared under the condition that there were no guide plates inside the conveyor and desulfurization and denitrification unit tower. The ozone concentration, desulfurization efficiency and denitrification efficiency in No. 1 flue gas outlet corresponding to different ozone gas generation rates are shown in Table 8, H1-H9.

[0177] Table 8

[0178]

[0179]

[0180] Comparing Examples H1-H9 with Example 3 reveals that the conveyor and guide plate designed in the device of this invention can achieve efficient pollutant removal with low ozone usage. Comparing H1-H3, it is found that reducing the conveyor and guide plate decreases ozone utilization, leading to an increase in ozone concentration at exhaust port 1, causing ozone escape, environmental pollution, and pipeline corrosion, and also reducing the denitrification efficiency of the device and process. While increasing the ozone concentration can achieve higher denitrification efficiency, the lack of a conveyor or guide plate, or the simultaneous lack of both, significantly increases ozone escape. Therefore, the conveyor and guide plate designed in the device of this invention can significantly improve ozone utilization, achieving efficient pollutant degradation with low ozone usage.

[0181] Comparative Examples 1-8

[0182] Using the process method described in Example 1, keeping the operating conditions unchanged, but using a traditional aeration method to generate ozone, and no longer using the guide plate structure used in this invention, and changing the amount of ozone used, the corresponding pollutant removal rates are shown in the table below:

[0183] Table 9

[0184]

[0185]

[0186] Comparative results show that the micro-nano bubble ozone generation method used in this invention, along with the synergistic use of the internal guide plate in the desulfurization and denitrification unit tower of the reactor, significantly improves ozone utilization efficiency and denitrification efficiency. Compared with traditional aeration heads (such as Comparative Examples 2 and 3), the denitrification efficiency is increased by 60-70% with a similar ozone aeration volume. Traditional aeration methods require a larger ozone consumption to improve flue gas denitrification efficiency. Under the same removal effect as this invention (such as Comparative Example 8), the optimized process device of this invention can save approximately 65% ​​of ozone consumption, demonstrating significant economic benefits.

[0187] Comparative Example 9

[0188] The method disclosed in invention patent CN 109675425 B is used to purify the flue gas. The SO2 and NO treatment processes are as follows:

[0189] The flue gas contains 800 mg / m³ of SO2. 3NO 350mg / m 3 The red mud processed was Bayer process red mud, whose main components included: CaO 19.1%, Fe2O3 16.9%, SiO2 17.2%, Al2O3 20.4%, Na2O 6.18%, and other components.

[0190] Red mud is added to a mixing tank and mixed with the return water from the anaerobic biological treatment tank to obtain red mud slurry. The solid content of the red mud slurry is 13-15% by mass, and the pH value is 5-5.5. The amount of red mud slurry added is 0.1 m³. 3 / h; spray the red mud slurry into the desulfurization spray tower and the denitrification spray tower;

[0191] The liquid-to-gas volume ratio (L:m) of red mud slurry to flue gas in the desulfurization spray tower 3 The ratio is 13.5:1; the flue gas volume of the desulfurization spray tower is 1500 m³. 3 / h; Slurry A circulation rate is 20m³ / h. 3 / h; The volume ratio of O3 to NO in the denitrification spray tower is 1:1, and the liquid-to-gas volume ratio of red mud slurry to desulfurization flue gas is L:m 3 The ratio is 13.5:1; the circulation volume of slurry B is 20m³. 3 / h; to perform purification.

[0192] Because the gas-liquid contact efficiency in the spraying process is limited, the liquid-to-gas volume ratio L:m used in the method employed in Comparative Example 9 is... 3 The ratio is (13.5):1, the liquid-to-gas ratio is high, the utilization rate of red mud slurry is low, and the usage is large.

[0193] Under conditions where the concentrations of SO2 and NO in the treated flue gas are similar (SO2 800 mg / m³ in Comparative Example 9), 3 NO 350mg / m 3 In Example 1, SO2 was 867 mg / m³. 3 NO 455mg / m 3 Even in cases where the pollutant concentration in the flue gas treated in Embodiment 1 of the present invention is higher, the method of the present invention, as described in Embodiment 1, enhances the mass transfer process through micro-nano bubbles. The gas is forced to flow through the guide plate in the desulfurization and denitrification reaction tower, thereby improving the mass transfer efficiency and achieving a volume ratio of red mud slurry usage to flue gas treatment volume L:m 3 With a ratio of approximately 2:1, compared to other processes, this invention reduces red mud slurry consumption by more than 60%, while simultaneously achieving an integrated reactor for removing SO2 and NO, reducing the plant's footprint by more than 30%, resulting in significant economic performance.

[0194] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0195] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. An ozone oxidation device for removing pollutants, characterized in that, The device includes: flue gas inlet pipe (1), heat exchange device (2), pre-dust removal device (3), red mud inlet pipe (5), ozone generator (7), conveyor (9), desulfurization and denitrification unit tower (11) and red mud recycling device (18); The desulfurization and denitrification unit tower (11) is divided into red mud discharge zone (A1), mixing zone (A2), dust removal and desulfurization zone (A3), denitrification zone (A4) and flue gas discharge zone (A5) from bottom to top; The flue gas inlet pipe (1) is connected in sequence to the heat exchange device (2) and the pre-dust removal device (3) and then extends into the mixing zone (A2). An aeration device (12) is installed on the pipe extending into the mixing zone (A2). The red mud inlet pipe (5) is connected to the upper part of the denitrification zone (A4). A red mud conveyor pipe (6) is also provided on the red mud inlet pipe (5). An ozone generator (7) is provided with an ozone conveyor pipe (8). A red mud slurry return pipe (10) is provided in the mixing zone (A2). The red mud conveyor pipe (6), the ozone conveyor pipe (8) and the red mud slurry return pipe (10) are all connected to the conveyor (9). The conveyor (9) is located at the junction of the dust removal and desulfurization zone (A3) and the denitrification zone (A4). The red mud discharge zone (A1) is equipped with a red mud discharge pipe (14), which is connected to the bottom of the red mud recycling device (18). The flue gas discharge zone (A5) is equipped with a No. 1 flue pipe (4), which is connected to the heat exchange device (2).

2. The apparatus according to claim 1, wherein, The conveyor (9) is a micro-nano bubble generator. The micro-nano bubble generator has at least one swirling structure and multiple breaking structures distributed inside. Preferably, the number of swirling structures is 1 to 5, more preferably 3 to 4, and the number of breaking structures is 12 to 36, more preferably 15 to 20.

3. The apparatus according to claim 1, wherein, The number of conveyors (9) is 2 to 8, preferably 3 to 5.

4. The apparatus according to claim 1, wherein, The red mud slurry return pipe (10), the red mud conveyor pipe (6) and the ozone conveyor pipe (8) are combined and then connected to the conveyor (9).

5. The apparatus according to claim 1, wherein, The height ratio of the dust removal and desulfurization zone (A3) to the denitrification zone (A4) is 1:1 to 4, preferably 1:2 to 3.

6. The apparatus according to claim 1, wherein, The denitrification zone (A4) is provided with a guide plate, which includes at least a first guide plate (B1). The first guide plate (B1) is a first conical surface. The axis of the first conical surface is set in the vertical direction. The center height of the first conical surface is consistent with the horizontal height of the outlet of the conveyor (9). The angle between the generatrix of the first conical surface and the horizontal direction is 20° to 45°. Preferably, the guide plate further includes a second guide plate (B2), which is an inverted cone. The longitudinal profile of the cone includes a pair of first arcs (B2-1) symmetrically arranged with respect to the axis of the cone and a bottom edge tangent to the pair of first arcs. The center of each first arc is located on the extension line of the outlet of the conveyor (9), and the intersection of the pair of first arcs or the intersection of their extensions is also located on the extension line of the outlet of the conveyor (9). The arc of the first arc is 100° to 160°. More preferably, the guide plate further includes a third guide plate (B3), which is a second conical surface. The second conical surface is attached to the inner wall of the denitrification zone (A4), and its axis is set in the horizontal direction. The longitudinal profile of the second conical surface includes a pair of second arcs (B3-1) symmetrically arranged with respect to the axis of the second conical surface. The distance between the vertex of the second conical surface and the top of the second guide plate (B2) is equal to the distance between it and the bottom of the red mud inlet pipe (5). The arc of the second arc is 60° to 80°.

7. The apparatus according to claim 1, wherein, The pre-dust removal device (3) is at least one of gravity dust removal device, cyclone dust removal device, bag dust removal device, electrostatic dust removal device and electrostatic bag dust removal device.

8. The apparatus according to any one of claims 1-7, wherein, The device also includes a heating device (16), which is provided with a heating pipeline (17) connected to the lower part of the red mud recycling device (18); The No. 1 exhaust pipe (4) is connected to the heat exchange device (2) and then splits into two branches. One branch is connected to the lower part of the red mud recycling device (18) through the No. 2 air inlet pipe (19), and the other branch is connected to the outside of the boundary as a flue gas exhaust pipeline (21). A flue gas flow meter (22) is installed on the pipeline.

9. The apparatus according to claim 8, wherein, The red mud recycling device (18) is equipped with a material recycling pipe (15) at the bottom and a No. 2 exhaust pipe (20) at the top, which is connected to the flue gas inlet pipe (1).

10. A method for removing pollutants by ozone oxidation, characterized in that, The ozone oxidation apparatus for removing pollutants according to any one of claims 1-9 is used, comprising the following steps: S1: The flue gas to be treated enters the device through the flue gas inlet pipe (1), and after the temperature is reduced by the heat exchange device (2), the flue gas to be treated after cooling is obtained. It then enters the pre-dust removal device (3) for pre-dust removal treatment, and the flue gas after pre-dust removal treatment is obtained. S2: Red mud slurry is continuously transported to the desulfurization and denitrification unit tower (11) through the red mud inlet pipe (5) and the conveyor (9). Oxygen source generates ozone-containing gas through the ozone generator (7). The ozone-containing gas is continuously transported to the desulfurization and denitrification unit tower (11) through the conveyor (9). The red mud slurry entering the desulfurization and denitrification unit tower (11) through the conveyor (9) comes from the red mud conveyor pipe (6) and the red mud slurry return pipe (10). S3: After pre-dust removal treatment, the flue gas enters the mixing zone (A2) and comes into contact with the red mud slurry. Dust removal and desulfurization are carried out in the dust removal and desulfurization zone (A3), and ozone denitrification reaction is carried out in the denitrification zone (A4) in contact with ozone-containing gas. S4: The gas generated in step S3 is discharged from the top of the flue gas discharge zone (A5) through the No. 1 flue pipe (4), and exchanges heat with the flue gas to be treated through the heat exchange device (2). The red mud slurry after the reaction in step S3 is discharged from the bottom of the red mud discharge zone (A1) and transported to the red mud recycling device (18).

11. The method according to claim 10, wherein, In step S1, the temperature of the cooled flue gas to be treated is 80-200°C, preferably 100-120°C; The concentration of particulate matter in the flue gas after the pre-dust removal treatment is 10–200 mg / m³. 3 Preferably 10–70 mg / m³ 3 .

12. The method according to claim 10, wherein, In step S2, the red mud slurry is selected from at least one of Bayer process red mud, sintered red mud and composite red mud; the red mud content in the red mud slurry is 1 to 15 wt%, preferably 8 to 12 wt%; The flow rate of red mud slurry in the red mud inlet pipe (5) is 0.1-1 m³ / s. 3 / h, preferably 0.4~0.6m 3 / h; The flow rate of the red mud slurry entering the desulfurization and denitrification unit tower (11) through the conveyor (9) is 1-6 m³ / s. 3 / h, wherein the flow rate of the red mud slurry in the red mud conveyor pipe (6) is 0.01~1m 3 / h; the flow rate of red mud slurry in the red mud slurry return pipe (10) is 0.1~5m³ / h. 3 / h.

13. The method according to claim 10, wherein, In step S2, the oxygen source is at least one of air, oxygen, and oxygen-containing industrial waste gas; The ozone generator produces ozone-containing gas at a rate of 100-400 g / h, preferably 150-250 g / h, with an ozone concentration of 30-150 g / m³. 3 Preferably 60-90 mg / m³ 3 ; Preferably, the flow ratio of ozone to red mud slurry in the conveyor (9) is 0.2-1.2:

1.

14. The method of claim 10, wherein, In step S3, the flow rate of the flue gas after pre-dust removal is 50-600 m³ / h. 3 / h, preferably 200-300m 3 / h; The residence time of the flue gas after pre-dust removal in the desulfurization and denitrification unit tower (11) is 5 to 60 seconds, preferably 20 to 40 seconds; The ratio of flue gas to red mud slurry treated in the desulfurization and denitrification unit tower is in the range of 200 to 800:1, preferably 400 to 600:1; The hydraulic residence time of the red mud slurry in the desulfurization and denitrification unit tower (11) is 1 to 6 hours, preferably 3 to 4 hours.

15. The method according to claim 10, wherein, In step S4, the gas generated in step S3 includes the flue gas after oxidation and absorption and the ozone-containing gas after reaction.

16. The method of claim 10, wherein, The method further includes step S5: the red mud slurry after the reaction in step S3 is treated with additives and calcined in the red mud recycling device (18) to prepare building materials through resource utilization.

17. The method according to claim 16, wherein, After the flue gas discharged from the top of the flue gas discharge zone (A5) exchanges heat with the flue gas to be discharged through the heat exchange device (2), part of it enters the red mud recycling device (18) to provide oxygen and heat energy. The ratio of the flue gas entering the red mud recycling device (18) to the flue gas discharged from the top of the flue gas discharge zone (A5) is 1:10 to 1:50; preferably 1:22 to 1:

28.

18. The method according to claim 17, wherein, The mixing ratio of the reacted red mud slurry to the additive is 1:0.8 to 1:2; preferably 1:1.1 to 1:1.5; the additive includes fly ash and at least one of the following components: coal gangue, desulfurization ash, cement, lime, gypsum, sand, graphite, clay, sludge, bentonite and steel slag. The calcination conditions include: a temperature of 1000–1350℃, preferably 1150–1250℃, and a time of 0.5–5h, preferably 1.5–2.5h.

19. The method of claim 16, wherein, The flue gas produced by calcination is mixed with the flue gas to be treated.

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