Preparation of red mud-based denitration catalyst and matching circulating regeneration system

Abstract

The utility model discloses a kind of preparation device and matching circulating regeneration system of red mud-based denitration catalyst, belong to the cross field of solid waste resource utilization and air pollution control;The device includes: including feeder, pulverizer, mixer, granulator, first screening device, second screening device, third screening device, water washing and drying device, conveyor, catalyst bin and water washing regeneration device.This device is optimized to red mud catalyst forming process and repeatedly washed and regenerated, and the amorphous structure of metal oxide such as Fe2O3, Al2O3 in red mud is converted into α-Fe2O3 / γ-Al2O3 composite crystal phase with rich Lewis acid site.The utility model provides matching water washing regeneration system can realize the targeted removal of catalyst surface deposits.

Description

Technical Field

[0001] This utility model belongs to the interdisciplinary field of solid waste resource utilization and air pollution control. Specifically, it relates to a method for preparing a red mud-based denitrification catalyst and a supporting recycling system, which is applicable to the synergistic treatment of nitrogen oxides (NOx) in industrial waste gas from coal-fired power plants, steel sintering, cement kilns, etc., and the large-scale disposal of red mud solid waste. Background Technology

[0002] Nitrogen oxides (NOx) are one of the major air pollutants, and their emission control has become a key focus of air pollution prevention and control in my country. Existing denitrification technology, SCR, mainly uses the VO5-WO3 / TiO2 catalyst system, and faces the following technical bottlenecks:

[0003] (1) The active temperature window is too high (300-400℃), making it difficult to adapt to low-temperature flue gas conditions such as steel sintering and glass kilns;

[0004] (2) The biotoxicity of vanadium species leads to the classification of spent catalysts as hazardous waste;

[0005] (3) The production cost of TiO2 support is high, accounting for more than 60% of the total cost of catalyst.

[0006] Red mud, a highly alkaline waste residue (pH 10-13) generated during the aluminum industry, accounts for over 150 million tons of global annual emissions, with a comprehensive utilization rate of less than 15%. This waste residue is rich in Fe₂O₃ (30-60%), Al₂O₃ (12-25%), SiO₂ (5-20%), and TiO₂ (2-10%), and contains small amounts of alkaline metal oxides such as Na and Ca. Research has found that iron oxides in red mud, after appropriate crystal phase regulation, can provide redox active sites required for SCR reactions, while aluminum oxides can act as structural stabilizers, possessing potential catalytic activity to remove acidic gases such as NOx from flue gas. Existing red mud denitrification technologies mostly employ acid washing pretreatment or noble metal doping modification, which, while improving activity, significantly increases treatment costs. However, these methods involve complex preparation processes and suffer from high costs and long processing times. This invention develops a method to achieve targeted regulation of the red mud phase structure without chemical modification and innovatively introduces a dynamic water washing and regeneration system to solve the problem of alkali metal migration. To achieve comprehensive utilization of red mud resources will provide a broader direction for red mud dealkali treatment and subsequent large-scale industrial applications. Utility Model Content

[0007] This invention provides a method for preparing a red mud-based denitrification catalyst and a supporting recycling system. The denitrification catalyst is prepared using red mud as raw material. The method achieves directional control of the phase structure of red mud without chemical modification. Furthermore, it innovatively introduces a dynamic water washing and regeneration system to solve the problem of alkali metal migration and realize the comprehensive utilization of red mud resources.

[0008] To solve the above technical problems, this utility model provides a method for preparing a red mud-based denitrification catalyst, comprising the following steps:

[0009] The raw materials are fed into a crusher and crushed to obtain crushed red mud;

[0010] The crushed red mud is filtered through the first screening device to obtain red mud powder after the first screening.

[0011] The red mud powder after the first screening is mixed by a mixer to obtain moistened red mud;

[0012] The moistened red mud is granulated using a granulator to obtain red mud particles;

[0013] The red mud particles are screened through a second screening device to obtain red mud particles after the second screening.

[0014] The sieved red mud particles are dried using a water washing and drying device to obtain dried red mud particles.

[0015] The dried red mud particles are sieved through a third sieve device to obtain red mud particles after the third sieve.

[0016] The red mud particles after the third screening are conveyed to the catalyst silo for storage as denitrification catalyst.

[0017] Preferably, the moisture content of the feeder is between 5% and 15%.

[0018] Preferably, the mixture is moistened to 20-25% by spraying water through a mixer, while 2%-5% calcium hydroxide is added by mass fraction.

[0019] Preferably, the granulator controls the particle size to be between 2-5 mm, the pelletizing rate to be ≥90%, and the strength to be ≥10.

[0020] Preferably, the screen of the first screening device has an aperture of 0.5 mm. Red mud powder larger than 0.5 mm screened out by the first screening device is returned to the crusher, and the rest enters the water washing and drying device.

[0021] The second screening device includes two screens with apertures of 2mm and 5mm respectively. Red mud particles smaller than 2mm and larger than 5mm screened out by the second screening device are returned to the crusher, while the rest enter the conveyor.

[0022] The screen of the third screening device has a mesh size of 2mm. Red mud particles smaller than 2mm that are screened out by the third screening device are returned to the granulator, while the rest enter the conveyor.

[0023] Preferably, the water washing and drying device reduces the particle moisture content of the screened red mud particles to 10%.

[0024] This utility model also provides a red mud-based denitrification catalyst preparation and supporting recycling system, including a feeder, a crusher, a mixer, a granulator, a first screening device, a second screening device, a water washing and drying device, a conveyor, a catalyst silo, and a water washing and regeneration device;

[0025] The feeder's outlet is connected to the crusher's inlet;

[0026] The discharge port of the crusher is connected to the inlet of the first screening device;

[0027] The first discharge port of the first screening device is connected to the feed port of the crusher;

[0028] The second discharge port of the first screening device is connected to the feed port of the mixer;

[0029] The discharge port of the mixer is connected to the inlet of the granulator;

[0030] The discharge port of the granulator is connected to the inlet of the second screening device;

[0031] The first discharge port of the second screening device is connected to the feed port of the granulator;

[0032] The second discharge port of the second screening device is connected to the inlet of the water washing and drying device;

[0033] The outlet of the washing and drying device is connected to the inlet of the third screening device;

[0034] The first discharge port of the third screening device is connected to the feed port of the granulator;

[0035] The second discharge port of the third screening device is connected to the catalyst silo via a conveyor.

[0036] The water washing and regeneration device is connected to the feed inlet of the crusher.

[0037] Preferably, the aperture of the screen in the first screening device is 0.5mm, the first discharge port of the first screening device is located above the screen, and the second discharge port of the first screening device is located below the screen.

[0038] The second screening device includes two screens with apertures of 2mm and 5mm respectively, arranged from bottom to top. The first discharge port of the first screening device is located above and below its two screens respectively, and the second discharge port of the second screening device is located between its two screens.

[0039] The screen of the third screening device has a mesh size of 2mm. The first discharge port of the third screening device is located below its screen, and the second discharge port of the third screening device is located above its screen.

[0040] Preferably, the mixer is connected to a water storage tank and an alkaline substance storage tank;

[0041] The alkaline substance stored in the alkaline substance storage tank is calcium hydroxide.

[0042] Preferably, the water washing and regeneration device includes a water washing and regeneration crushing device, a first filtration device, a second filtration device, a third filtration device, a fourth filtration device, and an evaporation and crystallization device;

[0043] The discharge port of the water washing and recycling crushing device is connected to the inlet of the first filter device;

[0044] The filtrate outlet of the first filtration device is connected to the evaporation and crystallization device;

[0045] The filter residue outlet of the first filter device is connected to the feed inlet of the second filter device;

[0046] The filtrate outlet of the second filtration device is connected to the feed inlet of the first filtration device;

[0047] The filter residue outlet of the second filter device is connected to the inlet of the water washing and drying device and the inlet of the third filter device, respectively.

[0048] The discharge port of the washing and drying device is connected to the feed port of the crusher;

[0049] The filtrate outlet of the third filtration device is connected to the feed inlet of the second filtration device and the feed inlet of the fourth filtration device, respectively.

[0050] The filter residue outlet of the third filter device is connected to the feed inlet of the fourth filter device;

[0051] The fourth filtration device is connected to the water supply tank;

[0052] The discharge port of the fourth filtration device is connected to the external discharge treatment device.

[0053] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0054] This invention optimizes the red mud catalyst forming process and employs repeated water washing and regeneration to transform the amorphous structure of metal oxides such as Fe2O3 and Al2O3 in red mud into an α-Fe2O3 / γ-Al2O3 composite crystalline phase with abundant Lewis acid sites. The invention provides a matching water washing and regeneration system that enables targeted removal of deposits on the catalyst surface. Even after multiple cycles, it maintains a denitrification efficiency of over 50%. Compared to traditional vanadium-titanium catalysts, this invention reduces catalyst raw material costs and CO2 emissions, resulting in significant environmental and economic benefits. Attached Figure Description

[0055] The specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0056] Figure 1 This is a schematic diagram of the process for preparing a red mud-based denitrification catalyst according to this utility model;

[0057] Figure 2 This is a flowchart of a recycling system.

[0058] In the picture:

[0059] 1-Feeder; 2-Crusher; 3-First screening device; 4-Mixer; 5-Granulator; 6-Second screening device; 7-Washing and drying device; 8-Third screening device; 9-Conveyor; 10-Catalyst silo; 11-Washing, regeneration, and crushing device; 12-First filtration device; 13-Second filtration device; 14-Third filtration device; 15-Fourth filtration device; 16-Evaporation and crystallization device; 17-Washing and drying device; 18-Water replenishment tank; 19-External discharge treatment device. Detailed Implementation

[0060] Many specific details are set forth in the following description to provide a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0061] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of this specification. The singular forms “a,” “described,” and “the” as used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0062] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this specification, and similarly, second may also be referred to as first. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0063] The present invention will now be described in further detail with reference to the accompanying drawings:

[0064] This utility model provides a red mud-based denitrification catalyst preparation device, including a feeder 1, a crusher 2, a mixer 4, a granulator 5, a first screening device 3, a second screening device 6, a water washing and drying device 7, a third screening device 8, a conveyor 9, a catalyst silo 10, and a water washing and regeneration device.

[0065] The discharge port of the feeder 1 is connected to the inlet of the crusher 2;

[0066] The discharge port of the crusher 2 is connected to the inlet of the first screening device 3;

[0067] The first discharge port of the first screening device 3 is connected to the feed port of the crusher 2;

[0068] The second discharge port of the first screening device 3 is connected to the feed port of the mixer 4;

[0069] The discharge port of the mixer 4 is connected to the inlet of the granulator 5;

[0070] The discharge port of the granulator 5 is connected to the inlet of the second screening device 6;

[0071] The first discharge port of the second screening device 6 is connected to the feed port of the granulator 5;

[0072] The second discharge port of the second screening device 6 is connected to the inlet of the water washing and drying device 7;

[0073] The outlet of the washing and drying device 7 is connected to the inlet of the third screening device 8;

[0074] The first discharge port of the third screening device 8 is connected to the feed port of the granulator 5;

[0075] The second discharge port of the third screening device 8 is connected to the catalyst silo 10 via a conveyor 9.

[0076] The water washing and regeneration device is connected to the feed inlet of the crusher 2.

[0077] Preferably, the aperture of the screen in the first screening device 3 is 0.5mm, the first discharge port of the first screening device 3 is located above its screen, and the second discharge port of the first screening device 3 is located below its screen.

[0078] The second screening device 6 includes two screens with apertures of 2mm and 5mm respectively, arranged sequentially from bottom to top. The first discharge port of the first screening device 3 is located above and below its two screens, and the second discharge port of the second screening device 6 is located between its two screens.

[0079] The screen of the third screening device 8 has a mesh size of 2mm. The first discharge port of the third screening device 8 is located below its screen, and the second discharge port of the third screening device 8 is located above its screen.

[0080] Preferably, the mixer 4 is connected to a water storage tank and an alkaline substance storage tank;

[0081] The alkaline substance stored in the alkaline substance storage tank is calcium hydroxide.

[0082] Preferably, the water washing and regeneration device includes a water washing and regeneration crushing device 11, a first filtration device 12, a second filtration device 13, a third filtration device 14, a fourth filtration device 15, and an evaporation and crystallization device 16.

[0083] The discharge port of the water washing and recycling crushing device 11 is connected to the inlet of the first filter device 12;

[0084] The filtrate outlet of the first filtration device 12 is connected to the evaporation crystallization device 16;

[0085] The filter residue outlet of the first filter device 12 is connected to the feed inlet of the second filter device 13;

[0086] The filtrate outlet of the second filtration device 13 is connected to the feed inlet of the first filtration device 12;

[0087] The filter residue outlet of the second filter device 13 is connected to the feed inlet of the water washing and drying device 17 and the feed inlet of the third filter device 14, respectively.

[0088] The outlet of the washing and drying device 7 is connected to the inlet of the crusher 2;

[0089] The filtrate outlet of the third filter device 14 is connected to the feed inlet of the second filter device 13 and the feed inlet of the fourth filter device 15, respectively.

[0090] The filter residue outlet of the third filter device 14 is connected to the feed inlet of the fourth filter device 15.

[0091] The fourth filtration device 15 is connected to the water supply tank 18;

[0092] The discharge port of the fourth filter device 15 is connected to the external discharge treatment device 19.

[0093] This utility model is achieved through the following technical solution:

[0094] 1. Crushing: After the raw materials are crushed by the feeder 1 to the crusher 2, the particles are less than 0.5mm. After the crushed material exits the crusher 2, it is screened. Particles larger than 0.5mm are returned to the crusher. The feed moisture content is controlled between 5-15%. After some of the washed material is filtered, the red mud moisture content is between 40-60%. It needs to be dried first to reduce the moisture content to 30%, and then crushed into particles less than 5cm. It is then fed into the crusher 2 to be mixed and crushed with the raw materials.

[0095] 2. Mixing and Humidification: The red mud after crushing has low moisture content and is not suitable for granulation by stirring teeth. It needs to be humidified to 20-25% by spraying water through the mixer 4. At the same time, alkaline substances should be added in proportion, such as 2%-5% calcium hydroxide.

[0096] 3. Stirring tooth granulation: control the particle size between 2-5mm, the pelleting rate ≥90%, and the strength ≥10N.

[0097] 4. Screening: Particles smaller than 2mm and larger than 5mm are returned to the inlet of granulator 5 for regranulation.

[0098] 5. Natural drying: When the outdoor temperature is above 30℃, the moisture content of the 20% granules can be reduced to 10% in 10 hours. However, the granules will break during the mechanical spreading and collection process, so they need to be sieved again after drying.

[0099] 6. After preparation, the catalyst is conveyed to the catalyst silo 10 via conveyor 9 for later use.

[0100] Catalyst regeneration process

[0101] Simplified regeneration: Saturated catalyst crushing → granulation → screening → mixing with new material → regenerated catalyst → denitrification application

[0102] Water washing regeneration mainly includes steps such as crushing, dilution, sedimentation separation, filtration, and backwashing of the filtrate, such as... Figure 2 As shown;

[0103] Compared with existing technologies, this invention has the following advantages: By optimizing the red mud catalyst forming process and repeatedly washing and regenerating it, the amorphous structure of metal oxides such as Fe2O3 and Al2O3 in the red mud is transformed into an α-Fe2O3 / γ-Al2O3 composite crystalline phase with abundant Lewis acid sites. Continuous drum granulation technology is used to achieve directional control of the pore size of the catalyst particles (pore size distribution 15-50 nm, specific surface area > 50 m²). 2The catalyst exhibits excellent NH3-SCR activity (denitrification efficiency ≥90%) in the low temperature range of 90-140℃. At the same time, the present invention provides a matching water washing and regeneration system to achieve targeted removal of deposits on the catalyst surface. After 40 cycles, it still maintains a denitrification efficiency of more than 50%. Compared with traditional vanadium-titanium catalysts, the raw material cost of the catalyst of the present invention is reduced by 58%, and the CO2 emission per ton of catalyst is reduced by 2.3 tons, which has significant environmental and economic benefits.

[0104] This invention provides a method for preparing a red mud-based denitrification catalyst. By optimizing the red mud catalyst forming process, including crushing, mixing and moisture conditioning, stirring tooth granulation, sieving, natural drying, and conveying via conveyor 9 to the catalyst silo 10, and through repeated water washing and regeneration, the amorphous structure of metal oxides such as Fe2O3 and Al2O3 in the red mud is transformed into an α-Fe2O3 / γ-Al2O3 composite crystalline phase with abundant Lewis acid sites. Continuous drum granulation technology is used to achieve directional control of the pore size of the catalyst particles (pore size distribution 15-50 nm, specific surface area > 50 m²). 2 The catalyst exhibits excellent NH3-SCR activity (denitrification efficiency ≥90%) in the low-temperature range of 90-140℃. Simultaneously, a matching water washing and regeneration system is provided to achieve targeted removal of deposits on the catalyst surface, maintaining a denitrification efficiency of over 50% even after 40 cycles.

[0105] A method for preparing a red mud-based denitrification catalyst specifically includes the following steps:

[0106] After the raw material is crushed by feeder 1 to crusher 2, the particles are less than 0.5mm. After the crushed material exits crusher 2, it is screened. Particles larger than 0.5mm are returned to the crusher. The feed moisture content is controlled between 5-15%.

[0107] After being washed and filtered, the red mud has a moisture content between 40-60%. It needs to be dried first to reduce the moisture content to 30%, and then crushed into particles smaller than 5cm. The particles are then fed into crusher 2 to be mixed and crushed with the raw materials.

[0108] The crushed red mud has a low moisture content and is not suitable for granulation with stirring teeth. It needs to be moistened to 20-25% by spraying water through the mixer 4, and alkaline substances such as 2%-5% calcium hydroxide should be added in proportion.

[0109] The particle size is controlled between 2-5mm, the sphericity is ≥90%, and the strength is ≥10N.

[0110] Particles smaller than 2mm and larger than 5mm are returned to the inlet of granulator 5 for regranulation.

[0111] When the outdoor temperature is above 30℃, the moisture content of 20% granules can be reduced to 10% in 10 hours. However, the granules will break during the mechanical spreading and collection process, so they need to be sieved again after drying.

[0112] The water washing and regeneration process includes steps such as crushing, dilution, sedimentation separation, filtration, and backwashing of the filtrate.

[0113] Even after 40 cycles, it still maintains a denitrification efficiency of more than 50%.

[0114] This invention discloses a method for preparing a red mud-based denitrification catalyst and a recycling system. Using red mud, a waste residue from the aluminum industry, as the main raw material, a novel catalyst is prepared to achieve efficient NOx removal under low-temperature conditions (90-140℃). This method optimizes the red mud catalyst forming process and uses repeated water washing and regeneration to transform the amorphous structure of metal oxides such as Fe2O3 and Al2O3 in the red mud into an α-Fe2O3 / γ-Al2O3 composite crystalline phase with abundant Lewis acid sites. Continuous drum granulation technology is used to achieve directional control of the catalyst particle pore size (pore size distribution 15-50 nm, specific surface area > 50 m²). 2 The catalyst exhibits excellent NH3-SCR activity (denitrification efficiency ≥90%) in the low temperature range of 90-140℃. At the same time, the present invention provides a matching water washing and regeneration system to achieve targeted removal of deposits on the catalyst surface. After 40 cycles, it still maintains a denitrification efficiency of more than 50%. Compared with traditional vanadium-titanium catalysts, the raw material cost of the catalyst of the present invention is reduced by 58%, and the CO2 emission per ton of catalyst is reduced by 2.3 tons, which has significant environmental and economic benefits.

[0115] To better illustrate the technical effects of this utility model, the present utility model provides the following specific embodiments to explain the above technical process:

[0116] Example 1: A method for preparing a red mud-based denitrification catalyst preparation device, comprising the following steps:

[0117] 1. Crushing: After the raw materials are crushed by the feeder 1 to the crusher 2, the particles are less than 0.5mm. After the crushed material exits the crusher 2, it is screened. The particles larger than 0.5mm in the first screening device 3 are returned to the crusher 2. The feed moisture content is controlled between 5-15%. After some of the washed material is filtered, the red mud moisture content is between 40-60%. It needs to be dried first to reduce the moisture content to 30%, and then crushed into particles less than 5cm. It is then fed into the crusher 2 to be mixed and crushed with the raw materials.

[0118] 2. Mixing and Humidification: The red mud after crushing has low moisture content and is not suitable for granulation by stirring teeth. It needs to be humidified to 20-25% by spraying water through the mixer 4. At the same time, alkaline substances are added in proportion, such as adding calcium hydroxide with a mass fraction of 2%-5%.

[0119] 3. Grinding with stirring teeth: The roller controls the particle size to be between 2-5mm, with a pelletizing rate of ≥90% and a strength of ≥10N.

[0120] 4. Screening: The second screening device 6 returns particles smaller than 2mm and larger than 5mm to the inlet of the granulator 5 for regranulation;

[0121] 5. Natural drying: When the outdoor temperature is above 30℃, the moisture content of the 20% particles can be reduced to 10% in 10 hours. However, the particles will break during the mechanical spreading and collection process, so a third screening device 8 is needed to screen them again after drying.

[0122] 6. After preparation, the catalyst is conveyed to the catalyst silo 10 via conveyor 9 for later use.

[0123] Catalyst regeneration process

[0124] Simplified regeneration: Saturated catalyst crushing → granulation → screening → mixing with new material → regenerated catalyst → denitrification application

[0125] Water washing regeneration mainly includes the following steps: crushing waste catalyst with a water washing regeneration crushing device → diluting slurry → first filtration device to achieve coarse solid-liquid separation (filtrate is sent to evaporation and crystallization) → second filtration device to perform fine filtration and reverse washing of filter residue → third filtration device to treat fine particulate suspended solids → fourth filtration device to finally purify filtrate.

[0126] The main steps include:

[0127] Crushing: The saturated catalyst is initially crushed by the water washing and regeneration crushing device 11 to destroy the surface deposit structure.

[0128] Dilution: The crushed catalyst is mixed with water to dilute it and form a slurry to dissolve the soluble salts.

[0129] Sedimentation and separation: The diluted slurry enters the first filtration device 12 for coarse solid-liquid separation.

[0130] The filtrate (containing a high concentration of soluble salts) is transported to the evaporation and crystallization unit 16 to recover the salts;

[0131] The filter residue (containing solid particles) enters the second filtration device 13.

[0132] Filtrate backwashing:

[0133] The filtrate (containing lower salt content) from the third filtration device 14 is fed back into the second filtration device 13 to wash the filter residue in a countercurrent manner, reducing the amount of fresh water used and improving the efficiency of impurity removal.

[0134] The filtrate from the second filtration device 13 is returned to the inlet of the first filtration device 12, realizing the cascade utilization of wastewater.

[0135] Multi-stage filtration and purification:

[0136] The filter residue from the second filtration device 13 is diverted to the third filtration device 14 and the water washing and drying device 17.

[0137] Water washing and drying device 17: After drying, the product is returned to the pulverizer 2 for regranulation (regenerable catalyst);

[0138] Third filtration device 14: further separates fine particles.

[0139] The filter residue from the third filtration device 14 enters the fourth filtration device 15 for fine filtration, and the filtrate is reused for system makeup water or discharged externally.

[0140] Waste disposal: The concentrated residue from the fourth filtration device 15 is transported to the external discharge treatment device 19 for safe disposal.

[0141] Synergistic effect of filtration devices:

[0142] First filtration device 12: coarsely separates soluble salts from solids, and the filtrate directly crystallizes.

[0143] Second filtration device 13: Receives coarse filter residue and washes it with reverse filtrate to reduce the salt content of the filter residue.

[0144] Third filtration device 14: After refining and washing the slurry, the filtrate is circulated to the second filter 13 for enhanced washing, and the filter residue enters the final filtration stage.

[0145] Fourth filtration device 15: final solid-liquid separation, filtrate reuse / discharge, and residue disposal.

[0146] Differences between filtrate and filter residue:

[0147] Filtrate: Contains soluble alkali metal salts (such as Na2SO4), with the concentration decreasing stepwise, and is eventually reused or recovered by crystallization.

[0148] Filter residue: As the process progresses, the alkali metal content in the solid gradually decreases, eventually yielding regenerated active components (α-Fe2O3 / γ-Al2O3).

[0149] The water washing and regeneration device includes a water washing and regeneration crushing device 11, a first filtration device 12, a second filtration device 13, a third filtration device 14, a fourth filtration device 15, and an evaporation and crystallization device 16.

[0150] The discharge port of the water washing and recycling crushing device 11 is connected to the inlet of the first filter device 12;

[0151] The filtrate outlet of the first filtration device 12 is connected to the evaporation crystallization device 16;

[0152] The filter residue outlet of the first filter device 12 is connected to the feed inlet of the second filter device 13;

[0153] The filtrate outlet of the second filtration device 13 is connected to the feed inlet of the first filtration device 12;

[0154] The filter residue outlet of the second filter device 13 is connected to the feed inlet of the water washing and drying device 17 and the feed inlet of the third filter device 14, respectively.

[0155] The outlet of the washing and drying device 7 is connected to the inlet of the crusher 2;

[0156] The filtrate outlet of the third filter device 14 is connected to the feed inlet of the second filter device 13 and the feed inlet of the fourth filter device 15, respectively.

[0157] The filter residue outlet of the third filter device 14 is connected to the feed inlet of the fourth filter device 15.

[0158] The fourth filtration device 15 is connected to the water supply tank 18;

[0159] The discharge port of the fourth filter device 15 is connected to the external discharge treatment device 19.

[0160] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A red mud-based denitrification catalyst preparation and supporting recycling system, characterized in that: It includes a feeder, crusher, mixer, granulator, first screening device, second screening device, third screening device, water washing and drying device, conveyor, catalyst silo and water washing and regeneration device; The feeder's outlet is connected to the crusher's inlet; The discharge port of the crusher is connected to the inlet of the first screening device; The first discharge port of the first screening device is connected to the feed port of the crusher; The second discharge port of the first screening device is connected to the feed port of the mixer; The discharge port of the mixer is connected to the inlet of the granulator; The discharge port of the granulator is connected to the inlet of the second screening device; The first discharge port of the second screening device is connected to the feed port of the granulator; The second discharge port of the second screening device is connected to the inlet of the water washing and drying device; The outlet of the washing and drying device is connected to the inlet of the third screening device; The first discharge port of the third screening device is connected to the feed port of the granulator; The second discharge port of the third screening device is connected to the catalyst silo via a conveyor. The water washing and regeneration device is connected to the feed inlet of the crusher.

2. The preparation of the red mud-based denitrification catalyst and the corresponding recycling system according to claim 1, characterized in that: The screen mesh of the first screening device has an aperture of 0.5 mm. The first discharge port of the first screening device is located above the screen mesh, and the second discharge port of the first screening device is located below the screen mesh. The second screening device includes two screens with apertures of 2mm and 5mm respectively, arranged from bottom to top. The first discharge port of the first screening device is located above and below its two screens respectively, and the second discharge port of the second screening device is located between its two screens. The screen of the third screening device has a mesh size of 2mm. The first discharge port of the third screening device is located below its screen, and the second discharge port of the third screening device is located above its screen.

3. The preparation of the red mud-based denitrification catalyst and the corresponding recycling system according to claim 2, characterized in that: The mixer is connected to a water storage tank and an alkaline substance storage tank; The alkaline substance stored in the alkaline substance storage tank is calcium hydroxide.

4. The preparation and regeneration system of the red mud-based denitrification catalyst according to claim 3, characterized in that, The water washing and regeneration device includes a water washing and regeneration crushing device, a first filtration device, a second filtration device, a third filtration device, a fourth filtration device, and an evaporation and crystallization device; The discharge port of the water washing and recycling crushing device is connected to the inlet of the first filter device; The filtrate outlet of the first filtration device is connected to the evaporation and crystallization device; The filter residue outlet of the first filter device is connected to the feed inlet of the second filter device; The filtrate outlet of the second filtration device is connected to the feed inlet of the first filtration device; The filter residue outlet of the second filter device is connected to the inlet of the water washing and drying device and the inlet of the third filter device, respectively. The discharge port of the washing and drying device is connected to the feed port of the crusher; The filtrate outlet of the third filtration device is connected to the feed inlet of the second filtration device and the feed inlet of the fourth filtration device, respectively. The filter residue outlet of the third filter device is connected to the feed inlet of the fourth filter device; The fourth filtration device is connected to the water supply tank; The discharge port of the fourth filtration device is connected to the external discharge treatment device.

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