Method for removing arsenic from sulfurized flue gas through gas phase reinforced composite catalysis

Abstract

The invention provides a method for removing arsenic in flue gas through gas phase reinforced composite catalysis and sulfuration. The method can directly realize efficient removal of arsenic in the flue gas under a high-temperature condition (300-400 DEG C), does not need to cool the flue gas, can be directly connected with a denitration system, and reduces energy consumption; meanwhile, generation of waste acid is avoided, the environment-friendly treatment cost is reduced, the arsenic removal efficiency is improved, and stable operation of a subsequent denitration catalyst is guaranteed. The method is particularly suitable for treating high-arsenic flue gas generated in the non-ferrous smelting process of copper, lead, zinc and the like, can realize direct arsenic removal of the flue gas at high temperature, is cooperatively operated with a denitration system, and has the dual advantages of deep purification and energy conservation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-ferrous smelting flue gas treatment and environmental protection, and specifically relates to a method for removing arsenic from sulfidation flue gas by gas phase strengthening and composite catalysis. BACKGROUND

[0002] The non-ferrous smelting industry (such as the smelting process of copper, lead, zinc, etc.) will produce a large amount of flue gas containing high-concentration arsenic. The arsenic in these flue gases mainly exists in the form of arsenic trioxide, etc. If effective arsenic removal treatment is not performed, it will seriously threaten the activity of the catalyst in the subsequent flue gas denitration system, leading to catalyst poisoning and deactivation, greatly shortening the service life of the catalyst, and increasing the cost of flue gas treatment (Non-ferrous smelting flue gas denitration technology status and development trend, China Nonferrous Metals, 2023, Vol. 33). Therefore, the arsenic removal treatment before the smelting flue gas enters the denitration system is a key link to ensure the stable operation of the entire flue gas treatment system.

[0003] At present, the existing technologies for removing arsenic from non-ferrous smelting flue gas in the industry mainly fall into two categories: The first type is wet sodium sulfide solution arsenic removal method. This method uses sodium sulfide solution as the arsenic removal agent, by directly spraying the solution into the smelting flue gas, making the arsenic in the flue gas react with sodium sulfide to form arsenic sulfide precipitate, thereby achieving arsenic removal (Research progress of wet flue gas desulfurization and arsenic removal technology, Journal of Environmental Engineering, 2022, Vol. 16). The technical structure mainly includes a spray tower, a sedimentation tank, a wastewater treatment unit, etc., which are connected through pipelines. The flue gas enters from the bottom of the spray tower, is in countercurrent contact with the sodium sulfide solution sprayed from the top, and the reacted flue gas is discharged from the top of the tower. The slurry containing arsenic precipitate is separated in the sedimentation tank, and the generated waste acid is sent to the wastewater treatment unit for disposal. However, this method has significant defects: on the one hand, a large amount of waste acid is generated during the reaction process. For every 10,000 Nm³ of arsenic-containing smelting flue gas (arsenic content 50 mg / Nm³), about 1.2 m³ of waste acid is generated, and the arsenic concentration in the waste acid can reach 800-1200 mg / L. Subsequent waste acid disposal requires multiple processes such as neutralization, precipitation, and filtration, with disposal costs of up to 800-1200 yuan per ton of waste acid, significantly increasing the environmental protection costs of enterprises; on the other hand, the reaction activity of sodium sulfide solution is greatly affected by temperature. To ensure the arsenic removal efficiency, the reaction temperature needs to be controlled, resulting in a decrease in the temperature of the treated flue gas. If subsequent denitration treatment is required, the flue gas needs to be reheated to 300-400°C (the active temperature range of denitration catalysts). For every 100°C of heating, the energy consumption of every 10,000 Nm³ of flue gas increases by about 200 kWh, causing serious energy waste and rising operating costs.

[0004] The second type is the staged temperature reduction arsenic removal method. This method can make arsenic in the flue gas precipitate in the form of solid particles by gradually reducing the flue gas temperature, and then capture the arsenic by dust removal equipment (Multi-pollutant simultaneous control technology of smelting flue gas, Metallurgical Industry Press, 2021). The core equipment includes multi-stage heat exchanger, electric precipitator, etc. The flue gas is sequentially cooled by each stage of heat exchanger, and the temperature is reduced from the initial 500-600℃ to 150-200℃. The arsenic particles coagulate and grow during the cooling process, and then are captured by the electric precipitator. The main problem of this method is that the high-temperature flue gas needs to be cooled significantly during the arsenic removal process, and the subsequent denitration system requires a high-temperature environment, so there is also a problem of energy waste caused by repeated heating of the flue gas. In addition, the investment in the staged temperature reduction equipment is large, and the land occupation is wide. The equipment investment for processing 10,000 Nm³ of flue gas is about 30%-40% higher than that of the wet sodium sulfide method. At the same time, the arsenic removal efficiency of this method is limited, and the capture efficiency of fine particle arsenic with a particle size less than 1 μm in the flue gas is only 60%-70%, which is difficult to meet the strict requirements of the subsequent denitration catalyst for arsenic content (usually the arsenic content of the flue gas entering the denitration system should be less than 5 mg / Nm³).

[0005] In summary, the existing arsenic removal technologies generally have problems such as high energy consumption, high operating cost, and limited arsenic removal efficiency, which cannot well adapt to the needs of the non-ferrous smelting flue gas "arsenic removal-denitration" collaborative treatment, and a new type of arsenic removal technology that can efficiently remove arsenic in a high-temperature environment and is compatible with the denitration system is urgently needed. SUMMARY

[0006] The present application aims to solve the three core problems existing in the current non-ferrous smelting flue gas arsenic removal technology: first, the wet sodium sulfide solution arsenic removal method produces a large amount of high-concentration waste acid, and the disposal cost of the waste acid is high; second, the existing arsenic removal technology needs to cool the high-temperature smelting flue gas, and the subsequent denitration needs to be reheated, resulting in serious energy waste and increased operating cost; third, the staged temperature reduction arsenic removal method has low capture efficiency for fine particle arsenic, which is difficult to meet the inlet requirements of the subsequent denitration system. In view of the above defects of the existing technology, the present application provides a method for removing arsenic from sulfidized flue gas by gas phase strengthening and composite catalysis, which can directly achieve efficient removal of arsenic in the flue gas under high-temperature conditions (300-400℃), without the need for cooling the flue gas, and can directly connect the denitration system to reduce energy consumption. At the same time, it avoids the generation of waste acid, reduces the environmental protection disposal cost, improves the arsenic removal efficiency, and ensures the stable operation of the subsequent denitration catalyst. The present application is especially suitable for the treatment of high-arsenic flue gas generated in the process of copper, lead, zinc and other non-ferrous smelting, and can realize direct arsenic removal at high temperature, collaborative operation with the denitration system, and has the dual advantages of deep purification and energy saving.

[0007] The present application is realized by the following technical solutions: A method for removing arsenic from sulfidized flue gas by gas phase strengthening and composite catalysis, comprising the following steps: (1) Flue gas pretreatment: the non-ferrous smelting flue gas with a temperature of 500-600℃ is introduced into a waste heat recovery device, the flue gas temperature is adjusted to 300-400℃, and the dust with a particle size greater than 10 μm in the flue gas is removed; (2) Gas phase strengthening arsenic removal reaction: the pretreated flue gas is introduced into a gas phase strengthening reactor, and a sulfiding agent is introduced into the reactor at the same time, the amount of the sulfiding agent introduced is 3-6 times the molar amount of arsenic in the flue gas; the gas phase strengthening reactor is filled with a composite catalyst, under the condition of 300-400℃, the arsenic in the flue gas reacts with the sulfiding agent to generate solid arsenic sulfide particles; (3) Arsenic sulfide particle capture: the reacted flue gas is introduced into a dust removal equipment to capture the generated solid arsenic sulfide particles; (4) Synergistic denitration treatment: the flue gas after arsenic removal is directly introduced into a denitration reactor for denitration treatment.

[0008] Preferably, in step (2), the sulfiding agent is hydrogen sulfide H2S or carbon disulfide CS2; when the sulfiding agent is hydrogen sulfide, the amount introduced is 3-5 times the molar amount of arsenic in the flue gas; when the sulfiding agent is carbon disulfide, the amount introduced is 4-6 times the molar amount of arsenic in the flue gas.

[0009] Preferably, in step (2), the composite catalyst takes TiO2 or Al2O3 as a carrier, and loads active components and a catalyst promoter; the active component is V2O5 or MoO3, and the mass fraction is 3%-6%; the catalyst promoter is WO3, and the mass fraction is 8%-10%; the particle size of the composite catalyst is 3-5 mm.

[0010] Preferably, in step (2), the gas phase strengthening reactor is internally provided with a gas distribution plate, and the composite catalyst is filled in a fixed bed mode; the space velocity of the flue gas in the gas phase strengthening reactor is 1000-2000 h -1 , and the reaction time is 0.5-1 s.

[0011] Preferably, in step (3), the dust removal equipment is an electric bag composite dust collector or a ceramic filter dust collector, and the capture efficiency of the arsenic sulfide particles with a particle size of ≥0.1 μm is not less than 99%.

[0012] Preferably, the captured arsenic sulfide particles are recycled as arsenic-containing raw materials.

[0013] The flue gas arsenic removal system for realizing the method comprises, in sequence through pipelines, a waste heat recovery device, a gas phase strengthening reactor, a dust removal equipment, a denitration reactor and a desulfurization reactor; the system further comprises a sulfiding agent supply system connected with the inlet end of the gas phase strengthening reactor through a branch pipe.

[0014] Preferably, the gas-phase enhanced reactor includes a fixed-bed reactor shell, upper and lower gas distribution plates fixed inside the shell, and a composite catalyst bed filled between the two gas distribution plates.

[0015] Preferably, the dust removal equipment is an electrostatic precipitator / bag filter or a ceramic filter dust collector.

[0016] Preferably, the catalyst packed in the denitrification reactor is the same as the composite catalyst packed in the gas-phase enhanced reactor.

[0017] Compared with existing technologies, the present invention achieves significant improvements in technical, economic, and social aspects. Specific data is based on industrial test results treating 10000 Nm³ / h of non-ferrous smelting flue gas (flue gas parameters: arsenic content 50 mg / Nm³, initial temperature 550℃, dust content 100 mg / Nm³). (a) Technical effects (1) Significantly improved arsenic removal efficiency: The arsenic removal efficiency of this invention reaches over 98.5%, and the arsenic content in the flue gas after treatment is ≤0.75mg / Nm³, which is far lower than the existing wet sodium sulfide method (arsenic removal efficiency 85%-90%, arsenic content after treatment 5-7.5mg / Nm³) and staged cooling arsenic removal method (arsenic removal efficiency 60%-70%, arsenic content after treatment 15-20mg / Nm³), fully meeting the requirements of subsequent denitrification catalysts for arsenic content (≤5mg / Nm³).

[0018] (2) Significantly reduced energy consumption: Since the present invention does not require cooling-heating treatment of flue gas, compared with wet sodium sulfide method and staged cooling arsenic removal method, it can save about 800 kWh of heating energy per 10,000 Nm³ of flue gas (wet sodium sulfide method requires heating of 200°C, staged cooling arsenic removal method requires heating of 250°C). Calculated at an industrial electricity price of 0.6 yuan / kWh, it can save 384,000 yuan in electricity costs per year (8,000 hours of operation per year).

[0019] (3) Fast reaction speed and strong processing capacity: Under the action of composite catalyst, the reaction time of arsenic and hydrogen sulfide is only 0.5-1s. The volume load of the gas phase enhanced reactor is 3-5 times that of the existing wet scrubbing tower. Under the same processing capacity, the equipment footprint is reduced by more than 60% (the reactor of this invention occupies an area of ​​about 20m², and the wet scrubbing tower occupies an area of ​​about 50m²).

[0020] (II) Economic Effects (1) Reduce the cost of waste acid treatment: This invention adopts gas phase reaction and no waste acid is generated. Compared with the wet sodium sulfide method (1.2m³ of waste acid is generated per 10,000 Nm³ of flue gas, and the waste acid treatment cost is RMB 1,000 per ton), the waste acid treatment cost can be reduced by RMB 960,000 per year (1.2m³ / h×8,000h×1,000 RMB / m³).

[0021] (2) Operating cost reduction: The unit processing cost of the present application is 0.8 yuan / Nm3, which is reduced by 46.7% compared with the wet sodium sulfide method (1.5 yuan / Nm3) and reduced by 33.3% compared with the staged cooling arsenic removal method (1.2 yuan / Nm3). The annual operating cost can be saved by 5,600,000 yuan (10,000 Nm3 / h x 8,000 h x (1.5-0.8) yuan / Nm3).

[0022] (3) By-product recovery income: About 3.94 tons of arsenic sulfide dust can be captured per year (10,000 Nm3 / h x 50 mg / Nm3 x 98.5% x 8,000 h x 10 -9 -9 ×198 (molar mass of As2S3) / 148 (molar mass of 2As), the recovery value of arsenic sulfide as an arsenic-containing raw material is about 8,000 yuan / ton, and the annual recovery income can be increased by 31,520 yuan.

[0023] (Three) Social effect The present application avoids the generation of waste acid, reduces the pollution risk of arsenic-containing wastewater to soil and water, reduces energy consumption and carbon dioxide emissions (about 640 tons of carbon dioxide emissions can be reduced per 10,000 Nm3 of flue gas per year, and the carbon dioxide emissions are calculated at 0.8 kg per kWh of electricity), which meets the requirements of the "double carbon" strategy; in addition, the recycling of arsenic sulfide dust realizes the recycling of arsenic resources, reduces the amount of solid waste landfill, and has significant environmental and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 The figure is a process flow diagram of the gas phase reinforced composite catalytic sulfidation flue gas arsenic removal method of the present application; in the figure, the non-ferrous smelting flue gas discharge port is connected to the waste heat recovery device through a high-temperature resistant flue gas pipeline, the waste heat recovery device is connected to the gas phase reinforced reactor through a high-temperature resistant flue gas pipeline, the hydrogen sulfide supply system is connected to the inlet end of the gas phase reinforced reactor through a branch pipe, the gas phase reinforced reactor is connected to the electric bag composite dust collector through a high-temperature resistant flue gas pipeline, the bottom of the electric bag composite dust collector is connected to the arsenic sulfide dust collection device, the electric bag composite dust collector is connected to the denitration reactor through a high-temperature resistant flue gas pipeline, the denitration reactor is connected to the desulfurization reactor through a high-temperature resistant flue gas pipeline, and the desulfurization reactor is connected to the chimney through a high-temperature resistant flue gas pipeline.

[0025] Fig. 2 The figure is a schematic diagram of the internal structure distribution of the gas phase reinforced reactor. In the figure, the gas distribution plate (upper and lower) is a multi-hole plate structure with a hole diameter of 5 mm, and the composite catalyst bed is filled between the two distribution plates. The flue gas is evenly distributed to the catalyst bed through the lower distribution plate after entering from the inlet, and is discharged from the outlet through the upper distribution plate after reaction. DETAILED DESCRIPTION

[0026] The application will be further described in detail below in combination with the accompanying drawings and the best mode of the application. It should be noted that the accompanying drawings are only simplified schematic diagrams, and the devices in the system are mature structures in the art, and should not be understood as a limitation on the overall method and system of the application.

[0027] As Figs. 1-2 shown, the technical solution of the application is based on the gas phase strengthening reaction and the composite catalysis principle. Hydrogen sulfide (H2S) is used to replace the traditional sodium sulfide solution in the wet method as a sulfidizing agent. In the customized gas phase strengthening reactor, the arsenic in the flue gas and the hydrogen sulfide are rapidly reacted to generate solid arsenic sulfide (As2S3) under the catalysis of the composite catalyst in a high-temperature environment. Then the arsenic sulfide particles are captured by the high-efficiency dust removal equipment to achieve flue gas arsenic removal. The temperature of the flue gas after arsenic removal still maintains at 300-400℃, which can directly enter the denitration system for denitration treatment to form a “arsenic removal-denitration” collaborative process.

[0028] The specific technical steps are as follows: (1) Flue gas pretreatment: The high-temperature flue gas (temperature 500-600℃, arsenic content 20-100mg / Nm³) generated in the non-ferrous smelting process is introduced into the waste heat recovery device to adjust the flue gas temperature to 300-400℃ (this temperature range meets the arsenic removal reaction requirement of the application and also meets the activity temperature requirement of the subsequent denitration catalyst), and at the same time, the flue gas is removed from the flue gas with particle size greater than 10μm. Large particle dust to avoid affecting the subsequent reaction efficiency.

[0029] (2) Gas phase strengthening arsenic removal reaction: The pretreated flue gas is introduced into the gas phase strengthening reactor, and at the same time, the hydrogen sulfide gas is introduced into the reactor through the hydrogen sulfide supply system. The amount of hydrogen sulfide introduced is 3-5 times the molar amount of arsenic in the flue gas (to ensure that arsenic is fully reacted); the gas phase strengthening reactor is filled with a composite catalyst, which uses TiO2 as a carrier, loads V2O5 (active component, mass fraction 3%-5%) and WO3 (cocatalyst, mass fraction 8%-10%), and the catalyst particle size is 3-5mm. The flue gas has an air speed of 1000-2000h -1 in the reactor under the catalysis of the catalyst. The arsenic (mainly in the form of As2O3) in the flue gas reacts with hydrogen sulfide to generate solid As2S3 particles, and the reaction equation is: As2O3+3H2S =As2S3↓ + 3H2O, and the reaction time is 0.5-1s.

[0030] (3) Arsenic sulfide particle capture: The flue gas after the gas phase strengthening reactor reaction is introduced into the electric bag composite dust collector. The dust collector combines the advantages of electrostatic precipitation and filter bag dust removal, and the capture efficiency of arsenic sulfide particles with a particle size of ≥0.1μm is ≥99%. The captured arsenic sulfide dust can be collected and recycled as an arsenic-containing raw material.

[0031] (4) Synergistic denitration treatment: The flue gas after arsenic removal is directly introduced into the denitration reactor. Since the flue gas temperature still maintains at 300-400℃, it can directly meet the activity requirements of the denitration catalyst (the same as the arsenic removal catalyst component, realizing the unification of the catalyst). Under the condition of ammonia (NH3) as a reducing agent, the flue gas denitration treatment is completed, and the flue gas after the final purification by the desulfurization system is discharged in compliance with the standard.

[0032] Among them, the core equipment involved in the present application includes: a waste heat recovery device, a gas phase strengthening reactor, a hydrogen sulfide supply system, an electric bag composite dust collector, a denitration reactor, and each device is connected in series through a high-temperature flue gas pipeline, and the specific connection relationship is: non-ferrous smelting flue gas discharge port → waste heat recovery device → gas phase strengthening reactor → electric bag composite dust collector → denitration reactor → desulfurization system → chimney; wherein the hydrogen sulfide supply system is connected with the flue gas inlet end of the gas phase strengthening reactor through a branch pipe, to ensure that the hydrogen sulfide is fully mixed with the flue gas before entering the reactor; the gas phase strengthening reactor is internally provided with a catalyst fixed bed, and gas distribution plates are arranged above and below the bed to ensure uniform contact between the flue gas and the catalyst.

[0033] For the core technical solution, the following alternative solutions can be used to achieve the same purpose of the invention: (1) Sulfiding agent replacement: In the case where hydrogen sulfide supply is not convenient, carbon disulfide (CS2) can be used as a replacement sulfiding agent. Carbon disulfide can react with water vapor in the flue gas to generate hydrogen sulfide under the condition of 300-400℃, and then participate in the sulfidation reaction of arsenic. The amount of carbon disulfide introduced is 4-6 times the molar amount of arsenic in the flue gas. This scheme can reduce the storage risk of the sulfiding agent, but the operating cost is slightly higher than that of the hydrogen sulfide scheme (about 15%-20% increase).

[0034] (2) Catalyst replacement: The carrier of the composite catalyst can be replaced by Al2O3 instead of TiO2, and the active component can be replaced by MoO3 (mass fraction 4%-6%), and the auxiliary catalyst remains unchanged WO3. The arsenic removal efficiency of the alternative catalyst is equivalent to that of the original catalyst (≥98%), but the service life of the catalyst is slightly shorter (the service life of the original catalyst is 3-5 years, and the service life of the alternative catalyst is 2-3 years). It is suitable for scenarios sensitive to catalyst cost.

[0035] (3) Dust removal equipment replacement: The electric bag composite dust collector can be replaced by a ceramic filter dust collector, which has an arsenic sulfide particle capture efficiency of ≥99.5%, but the equipment investment cost is 25%-30% higher than that of the electric bag composite dust collector. It is suitable for scenarios with very high arsenic removal precision requirements. EMBODIMENT

[0036] The following is an example of a certain copper smelting plant flue gas treatment system, the system handles flue gas volume of 15000Nm³ / h, the initial parameters of flue gas: temperature 550℃, arsenic content 60mg / Nm³, dust content 120mg / Nm³, sulfur dioxide content 3%, nitrogen oxides content 800mg / Nm³. The method for treating arsenic in gaseous phase reinforced composite catalytic sulfurized flue gas of the application, the specific implementation steps are as follows: (1) flue gas pretreatment: the copper smelting flue gas is introduced into the tubular shell type waste heat recovery device, and the soft water is used as the heat exchange medium. By controlling the flow of the heat exchange medium, the temperature of the flue gas is reduced from 550℃ to 350℃. At the same time, a cyclone dust collector is arranged at the outlet of the waste heat recovery device to remove the dust with a particle size greater than 10μm in the flue gas, and the dust removal efficiency is 90%. After pretreatment, the dust content in the flue gas is reduced to 12mg / Nm³.

[0037] (2) gaseous phase reinforced arsenic removal reaction: the pretreated flue gas is introduced into the gaseous phase reinforced reactor through the high-temperature resistant pipeline (the material is 316L stainless steel). The reactor shell is welded by Q345R steel plate, the inner diameter is 1.5m, and the height is 4m. The hydrogen sulfide supply system uses liquid ammonia method to prepare hydrogen sulfide on site. The pressure of hydrogen sulfide is adjusted to 0.15MPa through a pressure reducing valve, and the flow rate is controlled to be 18Nm³ / h (the molar flow rate of arsenic in the flue gas is 15000×60×10 -9 ×1000=0.9mol / h, and the hydrogen sulfide input amount is 4 times the molar amount of arsenic). The reactor is filled with composite catalyst, the catalyst uses TiO2 as carrier, loads V2O5 (mass fraction 4%) and WO3 (mass fraction 9%), the catalyst particle size is 4mm, the loading height is 2.5m, the space velocity of flue gas in the reactor is 1500h -1 , and the reaction time is 0.8s. Under the action of the catalyst, As2O3 in the flue gas reacts with H2S to generate As2S3 solid particles.

[0038] (3) arsenic sulfide particle capture: the reacted flue gas enters the electric bag composite dust collector. The electric field voltage of the dust collector is set to 60kV, the filter bag material is PTFE (polytetrafluoroethylene), and the filter wind speed is 1.2m / min. Through the synergistic effect of electrostatic adsorption and filter bag filtration, the capture efficiency of arsenic sulfide particles reaches 99.2%. The captured arsenic sulfide dust is sent to a sealed collection tank by a screw conveyor, and the purity of As2S3 in the dust is 95% after detection.

[0039] (4) synergistic denitration treatment: the flue gas after arsenic removal (temperature 348℃, arsenic content 0.86mg / Nm³) directly enters the denitration reactor, and the same composite catalyst as the arsenic removal reactor is filled in the denitration reactor (realizing unified procurement and replacement of the catalyst). Ammonia is introduced into the reactor through an ammonia injection grid. The ammonia input amount is 1.05 times the molar amount of nitrogen oxides (i.e. 15000×800×10-9 × 1000 x 1.05 = 12.6 mol / h), at 348°C, nitrogen oxides and ammonia gas reduction reaction to generate nitrogen and water, denitration efficiency of 90%, after treatment of flue gas containing nitrogen oxides reduced to 80 mg / Nm3, arsenic content ≤0.86 mg / Nm3, meet the "copper, nickel, cobalt industry pollutant discharge standards" (GB 25467-2010) in the special emission limit requirements.

[0040] Effect of implementation detection: The example is continuously running for 30 days, the flue gas parameters of each key node are detected, the results are as follows: the arsenic content of the gas phase enhanced reactor outlet flue gas is stably at 0.8-0.9 mg / Nm3, the arsenic removal efficiency is ≥98.5%; the arsenic content of the electric bag composite dust collector outlet is ≤0.86 mg / Nm3, the capture efficiency is stable; the nitrogen oxides content of the denitration reactor outlet is ≤80 mg / Nm3, the catalyst activity has no obvious decrease (the denitration efficiency is maintained at about 90%); the whole system has no pollution acid, about 0.15 tons of arsenic sulfide dust is captured every day, the arsenic resource recovery is realized. Compared with the original wet sulfide arsenic removal system, the example saves electricity fee 14400 yuan per day, saves pollution acid disposal fee 36000 yuan, the comprehensive operation cost is reduced by 62%.

[0041] The above described, only for the preferred specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any skilled in the art of the technical personnel in the technical range disclosed by the present application, according to the technical scheme of the present application and the inventive concept of the application, equivalent replacement or change, should be covered within the protection scope of the present application.

Claims

1. A method for gas phase enhanced composite catalytic sulphidation of flue gas for arsenic removal, characterized by, The method comprises the following steps: (1) flue gas pretreatment: passing non-ferrous smelting flue gas with a temperature of 500-600℃ into a waste heat recovery device, adjusting the flue gas temperature to 300-400℃, and removing dust with a particle size greater than 10μm in the flue gas; (2) gas phase strengthening arsenic removal reaction: introducing the pretreated flue gas into a gas phase strengthening reactor, and simultaneously passing a sulfidizing agent into the reactor, wherein the amount of the sulfidizing agent passed in is 3-6 times the molar amount of arsenic in the flue gas; the gas phase strengthening reactor is filled with a composite catalyst, and under the condition of 300-400℃, arsenic in the flue gas reacts with the sulfidizing agent to generate solid arsenic sulfide particles; (3) arsenic sulfide particle capture: introducing the reacted flue gas into a dust removal device to capture the generated solid arsenic sulfide particles; (4) collaborative denitration treatment: directly introducing the flue gas after arsenic removal into a denitration reactor for denitration treatment.

2. The method of removing arsenic from gas phase enhanced composite catalytic sulfurized flue gas according to claim 1, characterized in that: In step (2), the sulfidizing agent is hydrogen sulfide H2S or carbon disulfide CS2; when the sulfidizing agent is hydrogen sulfide, the amount passed in is 3-5 times the molar amount of arsenic in the flue gas; when the sulfidizing agent is carbon disulfide, the amount passed in is 4-6 times the molar amount of arsenic in the flue gas.

3. The method of removing arsenic from flue gas by gas phase enhanced composite catalytic sulfurization according to claim 1, characterized in that: In step (2), the composite catalyst takes TiO2 or Al2O3 as a carrier, and loads active components and a catalyst promoter; the active components are V2O5 or MoO3, and the mass fraction is 3%-6%; the catalyst promoter is WO3, and the mass fraction is 8%-10%; the particle size of the composite catalyst is 3-5mm.

4. The method of removing arsenic from flue gas by gas phase enhanced composite catalytic sulfurization according to claim 1 or 3, characterized in that: In step (2), the gas-phase strengthening reactor is internally provided with a gas distribution plate, and the composite catalyst is filled in a fixed bed mode; the space velocity of the flue gas in the gas-phase strengthening reactor is 1000-2000h -1 , and the reaction time is 0.5-1s.

5. The method of removing arsenic from flue gas by gas phase enhanced composite catalytic sulfurization according to claim 1, characterized in that: In step (3), the dust removal device is an electric bag composite dust collector or a ceramic filter dust collector, and the capture efficiency of arsenic sulfide particles with a particle size ≥0.1μm is not less than 99%.

6. The method of removing arsenic from flue gas by gas phase enhanced composite catalytic sulfurization according to claim 1 or 5, characterized in that: The captured arsenic sulfide particles are recycled as arsenic-containing raw materials.

7. A system for removing arsenic from flue gas for implementing the method according to any one of claims 1 to 6, characterized in that, The system comprises, in sequence through a pipeline, a waste heat recovery device, a gas phase strengthening reactor, a dust removal device, a denitration reactor, and a desulfurization reactor; the system further comprises a sulfidizing agent supply system connected with the inlet end of the gas phase strengthening reactor through a branch pipe.

8. The flue gas arsenic removal system of claim 7, wherein: The gas phase strengthening reactor comprises a fixed bed reactor shell, upper and lower gas distribution plates fixed in the shell, and a composite catalyst bed layer filled between the two gas distribution plates.

9. The flue gas arsenic removal system of claim 7, wherein: The dust removal device is an electric bag composite dust collector or a ceramic filter dust collector.

10. The flue gas arsenic removal system of claim 7, wherein: The catalyst loaded in the denitration reactor is the same as the composite catalyst loaded in the gas phase strengthening reactor.

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