Method for oxidizing absorption and reclamation of arsenic hydride-containing waste gas with reagent circulation

Abstract

The application discloses an oxidation absorption and medicament circulation regeneration method of arsine-containing waste gas, and belongs to the technical field of non-ferrous smelting waste gas treatment. The method is that arsine-containing waste gas is absorbed by an oxidation absorption liquid (containing a water-soluble heptavalent manganese compound and an alkaline compound) to obtain an oxidation absorption liquid containing arsenate; the oxidation absorption liquid containing arsenate is regenerated by ozone oxidation to obtain regenerated oxidation absorption liquid; after the method is used to treat arsine-containing waste gas with a concentration of less than or equal to 200 mg / m3, the concentration of arsine can be stably reduced to below 0.03 mg / m3, the recycling rate of the oxidation absorption liquid is high, solid waste can be avoided from blocking the oxidation absorption tower, pipelines and other equipment, the operation cost is low, and the method is particularly suitable for continuous purification of tail gas in smelting and other industries capable of generating arsine-containing waste gas.

Description

Technical Field

[0001] This invention relates to a method for treating arsine-containing waste gas, and particularly to a method for oxidizing and absorbing arsine-containing waste gas and recycling reagents, belonging to the field of non-ferrous smelting waste gas treatment technology. Background Technology

[0002] Arsine is a colorless, highly toxic gas with a garlic-like odor, commonly found in hydrometallurgical smelting of non-ferrous metals (such as zinc, copper, and lead), mineral roasting, and chemical production processes. Particularly in zinc oxygen pressure leaching and heavy metal purification filtration processes, arsenic impurities in the materials are readily reduced to high concentrations of arsine waste gas under acidic and reducing environments.

[0003] When the concentration of arsine in the air exceeds 250 ppm, inhalation will cause rapid death in humans. Current methods for treating arsine mainly employ disposable absorbent solutions or single-stage absorption processes. Oxidants primarily include KMnO4, H2O2, K2Cr2O7, CuSO4, KIO3, and NaClO. These methods suffer from high absorbent consumption, high operating costs, rapid absorbent decay, insufficient treatment stability, and significant pressure on subsequent waste residue and liquid disposal. Chinese patent (publication number CN103721562B) discloses a method for purifying arsine in waste gas, using hydrogen peroxide as an oxidant and silver salt as a catalyst. This method is characterized by simple equipment and low cost, but it still suffers from drawbacks such as high hydrogen peroxide consumption and the inability to recover the catalyst. Furthermore, for low to medium concentrations of arsine tail gas, if the absorption system lacks online control and recycling mechanisms, problems such as fluctuating absorption efficiency, low reagent utilization, and frequent operation and maintenance are likely to occur. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a method for the oxidation absorption and reagent recycling of arsine-containing waste gas. This method not only achieves efficient removal of arsine to ensure that the exhaust gas meets emission standards, but also only requires the consumption of inexpensive ozone throughout the process, allowing for effective recycling of the reagent and significantly reducing costs. Furthermore, it enables automated continuous treatment, greatly improving the treatment efficiency of arsine-containing waste gas.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for the oxidation absorption and reagent recycling of arsine-containing waste gas. The method involves absorbing the arsine-containing waste gas with an oxidation absorption liquid to obtain an arsenate-containing oxidation absorption liquid, which is then regenerated by ozone oxidation to obtain a regenerated oxidation absorption liquid. The oxidation absorption liquid contains a water-soluble heptavalent manganese compound and an alkaline compound.

[0006] The treatment process for arsine-containing waste gas of the present invention comprises two core reaction principles: oxidation absorption reaction and oxidation regeneration reaction.

[0007] (1) Oxidation absorption reaction: The key lies in the use of a special oxidation absorption liquid, which is an alkaline solution containing Mn(VII). On the one hand, alkaline conditions are beneficial to improving the absorption rate of weakly acidic arsine gas; on the other hand, providing an alkaline environment not only enables Mn(VII) compounds to selectively oxidize arsine (AsH3) to arsenic (… The compound is completely retained in the liquid phase and can directionally reduce manganese (VII) compounds to Mn (VI) compounds, and inhibit the disproportionation reaction of intermediate valence manganese.

[0008] (2) Oxidation and regeneration reaction: The key is to use ozone as an oxidant. By optimizing the ozone oxidation conditions, the intermediate Mn(VI) compound can be converted back into the active component of manganese(VII) compound, suppressing the side reaction of intermediate manganese and completely avoiding the disproportionation of Mn(VI) compound into manganese dioxide (MnO2) solid precipitate.

[0009] As a preferred embodiment, the mass concentration of water-soluble heptavalent manganese compounds in the oxidation absorbent is 4-6%, and the mass concentration of alkaline compounds is 8-11%, wherein the water-soluble heptavalent manganese compounds are measured by the mass of manganese (VII) ions. The water-soluble heptavalent manganese compounds in the oxidation absorbent are the main active components for oxidizing arsine, and their concentration can be appropriately adjusted according to the concentration of arsine in the arsine-containing waste gas. However, if the concentration of water-soluble heptavalent manganese compounds is too low, the absorption effect on arsine will be reduced, while if the concentration is too high, the solution is prone to saturation at low temperatures. The concentration of alkaline compounds primarily provides a suitable alkaline environment. The oxidizing power of water-soluble heptavalent manganese compounds varies at different pH levels, and the stability of their oxidation intermediates also differs. Generally, the stronger the alkalinity, the weaker the oxidizing power of water-soluble heptavalent manganese compounds. Conversely, the weaker the alkalinity, the less stable the reduction intermediates of water-soluble heptavalent manganese compounds, making them more prone to disproportionation reactions. Therefore, controlling the concentration of alkaline compounds ensures that arsine can be completely oxidized to higher-valent arsenates while avoiding disproportionation side reactions of the reduction intermediates of water-soluble heptavalent manganese compounds. Furthermore, stronger alkalinity accelerates ozone decomposition during subsequent ozone oxidation and regeneration processes, reducing ozone utilization efficiency.

[0010] As a preferred embodiment, the water-soluble heptavalent manganese compound includes permanganate. Common examples of permanganate include potassium permanganate.

[0011] As a preferred embodiment, the alkaline compound includes at least one of an alkali metal hydroxide and ammonia water. Examples of alkali metal hydroxides include sodium hydroxide and potassium hydroxide.

[0012] As a preferred embodiment, the ozone oxidation regeneration conditions are: pH value controlled at 11-12, and ozone introduction rate controlled to maintain the oxidation-reduction potential (ORP) within the range of 380-450 mV. The key to the ozone oxidation regeneration process of this invention lies in strictly controlling the pH range and ORP. When the ORP is below 380 mV, the overall oxidation reaction driving force of the system is insufficient, resulting in some water-soluble heptavalent manganese compound reduction intermediates not being fully oxidized and regenerated. During recycling, these reduction intermediates are further reduced to IV valence by arsine-containing waste gas, irreversibly generating manganese dioxide solid precipitate. When the ORP is above 450 mV, the regeneration effect on water-soluble heptavalent manganese compounds will not be further improved; instead, an "ozone escape" phenomenon will occur, increasing the oxidation regeneration cost. This not only fails to further improve the arsine removal efficiency (which has reached its limit), but also leads to excessive ozone entrainment in the exhaust gas, causing secondary gas phase pollution and a sharp increase in the energy consumption of the ozone generator.

[0013] As a preferred embodiment, the absorption employs a spray-countercurrent contact absorption method. This invention, through the spray-countercurrent contact absorption method, can significantly improve the gas-liquid contact reaction efficiency and enhance the adsorption effect on arsine gas.

[0014] As a preferred embodiment, during the absorption process, the flow rate of the arsine-containing waste gas is 100~400 m³. 3 / h, the concentration of arsine in the arsine-containing waste gas is ≤200mg / m³. 3 The liquid-to-gas ratio is 2~5 L / m³ 3 When the liquid-to-gas ratio is too high, the utilization rate of the oxidation absorbent is low; when the liquid-to-gas ratio is too low, the conversion rate of arsine gas in the arsine-containing waste gas is low.

[0015] As a preferred embodiment, the regenerated oxidation absorbent is circulated in a closed loop throughout the absorption process until the arsenate concentration in the oxidation absorbent reaches 15 g / L, at which point the open-loop portion of the oxidation absorbent undergoes arsenic removal treatment. If the arsenate concentration in the oxidation absorbent is below 15 g / L, the open-loop arsenic removal liquid phase is large, resulting in low arsenic removal efficiency. Furthermore, if the arsenate concentration in the oxidation absorbent accumulates to an excessively high level, it will affect the recycling efficiency of the oxidation absorbent. Therefore, performing open-loop arsenic removal treatment when the arsenate concentration in the oxidation absorbent reaches the limit of 15 g / L ensures both effective recycling of the oxidation absorbent and high open-loop arsenic removal efficiency.

[0016] As a preferred embodiment, the arsenic removal treatment uses at least one of calcium salts, iron salts, and polymeric chelating agents as the arsenic removal agent. Calcium salts primarily provide calcium ions; water-soluble calcium salts generally meet the requirements, such as calcium chloride. Iron salts primarily provide iron ions; water-soluble iron salts generally meet the requirements, such as ferric chloride. Polymeric chelating agents are, for example, thiophenol-containing polymers.

[0017] As a preferred embodiment, the arsine-containing waste gas is continuously introduced into the oxidation absorption tower from the bottom, where it comes into countercurrent contact with the oxidation absorption liquid sprayed from the top of the tower to remove the arsine. The exhaust gas after arsine removal is directly discharged from the top of the tower. The removed arsine is converted into arsenate, which enters the oxidation absorption liquid. The arsenate-containing oxidation absorption liquid is discharged from the bottom of the tower and enters a regeneration tower. In the regeneration tower, ozone is continuously bubbled in to regenerate the arsenate-containing oxidation absorption liquid, resulting in regenerated oxidation absorption liquid. This regenerated oxidation absorption liquid is then recycled back into the oxidation absorption tower. This invention achieves continuous oxidation absorption and regeneration of the oxidation absorption liquid by constructing a cyclic conversion mechanism between Mn(VI) and Mn(VII).

[0018] As a preferred embodiment, the oxidation absorption tower consists of a single-stage oxidation absorption tower or multiple single-stage oxidation absorption towers connected in series. The selection of a single-stage oxidation absorption tower or multiple single-stage oxidation absorption towers connected in series is based on the concentration and flow rate of arsine in the arsine-containing waste gas. When the concentration or flow rate of arsine in the waste gas is high, multiple single-stage oxidation absorption towers are connected in series, and the exhaust gas discharged from the first-stage oxidation absorption tower directly enters the next-stage oxidation absorption tower.

[0019] As a preferred embodiment, the oxidation absorption tower is a packed tower. Using a packed tower can improve the efficiency of the gas-liquid contact reaction. The packing material can be conventional Raschig rings, Pall rings, etc.

[0020] As a preferred embodiment, the residence time of the arsine-containing waste gas in the oxidation absorption tower is 2-5 seconds. Too short a residence time will result in incomplete oxidation-hydrogenation of the arsine, while too long a residence time will lead to low oxidation absorption efficiency.

[0021] As a preferred embodiment, the ozone flow rate is 4-5 m³ / h. 3 / h, ozone concentration is 120~200mg / L.

[0022] Compared with the prior art, the beneficial effects of the technical solution of this invention are as follows:

[0023] This invention constructs a cyclic conversion mechanism between Mn(VI) and Mn(VII). The Mn(VI) / Mn(VII) system is similar to a catalytic system, using ozone as the actual oxidant. It can not only achieve efficient and selective oxidation of arsine in arsine-containing waste gas into arsenate, but also ozone is relatively inexpensive and readily available compared to other oxidants, resulting in low cost.

[0024] This invention designs a cyclical conversion of Mn(VI) and Mn(VII), enabling the oxidation absorbent to continuously and cyclically remove arsine from waste gas containing arsine. The regeneration and reuse rate of the oxidation absorbent can reach over 98%, requiring only periodic replenishment of lost components, thus significantly reducing reagent procurement costs.

[0025] This invention, by selecting ozone as an oxidant and synergistically controlling the alkaline environment and a specific ORP range, can suppress the generation of manganese dioxide, avoid the technical problem of easy blockage of the oxidation absorption tower and pipelines during the recycling of the oxidation absorption liquid, and significantly extend the continuous operation cycle of the equipment.

[0026] This invention exhibits excellent removal efficiency for arsine-containing waste gas, especially when the inlet arsine concentration is <200 mg / m³. 3 Under operating conditions, the outlet concentration is consistently below 0.03 mg / m³. 3 It meets the requirements for ultra-low emissions.

[0027] This invention reduces the discharge of arsenic-containing wastewater by recycling the oxidation absorption liquid, resulting in a reduction of hazardous waste generation by more than 85% compared to traditional processes, and a significant decrease in environmental disposal costs. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be described in detail and clearly below with reference to specific embodiments, but the scope of protection of the claims of the present invention is not limited to the specific embodiments.

[0030] Example 1

[0031] To prepare the oxidation absorption solution, potassium permanganate, sodium hydroxide, and a certain amount of water were used to prepare Mn. 7+ An oxidation absorption solution with a mass concentration of 4% and a sodium hydroxide mass concentration of 10% was pumped into an oxidation absorption tower (spray-packed tower with Raschig ring packing) to spray and absorb arsine-containing waste gas. The arsine concentration was 180 mg / m³. 3 The flow rate is 200m³. 3Based on the concentration and flow rate of the arsine-containing waste gas, two single-stage oxidation absorption towers are connected in series for two-stage absorption and purification of arsine. The exhaust gas discharged from the top of the first-stage oxidation absorption tower directly enters the second-stage oxidation absorption tower for further absorption, with a liquid-to-gas ratio of 5 L / m³. 3 Arsine-containing waste gas is held for 3 seconds in a single oxidation absorption tower to obtain an oxidized liquid. The oxidized liquid discharged from each single-stage oxidation absorption tower is pumped into a regeneration tower for oxidant regeneration. The flow rate of the gaseous oxidant (ozone) is controlled at 4 m³ / s. 3 The concentration was 150 mg / L / h, and the pH and ORP of the post-oxidation solution were monitored in real time. The system pH was maintained at 11-12 and the ORP at 390-410 mV for 4 hours. The regenerated oxidant was then circulated to the primary and secondary oxidation absorption towers. A total of 800 m³ of oxidant was treated. 3 Arsine tail gas. When the arsenate concentration in the oxidation absorption liquid reaches 15 g / L, a portion is drawn off for arsenic removal. The arsenic removal agent is iron salt (ferric chloride). The dissolved arsenic is converted into an insoluble solid through precipitation or flocculation, thereby removing arsenic from the waste liquid.

[0032] Using this method, the highest concentration of arsine gas at the exhaust outlet that meets the standards is 1.85 μg / m³. 3 The removal rate was 99.99%, meeting the requirements of "Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors" (GBZ2.1-2019). No solid precipitates were generated during operation, and the pipelines and packing were unobstructed.

[0033] Example 2

[0034] To prepare the oxidation absorption solution, potassium permanganate, sodium hydroxide, and a certain amount of water were used to prepare Mn. 7+ An oxidation absorption solution with a mass concentration of 5% and a sodium hydroxide mass concentration of 10% is pumped into an oxidation absorption tower (spray-packed tower, Raschig ring packing) to absorb arsine-containing waste gas. The arsine concentration is 200 mg / m³. 3 The flow rate is 400m³. 3 Based on the concentration and flow rate of the arsine-containing waste gas, two single-stage oxidation absorption towers are connected in series for two-stage absorption and purification of arsine. The exhaust gas discharged from the top of the first-stage oxidation absorption tower directly enters the second-stage oxidation absorption tower for further absorption, with a liquid-to-gas ratio of 2 L / m³. 3 Arsine-containing waste gas is held for 5 seconds in a single oxidation absorption tower to obtain an oxidized liquid. The oxidized liquid discharged from each single-stage oxidation absorption tower is pumped into a regeneration tower for oxidant regeneration. The flow rate of the gaseous oxidant (ozone) is controlled at 5 m³ / s. 3 The concentration was 200 mg / L, and the pH and ORP of the post-oxidation solution were monitored in real time. The system pH was maintained at 11-12 and the ORP at 380-400 mV for 4 hours. The regenerated oxidant was then circulated to the primary and secondary oxidation absorption towers. A total of 1600 m³ of oxidant was treated.3 Arsine tail gas. When the arsenate concentration in the oxidation absorption liquid reaches 15 g / L, a portion is drawn off for arsenic removal. The arsenic removal agent is iron salt (ferric chloride). The dissolved arsenic is converted into an insoluble solid through precipitation or flocculation, thereby removing arsenic from the waste liquid.

[0035] Using this method, the highest concentration of arsine gas at the exhaust outlet that meets the standards is 2.63 μg / m³. 3 The removal rate was 99.99%, meeting the requirements of "Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors" (GBZ2.1-2019). No solid precipitates were generated during operation, and the pipelines and packing were unobstructed.

[0036] Example 3

[0037] To prepare the oxidation absorption solution, potassium permanganate, sodium hydroxide, and a certain amount of water were used to prepare Mn. 7+ An oxidation absorption solution with a mass concentration of 4% and a sodium hydroxide mass concentration of 8% was pumped into an oxidation absorption tower (spray-packed tower with Raschig ring packing) to spray the arsine-containing waste gas at a concentration of 200 mg / m³. 3 The flow rate is 130m³. 3 Based on the concentration and flow rate of the arsine-containing waste gas, a single-stage oxidation absorption tower is used for single-stage absorption and purification of arsine, with a liquid-to-gas ratio of 6 L / m³. 3 Arsine-containing waste gas is held in the oxidation absorption tower for 3 seconds to obtain an oxidized liquid. This oxidized liquid is then pumped into a regeneration tower for oxidant regeneration, with the flow rate of the gaseous oxidant controlled at 4 m³ / s. 3 The concentration was 120 mg / L, and the pH and ORP of the post-oxidation solution were monitored in real time. The system pH was maintained at 11-12 and the ORP at 380-400 mV for 4 hours. The regenerated oxidant was then circulated back to the oxidation absorption tower, and a total of 520 m³ of solution was treated. 3 Arsine tail gas. When the arsenate concentration in the oxidation absorption liquid reaches 15 g / L, a portion is drawn off for arsenic removal, and the oxidized liquid is also drawn off for arsenic removal. The arsenic removal agent is an iron salt, which converts dissolved arsenic into an insoluble solid through precipitation or flocculation, thereby removing arsenic from the waste liquid.

[0038] Using this method, the highest concentration of arsine gas at the exhaust outlet that meets the standards is 0.51 μg / m³. 3 The removal rate was 99.99%, meeting the requirements of "Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors" (GBZ2.1-2019). No solid precipitates were generated during operation, and the pipelines and packing were unobstructed.

[0039] Comparative Example 1

[0040] Compared to Example 1, the only difference is that during the regeneration reaction, the automatic alkali replenishment device is turned off, and the pH value of the system is not controlled in a chain, allowing the acid produced by the reaction to consume the alkalinity of the system. Online monitoring shows that as the reaction proceeds, the pH value of the system liquid phase gradually drops and is maintained between 9.0 and 9.5; during this period, the system ORP is maintained at 390–410 mV by adjusting the amount of gaseous oxidant input, and the system continues to operate.

[0041] When the system ran continuously for 2.2 hours, due to the pH value being below 11, a violent disproportionation reaction of low-valent manganese intermediates occurred within the solution. The circulating absorbent rapidly changed from its initial deep purplish-red color to blackish-brown, accompanied by the precipitation of a large amount of flocculent and granular manganese dioxide (MnO2) solid precipitates. These solid precipitates, after entering the oxidation absorption tower with the circulating liquid, quickly adhered to and deposited on the packing surface and at the water distribution nozzles, leading to scaling and blockage in the oxidation absorption tower. With the airflow obstructed, the post-oxidation liquid was then drawn off for arsenic removal treatment with iron salts. However, due to the large amount of MnO2 sludge entrained in the waste liquid, the total amount of arsenic-containing solid waste generated increased significantly, and the effective recycling rate of manganese in the oxidation absorbent liquid plummeted to below 45%.

[0042] Comparative Example 2

[0043] The only difference compared to Example 1 is that, during the regeneration reaction operation, the supply of the gaseous oxidant (ozone) is restricted, and its inlet flow rate is reduced to 1.5 m³ / s. 3 / h (inlet gas concentration remains 150 mg / L). Due to insufficient flow of the strong oxidizing medium, the reduction consumption rate of high-valent manganese by arsine cannot be matched. Online monitoring shows that the system's ORP is controlled to drop and remains between 300 and 320 mV. The system has run for a total of 4 hours, treating a total waste gas volume of 800 m³. 3 .

[0044] Operating phenomena and results: Although the system suppressed the disproportionation reaction by adding alkali, the reduced low-valent manganese intermediate could not be reformed into Mn in situ by ozone due to the low potential (insufficient oxidation kinetics). 7+ The low-valent manganese AsH3 waste gas remaining in the liquid phase undergoes deep reduction, and manganese dioxide precipitates slowly from it as well. This is because the available Mn in the liquid phase... 7+ The concentration of the active component continued to decrease over 4 hours, and the reaction driving force of the packed tower decreased. By the 4th hour of operation, the outlet concentration of arsine in the exhaust gas had risen from the initial acceptable level to 14.2 mg / m³, indicating insufficient system purification capacity and exhaust gas emissions that did not meet the requirements of "Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors" (GBZ2.1-2019).

[0045] Comparative Example 3

[0046] The only difference compared to Example 1 is that the alkali concentration in the oxidation absorption solution is reduced from 10% to 4%.

[0047] To prepare the oxidation absorption solution, potassium permanganate, sodium hydroxide, and a certain amount of water were used to prepare Mn. 7+ An oxidation absorption liquid with a mass concentration of 4% and a sodium hydroxide mass concentration of 4% was pumped into an oxidation absorption tower (spray-packed tower with Raschig ring packing) to spray and absorb arsine-containing waste gas. The arsine concentration was 180 mg / m³, and the flow rate was 200 m³ / h. Based on the concentration and flow rate of the arsine-containing waste gas, two single-stage oxidation absorption towers were connected in series for two-stage absorption and purification of arsine. The liquid-to-gas ratio was 5 L / m³, and the arsine-containing waste gas was retained in each oxidation absorption tower for 3 seconds to obtain the oxidized liquid. The oxidized liquid discharged from each single-stage oxidation absorption tower was pumped into a regeneration tower for oxidant regeneration. The flow rate of the gaseous oxidant was controlled at 4 m³ / h, and the concentration was 150 mg / L. The pH and ORP values ​​of the oxidized liquid were monitored in real time, with the target system pH value maintained at 11-12 and the ORP value at 390-410 mV.

[0048] Operational Phenomena and Results: Due to the initially low alkalinity concentration of the absorbent and insufficient buffer capacity of the system, the acid generated by the continuous arsenic hydroxide reaction constantly consumed the alkalinity of the system, making it difficult to maintain a stable pH value above 11. After approximately 1.5 hours of operation, the system pH value gradually decreased to 9.5-10.0. Simultaneously with the pH decrease, the stability of the Mn(VI) reduction intermediate in the liquid phase deteriorated, and the Mn(VI) component in the potassium permanganate absorbent continuously underwent disproportionation reactions. The circulating absorbent gradually changed from its initial deep purplish-red color to blackish-brown, accompanied by the precipitation of small amounts of flocculent and granular manganese dioxide (MnO2) solid precipitates. These solid precipitates, after entering the oxidation absorption tower with the circulating liquid, quickly adhered to and deposited on the packing surface and at the water distribution nozzles, leading to scaling and blockage in the oxidation absorption tower. With the airflow obstructed, the post-oxidation liquid was then drawn off for arsenic removal treatment with iron salts. Due to the presence of small amounts of MnO2 sludge in the waste liquid, the total amount of arsenic-containing solid waste generated increased significantly. After 4 hours of operation, the concentration of arsine in the exhaust gas increased from the initial acceptable level to 5.8 mg / m³, far exceeding the requirements of "Occupational Exposure Limits for Hazardous Factors in the Workplace Part 1: Chemical Hazardous Factors" (GBZ 2.1-2019). The system's purification capacity decreased significantly, and it could not stably meet the emission standards. Furthermore, the effective recycling rate of manganese in the oxidation absorption liquid dropped sharply to below 45%.

[0049] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the oxidation absorption and reagent recycling of arsine-containing waste gas, characterized in that: The waste gas containing arsine is absorbed by an oxidation absorbent to obtain an oxidation absorbent containing arsenate; the oxidation absorbent containing arsenate is then regenerated by ozone oxidation to obtain a regenerated oxidation absorbent. The oxidation absorption liquid contains water-soluble heptavalent manganese compounds and alkaline compounds; The mass concentration of water-soluble heptavalent manganese compounds in the oxidation absorption liquid is 4-6%, and the mass concentration of alkaline compounds is 8-11%, wherein the water-soluble heptavalent manganese compounds are measured by the mass of manganese ions. The alkaline compound is an alkali metal hydroxide; The conditions for ozone oxidation regeneration are: pH value controlled at 11~12, and ozone introduction rate controlled at oxidation-reduction potential within the range of 380~450mV.

2. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 1, characterized in that: The water-soluble heptavalent manganese compounds include permanganates.

3. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 1, characterized in that: The absorption process employs a spray-countercurrent contact method. During the absorption process, the flow rate of the arsine-containing waste gas is 100~400 m³ / h. 3 / h, the concentration of arsine in the arsine-containing waste gas is ≤200mg / m³. 3 The liquid-to-gas ratio is 2~5 L / m³ 3 .

4. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 1, 2 or 3, characterized in that: The regenerated oxidation absorbent is circulated in a closed loop to the absorption process until the concentration of arsenate in the oxidation absorbent reaches 15 g / L, at which point the open-loop portion of the oxidation absorbent is subjected to arsenic removal treatment.

5. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 4, characterized in that: The arsenic removal treatment uses at least one of calcium salt, iron salt, and polymeric chelating agent as the arsenic removal agent.

6. A method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 1, 2, or 5, characterized in that: Arsine-containing waste gas is continuously fed into the oxidation absorption tower from the bottom, where it comes into countercurrent contact with the oxidation absorption liquid sprayed from the top of the tower to remove the arsine. The arsine-containing exhaust gas is discharged from the top of the oxidation absorption tower, and the removed arsine is converted into arsenate, which enters the oxidation absorption liquid. The arsenate-containing oxidation absorption liquid is discharged from the bottom of the oxidation absorption tower and enters the regeneration tower. In the regeneration tower, ozone is continuously bubbled in to achieve oxidation regeneration of the arsenate-containing oxidation absorption liquid, resulting in regenerated oxidation absorption liquid, which is then recycled back into the oxidation absorption tower.

7. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 6, characterized in that: The oxidation absorption tower is composed of a single-stage oxidation absorption tower or multiple single-stage oxidation absorption towers connected in series.

8. The method for oxidation absorption and reagent recycling of arsine-containing waste gas according to claim 6, characterized in that: The oxidation absorption tower is a packed tower.

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