CN104803416B - A method for collecting arsenic from flue gas containing arsenic - Google Patents

Abstract

The invention discloses an arsenic collecting method of arsenic-containing flue gas, which comprises the following steps: after being sequentially treated by an air cooling tower cooling procedure, a dynamic wave washing procedure, a two-stage packed tower purifying procedure and a two-stage electric defogging procedure, the arsenic-containing flue gas is sent into an acid making system to be made into acid conventionally; returning the arsenic-containing solution discharged from each process to the previous process as a circulating liquid of the previous process, and feeding the high-arsenic solution discharged from the cooling process of the air cooling tower into a desorption tower for desorption treatment; feeding the high-arsenic solution after desorption treatment into a thickener for concentration separation, performing solid-liquid separation, returning the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by concentration separation to the circulating liquid of the dynamic wave washing process, wherein the solid obtained by solid-liquid separation is As₂O₃Thereby realizing arsenic collection. The embodiment of the invention not only has low acid concentration, can effectively avoid high acid from corroding equipment and blocking pipelines, but also can collectThe method has the advantages of high arsenic efficiency, simple operation process, safety and environmental protection, and can greatly improve the recovery rate of arsenic in the flue gas.

Description

A method for collecting arsenic from flue gas containing arsenic

technical field

The invention relates to the technical field of environmental protection and clean production, in particular to a method for collecting arsenic from flue gas containing arsenic.

Background technique

At present, the methods for recovering arsenic in smelting flue gas mainly include dry bag arsenic collection process and wet arsenic collection process. The dry cloth bag arsenic collection process widely used in China is mature and reliable, but during the production process, workers come into contact with arsenic more, which will not only cause damage to the health of the workers, but also cause considerable damage to the environment due to the generated dust. harm. The wet arsenic collection process avoids the above-mentioned shortcomings of the dry bag arsenic collection process, and is a safe and environmentally friendly clean production process.

In recent years, the domestic wet arsenic collection process mainly has the following two types: the first one is the wet arsenic collection process described in the Chinese patent with the publication number CN101734718A, which uses 50-60%wt sulfuric acid to wash and cool the smelting smoke gas, and then collect As ₂ O ₃ by wet method, but this process uses high-acid washing, which requires high equipment materials, many equipment needs to be imported, and the equipment cost is high. Moreover, the solubility of As ₂ O ₃ in high acid is low, and a large amount of As ₂ O ₃ crystallization will come out and block the pipes and nozzles, causing the production to fail normally; the second is the three-stage washing wet arsenic collection process described in the Chinese patent with the publication number CN202099361U. The acid concentration it adopts is relatively low, but the The process is too simple and the collection of arsenic is not complete, causing most of the arsenic to crystallize on the tube wall and electrodes, requiring frequent stops to clean up the electrostatic demisting, and some arsenic will enter the conversion system of acid production and damage the catalyst.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, combined with the slow growth rate of As ₂ O ₃ crystals, the present invention provides a method for collecting arsenic from arsenic-containing flue gas, which not only has low acid concentration, but also can effectively avoid high acid concentration. Corrosion of equipment and blockage of pipelines, high arsenic collection efficiency, simple operation process, safety and environmental protection, can greatly improve the recovery rate of arsenic in flue gas.

The purpose of the present invention is achieved through the following technical solutions:

A method for collecting arsenic from flue gas containing arsenic, comprising the following steps:

Air-cooling tower cooling process: Pass the arsenic-containing flue gas into the air-cooling tower for cooling treatment. The acid concentration in the air-cooling tower is 2-10% (by mass percentage), and the high-arsenic solution discharged from the liquid outlet of the air-cooling tower It is sent to the solution collecting arsenic process, and the cooled flue gas discharged from the air outlet of the air cooling tower is sent to the power wave washing process;

Power wave washing process: The cooled flue gas discharged from the air cooling tower is sent to the power wave scrubber for power wave washing treatment. The spray acid concentration in the power wave scrubber is 2-10% (by mass percentage), and The arsenic-containing solution discharged from the liquid outlet of the wave scrubber is returned to the air-cooling tower as the circulating liquid of the air-cooling tower, while the washed flue gas discharged from the outlet of the power wave scrubber is sent to the two-stage packed tower purification process;

Two-stage packed tower purification process: The washed flue gas discharged from the power wave scrubber is sequentially passed through the first-stage packed tower and the second-stage packed tower for two-stage purification treatment, and the spray acid concentration in the two packed towers is 2-10% (by mass percentage), the arsenic-containing solution discharged from the liquid outlets of the two packed towers is returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, and the purified smoke discharged from the gas outlet of the secondary packed tower The gas is sent to the two-stage electrostatic demisting process;

Two-stage electrostatic demisting process: the purified flue gas discharged from the secondary packed tower is sequentially passed through two electric demisters for two-stage electric demisting treatment, and the acid solution discharged from the outlets of the two electric demisters Return to the two packed towers as the circulating liquid of the two packed towers, and the flue gas after the two-stage electrostatic demisting treatment is sent to the acid system for conventional acid production;

Solution collecting arsenic process: Send the high-arsenic solution discharged from the liquid outlet of the air-cooling tower into the desorption tower for desorption treatment, and send the high-arsenic solution after desorption treatment to the thickener for dense separation, and then separate the separated The underflow arsenic pulp of the thickener is used for solid-liquid separation. The arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, while the solid liquid obtained from solid-liquid separation For As ₂ O ₃ , that is to achieve the collection of arsenic.

Preferably, in the process of collecting arsenic from the solution, the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation are divided into two processing branches: one part is returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, The other part is sent to the wastewater treatment process;

Wastewater treatment process: the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are subjected to sulfidation and arsenic precipitation treatment to obtain arsenic-containing slag and arsenic-precipitated solution; arsenic-containing slag is reused as arsenic smelting raw material, and The post-arsenic solution is neutralized to obtain gypsum slag and reused water.

Preferably, in the process of collecting arsenic from the solution, the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are brought together to form a mixed liquid containing arsenic; When the acid concentration is greater than 8%, the arsenic-containing mixed solution will be sent to the wastewater treatment process, otherwise the arsenic-containing mixed solution will only be returned to the power wave scrubber as the circulating fluid of the power wave scrubber.

Preferably, in the wastewater treatment process, sodium sulfide solution and sulfuric acid need to be added to the arsenic-containing mixed solution for sulfidation and arsenic precipitation until the overall pH value of the mixed solution is 1 to 3; neutralization treatment needs to add Milk of lime and iron salt until the pH of the solution after arsenic precipitation is 7-9, and the molar ratio of Fe to As is 7:1-30:1.

Preferably, in the air-cooling tower cooling process, the temperature of the arsenic-containing flue gas entering the air-cooling tower is 250-400°C, and the content of As ₂ O ₃ in the arsenic-containing flue gas is 0.1- 1.0%, while the content of SO ₂ is 5-10%.

Preferably, in the cooling process of the air-cooling tower, the flue gas temperature at the outlet of the air-cooling tower is 70°C-110°C, the gas flow rate in the air-cooling tower is 0.5-2m/s, and the spray density in the air-cooling tower is 10-30m ³ /(m ² ·h).

Preferably, in the dynamic wave scrubbing process, the flue gas temperature at the gas outlet of the dynamic wave scrubber is 50°C-85°C, the gas flow rate in the dynamic wave scrubber is 10-20m/s, and the spray in the dynamic wave scrubber The spray density is 100~300m ³ /(m ² ·h).

Preferably, in the two-stage packed tower purification process, the flue gas temperatures at the gas outlets of the two packed towers are both 35°C to 45°C, and the gas flow rates in the two packed towers are both 0.5 to 1.5m/s. The spray density in the packed tower is 20-35m ³ /(m ² ·h).

Preferably, in the two-stage electrostatic demisting process, the flue gas temperatures at the gas outlets of the two electric demisters are both lower than 40° C., and the gas flow rates in the two electric demisters are both 0.3-1.0 m/s.

Preferably, in the liquid circulation formed by the air-cooling tower cooling process, the dynamic wave washing process, the two-stage packed tower purification process, the two-stage electric demisting process, and the solution collecting arsenic process, when the circulating liquid is insufficient, the air-cooling tower is cooled Add new water to the air-cooling tower in the process, and/or add new water to the two electrostatic demisters in the two-stage electrostatic demisting process.

It can be seen from the above-mentioned technical solution provided by the present invention that the arsenic-containing flue gas collection method provided by the embodiment of the present invention makes the arsenic-containing flue gas go through the air cooling tower cooling process, the power wave washing process, and the two-stage packed tower purification process in sequence. process, two-stage electrostatic defogging process, and the air cooling tower in the air cooling tower cooling process and the power wave scrubber in the power wave washing process all use a low-acid concentrated circulating fluid with a mass percentage concentration of 2-10%. Therefore, this arsenic collection method can not only greatly reduce the corrosion of the equipment by the circulating fluid, reduce the material requirements for the equipment, but also ensure that the arsenic grows step by step without causing blockage of the equipment or pipelines, effectively solving the problem of low The problem of incomplete collection of arsenic by acid concentration. The high-arsenic solution discharged from the air-cooling tower is sent to the thickener for cooling crystallization _- thickness separation after the desorption tower removes SO2 gas, and the separated thickener underflow arsenic slurry is then subjected to solid-liquid separation to obtain recovered As ₂ O ₃ solid product. The upper clarified liquid obtained from dense separation and the arsenic-containing filtrate obtained from solid-liquid separation converge together to form arsenic-containing mixed liquid; most of the arsenic-containing mixed liquid is returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber. Effectively reduce waste water treatment and discharge; and the excess part is sent to the waste water treatment process for arsenic sulfide precipitation and neutralization treatment, resulting in arsenic-containing slag, gypsum slag and backwater, which can be returned to the raw material workshop of the smelter for batching used, and the return water meets the requirements of production reuse water, and can be returned to other production processes in the smelter such as pulping, so this can realize the effective recycling of waste liquid, no need for external discharge, safety and environmental protection, and effectively reduce the impact on the environment. pollute. It can be seen that the embodiment of the present invention not only has low acid concentration, can effectively avoid high acid corrosion of equipment and blockage of pipelines, but also has high arsenic collection efficiency, simple operation process, safety and environmental protection, and can greatly improve the recovery rate of arsenic in flue gas.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those skilled in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is a schematic flowchart of a method for collecting arsenic from arsenic-containing flue gas provided by an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The method for collecting arsenic from arsenic-containing flue gas provided by the embodiments of the present invention will be described in detail below.

As shown in Figure 1, a method for collecting arsenic from arsenic-containing flue gas may include the following steps:

(1) Air-cooling tower cooling process: Pass the arsenic-containing flue gas into the air-cooling tower (i.e. air cooling tower) for cooling treatment. In terms of mass percentage, the spray acid concentration in the air-cooling tower is 2 to 10% (in practical application It is best to meet: 2% ≤ spray acid concentration in the air cooling tower <5%), the high arsenic solution discharged from the liquid outlet of the air cooling tower is sent to the solution arsenic collection process, and the cooled smoke discharged from the air outlet of the air cooling tower The gas is sent to the power wave washing process.

Wherein, the temperature of the arsenic-containing flue gas entering the air-cooling tower is preferably 250-400° C., and in terms of volume percentage, the content _of As2O3 in the arsenic _- containing flue gas is preferably 0.1-1.0%, while _The content of SO2 is preferably 5-10%. The temperature of the flue gas at the air outlet of the air cooling tower is preferably 70 ℃ ~ 110 ℃, the gas flow rate in the air cooling tower is preferably 0.5 ~ 2m/s, and the spray density in the air cooling tower is preferably 10 ~ 30m ³ /(m ² h). In the cooling process of the air-cooling tower, when the temperature of the arsenic-containing flue gas drops below 120°C, the As ₂ O ₃ in the arsenic-containing flue gas is transformed from a gaseous state into a solid form of As ₂ O ₃ grains, which are circulated in the air-cooling tower The sprayed dilute acid traps into the solution to form a high-arsenic solution, so that most of the arsenic in the arsenic-containing flue gas can be captured into the high-arsenic solution, and the high-arsenic solution only needs to be subjected to the solution arsenic collection process. Recycling of arsenic can be achieved.

(2) Power wave washing process: send the cooled flue gas discharged from the air-cooling tower into the power wave scrubber for power wave washing treatment. In terms of mass percentage, the spray acid concentration in the power wave scrubber is 2 to 10%. (In practical application, it is best to meet: 2%≤the spray acid concentration in the power wave scrubber<5%), the arsenic-containing solution discharged from the liquid outlet of the power wave scrubber returns to the air cooling tower as the circulating fluid of the air cooling tower , and the washed flue gas discharged from the outlet of the dynamic wave scrubber is sent to the two-stage packed tower purification process.

Among them, the flue gas temperature at the gas outlet of the dynamic wave scrubber is preferably 50°C-85°C, the gas flow rate in the dynamic wave scrubber is preferably 10-20m/s, and the spray density in the dynamic wave scrubber is the best 100 to 300 m ³ /(m ² ·h). In the dynamic wave washing process, the dilute acid sprayed in the dynamic wave scrubber can efficiently capture the As ₂ O ₃ grains carried in the cooled flue gas, and enter the solution to form an arsenic-containing solution, thereby The arsenic in the flue gas can be further captured into the arsenic-containing solution and returned to the air-cooling tower as the circulating liquid of the air-cooling tower. In practical applications, the liquid outlet of the dynamic wave scrubber is preferably to regularly discharge the arsenic-containing solution and return to the air-cooling tower (for example: return to the liquid inlet or circulation tank of the air-cooling tower), as the circulating liquid of the air-cooling tower, and The specific time interval can be determined according to actual requirements.

(3) Two-stage packed tower purification process: The washed flue gas discharged from the dynamic wave scrubber passes through the first-stage packed tower and the second-stage packed tower for two-stage purification treatment. According to the mass percentage, the two packed towers are sprayed Acid concentration is 2～10% (in actual application preferably meets: 2%≤spray acid concentration＜5% in two packed towers), the arsenic solution that the liquid outlet of two packed towers discharges all returns to The dynamic wave scrubber is used as the circulating fluid of the dynamic wave scrubber, and the purified flue gas discharged from the gas outlet of the two-stage packed tower is sent to the two-stage electrostatic demisting process.

Among them, the flue gas temperature at the gas outlets of the two packed towers is preferably 35°C-45°C, the gas flow rate in the two packed towers is preferably 0.5-1.5m/s, and the spraying in the two packed towers The density is preferably 20-35m ³ /(m ² ·h). In the two-stage packed tower purification process, the dilute acid sprayed in the two packed towers can capture the As ₂ O ₃ grains carried in the flue gas after washing, and enter the solution to form an arsenic-containing solution. Thereby, the residual arsenic in the flue gas can be further captured in the arsenic-containing solution, and returned to the dynamic wave scrubber as the circulating fluid of the dynamic wave scrubber; after the two-stage packed tower purification process, the arsenic in the flue gas The content is very small, that is, only a small amount of arsenic will enter the electrostatic demister in the two-stage electrostatic defogging process, which can avoid the crystallization of arsenic in the electrostatic defogger. In practical application, it is better to discharge the arsenic-containing solution regularly from the liquid outlets of the two packed towers and return to the dynamic wave scrubber (for example: return to the liquid inlet or circulation tank of the dynamic wave scrubber) as a dynamic wave scrubber. The circulating fluid of the device, and the specific time interval can be determined according to actual needs.

(4) Two-stage electrostatic demisting process: The purified flue gas discharged from the secondary packing tower is sequentially passed through two electric demisters for two-stage electric demisting treatment, and the liquid discharged from the discharge ports of these two electric demisters The acid solutions are all returned to the two packed towers as the circulating liquid of the two packed towers, and the flue gas after the two-stage electrostatic demisting treatment is sent to the acid making system in the prior art for conventional acid making.

Wherein, the flue gas temperatures at the gas outlets of the two electric demisters are preferably both lower than 40° C., and the gas flow rates in the two electric demisters are preferably both 0.3-1.0 m/s. In the two-stage electrostatic demisting process, the two electric demisters can purify and settle the acid mist in the purified flue gas to form an acid solution, thereby removing the acid mist in the flue gas and making the two-stage electric demisting The content of acid mist in the treated flue gas is less than 5mg/m ³ , and the temperature of the flue gas drops below 40°C, making it a qualified flue gas for acid production that meets the requirements of the existing acid production system. At the same time, the acid solution can be returned to the two packed towers as the circulating fluid of the two packed towers. In practical applications, it is best to discharge the acid solution from the outlets of the two electrostatic precipitators regularly and return it to the two packed towers (For example: return to the liquid inlet or circulation tank of the two packed towers), as the circulating liquid of the two packed towers, and the specific time interval can be determined according to actual needs.

(5) Solution receiving arsenic process: send the high arsenic solution discharged from the liquid outlet of the air-cooling tower into the desorption tower for desorption treatment, and send the high arsenic solution after the desorption treatment into the thickener for dense separation, and then The separated thickener underflow arsenic ore slurry is subjected to solid-liquid separation (for example: a filter press in the prior art can be used to carry out solid-liquid separation), and the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation are returned to The dynamic wave scrubber is used as the circulating liquid of the dynamic wave scrubber, and the solid obtained by solid-liquid separation is As ₂ O ₃ , which realizes the collection of arsenic.

Among them, the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation can be divided into two processing branches: one part is returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, while the other part is sent to the waste water Processing procedure. These two treatment branches can be carried out simultaneously (for example: most of them are returned to the dynamic wave scrubber, and the excess part is sent to the wastewater treatment process), or they can be carried out separately, and the second treatment branch can be used only when certain conditions are met. For example: the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation can be gathered together (for example: gathered in the filtrate tank) to form arsenic-containing mixed liquid, when the arsenic collection system (the arsenic collection system refers to It is composed of an air cooling tower in the cooling process of the air cooling tower, a power wave scrubber in the power wave washing process, two packed towers in the purification process of the two-stage packed tower, and two electric demisters in the two-stage electric demisting process When the circulating liquid in the arsenic-containing flue gas collection system) is excessive or the acid concentration of the arsenic-containing mixture is greater than 8%, the arsenic-containing mixture will be sent to the wastewater treatment process, otherwise the arsenic-containing mixture will only be returned to the Power wave scrubber, as the circulating fluid of power wave scrubber.

(6) Wastewater treatment process: the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are subjected to sulfidation and arsenic precipitation treatment to obtain arsenic-containing slag and arsenic-precipitated solution; the arsenic-containing slag is returned to the raw material workshop of the smelter , and after arsenic precipitation, the solution is neutralized to obtain gypsum slag and reused water.

Among them, the sulfide arsenic treatment needs to add sodium sulfide solution and sulfuric acid to the arsenic-containing mixed solution until the overall pH value of the mixed solution is 1 to 3, and the amount of sodium sulfide is 1 to 1.5 times the theoretical value. The filter press in the prior art performs solid-liquid separation to obtain arsenic-containing slag and arsenic-precipitated solution; the arsenic-containing slag can be returned to the raw material workshop of the smelter. After the arsenic precipitation, the solution is then neutralized. In the neutralization treatment, lime milk and iron salt are added to the arsenic precipitation solution until the pH value of the arsenic precipitation solution is 7-9, and the molar ratio of Fe and As is controlled to be 7: 1 to 30:1; the neutralized ore slurry can be filtered to obtain gypsum slag and recycled water that meets the requirements of production recycled water, and the recycled water can be returned to other production processes in the smelter such as pulping, so the present invention The method for collecting arsenic from arsenic-containing flue gas provided in the embodiment does not need to discharge waste liquid, which is safe and environment-friendly.

(7) In addition to the above-mentioned technical scheme, the method for collecting arsenic in the arsenic-containing flue gas may also include: in the air cooling tower cooling process, the dynamic wave washing process, the two-stage packing tower purification process, the two-stage electric demisting process, and the arsenic collection in the solution In the liquid cycle formed by the process, when the circulating liquid is insufficient, add new water to the air-cooling tower in the air-cooling tower cooling process, and/or replenish water to the two electric demisters in the two-stage electric demisting process For example: in the process of collecting arsenic from the solution, when the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are sent to the waste water treatment process, the circulating liquid is insufficient. Add new water to the air-cooling tower in the cooling process, and/or add new water to the two electrostatic demisters in the two-stage electrostatic demisting process.

It should be noted that the arsenic recovery method of the arsenic-containing flue gas provided by the embodiment of the present invention can reach more than 99% of the arsenic recovery, and the arsenic content of the wastewater after the wastewater treatment process is less than 0.5mg/L, which meets the requirements of the production cycle. Water requirements.

In summary, the method for collecting arsenic from flue gas containing arsenic provided by the embodiment of the present invention has at least the following characteristics:

(1) in this receiving arsenic method, the air-cooling tower in the air-cooling tower cooling process and the power wave scrubber in the power wave washing process have all adopted the dilute acid that mass percent concentration is 2～10% as circulation fluid, and can Adopt the dilute acid that mass percent concentration is 2～5% as circulation fluid; Compared with prior art, the acid concentration that this arsenic collection method adopts is low (can reach 2%≤the acid concentration of circulation fluid＜5%), This can greatly reduce the corrosion of the equipment by the circulating fluid, reduce the material requirements for the equipment, and save the equipment cost.

(2) In this arsenic collection method, after the dynamic wave washing process, a two-stage packed tower purification process and a two-stage electrostatic demisting process are added, that is, an air cooling tower-dynamic wave scrubber-two-stage packed tower-two-stage The flue gas purification equipment with electric demister combined washing, the arsenic-containing flue gas passes through the above-mentioned equipment in sequence, which can ensure that the arsenic grows step by step and will not cause the above-mentioned equipment to be blocked, so this can effectively solve the problem of existing technology The problem of incomplete collection of arsenic by medium and low acid concentration not only ensures a high efficiency of collecting arsenic, but also ensures that the flue gas purification equipment of the combined washing can operate normally and stably for a long time according to the method of collecting arsenic.

(3) In this arsenic collection method, the high-arsenic solution discharged from the air-cooling tower is sent to the thickener for cooling crystallization _- dense separation after the SO2 gas is removed by the desorption tower, and the separated thickener underflows the arsenic slurry Carry out solid-liquid separation again; In this process, except that solid-liquid separation obtains the As ₂ O ₃ solid that reclaims, remaining liquid (can comprise the supernatant liquid that dense separation obtains and the arsenic-containing filtrate that solid-liquid separation obtains ) Most of them are returned to the power wave scrubber as the circulating fluid of the power wave scrubber, which effectively reduces waste water treatment and discharge.

(4) In this arsenic collection method, when the solution produces a lot of liquid in the arsenic collection process, except that most of the liquid is returned to the dynamic wave scrubber, the excess liquid can enter the waste water treatment process, and carry out sulfide arsenic precipitation and neutralization in sequence treatment to obtain arsenic-containing slag, gypsum slag, and reused water; the arsenic-containing slag can be returned to the arsenic smelting process as a raw material for arsenic smelting, while the recycled water meets the requirements for production reused water and can be returned to other production in the factory such as pulping In the process, it can realize the effective recycling of waste liquid, no need to discharge, safe and environmentally friendly, and effectively reduce the pollution to the environment.

(5) In terms of volume percentage, the method for collecting arsenic can treat the arsenic-containing flue gas whose content of As ₂ O ₃ is 0.1-1.0%, and the content of SO ₂ is 5-10%. The content of arsenic in the gas has strong adaptability and can be applied to the purification of various arsenic-containing smelting flue gases.

(6) The arsenic collection method is a wet arsenic collection method, which can effectively avoid the generation of arsenic-containing dust, and the operating environment is relatively friendly.

In order to more clearly demonstrate the technical solutions provided by the present invention and the resulting technical effects, the method for collecting arsenic from arsenic-containing flue gas provided by the embodiments of the present invention will be described in detail below with several specific examples and in conjunction with the accompanying drawings.

Example 1

As shown in Figure 1, a gold smelter in Xinjiang adopts a two-stage roasting pretreatment method to process a certain arsenic-containing gold concentrate, and the roasting flue gas produced by roasting is subjected to cyclone dust collection and electric dust collection. The method for collecting arsenic from flue gas containing arsenic provided in the embodiment of the present invention is to collect arsenic by wet method. Among them, the temperature of the roasting flue gas discharged from the outlet of the electrostatic precipitator is 330-350°C, and the flue gas volume is 17072Nm ³ /h; calculated by volume percentage, the content of As ₂ O ₃ in the roasting flue gas is 0.21%, SO The content of ₂ is 6.99%.

Specifically, according to the technical parameters described in Table 1 below, and using the method for collecting arsenic-containing flue gas provided by the above-mentioned embodiments of the present invention, the roasting flue gas passes through the air cooling tower-dynamic wave scrubber-two-stage packed tower in sequence -Two-stage electric demister for flue gas purification. The dust content of the roasting flue gas discharged from the outlet of the electrostatic precipitator is 0.2-0.5g/m ³ , and after successively passing through the air cooling tower-dynamic wave scrubber-two-stage packed tower, the collection rate of arsenic has reached more than 99%, which is basically All collected; after that, the flue gas enters the two-stage electric demister to remove the residual acid mist. After the two-stage electric demisting process, the acid mist content in the flue gas is <5mg/m ³ , and the flue gas temperature drops below 40°C , which meets the requirements of the existing acid-making system, and can be connected to the existing acid-making system for conventional acid-making.

Table 1:

Further, the high-arsenic solution discharged from the air-cooling tower is sent to the thickener for cooling crystallization _- thickness separation after the desorption tower removes SO2, and the separated thickener underflow arsenic slurry is sent to the filter press for solidification. liquid separation, thereby obtaining the recovered As ₂ O ₃ solid product, and the supernatant liquid obtained from the dense separation and the arsenic-containing filtrate obtained from the solid-liquid separation are brought together to form an arsenic-containing mixed solution; most of the arsenic-containing mixed solution is returned to To the power wave scrubber, as the circulating fluid of the power wave scrubber, the excess part is sent to the wastewater treatment process. In the wastewater treatment process, sodium sulfide solution and sulfuric acid are added to the arsenic-containing mixed solution to carry out sulfidation and precipitation of arsenic until the overall pH value of the mixed solution is 1.5-2, and the reacted pulp can be passed through a filter press in the prior art Carry out solid-liquid separation to obtain arsenic-containing slag and arsenic-precipitated solution; the arsenic-containing slag can be returned to the raw material workshop of the smelter, and the arsenic-precipitated solution is then neutralized. Add milk of lime and iron salt until the pH of the solution after arsenic precipitation is 7-9, and the molar ratio of Fe to As is 20:1, blow in air for aeration, and filter the neutralized slurry to obtain Gypsum slag and reuse water; the reuse water meets the requirements of production reuse water, and can be returned to other production processes in the smelter such as pulping, so this can realize effective recycling of waste liquid, no need for external discharge, safety and environmental protection, and effectively reduce pollution to the environment.

In summary, the embodiment of the present invention not only has low acid concentration, can effectively avoid high acid corrosion of equipment and blockage of pipelines, but also has high arsenic collection efficiency, simple operation process, safety and environmental protection, and can greatly improve the recovery rate of arsenic in flue gas.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. A method for collecting arsenic in flue gas containing arsenic, characterized in that it comprises the following steps: Air-cooling tower cooling process: The arsenic-containing flue gas is passed into the air-cooling tower for cooling treatment. According to the mass percentage, the concentration of spraying acid in the air-cooling tower is 2-10%, and the high-arsenic solution discharged from the liquid outlet of the air-cooling tower is sent to into the solution to collect arsenic, and the cooled flue gas discharged from the air outlet of the air cooling tower is sent to the power wave washing process; Power wave washing process: The cooled flue gas discharged from the air cooling tower is sent to the power wave scrubber for power wave washing treatment. In terms of mass percentage, the concentration of spray acid in the power wave scrubber is 2-10%. The arsenic-containing solution discharged from the liquid outlet of the scrubber returns to the air-cooling tower as the circulating liquid of the air-cooling tower, while the washed flue gas discharged from the gas outlet of the dynamic wave scrubber is sent to the two-stage packed tower purification process; Two-stage packed tower purification process: The washed flue gas discharged from the power wave scrubber passes through the first-stage packed tower and the second-stage packed tower for two-stage purification treatment. In terms of mass percentage, the spray acid concentration in the two packed towers is equal to The arsenic-containing solution discharged from the liquid outlets of the two packed towers is returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, while the purified flue gas discharged from the gas outlet of the secondary packed tower Send to the two-stage electrostatic defogging process; Two-stage electrostatic demisting process: the purified flue gas discharged from the secondary packed tower is sequentially passed through two electric demisters for two-stage electric demisting treatment, and the acid solution discharged from the outlets of the two electric demisters Return to the two packed towers as the circulating liquid of the two packed towers, and the flue gas after the two-stage electrostatic demisting treatment is sent to the acid system for conventional acid production; Solution collecting arsenic process: Send the high-arsenic solution discharged from the liquid outlet of the air-cooling tower into the desorption tower for desorption treatment, and send the high-arsenic solution after desorption treatment to the thickener for dense separation, and then separate the separated The thickener underflow arsenic slurry for solid-liquid separation, the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are returned to the dynamic wave scrubber as the circulating liquid of the dynamic wave scrubber, while the solid-liquid separation obtained solid For As ₂ O ₃ , that is to achieve the collection of arsenic. 2. The method for collecting arsenic according to claim 1, characterized in that, in the process of collecting arsenic in the solution, the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation are divided into two processing branches: one part is returned to Power wave scrubber, as the circulating fluid of the power wave scrubber, and the other part is sent to the wastewater treatment process; Wastewater treatment process: the arsenic-containing filtrate obtained from solid-liquid separation and the supernatant liquid obtained from dense separation are subjected to sulfidation and arsenic precipitation treatment to obtain arsenic-containing slag and arsenic-precipitated solution; arsenic-containing slag is reused as arsenic smelting raw material, and The post-arsenic solution is neutralized to obtain gypsum slag and reused water. 3. The method for collecting arsenic according to claim 2, characterized in that, in the step of collecting arsenic in the solution, the arsenic-containing filtrate obtained by solid-liquid separation and the supernatant liquid obtained by dense separation are brought together to form an arsenic-containing mixed solution; When the circulating liquid in the arsenic collection system is excessive or the acid concentration of the arsenic-containing mixture is greater than 8%, the arsenic-containing mixture will be sent to the wastewater treatment process, otherwise the arsenic-containing mixture will only be returned to the power wave scrubber as Circulating fluid for power wave scrubbers. 4. The method for collecting arsenic according to claim 3, characterized in that, in the wastewater treatment process, adding sodium sulfide solution and sulfuric acid to the arsenic-containing mixed solution until the overall pH value of the mixed solution is 1 ~3; Neutralization treatment needs to add milk of lime and iron salt to the solution after arsenic precipitation, until the pH of the solution after arsenic precipitation is 7-9, and the molar ratio of Fe to As is 7:1-30:1. 5. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the air-cooling tower cooling process, the temperature of the arsenic-containing flue gas entering the air-cooling tower is 250-400°C, and by volume In terms of percentage, in the arsenic-containing flue gas, the content of As ₂ O ₃ is 0.1-1.0%, and the content of SO ₂ is 5-10%. 6. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the cooling process of the air-cooling tower, the flue gas temperature at the gas outlet of the air-cooling tower is 70°C to 110°C, and the temperature in the air-cooling tower The gas flow rate is 0.5-2m/s, and the spray density in the air cooling tower is 10-30m ³ /(m ² ·h). 7. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the dynamic wave washing process, the flue gas temperature at the gas outlet of the dynamic wave scrubber is 50°C to 85°C, and the dynamic wave The gas flow rate in the scrubber is 10-20m/s, and the spray density in the dynamic wave scrubber is 100-300m ³ /(m ² ·h). 8. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the two-stage packed tower purification process, the flue gas temperatures at the gas outlets of the two packed towers are both 35°C to 45°C , the gas flow rate in the two packed towers is 0.5-1.5m/s, and the spray density in the two packed towers is 20-35m ³ /(m ² ·h). 9. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the two-stage electrostatic demisting process, the flue gas temperatures at the gas outlets of the two electrostatic demisters are both less than 40°C, The gas flow velocity in the two electric demisters is 0.3-1.0m/s. 10. The method for collecting arsenic according to any one of claims 1 to 4, characterized in that, in the air cooling tower cooling process, dynamic wave washing process, two-stage packed tower purification process, two-stage electrostatic demisting process and solution collection In the liquid cycle formed by the arsenic process, when the circulating liquid is insufficient, add new water to the air cooling tower in the air cooling tower cooling process, and/or add new water to the two electric demisters in the two-stage electric demisting process Add new water.