A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid

Abstract

This invention belongs to the technical field of sulfidation arsenic removal treatment of waste acid wastewater, and discloses a method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid. Specifically, a high-arsenic liquid is pumped to a purging tower 1 to spray the tail gas. The sprayed high-arsenic liquid is then mixed with the waste acid solution in a certain proportion and pumped to a gas-liquid enhancer 1. Hydrogen sulfide gas is then introduced to react with the arsenic slag, and the gas and liquid mixture is then sent to a gas-liquid enhancer 2 to continue the reaction, extending the reaction time. Finally, the solid and liquid are separated by a thickener and a filter press to obtain a waste acid solution with an arsenic content of less than 50 mg / L. This invention can achieve continuous sulfidation treatment of waste acid with an arsenic content exceeding 20,000 mg / L to obtain a waste acid solution with an arsenic content of less than 50 mg / L.

Description

Technical Field

[0001] This invention relates to the field of sulfidation arsenic removal treatment of waste acid wastewater, and more specifically to a continuous sulfidation treatment method for high-concentration arsenic-containing waste acid in a sulfidation arsenic removal process. Background Technology

[0002] During the purification of smelting flue gas, waste acid containing high concentrations of arsenic and other heavy metals is generated. Currently, the most mature process in China is the "sulfidation arsenic removal" process. This process involves producing hydrogen sulfide, which reacts with arsenic and other heavy metal ions in the waste acid to form sulfide slag precipitate. This precipitate is then separated by pressure filtration, achieving solid-liquid separation and removing heavy metals from the waste acid. This process is simple and has a significant arsenic removal effect. When the arsenic content in the waste acid is below 12000 mg / L, good continuous sulfidation can be achieved, and the arsenic content in the sulfidated liquid can be maintained below 50 mg / L. However, when the arsenic content in the waste acid exceeds 12000 mg / L, continuous sulfidation cannot be achieved. To ensure that the arsenic content in the sulfidated liquid meets the standard, intermittent sulfidation treatment must be used. While this method can guarantee that the arsenic content in the sulfidated liquid meets the standard, the daily processing capacity of the waste acid cannot meet the daily production capacity of the upstream processes, thus forcing the upstream production to stop and affecting smelting production.

[0003] Therefore, developing a continuous sulfidation treatment method for high-concentration arsenic-containing waste acid is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid. The reaction mechanism of the present invention is that hydrogen sulfide reacts with arsenic and other heavy metals in the waste acid in the following sulfidation reaction:

[0005] 2AsO 3- +3H₂S=As₂S₃+6OH⁻ -

[0006] M n+ +H2S=MS n / 2 +2H +

[0007] Among them, M n+ It can be Cu 2+ Pb 2+ Cd 2+ Zn 2+ Metal ions, etc.

[0008] This invention adds waste acid solution to the reaction system, allowing it to carry away the sulfide slag precipitate generated during the reaction more quickly, increasing the gas-liquid contact area and improving reaction efficiency. At the same time, it makes full use of the residual hydrogen sulfide gas in the tail gas to pretreat the high-arsenic waste acid twice, treating waste with waste, which not only reduces the arsenic content of the waste acid, but also reduces the hydrogen sulfide content in the tail gas, thus reducing the consumption of alkaline solution for subsequent hydrogen sulfide recovery.

[0009] To achieve the above objectives, the present invention provides a method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid, comprising the following steps:

[0010] Step 1: Pump the high-concentration arsenic-containing waste acid into the high-arsenic liquid tank of the purifying tower 1. Introduce the hydrogen sulfide-containing tail gas into the bottom of the high-arsenic liquid tank for primary purification of the hydrogen sulfide-containing tail gas, and simultaneously perform primary pretreatment of the high-concentration arsenic-containing waste acid. At the same time, the high-concentration arsenic-containing waste acid sprays the hydrogen sulfide-containing tail gas entering from the bottom of the tower from top to bottom for secondary purification of the hydrogen sulfide-containing tail gas, and simultaneously perform secondary pretreatment of the high-concentration arsenic-containing waste acid. The sprayed high-concentration arsenic-containing waste acid is concentrated at the bottom of the purifying tower 1, with part flowing back to the high-arsenic liquid tank and the remainder flowing into the waste acid spray tank.

[0011] The beneficial effects of adopting the above technical solution are as follows: using hydrogen sulfide gas in the exhaust gas to pretreat the high arsenic liquid not only reduces the arsenic content in the waste acid, but also achieves the effect of purifying hydrogen sulfide in the exhaust gas, thereby reducing the consumption of alkaline solution in the subsequent treatment of the exhaust gas.

[0012] Step 2: Mix the high-concentration arsenic-containing waste acid after spraying with the waste acid clear liquid evenly to obtain mixed waste acid, and pump it to the gas-liquid enhancer 1.

[0013] The beneficial effects of adopting the above technical solution are as follows: adding waste acid clear liquid can increase the waste acid inlet flow rate, carry away the sulfide slag precipitate generated by the reaction more quickly, increase the gas-liquid contact area, and improve the reaction efficiency.

[0014] Step 3: Hydrogen sulfide gas is introduced into the top of the gas-liquid enhancer 1, and the circulating liquid from the alkaline spray tank is introduced into the middle of the gas-liquid enhancer 1 to carry out a primary gas-liquid enhanced sulfidation arsenic removal reaction with the mixed waste acid at the bottom of the gas-liquid enhancer 1. The reaction takes 40 minutes to generate sulfide slag.

[0015] The beneficial effects of adopting the above technical solution are: the arsenic removal rate after the first-stage gas-liquid enhanced sulfidation arsenic removal reaction can reach more than 80%.

[0016] Step 4: The gas, liquid and sulfide residue after the reaction in gas-liquid enhancer 1 are introduced into gas-liquid enhancer 2, and hydrogen sulfide is added to gas-liquid enhancer 2 to carry out a two-stage gas-liquid enhanced sulfide removal reaction. The reaction is carried out for 40 minutes to generate sulfide residue and obtain arsenic removal waste liquid.

[0017] The beneficial effects of adopting the above technical solution are: the total arsenic removal rate after the two-stage gas-liquid enhanced sulfidation arsenic removal reaction can reach more than 99%.

[0018] Step 5: Separate the solid and liquid components of the arsenic removal waste liquid through a thickener sedimentation and plate and frame filter press to obtain a waste acid clear liquid with arsenic content meeting the standard. Pump the clear waste acid liquid into the waste acid tank and return it to the waste acid spray tank or carry out subsequent neutralization treatment.

[0019] Step 6: When the internal pressure of the gas-liquid enhancer 2 is >75KPa, open the exhaust valve and introduce the hydrogen sulfide-containing tail gas after the reaction into the bottom of the high arsenic liquid tank through the pipeline. It will react with the high arsenic liquid in the high arsenic liquid tank from bottom to top, so as to achieve the first purification of the tail gas and the first pretreatment of the high arsenic liquid. When the pressure is <60KPa, close the exhaust valve.

[0020] Step 7: The purified exhaust gas is introduced into the scavenging tower 2. The pipes between scavenging towers 1 and 2, as well as inside scavenging tower 2, are sprayed with sodium hydroxide solution to absorb residual hydrogen sulfide. The exhaust gas is treated until the hydrogen sulfide content is <10 mg / m³. 3 The liquid is discharged externally and returned to the alkaline spray tank for recycling. After recycling, the liquid is pumped into the gas-liquid enhancer 1 at a certain flow rate.

[0021] The beneficial effects of adopting the above technical solution are as follows: the recycled liquid reacts with sulfuric acid in the mixed waste acid to generate hydrogen sulfide gas, which then reacts with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitate, which is then recycled.

[0022] Preferably, in step 1, the arsenic content of the high-concentration arsenic-containing waste acid is >20 g / L, at a concentration of 30 m³ / L. 3 Pumped into the pest control tower 1 at a rate of / h.

[0023] Preferably, in step 1, the spraying is reverse spraying, and the spraying resistance is 1-2 kPa.

[0024] Preferably, in step 2, the arsenic content of the waste acid solution is <50 mg / L.

[0025] Preferably, in step 2, the arsenic content of the mixed waste acid is <8000 mg / L.

[0026] Preferably, in step 3, the introduction rate of the hydrogen sulfide gas is 90 Nm. 3 / h, the purity of the hydrogen sulfide gas is ≥95%, and the reaction pressure of the gas-liquid enhancer 1 is 60KPa-75KPa.

[0027] Preferably, in step 3, the flow rate of the circulated liquid introduced is 0.3 m / s. 3 / h.

[0028] The beneficial effects of adopting the above technical solution are as follows: To avoid excessively vigorous reaction after a large amount of circulating liquid is added to the gas-liquid enhancer 1, resulting in the generation of a large amount of hydrogen sulfide gas and causing excessive hydrogen sulfide emissions in the tail gas, the circulating liquid is controlled by a regulating valve to maintain a flow rate of 0.3m. 3 A flow rate of / h is added to the gas-liquid enhancer 1.

[0029] Preferably, in step 3, the main components of the recycled liquid are sodium hydroxide and sodium sulfide.

[0030] Preferably, the concentration of sodium hydroxide is <15%, and the concentration of sodium sulfide is >3%.

[0031] Preferably, in step 4, the introduction rate of the hydrogen sulfide gas is 40 Nm. 3 / h, the purity of the hydrogen sulfide gas is ≥95%, and the reaction pressure of the gas-liquid enhancer 2 is 60KPa-75KPa.

[0032] Preferably, in step 7, the concentration of the sodium hydroxide solution is 20%.

[0033] As can be seen from the above technical solution, compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0034] 1. Treatment effect: By adding waste acid clear liquid to co-treat high arsenic waste acid, continuous sulfidation treatment of high arsenic waste acid with arsenic content exceeding 20,000 mg / L was achieved when the arsenic content of the clear liquid was below 50 mg / L. This reached the highest level of high arsenic waste acid treatment technology in copper smelting. The average daily arsenic treatment capacity of high arsenic liquid can reach more than 5 tons, while the average daily arsenic treatment capacity of existing sodium sulfide arsenic removal technology for high arsenic liquid in China is only 2 tons, which is 3 tons higher than that of the previous technology.

[0035] 2. Safety: Sodium sulfide is added to the gas-liquid enhancer 1 at a low and stable speed, ensuring a stable hydrogen sulfide generation process and achieving standard emissions of hydrogen sulfide in the exhaust gas.

[0036] 3. Technical analysis shows that the high-arsenic liquid was pretreated twice using hydrogen sulfide from the exhaust gas, which consumed most of the hydrogen sulfide in the exhaust gas, improved the utilization rate of hydrogen sulfide, reduced the consumption of sodium hydroxide in the subsequent exhaust gas treatment, and reduced the cost of exhaust gas treatment. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1This is a flow chart of a continuous sulfidation process for treating high-arsenic-content waste acid. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0042] Step 1: Dissolve the high-arsenic solution (20385 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the purging tower 1 at a rate of / h to spray the exhaust gas. The high arsenic liquid after spraying flows into the waste acid spray tank at the bottom and flows back to the original liquid tank at the top.

[0043] Step 2: Introduce the waste acid solution from the waste acid solution tank into the waste acid spray tank, mix it with the high arsenic solution from Step 1, adjust the arsenic content to 7689 mg / L, and pump it into the gas-liquid enhancer 1.

[0044] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the gas-liquid intensifier 1 at a rate of / h to carry out a first-stage gas-liquid intensified sulfidation arsenic removal reaction with the high-arsenic solution. The reaction pressure is 60-75KPa and the reaction time is 40min. Fluidized slag is generated and the arsenic removal rate is 80.98%.

[0045] Step 4: The gas and liquid from gas-liquid enhancer 1 are transferred to gas-liquid enhancer 2 for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and 40 Nm³ of gas is introduced into gas-liquid enhancer 2. 3 Hydrogen sulfide is added at a rate of / h, the reaction pressure is 60-75 kPa, the reaction time is 40 min, and fluidized slag is generated.

[0046] Step 5: The high-arsenic solution after arsenic removal is subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 22 mg / L, and the arsenic removal rate is 99.89%.

[0047] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the gas-liquid enhancer 2 is introduced into the bottom of the high arsenic liquid tank through the pipeline, and reacts with the high arsenic liquid in the high arsenic liquid tank from bottom to top to achieve the first purification of the exhaust gas and the first pretreatment of the high arsenic liquid. When the pressure is <60 kPa, the exhaust valve is closed.

[0048] Step 7: The exhaust gas is introduced into the purifying tower 1. The gas enters from the bottom of the tower and reacts with the high-arsenic liquid sprayed from top to bottom in Step 1. The spray nozzle is used instead of the packing layer. The spray resistance is 1-2 kPa, which completes the secondary purification of the exhaust gas and the secondary pretreatment of the high-arsenic liquid.

[0049] Step 8: After the exhaust gas is introduced into the scavenging tower 2, it is discharged externally. The intermediate connecting pipes and scavenging tower 2 are sprayed and circulated with a 20% sodium hydroxide solution to absorb residual hydrogen sulfide. After circulation, the liquid is discharged at a rate of 0.3m. 3 The gas is fed into the gas-liquid enhancer 1 at a flow rate of / h, reacts with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then reacts with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitate, which is then recycled.

[0050] Example 2

[0051] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0052] Step 1: Dissolve the high-arsenic solution (22135 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the purging tower 1 at a rate of / h to spray the exhaust gas. The high arsenic liquid after spraying flows into the waste acid spray tank at the bottom and flows back to the original liquid tank at the top.

[0053] Step 2: Introduce the waste acid solution from the waste acid solution tank into the waste acid spray tank, mix it with the high arsenic solution from Step 1, adjust the arsenic content to 7980 mg / L, and pump it into the gas-liquid enhancer 1.

[0054] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the gas-liquid intensifier 1 at a rate of / h to carry out a first-stage gas-liquid intensified sulfidation arsenic removal reaction with the high-arsenic solution. The reaction pressure is 60-75KPa and the reaction time is 40min. Fluidized slag is generated and the arsenic removal rate is 80.97%.

[0055] Step 4: The gas and liquid from gas-liquid enhancer 1 are transferred to gas-liquid enhancer 2 for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and 40 Nm³ of gas is introduced into gas-liquid enhancer 2. 3 Hydrogen sulfide is added at a rate of / h, the reaction pressure is 60-75 kPa, the reaction time is 40 min, and fluidized slag is generated.

[0056] Step 5: The high-arsenic solution after arsenic removal is subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 28 mg / L, and the arsenic removal rate is 99.87%.

[0057] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the gas-liquid enhancer 2 is introduced into the bottom of the high arsenic liquid tank through the pipeline, and reacts with the high arsenic liquid in the high arsenic liquid tank from bottom to top to achieve the first purification of the exhaust gas and the first pretreatment of the high arsenic liquid. When the pressure is <60 kPa, the exhaust valve is closed.

[0058] Step 7: The exhaust gas is introduced into the purifying tower 1. The gas enters from the bottom of the tower and reacts with the high-arsenic liquid sprayed from top to bottom in Step 1. The spraying method is reverse spraying, and the spraying resistance is controlled at 1-2 kPa to complete the secondary purification of the exhaust gas and the secondary pretreatment of the high-arsenic liquid.

[0059] Step 8: After the exhaust gas is introduced into the scavenging tower 2, it is discharged externally. The intermediate connecting pipes and scavenging tower 2 are sprayed and circulated with a 20% sodium hydroxide solution to absorb residual hydrogen sulfide. After circulation, the liquid is discharged at a rate of 0.3m. 3 The gas is fed into the gas-liquid enhancer 1 at a flow rate of / h, reacts with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then reacts with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitate, which is then recycled.

[0060] Example 3

[0061] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0062] Step 1: Dissolve the high-arsenic solution (25048 mg / L) at a flow rate of 30 m³. 3 The exhaust gas is pumped to the purging tower 1 at a rate of / h to spray the exhaust gas. The high arsenic liquid after spraying flows into the waste acid spray tank at the bottom and flows back to the original liquid tank at the top.

[0063] Step 2: Introduce the waste acid solution from the waste acid solution tank into the waste acid spray tank, mix it with the high arsenic solution from Step 1, adjust the arsenic content to 7835 mg / L, and pump it into the gas-liquid enhancer 1.

[0064] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the gas-liquid intensifier 1 at a rate of / h to carry out a first-stage gas-liquid intensified sulfidation arsenic removal reaction with the high-arsenic solution. The reaction pressure is 60-75 kPa and the reaction time is 40 min. Fluidized slag is generated and the arsenic removal rate is 80.96%.

[0065] Step 4: The gas and liquid from gas-liquid enhancer 1 are transferred to gas-liquid enhancer 2 for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and 40 Nm³ of gas is introduced into gas-liquid enhancer 2. 3 Hydrogen sulfide is added at a rate of / h, the reaction pressure is 60-75 kPa, the reaction time is 40 min, and fluidized slag is generated.

[0066] Step 5: The high-arsenic solution after arsenic removal is subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 33 mg / L, and the arsenic removal rate is 99.86%.

[0067] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the gas-liquid enhancer 2 is introduced into the bottom of the high arsenic liquid tank through the pipeline, and reacts with the high arsenic liquid in the high arsenic liquid tank from bottom to top to achieve the first purification of the exhaust gas and the first pretreatment of the high arsenic liquid. When the pressure is <60 kPa, the exhaust valve is closed.

[0068] Step 7: The exhaust gas is introduced into the purifying tower 1. The gas enters from the bottom of the tower and reacts with the high-arsenic liquid sprayed from top to bottom in Step 1. The spraying method is reverse spraying, and the spraying resistance is controlled at 1-2 kPa to complete the secondary purification of the exhaust gas and the secondary pretreatment of the high-arsenic liquid.

[0069] Step 8: After the exhaust gas is introduced into the scavenging tower 2, it is discharged externally. The intermediate connecting pipes and scavenging tower 2 are sprayed and circulated with a 20% sodium hydroxide solution to absorb residual hydrogen sulfide. After circulation, the liquid is discharged at a rate of 0.3m. 3 The gas is fed into the gas-liquid enhancer 1 at a flow rate of / h, reacts with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then reacts with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitate, which is then recycled.

[0070] Example 4

[0071] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0072] Step 1: Dissolve the high-arsenic solution (30025 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the purging tower 1 at a rate of / h to spray the exhaust gas. The high arsenic liquid after spraying flows into the waste acid spray tank at the bottom and flows back to the original liquid tank at the top.

[0073] Step 2: Introduce the waste acid solution from the waste acid solution tank into the waste acid spray tank, mix it with the high arsenic solution from Step 1, adjust the arsenic content to 7906 mg / L, and pump it into the gas-liquid enhancer 1.

[0074] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the gas-liquid intensifier 1 at a rate of / h to carry out a first-stage gas-liquid intensified sulfidation arsenic removal reaction with the high-arsenic solution. The reaction pressure is 60-75KPa and the reaction time is 40min. Fluidized slag is generated and the arsenic removal rate is 80.98%.

[0075] Step 4: The gas, liquid, and fluidized bed from gas-liquid enhancer 1 are transferred to gas-liquid enhancer 2, and then injected into gas-liquid enhancer 2 at a rate of 40 Nm³. 3 Hydrogen sulfide is added at a rate of / h, and the reaction pressure is 60-75 kPa to carry out a two-stage gas-liquid enhanced sulfide arsenic removal reaction. The reaction takes 40 min to generate fluidized slag.

[0076] Step 5: The high-arsenic solution after arsenic removal is subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 42 mg / L, and the arsenic removal rate is 99.86%.

[0077] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the gas-liquid enhancer 2 is introduced into the bottom of the high arsenic liquid tank through the pipeline, and reacts with the high arsenic liquid in the high arsenic liquid tank from bottom to top to achieve the first purification of the exhaust gas and the first pretreatment of the high arsenic liquid. When the pressure is <60 kPa, the exhaust valve is closed.

[0078] Step 7: The exhaust gas is introduced into the purifying tower 1. The gas enters from the bottom of the tower and reacts with the high-arsenic liquid sprayed from top to bottom in Step 1. The spraying method is reverse spraying, and the spraying resistance is controlled at 1-2 kPa to complete the secondary purification of the exhaust gas and the secondary pretreatment of the high-arsenic liquid.

[0079] Step 8: After the exhaust gas is introduced into the scavenging tower 2, it is discharged externally. The intermediate connecting pipes and scavenging tower 2 are sprayed and circulated with a 20% sodium hydroxide solution to absorb residual hydrogen sulfide. After circulation, the liquid is discharged at a rate of 0.3m. 3 The gas is fed into the gas-liquid enhancer 1 at a flow rate of / h, reacts with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then reacts with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitate, which is then recycled.

[0080] Comparative Example 1

[0081] The high-arsenic solution with an arsenic content of 20385 mg / L from Example 1 was diluted at 30 m... 3 The solution was directly pumped into gas-liquid enhancers 1 and 2 at a rate of / h, with other conditions remaining unchanged. The high-arsenic solution after arsenic removal was subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 14042 mg / L. The arsenic removal rate was 31.11%.

[0082] Comparative Example 2

[0083] The high-arsenic solution with an arsenic content of 30025 mg / L from Example 4 was diluted at 30 m 3 The solution was directly pumped into gas-liquid enhancers 1 and 2 at a rate of / h, with other conditions remaining unchanged. The high-arsenic solution after arsenic removal was subjected to solid-liquid separation treatment to obtain a waste acid solution with an arsenic content of 24542 mg / L. The arsenic removal rate was 18.26%.

[0084] Comparative Example 3

[0085] The high-arsenic solution with an arsenic content of 20385 mg / L from Example 1 was diluted at 30 m... 3 The solution is directly pumped into gas-liquid enhancers 1 and 2 at a rate of / h. Pumping is stopped when the liquid level reaches the high point, and then pumped at 65Nm. 3Hydrogen sulfide is introduced into gas-liquid enhancers 1 and 2 at a rate of / h. After the arsenic concentration in the liquid drops to 22mg / L after the reaction, solid-liquid separation is performed. Other conditions remain unchanged. The arsenic removal rate is 99.89%, but the required reaction time is 6h. The average daily arsenic treatment capacity of the high-arsenic liquid in Example 1 is 5.76t / d. In this comparative example, the average daily arsenic treatment capacity of the high-arsenic liquid is 3.20t / d, which is 2.56t / d lower than that in Example 1.

[0086] Comparative Example 4

[0087] The high-arsenic solution with an arsenic content of 30025 mg / L from Example 4 was diluted at 30 m 3 The solution is directly pumped into gas-liquid enhancers 1 and 2 at a rate of / h. Pumping is stopped when the liquid level reaches the high point, and then pumped at 65Nm. 3 Hydrogen sulfide was introduced into gas-liquid enhancers 1 and 2 at a rate of / h. After the arsenic concentration in the liquid dropped to 42mg / L after the reaction, solid-liquid separation was performed. Other conditions remained unchanged. The arsenic removal rate was 99.86%, but the required reaction time was 12h. The average daily arsenic treatment capacity of the high-arsenic liquid in Example 4 was 5.68t / d. In this comparative example, the average daily arsenic treatment capacity of the high-arsenic liquid was 2.40t / d, which was 3.28t / d lower than that in Example 1.

[0088] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid, characterized in that, Includes the following steps: Step 1: Pump the high-concentration arsenic-containing waste acid into the high-arsenic liquid tank of the purifying tower 1. Introduce the hydrogen sulfide-containing tail gas into the bottom of the high-arsenic liquid tank for primary purification of the hydrogen sulfide tail gas and primary pretreatment of the high-concentration arsenic-containing waste acid. Simultaneously, spray the high-concentration arsenic-containing waste acid onto the hydrogen sulfide tail gas for secondary purification and secondary pretreatment of the high-concentration arsenic-containing waste acid. The sprayed high-concentration arsenic-containing waste acid is concentrated at the bottom of the purifying tower 1, with part flowing back to the high-arsenic liquid tank and the remainder flowing into the waste acid spray tank. Step 2: Mix the high-concentration arsenic-containing waste acid after spraying with the waste acid clear liquid evenly to obtain mixed waste acid, and pump it to gas-liquid enhancer 1; Step 3: Hydrogen sulfide gas is introduced into the top of the gas-liquid enhancer 1, and the circulating liquid from the alkaline spray tank is introduced into the middle of the gas-liquid enhancer 1 to carry out a primary gas-liquid enhanced sulfidation arsenic removal reaction with the mixed waste acid at the bottom of the gas-liquid enhancer 1 for 40 minutes. Step 4: The gas, liquid and sulfide residue after the reaction in gas-liquid enhancer 1 are led to gas-liquid enhancer 2, and hydrogen sulfide is continued to be introduced into gas-liquid enhancer 2 to carry out a secondary gas-liquid enhanced sulfide arsenic removal reaction. The reaction is carried out for 40 minutes to obtain arsenic removal waste liquid. Step 5: Separate the solid and liquid components of the arsenic removal waste liquid through a thickener sedimentation and plate and frame filter press to obtain a waste acid clear liquid with arsenic content meeting the standard. Pump the clear liquid into the waste acid tank and return it to the waste acid spray tank or carry out subsequent neutralization treatment. Step 6: When the pressure inside the gas-liquid enhancer 2 is >75KPa, open the exhaust valve to introduce the hydrogen sulfide-containing tail gas into the purifying tower 1 for purification. When the pressure is <60KPa, close the exhaust valve. Step 7: The purified exhaust gas is introduced into the purifying tower 2 through a pipeline. The pipeline between purifying towers 1 and 2, as well as inside purifying tower 2, is sprayed with sodium hydroxide solution to absorb residual hydrogen sulfide. The sprayed solution is returned to the alkaline spray tank for recycling. The exhaust gas is treated until the hydrogen sulfide content is <10mg / m³. 3 After being discharged externally, the circulating liquid is pumped into the gas-liquid enhancer 1.

2. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 1, the arsenic content of the high-concentration arsenic-containing waste acid is >20g / L, and it is prepared at 30m 3 Pumped into the pest control tower 1 at a rate of / h.

3. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 1, the spraying is reverse spraying, and the spraying resistance is 1-2 kPa.

4. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 2, the arsenic content of the waste acid solution is <50mg / L.

5. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 2, the arsenic content of the mixed waste acid is <8000 mg / L.

6. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 3, the hydrogen sulfide gas is introduced at a rate of 90 Nm. 3 The hydrogen sulfide gas has a purity of ≥95% per hour, and the inlet flow rate of the recycled liquid is 0.3 m / h. 3 / h, the reaction pressure of the gas-liquid enhancer 1 is 60KPa-75KPa.

7. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 6, characterized in that, In step 3, the main components of the recycled liquid are sodium hydroxide and sodium sulfide.

8. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 7, characterized in that, The concentration of sodium hydroxide is <15%, and the concentration of sodium sulfide is >3%.

9. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 4, the hydrogen sulfide gas is introduced at a rate of 40 Nm. 3 / h, the purity of the hydrogen sulfide gas is ≥95%, and the reaction pressure of the gas-liquid enhancer 2 is 60KPa-75KPa.

10. The method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1, characterized in that, In step 7, the concentration of the sodium hydroxide solution is 20%.

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