Method for continuous sulfidation treatment of high-concentration arsenic-containing spent acid

Abstract

The present application belongs to the technical field of sulfidation arsenic removal treatment of spent acid and wastewater. Disclosed is a method for a continuous sulfidation treatment of high-concentration arsenic-containing spent acid. The method comprises: pumping a high-arsenic liquid to a first decontamination tower and spraying tail gas; mixing in proportion the sprayed high-arsenic liquid with a spent acid supernatant and then pumping same to a first gas-liquid intensifier; then introducing hydrogen sulfide gas thereto to react with same, so as to generate sulfide slag; subsequently, feeding the gas-liquid mixture to a second gas-liquid intensifier to continue to perform a reaction, thereby prolonging the reaction time thereof; and finally, treating the solid-liquid mixture by using a thickener and a filter press to achieve solid-liquid separation, so as to obtain a spent acid supernatant having an arsenic content of 50 mg / L or less. The present application can realize a continuous sulfidation treatment of spent acid having an arsenic content of more than 20,000 mg / L, so as to obtain a spent acid supernatant having an arsenic content of 50 mg / L or less.

Description

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

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 202510069367.7, filed on January 16, 2025, entitled "A Method for Continuous Sulfation Treatment of High-Concentration Arsenic-Containing Waste Acid", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application 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

[0004] 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.

[0005] 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

[0006] One or more embodiments of this application provide a method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid, comprising the following steps:

[0007] Step 1: Pump the high-concentration arsenic-containing waste acid into the high-arsenic liquid tank of the first purifying tower. 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 pre-treat the high-concentration arsenic-containing waste acid. At the same time, spray 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 pre-treat the high-concentration arsenic-containing waste acid. The sprayed high-concentration arsenic-containing waste acid is concentrated at the bottom of the first purifying tower, with part flowing back to the high-arsenic liquid tank and the remainder flowing into the waste acid spray tank.

[0008] 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 first gas-liquid enhancer.

[0009] Step 3: Hydrogen sulfide gas is introduced into the top of the first gas-liquid enhancer, and the circulating liquid from the alkaline spray tank is introduced into the middle of the first gas-liquid enhancer to carry out a primary gas-liquid enhanced sulfidation and arsenic removal reaction with the mixed waste acid at the bottom of the first gas-liquid enhancer. The reaction takes 40 minutes to generate sulfide slag.

[0010] Step 4: The gas, liquid and sulfide residue after the reaction in the first gas-liquid enhancer are introduced into the second gas-liquid enhancer, and hydrogen sulfide is added to the second gas-liquid enhancer 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.

[0011] 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.

[0012] Step 6: When the pressure inside the second gas-liquid enhancer 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.

[0013] Step 7: The purified exhaust gas is introduced into the second treatment tower. The pipes between the first and second treatment towers, as well as the interior of the second treatment tower, are sprayed with sodium hydroxide solution to absorb residual hydrogen sulfide, treating the exhaust gas 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 first gas-liquid enhancer at a certain flow rate.

[0014] In one or more embodiments, in step 1, the arsenic content of the high-concentration arsenic-containing waste acid is >20g / L.

[0015] In one or more embodiments, in step 1, the high-concentration arsenic-containing waste acid is at a concentration of 30m³. 3 It is pumped into the first pest control tower at a rate of / h.

[0016] In one or more embodiments, in step 1, the spraying is reverse spraying.

[0017] In one or more embodiments, in step 1, the resistance of the spray is 1-2 kPa.

[0018] In one or more embodiments, in step 2, the arsenic content of the waste acid solution is <50 mg / L.

[0019] In one or more embodiments, in step 2, the arsenic content of the mixed waste acid is <8000 mg / L.

[0020] In one or more embodiments, in step 3, the introduction rate of hydrogen sulfide gas is 90 Nm. 3 / h.

[0021] In one or more embodiments, in step 3, the purity of the hydrogen sulfide gas is ≥95%.

[0022] In one or more embodiments, in step 3, the reaction pressure of the first gas-liquid enhancer is 60 kPa-75 kPa.

[0023] In one or more embodiments, in step 3, the introduced flow rate of the circulated liquid is 0.3 m / s. 3 / h.

[0024] In one or more embodiments, in step 3, the main components of the recycled liquid are sodium hydroxide and sodium sulfide.

[0025] In one or more embodiments, the concentration of sodium hydroxide is <15%.

[0026] In one or more embodiments, the concentration of sodium sulfide is >3%.

[0027] In one or more embodiments, in step 4, the hydrogen sulfide gas is introduced at a rate of 40 Nm. 3 / h.

[0028] In one or more embodiments, in step 4, the purity of the hydrogen sulfide gas is ≥95%.

[0029] In one or more embodiments, in step 4, the reaction pressure of the second gas-liquid enhancer is 60 kPa-75 kPa.

[0030] In one or more embodiments, in step 7, the concentration of the sodium hydroxide solution is 20%. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 is a process flow diagram of continuous sulfidation treatment of high-arsenic-containing waste acid according to one or more embodiments of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0034] The reaction mechanism of this application involves hydrogen sulfide reacting with arsenic and other heavy metals in waste acid via the following sulfidation reaction: 2AsO 3- +3H₂S=As₂S₃+6OH⁻ - M n+ +H2S=MS n / 2 +2H +

[0035] Among them, M n+ It can be Cu 2+ Pb 2+ Cd 2+ Zn 2+ Metal ions, etc.

[0036] This application introduces waste acid solution into the reaction system to carry away the precipitate sulfide residue 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.

[0037] To achieve the above objectives, this application provides a method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid, comprising the following steps:

[0038] Step 1: Pump the high-concentration arsenic-containing waste acid into the high-arsenic liquid tank of the first purifying tower. 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 pre-treat the high-concentration arsenic-containing waste acid. At the same time, spray 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 pre-treat the high-concentration arsenic-containing waste acid. The sprayed high-concentration arsenic-containing waste acid is concentrated at the bottom of the first purifying tower, with part flowing back to the high-arsenic liquid tank and the remainder flowing into the waste acid spray tank.

[0039] 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.

[0040] 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 first gas-liquid enhancer.

[0041] 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.

[0042] Step 3: Hydrogen sulfide gas is introduced into the top of the first gas-liquid enhancer, and the circulating liquid from the alkaline spray tank is introduced into the middle of the first gas-liquid enhancer to carry out a primary gas-liquid enhanced sulfidation and arsenic removal reaction with the mixed waste acid at the bottom of the first gas-liquid enhancer. The reaction takes 40 minutes to generate sulfide slag.

[0043] The beneficial effects of adopting the above technical solution are as follows: To avoid excessively vigorous reaction after a large amount of recycled liquid is added to the first gas-liquid enhancer, resulting in the generation of a large amount of hydrogen sulfide gas and causing excessive hydrogen sulfide emissions in the tail gas, the recycled liquid is controlled by a regulating valve to maintain a flow rate of 0.3m. 3 The first gas-liquid intensifier is fed at a flow rate of / h. After the first-stage gas-liquid intensified sulfide arsenic removal reaction, the arsenic removal rate can reach over 80%.

[0044] Step 4: The gas, liquid and sulfide residue after the reaction in the first gas-liquid enhancer are introduced into the second gas-liquid enhancer, and hydrogen sulfide is added to the second gas-liquid enhancer 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.

[0045] 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%.

[0046] 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.

[0047] Step 6: When the pressure inside the second gas-liquid enhancer 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.

[0048] Step 7: The purified exhaust gas is introduced into the second treatment tower. The pipes between the first and second treatment towers, as well as the interior of the second treatment tower, are sprayed with sodium hydroxide solution to absorb residual hydrogen sulfide, treating the exhaust gas 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 first gas-liquid enhancer at a certain flow rate.

[0049] 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.

[0050] In one or more embodiments, in step 1, the arsenic content of the high-concentration arsenic-containing waste acid is >20g / L.

[0051] In one or more embodiments, in step 1, the high-concentration arsenic-containing waste acid is at a concentration of 30m³. 3 It is pumped into the first pest control tower at a rate of / h.

[0052] In one or more embodiments, in step 1, the spraying is reverse spraying.

[0053] In one or more embodiments, in step 1, the resistance of the spray is 1-2 kPa.

[0054] In one or more embodiments, in step 2, the arsenic content of the waste acid solution is <50 mg / L.

[0055] In one or more embodiments, in step 2, the arsenic content of the mixed waste acid is <8000 mg / L.

[0056] In one or more embodiments, in step 3, the introduction rate of hydrogen sulfide gas is 90 Nm. 3 / h.

[0057] In one or more embodiments, in step 3, the purity of the hydrogen sulfide gas is ≥95%.

[0058] In one or more embodiments, in step 3, the reaction pressure of the first gas-liquid enhancer is 60 kPa-75 kPa.

[0059] In one or more embodiments, in step 3, the introduced flow rate of the circulated liquid is 0.3 m / s. 3 / h.

[0060] In one or more embodiments, in step 3, the main components of the recycled liquid are sodium hydroxide and sodium sulfide.

[0061] In one or more embodiments, the concentration of sodium hydroxide is <15%.

[0062] In one or more embodiments, the concentration of sodium sulfide is >3%.

[0063] In one or more embodiments, in step 4, the hydrogen sulfide gas is introduced at a rate of 40 Nm. 3 / h.

[0064] In one or more embodiments, in step 4, the purity of the hydrogen sulfide gas is ≥95%.

[0065] In one or more embodiments, in step 4, the reaction pressure of the second gas-liquid enhancer is 60 kPa-75 kPa.

[0066] In one or more embodiments, in step 7, the concentration of the sodium hydroxide solution is 20%.

[0067] Compared with the prior art, the beneficial effects achieved by this application are as follows:

[0068] 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.

[0069] 2. Safety: Sodium sulfide is added to the first gas-liquid intensifier at a low and stable speed, ensuring a stable hydrogen sulfide generation process and achieving standard emissions of hydrogen sulfide in the exhaust gas.

[0070] 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.

[0071] To better understand this application, the following embodiments are provided for further detailed explanation of this application, but they should not be construed as limiting this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of this application.

[0072] Example 1

[0073] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0074] Step 1: Dissolve the high-arsenic solution (20385 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the first treatment tower 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.

[0075] 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 to the first gas-liquid enhancer.

[0076] Step 3, hydrogen sulfide gas is released at 90 Nm 3The solution is fed into the first gas-liquid intensifier 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, generating fluidized slag. The arsenic removal rate is 80.98%.

[0077] Step 4: The gas and liquid from the first gas-liquid enhancer are transferred to the second gas-liquid enhancer for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and a 40 Nm³ / h injection is introduced into the second gas-liquid enhancer. 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.

[0078] 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%.

[0079] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the second gas-liquid enhancer 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.

[0080] Step 7: The exhaust gas is led to the first purification tower. 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.

[0081] Step 8: After the exhaust gas is introduced into the second treatment tower, it is discharged. The intermediate connecting pipe and the second treatment tower 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 first gas-liquid intensifier 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.

[0082] Example 2

[0083] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0084] Step 1: Dissolve the high-arsenic solution (22135 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the first treatment tower 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.

[0085] 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 to the first gas-liquid enhancer.

[0086] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the first gas-liquid intensifier 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, generating fluidized slag. The arsenic removal rate is 80.97%.

[0087] Step 4: The gas and liquid from the first gas-liquid enhancer are transferred to the second gas-liquid enhancer for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and a 40 Nm³ / h injection is introduced into the second gas-liquid enhancer. 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.

[0088] 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%.

[0089] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the second gas-liquid enhancer 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.

[0090] Step 7: The exhaust gas is led to the first purification tower. 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.

[0091] Step 8: After the exhaust gas is introduced into the second treatment tower, it is discharged. The intermediate connecting pipe and the second treatment tower 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 first gas-liquid intensifier 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.

[0092] Example 3

[0093] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0094] 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 first treatment tower 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.

[0095] 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 to the first gas-liquid enhancer.

[0096] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the first gas-liquid intensifier 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, generating fluidized slag. The arsenic removal rate is 80.96%.

[0097] Step 4: The gas and liquid from the first gas-liquid enhancer are transferred to the second gas-liquid enhancer for a two-stage gas-liquid enhanced sulfide arsenic removal reaction, and a 40 Nm³ / h injection is introduced into the second gas-liquid enhancer. 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.

[0098] 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%.

[0099] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the second gas-liquid enhancer 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.

[0100] Step 7: The exhaust gas is led to the first purification tower. 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.

[0101] Step 8: After the exhaust gas is introduced into the second treatment tower, it is discharged. The intermediate connecting pipe and the second treatment tower 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 first gas-liquid intensifier 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.

[0102] Example 4

[0103] A continuous sulfidation treatment method for high-concentration arsenic-containing waste acid includes the following steps:

[0104] Step 1: Dissolve the high-arsenic solution (30025 mg / L) in 30 ml of water. 3 The exhaust gas is pumped to the first treatment tower 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.

[0105] 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 to the first gas-liquid enhancer.

[0106] Step 3, hydrogen sulfide gas is released at 90 Nm 3 The solution is fed into the first gas-liquid intensifier 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, generating fluidized slag. The arsenic removal rate is 80.98%.

[0107] Step 4: The gas, liquid, and fluidized slag from the first gas-liquid enhancer are transferred to the second gas-liquid enhancer, and then injected into the second gas-liquid enhancer 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.

[0108] 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%.

[0109] Step 6: When the pressure is higher than 75 kPa, the exhaust gas after the reaction of the second gas-liquid enhancer 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.

[0110] Step 7: The exhaust gas is led to the first purification tower. 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.

[0111] Step 8: After the exhaust gas is introduced into the second treatment tower, it is discharged. The intermediate connecting pipe and the second treatment tower 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 first gas-liquid intensifier 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.

[0112] Comparative Example 1

[0113] 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 the first gas-liquid enhancer and the reaction in step 2 at a rate of / h. Under the same conditions, 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%.

[0114] Comparative Example 2

[0115] 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 the first gas-liquid enhancer and the reaction in step 2 at a rate of / h. Under the same conditions, 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%.

[0116] Comparative Example 3

[0117] The high-arsenic solution with an arsenic content of 20385 mg / L from Example 1 was diluted at 30 m... 3 Pumped directly to the first gas-liquid enhancer and the second reaction at a rate of / h, the pump is stopped when the liquid level reaches the high level, and then pumped at 65Nm. 3 Hydrogen sulfide is introduced into the first gas-liquid enhancer and the second gas-liquid enhancer at a rate of / h. After the reaction, the arsenic concentration in the liquid drops to 22mg / L, and then solid-liquid separation is performed. Under the same conditions, 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, while the average daily arsenic treatment capacity of the high arsenic liquid in this comparative example is 3.20t / d, which is 2.56t / d lower than that in Example 1.

[0118] Comparative Example 4

[0119] The high-arsenic solution with an arsenic content of 30025 mg / L from Example 4 was diluted at 30 m 3 Pumped directly to the first gas-liquid enhancer and the second reaction at a rate of / h, the pump is stopped when the liquid level reaches the high level, and then pumped at 65Nm. 3 Hydrogen sulfide is introduced into the first gas-liquid enhancer and 2 at a rate of / h. After the arsenic concentration in the liquid drops to 42mg / L after the reaction, solid-liquid separation is performed. Other conditions remain unchanged. The arsenic removal rate is 99.86%, but the required reaction time is 12h. The average daily arsenic treatment capacity of the high arsenic liquid in Example 4 is 5.68t / d. In this comparative example, the average daily arsenic treatment capacity of the high arsenic liquid is 2.40t / d, which is 3.28t / d lower than that in Example 1.

[0120] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. 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 this application. Therefore, this application 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. Industrial applicability

[0121] This application utilizes hydrogen sulfide from the exhaust gas to pretreat the high-arsenic liquid twice, consuming most of the hydrogen sulfide in the exhaust gas, improving the utilization rate of hydrogen sulfide, reducing the consumption of sodium hydroxide in the subsequent exhaust gas treatment, and lowering the cost of exhaust gas treatment.

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 first treatment tower. 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 first treatment tower, 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 the first gas-liquid enhancer; Step 3: Hydrogen sulfide gas is introduced into the top of the first gas-liquid enhancer, and the circulating liquid from the alkaline spray tank is introduced into the middle of the first gas-liquid enhancer to carry out a primary gas-liquid enhanced sulfidation arsenic removal reaction with the mixed waste acid at the bottom of the first gas-liquid enhancer for 40 minutes. Step 4: The gas, liquid and sulfide residue after the reaction in the first gas-liquid enhancer are introduced into the second gas-liquid enhancer, and hydrogen sulfide is continuously introduced into the second gas-liquid enhancer to carry out the secondary gas-liquid enhanced sulfide removal reaction for 40 minutes to obtain the 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 second gas-liquid enhancer is >75KPa, open the exhaust valve to introduce the hydrogen sulfide-containing tail gas into the first purifying tower for purification. When the pressure is <60KPa, close the exhaust valve. Step 7: The purified exhaust gas is introduced into the second treatment tower through a pipeline. The pipeline between the first and second treatment towers, as well as the interior of the second treatment tower, are 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 <10 mg / m³. 3 After being discharged externally, the circulating liquid is pumped into the first gas-liquid enhancer.

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.

3. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 1 or 2, characterized in that, In step 1, the high-concentration arsenic-containing waste acid is processed at a rate of 30m³. 3 It is pumped into the first pest control tower at a rate of / h.

4. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-3, characterized in that, In step 1, the spraying is reverse spraying.

5. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-4, characterized in that, In step 1, the resistance of the spray is 1-2 kPa.

6. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-5, characterized in that, In step 2, the arsenic content of the waste acid solution is <50mg / L.

7. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-6, characterized in that, In step 2, the arsenic content of the mixed waste acid is <8000 mg / L.

8. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-7, characterized in that, In step 3, the hydrogen sulfide gas is introduced at a rate of 90 Nm. 3 / h.

9. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-8, characterized in that, In step 3, the purity of the hydrogen sulfide gas is ≥95%.

10. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-9, characterized in that, In step 3, the flow rate of the circulated liquid is 0.3 m / s. 3 / h.

11. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-10, characterized in that, In step 3, the reaction pressure of the first gas-liquid enhancer is 60 kPa-75 kPa.

12. A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-11, characterized in that, In step 3, the main components of the recycled liquid are sodium hydroxide and sodium sulfide.

13. [Correction 16.09.2025 based on Rule 91] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 12, characterized in that, The concentration of sodium hydroxide is <15%.

14. [Corrected according to Rule 91, 16.09.2025] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to claim 12, characterized in that, The concentration of sodium sulfide is >3%.

15. [Correction 16.09.2025 according to Rule 91] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-14, characterized in that, In step 4, the hydrogen sulfide gas is introduced at a rate of 40 Nm. 3 / h.

16. [Corrected according to Rule 91, 16.09.2025] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-15, characterized in that, In step 4, the purity of the hydrogen sulfide gas is ≥95%.

17. [Correction 16.09.2025 according to Rule 91] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-16, characterized in that, In step 4, the reaction pressure of the second gas-liquid enhancer is 60 kPa-75 kPa.

18. [Correction 16.09.2025 according to Rule 91] A method for continuous sulfidation treatment of high-concentration arsenic-containing waste acid according to any one of claims 1-17, characterized in that, In step 7, the concentration of the sodium hydroxide solution is 20%.

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