Method for continuously vulcanizing high-concentration arsenic-containing waste acid

Abstract

The invention belongs to the technical field of sulfuration arsenic removal treatment of waste acid and sewage, and discloses a continuous sulfuration treatment method of high-concentration arsenic-containing waste acid. The method specifically comprises the following steps: pumping high-arsenic liquid into a harm removal tower 1 to spray tail gas, mixing the sprayed high-arsenic liquid with waste acid clear liquid according to a ratio, pumping the mixture into a gas-liquid intensifier 1, introducing hydrogen sulfide gas to react with the mixture to generate sulfurized slag, and continuously reacting gas and liquid into a gas-liquid intensifier 2 to prolong the reaction time; and finally, solid-liquid is treated by a thickener and a filter press to realize solid-liquid separation, and waste acid clear liquid with arsenic content below 50mg / L is obtained. According to the invention, the continuous vulcanization treatment of the waste acid with the arsenic content of more than 20000 mg / L can be realized, and the waste acid clear liquid with the arsenic content of less than 50 mg / L is obtained.

Description

Technical Field

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

[0002] During the smelting flue gas purification process, waste acid containing high concentrations of arsenic and other heavy metals will be produced. At present, the more mature process in China is to use the "sulfurization dearsenicization" process to treat smelting waste acid. By producing hydrogen sulfide and reacting with arsenic and other heavy metal ions in the waste acid to generate sulfide slag precipitation, and then through filter press treatment to achieve solid-liquid separation to achieve the effect of removing heavy metals in the waste acid. This process is simple and has a significant dearsenicization effect. When the arsenic content of the waste acid is within 12000mg / L, it can achieve a good continuous sulfidation effect, and the arsenic content of the liquid after sulfidation can be kept below 50mg / L; but when the arsenic content of the waste acid is higher than 12000mg / L, continuous sulfidation treatment cannot be achieved. In order to ensure that the arsenic content of the liquid after sulfidation meets the standard, intermittent sulfidation treatment can only be used. Although this method can ensure that the arsenic content of the liquid after sulfidation meets the standard, the daily treatment volume of the waste acid cannot meet the daily production of the front-end process, thereby forcing the front-end production to stop, affecting smelting production.

[0003] Therefore, developing a continuous sulfurization treatment method for high-concentration arsenic-containing waste acid is an urgent problem to be solved by technicians in this field. 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 to undergo the following sulfidation reaction:

[0005] 2AsO 3- +3H 2 S=As 2 S 3 +6OH -

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

[0007] Among them, M n+ It can be Cu 2+ , Pb 2+ 、Cd 2+ 、Zn 2+ And other metal ions.

[0008] The present invention adds waste acid clear liquid into the reaction system so that the waste acid clear liquid can carry away the precipitated sulfide slag generated in the reaction process faster, thereby increasing the gas-liquid contact area and improving the reaction efficiency; at the same time, the residual hydrogen sulfide gas in the tail gas is fully utilized to perform two pretreatments on the high-arsenic waste acid, thereby treating waste with waste, reducing the arsenic content of the waste acid, reducing the hydrogen sulfide content of the tail gas, and reducing the consumption of alkali solution for subsequent recovery of hydrogen sulfide.

[0009] In order to achieve the above object, 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 high-concentration arsenic-containing waste acid to the high-arsenic liquid tank of the harm removal tower 1, introduce the hydrogen sulfide tail gas into the bottom of the high-arsenic liquid tank, purify the hydrogen sulfide tail gas once, and pre-treat the high-concentration arsenic-containing waste acid once; at the same time, the high-concentration arsenic-containing waste acid is sprayed from top to bottom on the hydrogen sulfide tail gas entering from the bottom of the tower, purify the hydrogen sulfide tail gas twice, and pre-treat the high-concentration arsenic-containing waste acid twice; the high-concentration arsenic-containing waste acid after spraying is concentrated at the bottom of the harm removal tower 1, part of it is refluxed to the high arsenic liquid tank, and the rest flows into the waste acid spray tank.

[0011] The beneficial effect of adopting the above technical solution is: using the hydrogen sulfide gas in the tail gas to pretreat the high arsenic liquid, which not only reduces the arsenic content in the waste acid, but also achieves the effect of purifying the hydrogen sulfide in the tail gas, reducing the consumption of alkali solution in the subsequent treatment of the tail gas.

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

[0013] The beneficial effects of adopting the above technical solution are: adding waste acid clear liquid can increase the waste acid inlet flow rate, more quickly remove the precipitate sulfide slag produced by the reaction, 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 intensifier 1, and the circulating liquid from the alkali solution spray tank is introduced into the middle of the gas-liquid intensifier 1 to undergo a primary gas-liquid enhanced sulfidation and arsenic removal reaction with the mixed waste acid at the bottom of the gas-liquid intensifier 1. The reaction lasts for 40 minutes to generate sulfide slag.

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

[0016] Step 4: The gas, liquid and sulfide slag after the reaction in the gas-liquid intensifier 1 are introduced into the gas-liquid intensifier 2, and hydrogen sulfide is continuously added into the gas-liquid intensifier 2 to carry out a secondary gas-liquid enhanced sulfide dearsenication reaction for 40 minutes to generate sulfide slag and obtain dearsenication waste liquid.

[0017] The beneficial effect of adopting the above technical solution is that the total arsenic removal rate after the secondary gas-liquid enhanced sulfidation arsenic removal reaction can reach more than 99%.

[0018] Step 5: The dearsenicated waste liquid is separated into solid and liquid by thickener sedimentation and plate and frame filter pressing to obtain waste acid clear liquid with arsenic content meeting the standard, which is pumped into the waste acid clear liquid tank and returned to the waste acid spray tank or for subsequent neutralization treatment.

[0019] Step 6: When the pressure in the gas-liquid intensifier 2 is greater than 75 KPa, the exhaust valve is opened, and the hydrogen sulfide-containing tail gas after the reaction is introduced into the bottom of the high-arsenic liquid tank through a pipeline, and is contacted and reacted with the high-arsenic liquid in the high-arsenic liquid tank from bottom to top, thereby achieving a primary purification of the tail gas and a primary pretreatment of the high-arsenic liquid. When the pressure is less than 60 KPa, the exhaust valve is closed.

[0020] Step 7: The purified tail gas is introduced into the removal tower 2. The pipeline between the removal towers 1 and 2 and the removal tower 2 are sprayed with sodium hydroxide solution to absorb the residual hydrogen sulfide. The tail gas is treated to a hydrogen sulfide content of <10mg / m 3 The liquid after spraying is discharged externally and returned to the alkali solution spray tank for recycling. The liquid after recycling is pumped into the gas-liquid intensifier 1 at a certain flow rate.

[0021] The beneficial effects of adopting the above technical solution are: the circulating 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 precipitation for recycling.

[0022] Preferably, in step 1, the arsenic content of the high-concentration arsenic-containing waste acid is greater than 20 g / L, and the arsenic content of the high-concentration arsenic-containing waste acid is greater than 30 g / L. 3 / h and pumped into the pest removal tower 1.

[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 clear liquid 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 intensifier 1 is 60KPa-75KPa.

[0027] Preferably, in step 3, the introduction flow rate of the circulating liquid is 0.3m 3 / h.

[0028] The beneficial effects of the above technical solution are as follows: in order to prevent excessive reaction of a large amount of recycled liquid after being added to the gas-liquid intensifier 1, resulting in excessive emission of hydrogen sulfide in the tail gas, the recycled liquid is controlled by a regulating valve to be 0.3m 3 / h flow rate into the gas-liquid intensifier 1.

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

[0030] Preferably, the concentration of the sodium hydroxide is <15%, and the concentration of the 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 intensifier 2 is 60KPa-75KPa.

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

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

[0034] 1. Treatment effect: By adding waste acid clear liquid to coordinately treat high-arsenic waste acid, when the arsenic content of the treated clear liquid reaches below 50 mg / L, continuous sulfidation treatment of high-arsenic waste acid with an arsenic content of over 20,000 mg / L is achieved, reaching the highest level of copper smelting high-arsenic waste acid treatment technology. The average daily arsenic treatment capacity of high-arsenic liquid can reach more than 5 tons. The average daily arsenic treatment capacity of high-arsenic liquid treated by existing domestic sodium sulfide arsenic removal technology is only 2 tons, which is 3 tons higher than the same period last year.

[0035] 2. Safety: Control the sodium sulfide to be added to the gas-liquid intensifier 1 at a low and steady speed, so that the hydrogen sulfide production process is stable and the exhaust hydrogen sulfide is discharged up to the standard.

[0036] 3. Technical analysis shows that the high-arsenic liquid was pretreated twice using tail gas hydrogen sulfide, which consumed most of the hydrogen sulfide in the tail gas, improved the utilization rate of hydrogen sulfide, reduced the consumption of sodium hydroxide in subsequent tail gas treatment, and reduced the cost of tail gas treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0038] Figure 1This is the process flow chart for continuous sulfidation treatment of high-content arsenic-containing waste acid. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

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

[0042] Step 1: The high arsenic solution containing 20385 mg / L of arsenic is heated at 30 3 / h rate pump to the decontamination tower 1 to spray the tail gas, the lower part of the high arsenic liquid after spraying flows into the waste acid spray tank, and the upper part flows back to the original liquid tank;

[0043] Step 2, introducing the waste acid clear liquid in the waste acid clear liquid tank into the waste acid spray tank, mixing with the high arsenic liquid in step 1 to adjust the arsenic content to 7689 mg / L, and pumping to the gas-liquid intensifier 1;

[0044] Step 3: Add hydrogen sulfide gas at 90 Nm 3 / h rate into the gas-liquid intensifier 1, and carry out a primary gas-liquid intensified sulfidation dearsenicization reaction with the high-arsenic liquid, the reaction pressure is 60-75KPa, the reaction time is 40min, and fluidized slag is generated, and the arsenic removal rate is 80.98%;

[0045] Step 4: The gas and liquid in the gas-liquid enhancer 1 are introduced into the gas-liquid enhancer 2 to perform a secondary gas-liquid enhanced sulfidation dearsenication reaction, and 40 Nm 3 Hydrogen sulfide is continuously added at a rate of / h, the reaction pressure is 60-75KPa, the reaction is carried out for 40 minutes, and fluidized slag is generated;

[0046] Step 5, performing solid-liquid separation on the high-arsenic liquid after arsenic removal to obtain a waste acid clear liquid 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 75KPa, the waste gas after the reaction of the gas-liquid intensifier 2 is introduced into the bottom of the high-arsenic liquid tank through a pipeline, and is contacted and reacted with the high-arsenic liquid in the high-arsenic liquid tank from bottom to top, so as to achieve a primary purification of the tail gas and a primary pretreatment of the high-arsenic liquid, and the exhaust valve is closed when the pressure is less than 60KPa;

[0048] Step 7, the tail gas is introduced into the harm removal tower 1, and the gas enters from the lower part of the tower to react with the high-arsenic liquid sprayed from top to bottom in step 1, a nozzle is used to replace the packing layer, and the spray resistance is 1-2KPa, so as to complete the secondary purification of the tail gas and the secondary pretreatment of the high-arsenic liquid;

[0049] Step 8: The tail gas is continuously introduced into the detoxification tower 2 and then discharged. The intermediate connecting pipe and the detoxification tower 2 are sprayed with 20% sodium hydroxide solution to absorb the residual hydrogen sulfide. After the circulation, the liquid is 0.3m 3 / h flow rate into the gas-liquid intensifier 1, react with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then react with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitation, which is recycled.

[0050] Example 2

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

[0052] Step 1: The high arsenic solution containing 22135 mg / L of arsenic is heated at 30 3 / h rate pump to the decontamination tower 1 to spray the tail gas, the lower part of the high arsenic liquid after spraying flows into the waste acid spray tank, and the upper part flows back to the original liquid tank;

[0053] Step 2, introducing the waste acid clear liquid in the waste acid clear liquid tank into the waste acid spray tank, mixing with the high arsenic liquid in step 1 to adjust the arsenic content to 7980 mg / L, and pumping to the gas-liquid intensifier 1;

[0054] Step 3: Add hydrogen sulfide gas at 90 Nm 3 / h is passed into the gas-liquid intensifier 1 to carry out a first-level gas-liquid intensified sulfidation dearsenicization reaction with the high-arsenic liquid. The reaction pressure is 60-75KPa. The reaction time is 40 minutes to generate fluidized slag. The arsenic removal rate is 80.97%;

[0055] Step 4: The gas and liquid in the gas-liquid enhancer 1 are introduced into the gas-liquid enhancer 2 to perform a secondary gas-liquid enhanced sulfidation dearsenication reaction, and 40 Nm 3 Hydrogen sulfide is continuously added at a rate of / h, the reaction pressure is 60-75KPa, the reaction is carried out for 40 minutes, and fluidized slag is generated;

[0056] Step 5, performing solid-liquid separation on the high-arsenic liquid after arsenic removal to obtain a waste acid clear liquid 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 75KPa, the waste gas after the reaction of the gas-liquid intensifier 2 is introduced into the bottom of the high-arsenic liquid tank through a pipeline, and is contacted and reacted with the high-arsenic liquid in the high-arsenic liquid tank from bottom to top, so as to achieve a primary purification of the tail gas and a primary pretreatment of the high-arsenic liquid, and the exhaust valve is closed when the pressure is less than 60KPa;

[0058] Step 7, the tail gas is introduced into the harm removal tower 1, and the gas enters from the lower part of the tower to react with the high-arsenic liquid sprayed from top to bottom in step 1, and the nozzle is sprayed in reverse direction, and the spray resistance is controlled at 1-2KPa, so as to complete the secondary purification of the tail gas and the secondary pretreatment of the high-arsenic liquid;

[0059] Step 8: The tail gas is continuously introduced into the detoxification tower 2 and then discharged. The intermediate connecting pipe and the detoxification tower 2 are sprayed with 20% sodium hydroxide solution to absorb the residual hydrogen sulfide. After the circulation, the liquid is 0.3m 3 / h flow rate into the gas-liquid intensifier 1, react with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then react with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitation, which is recycled.

[0060] Example 3

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

[0062] Step 1: The high arsenic solution containing 25048 mg / L of arsenic is heated at 30 3 / h rate pump to the decontamination tower 1 to spray the tail gas, the lower part of the high arsenic liquid after spraying flows into the waste acid spray tank, and the upper part flows back to the original liquid tank;

[0063] Step 2, introducing the waste acid clear liquid in the waste acid clear liquid tank into the waste acid spray tank, mixing with the high arsenic liquid in step 1 to adjust the arsenic content to 7835 mg / L, and pumping to the gas-liquid intensifier 1;

[0064] Step 3: Add hydrogen sulfide gas at 90 Nm 3 / h rate into the gas-liquid intensifier 1, and carry out the first-level gas-liquid intensified sulfidation arsenic removal reaction with the high-arsenic liquid, the reaction pressure is 60-75KPa, the reaction time is 40min, and fluidized slag is generated, and the arsenic removal rate is 80.96%;

[0065] Step 4: The gas and liquid in the gas-liquid enhancer 1 are introduced into the gas-liquid enhancer 2 to perform a secondary gas-liquid enhanced sulfidation dearsenication reaction, and 40 Nm 3 Hydrogen sulfide is continuously added at a rate of / h, the reaction pressure is 60-75KPa, the reaction is carried out for 40 minutes, and fluidized slag is generated;

[0066] Step 5, performing solid-liquid separation on the high-arsenic liquid after arsenic removal to obtain a waste acid clear liquid 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 75KPa, the waste gas after the reaction of the gas-liquid intensifier 2 is introduced into the bottom of the high-arsenic liquid tank through a pipeline, and is contacted and reacted with the high-arsenic liquid in the high-arsenic liquid tank from bottom to top, so as to achieve a primary purification of the tail gas and a primary pretreatment of the high-arsenic liquid, and the exhaust valve is closed when the pressure is less than 60KPa;

[0068] Step 7, the tail gas is introduced into the harm removal tower 1, and the gas enters from the lower part of the tower to react with the high-arsenic liquid sprayed from top to bottom in step 1, and the nozzle is sprayed in reverse direction, and the spray resistance is controlled at 1-2KPa, so as to complete the secondary purification of the tail gas and the secondary pretreatment of the high-arsenic liquid;

[0069] Step 8: The tail gas is continuously introduced into the detoxification tower 2 and then discharged. The intermediate connecting pipe and the detoxification tower 2 are sprayed with 20% sodium hydroxide solution to absorb the residual hydrogen sulfide. After the circulation, the liquid is 0.3m 3 / h flow rate into the gas-liquid intensifier 1, react with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then react with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitation, which is recycled.

[0070] Example 4

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

[0072] Step 1: Add 30025 mg / L of high arsenic solution at 30 m 3 / h rate pump to the decontamination tower 1 to spray the tail gas, the lower part of the high arsenic liquid after spraying flows into the waste acid spray tank, and the upper part flows back to the original liquid tank;

[0073] Step 2, introducing the waste acid clear liquid in the waste acid clear liquid tank into the waste acid spray tank, mixing with the high arsenic liquid in step 1 to adjust the arsenic content to 7906 mg / L, and pumping to the gas-liquid intensifier 1;

[0074] Step 3: Add hydrogen sulfide gas at 90 Nm 3 / h rate into the gas-liquid intensifier 1, and carry out a primary gas-liquid intensified sulfidation dearsenicization reaction with the high-arsenic liquid, the reaction pressure is 60-75KPa, the reaction time is 40min, and fluidized slag is generated, and the arsenic removal rate is 80.98%;

[0075] Step 4: The gas, liquid and fluidized slag in the gas-liquid intensifier 1 are introduced into the gas-liquid intensifier 2, and the gas-liquid intensifier 2 is heated to 40 Nm 3 / h and continue to add hydrogen sulfide at a reaction pressure of 60-75KPa to carry out a secondary gas-liquid enhanced sulfidation dearsenicization reaction for 40 minutes to generate fluidized slag;

[0076] Step 5, performing solid-liquid separation on the high-arsenic liquid after arsenic removal to obtain a waste acid clear liquid 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 75KPa, the waste gas after the reaction of the gas-liquid intensifier 2 is introduced into the bottom of the high-arsenic liquid tank through a pipeline, and is contacted and reacted with the high-arsenic liquid in the high-arsenic liquid tank from bottom to top, so as to achieve a primary purification of the tail gas and a primary pretreatment of the high-arsenic liquid, and the exhaust valve is closed when the pressure is less than 60KPa;

[0078] Step 7, the tail gas is introduced into the harm removal tower 1, and the gas enters from the lower part of the tower to react with the high-arsenic liquid sprayed from top to bottom in step 1, and the nozzle is sprayed in reverse direction, and the spray resistance is controlled at 1-2KPa, so as to complete the secondary purification of the tail gas and the secondary pretreatment of the high-arsenic liquid;

[0079] Step 8: The tail gas is continuously introduced into the detoxification tower 2 and then discharged. The intermediate connecting pipe and the detoxification tower 2 are sprayed with 20% sodium hydroxide solution to absorb the residual hydrogen sulfide. After the circulation, the liquid is 0.3m 3 / h flow rate into the gas-liquid intensifier 1, react with sulfuric acid in the waste acid to generate hydrogen sulfide gas, and then react with arsenic and other heavy metals in the waste acid to generate sulfide slag precipitation, which is recycled.

[0080] Comparative Example 1

[0081] The high arsenic solution with an arsenic content of 20385 mg / L in Example 1 was heated to 30 3 / h rate and directly pumped to gas-liquid intensifiers 1 and 2 for reaction. The other conditions remained unchanged. The high-arsenic liquid after arsenic removal was subjected to solid-liquid separation to obtain a waste acid clear liquid with an arsenic content of 14042 mg / L, and the arsenic removal rate was 31.11%.

[0082] Comparative Example 2

[0083] The high arsenic solution containing 30025 mg / L of arsenic in Example 4 was heated to 300 mL 3 / h rate is directly pumped into gas-liquid intensifiers 1 and 2 for reaction, and other conditions remain unchanged. The high-arsenic liquid after arsenic removal is subjected to solid-liquid separation to obtain a waste acid clear liquid with an arsenic content of 24542 mg / L, and the arsenic removal rate is 18.26%.

[0084] Comparative Example 3

[0085] The high arsenic solution with an arsenic content of 20385 mg / L in Example 1 was heated to 30 3 / h rate directly pumped to the gas-liquid intensifier 1, 2 for reaction, pumped to the high liquid level when the pump stopped, press 65Nm 3 / h rate of hydrogen sulfide is introduced into the gas-liquid intensifiers 1 and 2, and solid-liquid separation treatment is carried out when the liquid arsenic concentration drops to 22 mg / L after the reaction. The 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, and 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.

[0086] Comparative Example 4

[0087] The high arsenic solution containing 30025 mg / L of arsenic in Example 4 was heated to 300 mL 3 / h rate directly pumped to the gas-liquid intensifier 1, 2 for reaction, pumped to the high liquid level when the pump stopped, press 65Nm 3 / h rate of hydrogen sulfide is introduced into the gas-liquid intensifiers 1 and 2, and solid-liquid separation treatment is performed when the liquid arsenic concentration drops to 42 mg / L after the reaction. The 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, and the average daily arsenic treatment capacity of the high-arsenic liquid in this comparative example is 2.40t / d, which is 3.28t / d lower than that in Example 1.

[0088] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to 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: The following steps are involved: Step 1: pumping high-concentration arsenic-containing waste acid to the high-arsenic liquid tank of the harm removal tower 1, introducing hydrogen sulfide tail gas into the bottom of the high-arsenic liquid tank, purifying the hydrogen sulfide tail gas once, and pre-treating the high-concentration arsenic-containing waste acid once; spraying the hydrogen sulfide tail gas with the high-concentration arsenic-containing waste acid, purifying the hydrogen sulfide tail gas twice, and pre-treating the high-concentration arsenic-containing waste acid twice; the high-concentration arsenic-containing waste acid after spraying is concentrated at the bottom of the harm removal tower 1, part of which is refluxed to the high-arsenic liquid tank, and the rest flows into the waste acid spray tank; Step 2: Evenly mix the high-concentration arsenic-containing waste acid after spraying with the waste acid clear liquid to obtain mixed waste acid, and pump it to the gas-liquid intensifier 1; Step 3: hydrogen sulfide gas is introduced into the top of the gas-liquid intensifier 1, and the circulating liquid of the alkali liquid spray tank is introduced into the middle of the gas-liquid intensifier 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 intensifier 1 for 40 minutes; Step 4: the gas, liquid and sulfide slag after the reaction in the gas-liquid intensifier 1 are introduced into the gas-liquid intensifier 2, and hydrogen sulfide is continuously introduced into the gas-liquid intensifier 2 to perform a secondary gas-liquid intensified sulfide dearsenication reaction for 40 minutes to obtain dearsenicated waste liquid; Step 5: The arsenic removal waste liquid is subjected to solid-liquid separation by thickener precipitation and plate-frame filter pressing to obtain a waste acid clear liquid with a qualified arsenic content, which is pumped into a waste acid clear liquid tank and returned to the waste acid spray tank or subjected to subsequent neutralization treatment; Step 6: When the pressure in the gas-liquid intensifier 2 is greater than 75 KPa, the exhaust valve is opened to introduce the hydrogen sulfide-containing tail gas into the decontamination tower 1 for purification, and the exhaust valve is closed when the pressure is less than 60 KPa; Step 7: The purified tail gas is introduced into the pest removal tower 2 through the pipeline. The pipeline between the pest removal towers 1 and 2 and the inside of the pest removal tower 2 are sprayed with sodium hydroxide solution to absorb the residual hydrogen sulfide. The sprayed liquid is returned to the alkali solution spray tank for recycling. The tail gas is treated to a hydrogen sulfide content of <10mg / m 3 After the liquid is discharged, it is pumped into the gas-liquid intensifier 1 after circulation.

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 greater than 20 g / L, and the arsenic content of the high-concentration arsenic-containing waste acid is greater than 20 g / L. 3 / h and pumped into the pest removal tower 1.

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 clear liquid is less than 50 mg / 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 less than 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 introduction rate of the hydrogen sulfide gas is 90Nm 3 / h, the purity of the hydrogen sulfide gas is ≥95%, and the introduction flow rate of the circulating liquid is 0.3m 3 / h, and the reaction pressure of the gas-liquid intensifier 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 circulating 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 the sodium hydroxide is <15%, and the concentration of the 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 introduction rate of the hydrogen sulfide gas is 40Nm 3 / h, the purity of the hydrogen sulfide gas is ≥95%, and the reaction pressure of the gas-liquid intensifier 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%.

Images