Method for removing arsenic hydride in industrial flue gas

Abstract

The invention relates to the technical field of waste gas treatment, in particular to a treatment technology suitable for industrial waste gas containing arsenic hydride, and discloses a method for removing arsenic hydride in industrial flue gas, which comprises the following steps: adding a copper sulfate solution with a certain concentration into a flue gas washing solution according to a certain proportion; arsenic hydride in the industrial flue gas is promoted to react with copper sulfate in the washing liquid in the spray tower, and then solid-liquid separation is carried out on the reaction product in the clarifier. And supplementing a certain amount of copper sulfate solution to the supernate, then returning the supernate to the flue gas scrubbing solution for recycling, and conveying the lower solid waste to a wet arsenic process or a pyrogenic process copper smelting system. According to the method, most of arsenic hydride in the industrial flue gas can be effectively removed and recycled, and is converted into a copper-containing intermediate material, so that the pollution of the arsenic hydride to the environment is solved, the environmental protection risk of an enterprise is reduced, and the environmental protection benefit of the enterprise is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, in particular to a method for removing arsenic hydrogen from industrial flue gas which is applicable to the treatment technology of industrial waste gas containing arsenic hydrogen. Background Art

[0002] Industrial production is an important source of air pollution. In recent years, with the rapid development of various chemical and smelting enterprises in my country, the amount and types of toxic and harmful gases produced have increased sharply, among which arsine (AsH 3 ) is a waste gas generated during industrial production. The emitted arsenic hydrogen will have adverse effects and risks on the environment, ecosystem and human health, which has attracted the attention of more and more researchers at home and abroad. 3 They are mainly concentrated in phosphorus chemical industry, coal chemical industry, non-ferrous metal smelting and petroleum processing and refining industries. These toxic and harmful industrial waste gases will have the most direct negative impact on human health. When people inhale these harmful gases, the respiratory mucosa and various organs will be damaged to varying degrees, causing damage to the normal functions of the human body.

[0003] There are many studies on atmospheric heavy metal pollution abroad, and many methods for removing AsH 3 In recent years, the domestic AsH 3 There is more and more attention on this field, but the methods and technologies are not mature enough.

[0004] Modified carbon adsorbents have the advantages of large specific surface area, high surface reactivity, low price and easy availability, and are widely used in industrial removal of AsH 3 However, it also has disadvantages such as poor thermal stability and poor selectivity.

[0005] To prevent and improve exposure to AsH 3 Arsenic poisoning in high-risk populations, mitigation and elimination of AsH 3 Due to the harm to the environment, it is urgent to remove AsH3 waste gas from industry.

[0006] It is necessary to find a method for removing AsH from industrial flue gas with simple process, convenient operation and low cost. 3 Therefore, we need to propose a method to remove hydrogen arsenide from industrial flue gas. Summary of the invention

[0007] The purpose of the present invention is to provide a method for removing hydrogen arsenide from industrial flue gas, so as to greatly reduce the addition of alkaline absorbent and reduce the generation of high-salt wastewater in the waste gas treatment process; by introducing copper sulfate solution, the existing alkaline absorbent is replaced, and hydrogen arsenide is separated from the system in the form of copper arsenide precipitation. At the same time, the spray waste liquid can be recycled after simple sedimentation and reagent addition, which reduces the pressure and cost of wastewater treatment; the process flow is simple and reliable, easy to industrialize, and has important economic and social benefits, so as to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for removing hydrogen arsine from industrial flue gas, comprising the following steps:

[0009] S1. Raw material preparation: Detect the concentration, purity and presence of impurities of copper sulfate solution and sulfuric acid solution, and use high-precision metering equipment to measure the required amount of copper sulfate solution and sulfuric acid solution respectively;

[0010] S2. Slowly add the copper sulfate solution into the sulfuric acid solution to mix, and stir while adding to prevent local overheating and splashing, to obtain a flue gas scrubbing liquid;

[0011] S3, sending the mixed flue gas washing liquid into the spray tower, the flue gas enters from the bottom of the spray tower, and contacts with the flue gas washing liquid from top to bottom in countercurrent, washing the flue gas to obtain a flue gas washing mixed solution;

[0012] S4. The flue gas scrubbing mixed solution is sent to a clarifier for natural sedimentation. The suspended matter settles to the bottom of the clarifier due to gravity to form sludge, and the clean liquid remains on the upper layer to form supernatant;

[0013] S5. Regularly monitor the clarity of the supernatant and the sedimentation of the bottom mud through the level gauge and sampling port installed in the clarifier, and adjust the parameters of the spray tower or the residence time of the clarifier according to the monitoring results, so that the supernatant and the bottom mud meet the separation requirements;

[0014] S6. When the supernatant in the clarifier reaches the set amount, the supernatant is drawn out through the overflow pipe, and the obtained supernatant is added with copper sulfate solution and returned to the spray tower for spraying again;

[0015] S7. Use the scraping equipment to scrape the sludge from the bottom of the clarifier, and send the sludge to the wet arsenic production process after filter pressing or send it to the pyrometallurgical copper smelting system after drying.

[0016] Preferably, in step S1, the concentrations of the copper sulfate solution and the sulfuric acid solution are respectively measured using a concentration meter or a titration method to ensure that the solubility of the copper sulfate solution and the sulfuric acid solution is within a preset range; if the copper sulfate solution and the sulfuric acid solution contain impurities, the impurities react with pollutants in the flue gas during the flue gas scrubbing process to generate by-products.

[0017] Preferably, in step S2, during the process of mixing the copper sulfate solution and the sulfuric acid solution, the pH value and color change of the mixed solution are monitored, and sufficient stirring is performed to ensure that the copper sulfate solution and the sulfuric acid solution are mixed evenly, and the concentration of copper ions in the flue gas scrubbing liquid obtained after mixing is 10-50 g / L, and the acidity of the flue gas scrubbing liquid is 100-200 g / L.

[0018] Preferably, in step S3, the flow rate of flue gas entering the spray tower is 10000-30000Nm 3 / h, the content of hydrogen arsenide in the flue gas after washing is less than or equal to 0.3mg / m 3 During the flue gas washing process, the spray volume, spray pressure and spray angle of the spray tower are monitored and adjusted to ensure that the flue gas is fully in contact with the flue gas washing liquid and effectively washed.

[0019] Preferably, in step S3, the smoke stays in the spray tower for 0.5-2s, and during the smoke spraying process, the smoke is sprayed in one, two or more sections, and each section of the spraying is provided with a plurality of nozzles equidistantly arranged in a circle.

[0020] Preferably, in step S4, the natural settling time of the flue gas scrubbing mixed solution in the clarification tank is 4-8 hours.

[0021] Preferably, in step S5, the liquid level meter is used to monitor the liquid level of the supernatant, and the sampling port is used to regularly extract the supernatant for clarity detection and to observe the sedimentation of the bottom mud.

[0022] Preferably, in step S6, after the supernatant is drawn out, the pH value and copper sulfate concentration of the supernatant need to be tested to facilitate the calculation of the amount of copper sulfate solution to be added so that the supernatant meets the requirements for being used as a flue gas scrubbing liquid again; and a metering pump is used to add copper sulfate solution to the supernatant, and stirring should be continued during the addition process to ensure that the copper sulfate solution and the supernatant are evenly mixed.

[0023] Preferably, in step S7, the scraped sludge is sent to a filter press for filter pressing and dehydration treatment to reduce the moisture content and volume of the sludge, and the filtrate generated during the filter pressing process is returned to the clarification tank for sedimentation treatment or harmless treatment again.

[0024] Preferably, in step S7, the sludge after the filter press dehydration treatment is classified and treated according to its composition and properties. If the arsenic content in the sludge is high, the sludge is sent to the wet arsenic production process for extraction and recovery; if the copper content in the sludge is high, the sludge is dried and sent to the pyrometallurgical copper smelting system for smelting treatment.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention can significantly reduce the addition of alkaline absorbent and reduce the generation of high-salt wastewater in the waste gas treatment process;

[0027] 2. The present invention replaces the existing alkaline absorbent by introducing a copper sulfate solution, and removes hydrogen arsenide from the system in the form of copper arsenide precipitation. At the same time, the spray waste liquid can be recycled after simple sedimentation and reagent addition, thereby reducing the pressure and cost of wastewater treatment;

[0028] 3. The process flow of the present invention is simple and reliable, easy to industrialize, and has important economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flowchart of the present invention;

[0030] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] Example 1

[0033] See also Figure 1-2 The present invention provides a technical solution: a method for removing arsine from industrial flue gas. Arsenic has a large solubility in copper sulfate solution and easily reacts chemically with copper sulfate and sulfuric acid to form insoluble compounds. The reaction equation is: 2AsH3+3CuSO4=Cu3As2+3H2SO4, thereby achieving the effect of adsorbing arsine gas.

[0034] By utilizing the existing waste gas treatment process equipment, the addition structure of the spray reagent in the existing waste gas treatment process is improved, the amount of reagent added is reduced, the generation of secondary pollutants is reduced, and the arsenic hydrogen in the flue gas is recycled and utilized. This method is simple to operate, easy to industrialize, environmentally friendly, and has important economic, environmental and social benefits.

[0035] The following steps are involved:

[0036] S1. Raw material preparation: Detect the concentration, purity and presence of impurities of copper sulfate solution and sulfuric acid solution to avoid adverse effects on subsequent steps, and use high-precision metering equipment to measure the required amount of copper sulfate solution and sulfuric acid solution respectively;

[0037] In step S1, the concentrations of the copper sulfate solution and the sulfuric acid solution are respectively measured using a concentration meter or a titration method to ensure that the solubility of the copper sulfate solution and the sulfuric acid solution is within a preset range; if the copper sulfate solution and the sulfuric acid solution contain impurities, the impurities react with the pollutants in the flue gas during the flue gas scrubbing process to generate by-products.

[0038] S2. Slowly add the copper sulfate solution into the sulfuric acid solution to mix, and stir while adding to prevent local overheating and splashing, and generation of harmful gases, to obtain a flue gas scrubbing liquid;

[0039] In step S2, during the process of mixing the copper sulfate solution and the sulfuric acid solution, the temperature should be controlled not to exceed the set upper limit, the pH value and color change of the mixed solution should be monitored, and sufficient stirring should be performed to ensure that the copper sulfate solution and the sulfuric acid solution are mixed evenly, and the concentration of copper ions in the flue gas scrubbing liquid obtained after mixing is 10-50 g / L, and the acidity of the flue gas scrubbing liquid is 100-200 g / L.

[0040] S3. The mixed flue gas washing liquid is sent into the spray tower. The flue gas washing liquid is sent into the spray tower using corrosion-resistant pipes and pumps. The flue gas enters from the bottom of the spray tower and contacts with the flue gas washing liquid from top to bottom in countercurrent to wash the flue gas to obtain a flue gas washing mixed solution. The particulate matter, sulfur dioxide and other pollutants in the flue gas are removed through physical and chemical effects, and the washed flue gas is discharged through the top of the tower.

[0041] During the spraying process, the nozzle blockage should be checked regularly and cleaned.

[0042] In step S3, the flow rate of flue gas entering the spray tower is 10000-30000Nm3 / h, and the content of hydrogen arsenide in the flue gas after washing is less than or equal to 0.3mg / m3. During the flue gas washing process, the spray volume, spray pressure and spray angle of the spray tower are monitored and adjusted to ensure that the flue gas is fully contacted with the flue gas washing liquid and effectively washed.

[0043] In step S3, the smoke stays in the spray tower for 0.5-2s. During the smoke spraying process, the smoke is sprayed in one, two or more sections, and each section is provided with a plurality of nozzles equidistantly arranged in a circle. The spraying angle of the nozzle is adjustable to achieve full contact with the smoke.

[0044] S4. The flue gas scrubbing mixed solution is sent to a clarifier for natural sedimentation. The suspended matter settles to the bottom of the clarifier due to gravity to form sludge, and the clean liquid remains on the upper layer to form supernatant;

[0045] In step S4, the natural sedimentation time of the flue gas scrubbing mixed solution in the clarifier is 4-8 hours, until the supernatant and the sludge are completely separated.

[0046] S5. Regularly monitor the clarity of the supernatant and the sedimentation of the bottom mud through the level gauge and sampling port installed in the clarifier, and adjust the parameters of the spray tower or the residence time of the clarifier according to the monitoring results, so that the supernatant and the bottom mud meet the separation requirements;

[0047] In step S5, the level meter is used to monitor the level of the supernatant, and the sampling port is used to regularly extract the supernatant for clarity testing and to observe the sedimentation of the bottom mud.

[0048] S6. When the supernatant in the clarifier reaches a set amount, the supernatant is drawn out through the overflow pipe, and the obtained supernatant is added with copper sulfate solution and returned to the spray tower for spraying again, forming a closed-loop system for recycling;

[0049] In step S6, after the supernatant is drawn out, the pH value and copper sulfate concentration of the supernatant need to be tested to facilitate the calculation of the amount of copper sulfate solution to be added so that the supernatant meets the requirements for being used as a flue gas scrubbing liquid again; and a metering pump is used to add copper sulfate solution to the supernatant. Stirring should be continued during the addition process to ensure that the copper sulfate solution and the supernatant are evenly mixed.

[0050] S7. Use the scraping equipment to scrape the sludge from the bottom of the clarifier, and send the sludge to the wet arsenic production process after filter pressing or send it to the pyrometallurgical copper smelting system after drying.

[0051] In step S7, the scraped sludge is sent to a filter press for filtration and dehydration treatment to reduce the moisture content and volume of the sludge, and the filtrate generated during the filtration is returned to the clarification tank for sedimentation treatment or harmless treatment again.

[0052] In step S7, the sludge after filter pressing and dehydration treatment is classified and treated according to its composition and properties. If the arsenic content in the sludge is high, the sludge is sent to the wet arsenic production process for extraction and recovery; if the copper content in the sludge is high, the sludge is dried and sent to the pyrometallurgical copper smelting system for smelting treatment.

[0053] Specifically, a 50 g / L copper sulfate solution, a 180 g / L sulfuric acid solution and a certain amount of water are prepared into a flue gas scrubbing liquid with a Cu2+ concentration of 10 g / L and an acidity of 150 g / L, which is pumped into a spray tower to scrub the flue gas. The flow rate of the flue gas is controlled at 10000 Nm3 / h to obtain a flue gas scrubbing mixed solution.

[0054] Among them, the industrial flue gas stays in the spray tower for 0.5s, and the flue gas is treated by a two-stage spraying method. The flue gas washing mixed solution is introduced into the clarification tank for natural sedimentation. After natural sedimentation for 4 hours, the supernatant is supplemented with copper sulfate solution and pumped back into the spray tower for circulating washing operations. The settled sludge is sent to the filter press for filtration, and the filter cake is sent to the wet arsenic production process.

[0055] The concentration of hydrogen arsenide in the initial flue gas is 1.102 mg / m 3 After the method of removing arsenic hydrogen from industrial flue gas is adopted, the concentration of arsenic hydrogen gas is 0.188 mg / m 3 The removal rate was 82.94%.

[0056] Example 2

[0057] The same as the above embodiment will not be repeated, the difference is

[0058] A 100 g / L copper sulfate solution, a 120 g / L sulfuric acid solution and a certain amount of water were prepared to prepare a Cu 2+ The flue gas washing liquid with a concentration of 30g / L and an acidity of 100g / L is pumped into the spray tower to wash the flue gas. The flow rate of the flue gas is controlled at 20000Nm 3 / h to obtain a flue gas scrubbing mixed solution.

[0059] Among them, the industrial flue gas stays in the spray tower for 1.5 seconds, and the flue gas is treated by a one-stage spraying method. The flue gas washing mixed solution is introduced into the clarification tank for natural sedimentation. After natural sedimentation for 6 hours, the supernatant is supplemented with copper sulfate solution and pumped back into the spray tower for cyclic washing operation. The sedimentation sludge is sent to the filter press for filtration operation, and the filter cake is dried and sent to the pyrometallurgical copper smelting system.

[0060] The concentration of hydrogen arsenide in the initial flue gas is 1.527 mg / m 3 After the method of removing arsenic hydrogen from industrial flue gas is adopted, the concentration of arsenic hydrogen gas is 0.276 mg / m 3 The removal rate was 81.93%.

[0061] Example 3

[0062] The same as the above embodiment will not be repeated, the difference is

[0063] A 150 g / L copper sulfate solution, a 220 g / L sulfuric acid solution and a certain amount of water were prepared to prepare a Cu 2+ The flue gas washing liquid with a concentration of 50g / L and an acidity of 200g / L is pumped into the spray tower to wash the flue gas. The flow rate of the flue gas is controlled at 30000Nm 3 / h to obtain a flue gas scrubbing mixed solution.

[0064] Among them, the industrial flue gas stays in the spray tower for 2.0s, and the flue gas is treated by three-stage spraying. The flue gas washing mixed solution is introduced into the clarification tank for natural sedimentation. After natural sedimentation for 8 hours, the supernatant is supplemented with copper sulfate solution and pumped back into the spray tower for cyclic washing operation. The sedimentation sludge is sent to the filter press for filtration operation, and the filter cake is sent to the wet arsenic production process.

[0065] The concentration of hydrogen arsenide in the initial flue gas is 1.331 mg / m 3 After the method of removing arsenic hydrogen from industrial flue gas is adopted, the concentration of arsenic hydrogen gas is 0.223 mg / m 3 The removal rate was 83.25%.

[0066] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for removing hydrogen arsenide from industrial flue gas, characterized in that: The following steps are involved: S1. Raw material preparation: Detect the concentration, purity and presence of impurities of copper sulfate solution and sulfuric acid solution, and use high-precision metering equipment to measure the required amount of copper sulfate solution and sulfuric acid solution respectively; S2. Slowly add the copper sulfate solution into the sulfuric acid solution to mix, and stir while adding to prevent local overheating and splashing, to obtain a flue gas scrubbing liquid; S3, sending the mixed flue gas washing liquid into the spray tower, the flue gas enters from the bottom of the spray tower, and contacts with the flue gas washing liquid from top to bottom in countercurrent, washing the flue gas to obtain a flue gas washing mixed solution; S4. The flue gas scrubbing mixed solution is sent to a clarifier for natural sedimentation. The suspended matter settles to the bottom of the clarifier due to gravity to form sludge, and the clean liquid remains on the upper layer to form supernatant; S5. Regularly monitor the clarity of the supernatant and the sedimentation of the bottom mud through the level gauge and sampling port installed in the clarifier, and adjust the parameters of the spray tower or the residence time of the clarifier according to the monitoring results, so that the supernatant and the bottom mud meet the separation requirements; S6. When the supernatant in the clarifier reaches the set amount, the supernatant is drawn out through the overflow pipe, and the obtained supernatant is added with copper sulfate solution and returned to the spray tower for spraying again; S7. Use the scraping equipment to scrape the sludge from the bottom of the clarifier, and send the sludge to the wet arsenic production process after filter pressing or send it to the pyrometallurgical copper smelting system after drying.

2. A method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S1, the concentrations of the copper sulfate solution and the sulfuric acid solution are respectively measured using a concentration meter or a titration method to ensure that the solubility of the copper sulfate solution and the sulfuric acid solution is within a preset range; if the copper sulfate solution and the sulfuric acid solution contain impurities, the impurities react with the pollutants in the flue gas during the flue gas scrubbing process to generate by-products.

3. A method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S2, during the process of mixing the copper sulfate solution and the sulfuric acid solution, the pH value and color change of the mixed solution are monitored, and sufficient stirring is performed to ensure that the copper sulfate solution and the sulfuric acid solution are mixed evenly, and the concentration of copper ions in the flue gas scrubbing liquid obtained after mixing is 10-50 g / L, and the acidity of the flue gas scrubbing liquid is 100-200 g / L.

4. A method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S3, the flow rate of flue gas entering the spray tower is 10000-30000Nm 3 / h, the content of hydrogen arsenide in the flue gas after washing is less than or equal to 0.3mg / m 3 During the flue gas washing process, the spray volume, spray pressure and spray angle of the spray tower are monitored and adjusted to ensure that the flue gas is fully in contact with the flue gas washing liquid and effectively washed.

5. The method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S3, the smoke stays in the spray tower for 0.5-2s. During the smoke spraying process, the smoke is sprayed in one, two or more sections, and each section is provided with a plurality of nozzles equidistantly arranged in a circle.

6. The method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S4, the natural settling time of the flue gas scrubbing mixed solution in the clarification tank is 4-8 hours.

7. The method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S5, the level meter is used to monitor the level of the supernatant, and the sampling port is used to regularly extract the supernatant for clarity testing and to observe the sedimentation of the bottom mud.

8. The method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S6, after the supernatant is drawn out, the pH value and copper sulfate concentration of the supernatant need to be tested to facilitate the calculation of the amount of copper sulfate solution to be added so that the supernatant meets the requirements for being used as a flue gas scrubbing liquid again; and a metering pump is used to add copper sulfate solution to the supernatant. Stirring should be continued during the addition process to ensure that the copper sulfate solution and the supernatant are evenly mixed.

9. The method for removing hydrogen arsenide from industrial flue gas according to claim 1, characterized in that: In step S7, the scraped sludge is sent to a filter press for filtration and dehydration treatment to reduce the moisture content and volume of the sludge, and the filtrate generated during the filtration is returned to the clarification tank for sedimentation treatment or harmless treatment again.

10. A method for removing hydrogen arsenide from industrial flue gas according to claim 9, characterized in that: In step S7, the sludge after filter pressing and dehydration treatment is classified and treated according to its composition and properties. If the arsenic content in the sludge is high, the sludge is sent to the wet arsenic production process for extraction and recovery; if the copper content in the sludge is high, the sludge is dried and sent to the pyrometallurgical copper smelting system for smelting treatment.

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