Elemental sulfur recovery and treatment method based on hydrogen sulfide waste gas absorption liquid

Abstract

The present invention belongs to the technical field of wastewater treatment, and specifically relates to a method for recovering and treating elemental sulfur based on hydrogen sulfide waste gas absorption liquid. The method comprises the following steps: (1) adding sodium sulfate to the hydrogen sulfide waste gas absorption liquid to obtain a sulfur-containing liquid; (2) injecting the sulfur-containing liquid into a water storage tank, and then adding a sodium sulfate solution to the upper layer to form a liquid seal layer; (3) uniformly injecting an acid solution into the water storage tank, controlling the pH value of the feed liquid in the water storage tank to be 1.5-3, and standing for reaction; (4) after the reaction is completed, extracting the supernatant, and then injecting the sulfur-containing liquid into the water storage tank again, repeating steps (2) and (3), until the hydrogen sulfide waste gas absorption liquid is treated, and collecting the generated elemental sulfur. By adopting a point-in-point micro-acid addition for static reaction, negative valence sulfur is effectively converted into elemental sulfur. This process not only significantly reduces the content of sulfate ions in the wastewater after the reaction, so that it can be directly discharged with water treatment, but also realizes efficient resource utilization of waste.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid. Background Art

[0002] In the process of wet smelting of rare earth concentrate, rare earth chloride needs to add alkali sulfide to complete the lead removal operation in the lead removal stage. In this process, hydrogen sulfide gas is generated, which is then absorbed by the spray absorption tower containing alkali solution and converted into sodium sulfide waste liquid. At present, in the field of rare earth wastewater disposal, the conventional treatment method for this type of wastewater is mainly to mix it with other wastewater for comprehensive treatment. The specific steps include: first acidifying the wastewater, then adding an oxidant to convert the negatively charged sulfide ions into sulfate ions; then, the sewage treatment is completed by adding the corresponding precipitant.

[0003] However, due to the presence of negatively charged sulfur ions, this treatment method has obvious defects. Specifically: First, in an acidic environment, negatively charged sulfur ions will regenerate highly toxic hydrogen sulfide gas. Since the sewage treatment process is usually carried out in a closed environment, this can easily lead to the enrichment of hydrogen sulfide gas, which poses a huge safety hazard. Secondly, negatively charged sulfur exhibits strong reducing properties in an acidic environment, which leads to a significant increase in the use of sewage oxidants, thereby increasing production costs. Finally, in the sulfate-containing wastewater formed after oxidation, the sulfate content fluctuates greatly, which may cause pollutants in the external drainage to exceed the standard.

[0004] In summary, there is an urgent need to find a process method that can operate at low cost and effectively recover and reuse sulfur resources in negatively valent hydrogen sulfide absorption wastewater. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for recovering and treating elemental sulfur based on hydrogen sulfide waste gas absorption liquid. By adopting a point-in type trace acid addition for static reaction, negatively valent sulfur is effectively converted into elemental sulfur. This process not only significantly reduces the content of sulfate ions in the wastewater after the reaction, so that it can be directly discharged with water treatment, but also realizes efficient resource utilization of waste, and the sulfur recovery rate is as high as over 93%.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The elemental sulfur recovery and treatment method based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0008] (1) Adding sodium sulfate to the hydrogen sulfide waste gas absorption liquid and stirring evenly to obtain a sulfur-containing liquid;

[0009] (2) After laying the growth base at the bottom of the water storage tank, inject the sulfur-containing liquid into the water storage tank, and then add sodium sulfate solution on the upper layer of the sulfur-containing liquid to form a liquid seal layer;

[0010] (3) Acid solution is uniformly injected into the water storage tank through the acid injection net, and the pH value of the feed liquid in the water storage tank is controlled to be 1.5-3. The solution is allowed to stand to allow the sulfur-containing liquid to react in an acidic environment. In this process, when the pH is higher than 3, no reaction occurs, but when the pH is lower than 1.5, a violent reaction occurs, and hydrogen sulfide escape occurs.

[0011] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is removed and the generated elemental sulfur is collected.

[0012] The hydrogen sulfide waste gas absorption liquid contains 6-12wt.% S 2- 、1.5-3wt.% OH - , 0.003-0.5wt.% Cl - , and 10-20wt.% Na + .

[0013] In the step (1), the amount of sodium sulfate added is calculated as follows: 2- , then add 15-25g of sodium sulfate.

[0014] In the step (2), the mass fraction of the sodium sulfate solution is 1-5.5%.

[0015] In the step (2), the thickness of the liquid seal layer is 6-10 cm. The purpose of the liquid seal is to allow the hydrogen sulfide generated during the acid injection process to react with the upper layer of sodium sulfate to prevent overflow and poisoning, while also avoiding the escape of hydrogen sulfide and sulfur waste.

[0016] In step (2), the growth substrate is a substrate material that can support, promote or regulate the occurrence of a chemical reaction, including but not limited to a porous material, a solid carrier, a biofilm, a chemical reaction medium or any other substance that can promote or regulate the desired process.

[0017] In the step (3), the acid solution is a hydrochloric acid solution or a sulfuric acid solution.

[0018] The mass fraction of the hydrochloric acid solution is 10-30%; the mass fraction of the sulfuric acid solution is 20-40%.

[0019] In the step (3), the acid injection net is evenly installed along the 1 / 4-2 / 3 interval of the water storage tank height to ensure that the feed liquid is fully acidified and there is no local over-acidity phenomenon. Each layer of the acid injection net is a mesh structure, and the intervals between layers are equal. The amount of sulfur-containing liquid added must cover the top layer of the acid injection net, and the height above the top layer of the acid injection net is less than 8 cm, otherwise it will cause the upper layer of sulfur-containing liquid to react insufficiently.

[0020] In the step (3), the standing time is 6-10 hours.

[0021] The present invention adds sodium sulfate to the hydrogen sulfide waste gas absorption liquid under static conditions, and then adds acid solution in a point-in manner. The acid addition process is carried out at multiple points and angles to ensure uniform reaction. During the reaction, by regulating the molar ratio of negative-valent sulfur to sulfate, negative-valent sulfur ions react with positive-valent sulfur ions in an acidic environment to produce intermediate-valent sulfur. These generated elemental sulfurs are then attached and grown through growth bases to eventually prepare block elemental sulfur. The reaction process is relatively slow, and this slow reaction rate provides good growth conditions for elemental sulfur in the water storage tank. The ionic equation of the reaction is as follows:

[0022] 3S 2- +8H + +SO4 2- =4S↓+4H2O.

[0023] If the acid injection net is not installed in the water storage tank, the local acidity of the sulfur-containing liquid will be too high, causing a large number of sulfur ions to react with hydrogen ions first to generate highly toxic gas hydrogen sulfide, which can easily lead to hydrogen sulfide poisoning. Therefore, the acid injection net must be used to allow the acid to be injected slowly and evenly, which not only provides an acidic reaction environment, but also prevents the escape of hydrogen sulfide due to local excessive acidity.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The elemental sulfur recovery and treatment method based on hydrogen sulfide waste gas absorption liquid described in the present invention is different from the traditional strong oxidant oxidation method. It uses the coupling reaction of sulfur element itself to prepare elemental sulfur, thereby effectively avoiding the waste of sulfur resources. The sulfur recovery rate is more than 93%, and the purity of the block elemental sulfur is more than 90%;

[0026] (2) The present invention adopts a static reaction mode, which can prevent the sodium sulfide solution from generating hydrogen sulfide and escaping during the acidification process, thereby avoiding the risk of hydrogen sulfide poisoning;

[0027] (3) Compared with the conventional method of preparing elemental sulfur by filtration, the present invention adopts a growth-base growth method to obtain elemental sulfur, which is easy to operate and effectively simplifies the processing steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the main structure of the water storage tank used in the embodiment of the present invention;

[0029] Figure 2 Schematic diagram of the top view of the water storage tank used in the embodiment of the present invention;

[0030] In the figure: 1. Water storage tank; 2. Growth base; 3. Acid injection net; 4. Liquid sealing layer. DETAILED DESCRIPTION

[0031] The present invention is further described below with reference to the embodiments, but they do not limit the implementation of the present invention.

[0032] The raw materials used in the examples and comparative examples are conventional commercially available raw materials unless otherwise specified, and the process methods used in the examples and comparative examples are conventional methods in the art unless otherwise specified.

[0033] The schematic diagram of the structure of the water storage tank used in the embodiments and comparative examples is as follows Figure 1-2 As shown, the acid injection net is evenly installed along the 1 / 4-2 / 3 interval of the water storage tank height, and each layer of the acid injection net is a 10cm×10cm mesh pipe with a spacing of 10cm between layers.

[0034] Example 1

[0035] The hydrogen sulfide waste gas absorption liquid contains 6.4wt.% S 2- 、1.82wt.%OH - 、0.14wt.%Cl - , and 11.62wt.% Na + .

[0036] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0037] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 20g of sodium sulfate;

[0038] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat mesh with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a thorny grinding edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection mesh; then, a sodium sulfate solution with a mass fraction of 1.5% is added to the upper layer of the sulfur-containing liquid to form a liquid seal layer, and the thickness of the liquid seal layer is 6 cm;

[0039] (3) Use a diaphragm pump to evenly inject a 30% hydrochloric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 2.0, and let it stand for 10 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0040] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.64%, and the sulfur recovery rate is 93.77%.

[0041] Example 2

[0042] The hydrogen sulfide waste gas absorption liquid contains 10.8wt.% S 2- , 2.86wt.% OH - 、0.47wt.%Cl - , and 19.44wt.% Na + .

[0043] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0044] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 25g of sodium sulfate;

[0045] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat net with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a barbed edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection net; then, a 5% mass fraction sodium sulfate solution is added to the upper layer of the sulfur-containing liquid to form a liquid seal layer, and the thickness of the liquid seal layer is 8 cm;

[0046] (3) Use a diaphragm pump to evenly inject a 10% hydrochloric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 2.0, and let it stand for 10 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0047] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.81%, and the sulfur recovery rate is 93.68%.

[0048] Example 3

[0049] The hydrogen sulfide waste gas absorption liquid contains 8.4wt.% S 2- 、1.51wt.%OH - 、0.008wt.%Cl - , and 14.12wt.% Na + .

[0050] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0051] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 15g of sodium sulfate;

[0052] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat net with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a thorny grinding edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection net; then, a sodium sulfate solution with a mass fraction of 1% is added to the upper layer of the sulfur-containing liquid to form a liquid sealing layer, and the thickness of the liquid sealing layer is 10 cm;

[0053] (3) Use a diaphragm pump to evenly inject a 20% hydrochloric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 2.0, and let it stand for 10 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0054] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.46%, and the sulfur recovery rate is 94.55%.

[0055] Example 4

[0056] The hydrogen sulfide waste gas absorption liquid contains 7.6wt.% S 2- 、2.77wt.%OH - 、0.14wt.%Cl - , and 13.24wt.% Na + .

[0057] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0058] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 20g of sodium sulfate;

[0059] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat mesh with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a thorny grinding edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection mesh; then, a sodium sulfate solution with a mass fraction of 1.5% is added to the upper layer of the sulfur-containing liquid to form a liquid seal layer, and the thickness of the liquid seal layer is 6 cm;

[0060] (3) Use a diaphragm pump to evenly inject 30% sulfuric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 2.0, and let it stand for 10 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0061] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.04%, and the sulfur recovery rate is 93.12%.

[0062] Example 5

[0063] The hydrogen sulfide waste gas absorption liquid contains 7.2wt.% S 2- 、2.47wt.%OH - 、0.21wt.%Cl - , and 13.56wt.% Na + .

[0064] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0065] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 20g of sodium sulfate;

[0066] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat mesh with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a thorny grinding edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection mesh; then, a sodium sulfate solution with a mass fraction of 1.5% is added to the upper layer of the sulfur-containing liquid to form a liquid seal layer, and the thickness of the liquid seal layer is 6 cm;

[0067] (3) Use a diaphragm pump to evenly inject a 20% sulfuric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 3.0, and let it stand for 10 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0068] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.14%, and the sulfur recovery rate is 93.08%.

[0069] Example 6

[0070] The hydrogen sulfide waste gas absorption liquid contains 11.7wt.% S 2- 、1.56wt.%OH - 、0.009wt.%Cl - , and 18.62wt.% Na + .

[0071] The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid comprises the following steps:

[0072] (1) Sodium sulfate is added to the hydrogen sulfide waste gas absorption liquid, and the mixture is stirred evenly to obtain a sulfur-containing liquid. The amount of sodium sulfate added is calculated as follows: 2- , then add 20g of sodium sulfate;

[0073] (2) After laying a 50 cm thick plastic porous growth base at the bottom of the water storage tank (a porous growth base formed by grinding a plastic flat mesh with a hole diameter of 0.6 cm, the grinding method is to grind with sand to generate a thorny grinding edge to obtain a sulfur attachment point), the sulfur-containing liquid is injected into the water storage tank, and the amount of sulfur-containing liquid added is 5 cm above the top layer of the acid injection mesh; then, a sodium sulfate solution with a mass fraction of 1.5% is added to the upper layer of the sulfur-containing liquid to form a liquid seal layer, and the thickness of the liquid seal layer is 6 cm;

[0074] (3) Use a diaphragm pump to evenly inject a 40% sulfuric acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 1.5, and let it stand for 6 hours to allow the sulfur-containing liquid to react in an acidic environment;

[0075] (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is taken out, rinsed with water twice, and the generated elemental sulfur is collected. The purity of the obtained elemental sulfur is 90.04%, and the sulfur recovery rate is 93.02%.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that in step (1), the amount of sodium sulfate added is calculated as follows: 2- , then add 10g of sodium sulfate, and the rest is the same as Example 1.

[0078] The purity of the produced elemental sulfur is 90.12%, and the sulfur recovery rate is 84.22%.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that in the step (3), a nitric acid solution with a mass fraction of 30% is uniformly injected into the water storage tank through the acid injection net, and the rest is the same as Example 1.

[0081] The purity of the produced elemental sulfur is 90.44%, and the sulfur recovery rate is 32.16%.

Claims

1. A method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid, characterized in that: The following steps are involved: (1) Adding sodium sulfate to the hydrogen sulfide waste gas absorption liquid and stirring evenly to obtain a sulfur-containing liquid; (2) After laying the growth base at the bottom of the water storage tank, inject the sulfur-containing liquid into the water storage tank, and then add sodium sulfate solution on the upper layer of the sulfur-containing liquid to form a liquid seal layer; (3) Evenly inject acid solution into the water storage tank through the acid injection net, control the pH value of the liquid in the water storage tank to 1.5-3, and let it stand to allow the sulfur-containing liquid to react in an acidic environment; (4) After the reaction is completed, the supernatant is extracted and then the sulfur-containing liquid is injected into the water storage tank again. Steps (2) and (3) are repeated until the hydrogen sulfide waste gas absorption liquid is treated. The growth base is removed and the generated elemental sulfur is collected.

2. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: The hydrogen sulfide waste gas absorption liquid contains 6-12wt.% S 2- 、1.5-3wt.% OH - , 0.003-0.5wt.% Cl - , and 10-20wt.% Na + .

3. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (1), the amount of sodium sulfate added is calculated as follows: 2- , then add 15-25g of sodium sulfate.

4. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (2), the mass fraction of the sodium sulfate solution is 1-5.5%.

5. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (2), the thickness of the liquid sealing layer is 6-10 cm.

6. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (2), the growth substrate is a base material that can support, promote or regulate the occurrence of chemical reactions.

7. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (3), the acid solution is a hydrochloric acid solution or a sulfuric acid solution.

8. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 7, characterized in that: The mass fraction of the hydrochloric acid solution is 10-30%; the mass fraction of the sulfuric acid solution is 20-40%.

9. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (3), the acid injection net is evenly installed along the 1 / 4-2 / 3 interval of the water storage tank height.

10. The method for recovering elemental sulfur based on hydrogen sulfide waste gas absorption liquid according to claim 1, characterized in that: In the step (3), the standing time is 6-10 hours.

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