A method for treating sodium-containing vanadium precipitation wastewater

Abstract

The application discloses a sodium vanadium precipitation wastewater treatment method, comprising the following steps: adding ferrous sulfate into sodium vanadium precipitation wastewater and stirring; stirring, precipitating and filtering after adjusting pH value by using a first alkaline solution to obtain vanadium-iron compound precipitate and a first filtrate; adding tetraacetyl diamine into the first filtrate and stirring; stirring, precipitating and filtering after adjusting pH value by using a second alkaline solution to obtain chromium-silicon compound precipitate and sodium sulfate solution. The scheme provided by the application uses ferrous sulfate for reduction, so that most vanadium is separated by adjusting a certain pH value and filtering, the vanadium can be applied to smelting vanadium-iron alloy, chromium-silicon slag is further recovered and smelted into chromium-iron, silicon is left in the chromium slag as an advantageous regulator for smelting chromium-iron, ammonia is removed in the process of adjusting pH value of the recovered chromium-silicon slag, special ammonia removal is not needed, and vanadium and chromium are not separated through vanadium-chromium filter cake.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, specifically to a method for treating sodium vanadium precipitation wastewater. Background Technology

[0002] In the vanadium extraction process of vanadium slag sodium leaching, the vanadium slag is roasted, water-leached and impurities removed to obtain qualified vanadium leaching liquid. The qualified liquid is then subjected to acidic ammonium salt precipitation process to obtain ammonium polyvanadate (APV). The ammonium polyvanadate is calcined at about 500℃ for 3 to 5 hours to obtain vanadium pentoxide.

[0003] The wastewater after vanadium precipitation by acidic ammonium salts is called sodium vanadium precipitation wastewater. This wastewater contains a large amount of ammonium ions, a small amount of silicon, and a small amount of vanadium and chromium. The traditional method mainly involves first reducing vanadium and chromium simultaneously, then adjusting the pH value to precipitate vanadium and chromium, followed by deammoniation, and finally concentration and distillation to recover sodium sulfate.

[0004] However, in general, vanadium-precipitated wastewater is first deamed and then reduced and precipitated to obtain vanadium-chromium filter cake, and the sodium sulfate solution is then concentrated to recover sodium sulfate. But because deaming is done first, the cost of deaming is high, the vanadium content in the obtained vanadium-chromium filter cake is also high, and the loss of vanadium is large. After the reduction and precipitation of vanadium-chromium, some silicates are still present in the sodium sulfate solution, which seriously affects the quality of sodium sulfate. Summary of the Invention

[0005] In view of this, in order to overcome at least one aspect of the above-mentioned problems, embodiments of the present invention propose a method for treating sodium vanadium precipitation wastewater, comprising the following steps:

[0006] Add ferrous sulfate to the sodium vanadium precipitation wastewater and stir;

[0007] After adjusting the pH value with the first alkaline solution, the mixture was stirred, precipitated, and filtered to obtain vanadium-iron compound precipitate and the first filtrate.

[0008] Add tetraacetyldiamine to the first filtrate and stir;

[0009] After adjusting the pH value with a second alkaline solution, the mixture was stirred, precipitated, and filtered to obtain a chromium-silicon compound precipitate and a sodium sulfate solution.

[0010] In some embodiments, adding ferrous sulfate to the sodium vanadium precipitation wastewater and stirring further includes:

[0011] Ferrous sulfate is added to the sodium vanadium precipitation wastewater based on a ferrous sulfate to chromium molar ratio of 2.5 to 3:1.

[0012] In some embodiments, the method further includes:

[0013] After adding ferrous sulfate to the sodium vanadium precipitation wastewater, stir for 20-40 minutes.

[0014] In some embodiments, after adjusting the pH value with a first alkaline solution, stirring, precipitation, and filtration are performed to obtain a vanadium-iron compound precipitate and a first filtrate, further comprising:

[0015] Adjust the pH value to 3.2-3.7 using sodium hydroxide solution and stir for 10-20 minutes.

[0016] In some embodiments, adding tetraacetyldiamine to the first filtrate and stirring further includes:

[0017] Tetraacetyldiamine is added to the first filtrate at a ratio of 0.2-0.5g of tetraacetyldiamine per liter of the first filtrate.

[0018] In some embodiments, the method further includes:

[0019] After adding the tetraacetyldiamine, stir for 20-40 minutes.

[0020] In some embodiments, adjusting the pH value using a second alkaline solution further includes:

[0021] Adjust the pH value to 8-9 using sodium hydroxide or calcium oxide solution, raise the temperature to 60-80℃, and stir for 10-30 minutes.

[0022] In some embodiments, the method further includes:

[0023] Vanadium-containing vanadium solution is precipitated with acidic ammonium salt to obtain sodium-containing vanadium-precipitated wastewater. The sodium-containing vanadium-precipitated wastewater contains 28-35 g / L sodium ions, 8-12 g / L ammonium ions, 1-3 g / L chromium, 1.0-2.0 g / L silicon ions, 0.1-0.4 g / L vanadium ions, and the remainder is sulfate ions.

[0024] In some embodiments, the method further includes:

[0025] The vanadium-iron compound is used to precipitate and smelt vanadium-iron alloy.

[0026] In some embodiments, the method further includes:

[0027] Ferrochromium alloys are smelted using the precipitation of the chromium-silicon compound.

[0028] This invention offers one of the following beneficial technical effects: The proposed solution utilizes ferrous sulfate for reduction, thereby achieving filtration by adjusting the pH value. This first separates most of the vanadium, which can be used in the smelting of ferrovanadium alloys. Further, the chromium-silicon slag is recovered for ferrochrome smelting, while silicon remains in the chromium slag as a beneficial regulator in ferrochrome smelting. During the pH adjustment process of recovering the chromium-silicon slag, by adjusting the pH to alkaline, ammonium ions in the wastewater are converted to ammonia, primarily existing in the form of free ammonia. During the heating process, this ammonia is carried out of the wastewater by a heat carrier, eliminating the need for dedicated ammonia removal or separation of vanadium and chromium through a vanadium-chromium filter cake. This overcomes the shortcomings of separate silicon removal, separate vanadium and chromium removal, and separate ammonia removal. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic flowchart of a method for treating vanadium precipitate wastewater provided in an embodiment of the present invention;

[0031] Figure 2 A flowchart illustrating the sodium vanadium precipitation wastewater treatment method provided in an embodiment of the present invention;

[0032] Figure 3 A schematic diagram of the main components of sodium vanadium precipitation wastewater and filtrate provided for embodiments of the present invention;

[0033] Figure 4 A schematic diagram showing the content and yield of the main components of the filter residue provided in the embodiments of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0035] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0036] According to one aspect of the present invention, embodiments of the present invention provide a method for treating sodium vanadium precipitation wastewater, such as... Figure 1 As shown, it may include the following steps:

[0037] Add ferrous sulfate to the sodium vanadium precipitation wastewater and stir;

[0038] After adjusting the pH value with the first alkaline solution, the mixture was stirred, precipitated, and filtered to obtain vanadium-iron compound precipitate and the first filtrate.

[0039] Add tetraacetyldiamine to the first filtrate and stir;

[0040] After adjusting the pH value with a second alkaline solution, the mixture was stirred, precipitated, and filtered to obtain a chromium-silicon compound precipitate and a sodium sulfate solution.

[0041] Typically, vanadium-containing wastewater undergoes deammoniation followed by reduction and precipitation to obtain a vanadium-chromium filter cake. The sodium sulfate solution is then concentrated to recover the sodium sulfate. However, deammoniation alone is costly, and the resulting vanadium-chromium filter cake has a high vanadium content, resulting in significant vanadium loss. Even after the reduction and precipitation of vanadium and chromium, some silicates remain in the sodium sulfate solution, severely impacting the quality of the sodium sulfate. The proposed solution utilizes ferrous sulfate for reduction, thereby achieving filtration by adjusting the pH value. This first separates most of the vanadium, which can be used in the smelting of ferrovanadium alloys. Further, the chromium-silicon slag is recovered for ferrochrome smelting, with silicon remaining in the chromium slag as a beneficial regulator in ferrochrome smelting. Deammoniation occurs during the pH adjustment process of the recovered chromium-silicon slag, eliminating the need for separate deammoniation and the separation of vanadium and chromium through the vanadium-chromium filter cake.

[0042] In some embodiments, a certain volume of sodium vanadium precipitation wastewater can be measured first and stirred. In this step, the sodium vanadium precipitation wastewater is the wastewater after vanadium precipitation by acidic ammonium salt of sodium vanadium solution. The main components of the wastewater are sodium ions (28-35 g / L), ammonium ions (8-12 g / L), chromium ions (1-3 g / L), silicon ions (1.0-2.0 g / L), vanadium ions (0.1-0.4 g / L), and sulfate ions. Then, a certain amount of ferrous sulfate is added, and stirring is continued for a certain time. In this step, the ratio of ferrous sulfate molar to chromium molar is 2.5-3:1, and the stirring time is 20-40 minutes. Next, the pH is adjusted to a certain range, stirred for a certain time, and then filtered to obtain the first filter residue and the first filtrate. In this step, sodium hydroxide is used to adjust the pH to 3.2-3.7, and the stirring time is 10-20 minutes. Next, a certain amount of tetraacetyldiamine is added to the first filtrate, and the mixture is stirred for a certain period of time. In this step, the amount of tetraacetyldiamine added is 0.2-0.5 g per liter of the first filtrate, and the stirring time is 20-40 minutes. Then, the pH is adjusted to a certain value using calcium oxide or sodium hydroxide, and the mixture is heated to a certain temperature and stirred for a certain period of time before filtration. In this step, the pH is 8-9, the temperature is raised to a certain temperature of 60-80℃, and the stirring time is 10-30 minutes. Finally, a second filter residue and a second filtrate are obtained. The second filtrate is a transparent, colorless sodium sulfate solution, and the second filter residue is mainly chromium-silicon slag, which can be used in the smelting of ferrochrome.

[0043] In some embodiments, adding ferrous sulfate to the sodium vanadium precipitation wastewater and stirring further includes:

[0044] Ferrous sulfate is added to the sodium vanadium precipitation wastewater based on a ferrous sulfate to chromium molar ratio of 2.5 to 3:1.

[0045] In some embodiments, the method further includes:

[0046] After adding ferrous sulfate to the sodium vanadium precipitation wastewater, stir for 20-40 minutes.

[0047] In some embodiments, after adjusting the pH value with a first alkaline solution, stirring, precipitation, and filtration are performed to obtain a vanadium-iron compound precipitate and a first filtrate, further comprising:

[0048] Adjust the pH value to 3.2-3.7 using sodium hydroxide solution and stir for 10-20 minutes.

[0049] In some embodiments, adding tetraacetyldiamine to the first filtrate and stirring further includes:

[0050] Tetraacetyldiamine is added to the first filtrate at a ratio of 0.2-0.5g of tetraacetyldiamine per liter of the first filtrate.

[0051] In some embodiments, the method further includes:

[0052] After adding the tetraacetyldiamine, stir for 20-40 minutes.

[0053] In some embodiments, adjusting the pH value using a second alkaline solution further includes:

[0054] Adjust the pH value to 8-9 using sodium hydroxide or calcium oxide solution, raise the temperature to 60-80℃, and stir for 10-30 minutes.

[0055] In some embodiments, the method further includes:

[0056] Vanadium-containing vanadium solution is precipitated with acidic ammonium salt to obtain sodium-containing vanadium-precipitated wastewater. The sodium-containing vanadium-precipitated wastewater contains 28-35 g / L sodium ions, 8-12 g / L ammonium ions, 1-3 g / L chromium, 1.0-2.0 g / L silicon ions, 0.1-0.4 g / L vanadium ions, and the remainder is sulfate ions.

[0057] In some embodiments, the method further includes:

[0058] The vanadium-iron compound is used to precipitate and smelt vanadium-iron alloy.

[0059] In some embodiments, the method further includes:

[0060] Ferrochromium alloys are smelted using the precipitation of the chromium-silicon compound.

[0061] Specifically, such as Figure 2 As shown, a certain volume of sodium vanadium-precipitated wastewater is first measured and stirred. Ferrous sulfate is added at a molar ratio of ferrous sulfate to chromium of 2.5–3:1, and stirring continues for 20–40 minutes. The pH is adjusted to 3.2–3.7, and after stirring for 10–20 minutes, the mixture is filtered to obtain the first filter residue (vanadium-iron compound precipitate) and the first filtrate. 0.2–0.5 g of tetraacetyldiamine is added to each liter of the first filtrate, and the mixture is stirred for 20–40 minutes. The pH is adjusted to 8–9 using calcium oxide or sodium hydroxide, and the mixture is heated to 60–80°C and stirred for 10–30 minutes, then filtered. This yields the second filter residue (chromium-silicon compound precipitate) and the second filtrate (sodium sulfate solution).

[0062] The proposed solution utilizes ferrous sulfate for reduction, thereby achieving filtration by adjusting a certain pH value. This first separates most of the vanadium, which can be used in the smelting of ferrovanadium alloys. Then, the chromium-silicon slag is further recovered to smelt ferrochrome, while silicon remains in the chromium slag as a beneficial regulator for ferrochrome smelting. During the pH adjustment process of recovering the chromium-silicon slag, ammonia is removed, eliminating the need for dedicated ammonia removal and separation of vanadium and chromium through vanadium-chromium filter cake.

[0063] Example 1

[0064] First, measure 200 mL of sodium vanadium precipitation wastewater and stir. Add 3.65 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 2.5:1) and continue stirring for 20 min. Adjust the pH to 3.2, stir for 10 min, and then filter to obtain the first filter residue and the first filtrate. Add 0.2 g of tetraacetyldiamine per liter of the first filtrate and stir for 20 min. Adjust the pH to 8 using sodium hydroxide, heat to 60℃, stir for 10 min, and then filter. Obtain the second filter residue and the second filtrate. The content of each component in the second filtrate, the first filter residue, and the second filter residue is shown in the figure. Figure 3 and Figure 4 .

[0065] Comparative Example 1-1 (without tetraacetyldiamine)

[0066] First, measure 200 mL of sodium vanadium precipitation wastewater and stir. Add 3.65 g of ferrous sulfate at a molar ratio of ferrous sulfate to chromium of 2.5:1, and continue stirring for 20 min. Adjust the pH to 3.2, stir for 10 min, and then filter to obtain the first filter residue and the first filtrate. Adjust the pH to 8 using sodium hydroxide, heat to 60℃, stir for 10 min, and then filter. Obtain the second filter residue and the second filtrate. See below for the content of each component. Figure 3 and Figure 4 .

[0067] Comparative Examples 1-2 (no filtration, no addition of tetraacetyldiamine)

[0068] First, measure 200 mL of sodium vanadium precipitation wastewater and stir. Add 3.65 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 2.5:1) and continue stirring for 20 min. Adjust the pH to 3.2 and stir for 10 min. Then, adjust the pH to 8 using sodium hydroxide, heat to 60℃ and stir for 10 min, then filter. Obtain the filter residue and filtrate. See below for the content of each component. Figure 3 and Figure 4 .

[0069] Therefore, the proposed method can effectively extract vanadium-iron compounds and chromium-silicon compounds.

[0070] Example 2

[0071] First, measure 400 mL of sodium vanadium precipitation wastewater and stir. Add 8.18 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 2.8:1) and continue stirring for 30 min. Adjust the pH to 3.5, stir for 15 min, and then filter to obtain the first filter residue and the first filtrate. Add 0.35 g of tetraacetyldiamine per liter of the first filtrate and stir for 30 min. Adjust the pH to 8.5 using calcium oxide or sodium hydroxide, heat to 70℃, stir for 20 min, and then filter. Obtain the second filter residue and the second filtrate. The content of each component is shown in the table below. Figure 3 and Figure 4 .

[0072] Comparative Example 2-1 (without tetraacetyldiamine)

[0073] First, measure 400 mL of sodium vanadium precipitation wastewater and stir. Add 8.18 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 2.8:1) and continue stirring for 30 min. Adjust the pH to 3.5, stir for 15 min, and then filter to obtain the first filter residue and the first filtrate. Adjust the pH to 8.5 using calcium oxide or sodium hydroxide, heat to 70℃, stir for 20 min, and then filter. Obtain the first filter residue, the second filter residue, and the second filtrate. The content of each component is shown in the figure. Figure 3 and Figure 4 .

[0074] Comparative Example 2-2 (no filtration, no addition of tetraacetyldiamine)

[0075] First, measure 400 mL of sodium vanadium precipitation wastewater and stir. Add 8.18 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 2.8:1) and continue stirring for 30 min. Adjust the pH to 3.5 and stir for 15 min. Then, adjust the pH to 8.5 using calcium oxide or sodium hydroxide, heat to 70℃ and stir for 20 min, then filter. Obtain the filter residue and filtrate. The content of each component is shown in the table below. Figure 3 and Figure 4 .

[0076] Therefore, the proposed method can effectively extract vanadium-iron compounds and chromium-silicon compounds.

[0077] Example 3

[0078] First, measure 1000 mL of sodium vanadium precipitation wastewater and stir. Add 21.92 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 3:1) and continue stirring for 40 min. Adjust the pH to 3.7, stir for 20 min, and then filter to obtain the first filter residue and the first filtrate. Add 0.5 g of tetraacetyldiamine per liter of the first filtrate and stir for 40 min. Adjust the pH to 9 using calcium oxide or sodium hydroxide, heat to 80℃, stir for 30 min, and then filter. Obtain the second filter residue and the second filtrate. The content of each component is shown in the figure. Figure 3 and Figure 4 .

[0079] Comparative Example 3-1 (without tetraacetyldiamine)

[0080] First, measure 1000 mL of sodium vanadium precipitation wastewater and stir. Add 21.92 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 3:1) and continue stirring for 40 min. Adjust the pH to 3.7, stir for 20 min, and then filter to obtain the first filter residue and the first filtrate. Adjust the pH to 9 using calcium oxide or sodium hydroxide, heat to 80℃, stir for 30 min, and then filter. Obtain the first filter residue, the second filter residue, and the second filtrate. The content of each component is shown in the figure. Figure 3 and Figure 4 .

[0081] Comparative Example 3-2 (no filtration, no addition of tetraacetyldiamine)

[0082] First, measure 1000 mL of sodium vanadium precipitation wastewater and stir. Add 21.92 g of ferrous sulfate (molar ratio of ferrous sulfate to chromium = 3:1) and continue stirring for 40 min. Adjust the pH to 3.7 and stir for 20 min. Then, adjust the pH to 9 using calcium oxide or sodium hydroxide, heat to 80℃ and stir for 30 min, and filter. Obtain the filter residue and filtrate. The content of each component is shown in the table below. Figure 3 and Figure 4 .

[0083] Therefore, the proposed method can effectively extract vanadium-iron compounds and chromium-silicon compounds.

[0084] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0085] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0086] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0087] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for treating sodium vanadium precipitation wastewater, characterized in that, Includes the following steps: Add ferrous sulfate to the sodium vanadium precipitation wastewater and stir; After adjusting the pH value to 3.2-3.7 using the first alkaline solution, the mixture was stirred, precipitated, and filtered to obtain vanadium-iron compound precipitate and the first filtrate. Add tetraacetyldiamine to the first filtrate and stir; The pH value was adjusted to 8-9 using a second alkaline solution. After the temperature was raised to 60-80℃, the mixture was stirred, precipitated, and filtered to obtain chromium-silicon compound precipitate and sodium sulfate solution. During the pH adjustment process, ammonium ions in the sodium vanadium precipitation wastewater were converted to ammonia and existed in the form of free ammonia. During the heating process, the ammonia was carried out of the wastewater by a heat carrier, without the need for special ammonia removal.

2. The method as described in claim 1, characterized in that, Adding ferrous sulfate to the sodium vanadium precipitation wastewater and stirring further includes: Ferrous sulfate is added to the sodium vanadium precipitation wastewater based on a ferrous sulfate to chromium molar ratio of 2.5 to 3:

1.

3. The method as described in claim 2, characterized in that, Also includes: After adding ferrous sulfate to the sodium vanadium precipitation wastewater, stir for 20-40 minutes.

4. The method as described in claim 1, characterized in that, After adjusting the pH value with a first alkaline solution, the mixture is stirred, precipitated, and filtered to obtain a vanadium-iron compound precipitate and a first filtrate, which further includes: Adjust the pH value to 3.2-3.7 using sodium hydroxide solution and stir for 10-20 minutes.

5. The method as described in claim 1, characterized in that, Adding tetraacetyldiamine to the first filtrate and stirring further includes: Tetraacetyldiamine is added to the first filtrate at a ratio of 0.2-0.5g of tetraacetyldiamine per liter of the first filtrate.

6. The method as described in claim 5, characterized in that, Also includes: After adding the tetraacetyldiamine, stir for 20-40 minutes.

7. The method as described in claim 1, characterized in that, Adjusting the pH value using a second alkaline solution further includes: Adjust the pH value to 8-9 using sodium hydroxide or calcium oxide solution, raise the temperature to 60-80℃, and stir for 10-30 minutes.

8. The method as described in claim 1, characterized in that, Also includes: Vanadium-containing vanadium solution is precipitated with acidic ammonium salt to obtain sodium-containing vanadium-precipitated wastewater. The sodium-containing vanadium-precipitated wastewater contains 28-35 g / L sodium ions, 8-12 g / L ammonium ions, 1-3 g / L chromium, 1.0-2.0 g / L silicon ions, 0.1-0.4 g / L vanadium ions, and the remainder is sulfate ions.

9. The method as described in claim 1, characterized in that, Also includes: The vanadium-iron compound is used to precipitate and smelt vanadium-iron alloy.

10. The method as described in claim 1, characterized in that, Also includes: Ferrochromium alloys are smelted using the precipitation of the chromium-silicon compound.

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