A method for treating vanadium electrolyte production wastewater

Abstract

This invention relates to the field of environmental protection technology, specifically to a method for treating wastewater from vanadium electrolyte production. The method includes feeding wastewater generated during vanadium electrolyte production into a microbubble reactor, followed by micro-reduction and neutralization precipitation. After the reaction is complete, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reactor, while the lower layer of slurry is discharged to a membrane concentration tank. In the high-potential catalytic oxidation reactor, the clear liquid containing organic matter undergoes catalytic oxidation treatment to obtain a purified solution. The sludge-containing wastewater is then concentrated and filtered through a membrane concentration tank to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure-filtered and washed to obtain vanadium-chromium sludge. The purified solution and filtrate are then fed into a mixing and evaporation concentration unit for further treatment to obtain anhydrous sodium sulfate. This invention solves the problem of difficult treatment or resource utilization of vanadium electrolyte production wastewater, achieving zero wastewater discharge.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a method for treating wastewater from vanadium electrolyte production. Background Technology

[0002] Low-cost vanadium electrolyte production uses a direct extraction process from vanadium precipitation solution. The solution after vanadium extraction contains approximately 0.5 g / L of vanadium, approximately 2.0 g / L of chromium, 10–15 mg / L of oil, 100–200 mg / L of organic matter, and approximately 18% of salt. This becomes wastewater that needs to be discharged for treatment, but achieving the required standards is difficult, and the process requires a large area and has a long process flow.

[0003] Currently, this type of wastewater is transported by tanker truck to a vanadium electrolyte wastewater treatment system for mixed treatment. However, because this system lacks oil and organic matter removal capabilities, it leads to system blockages, low product purity, poor appearance, and difficulty in utilizing sludge. Furthermore, since this wastewater is located in an industrial park, it must undergo harmless and resource-based treatment. Therefore, a method for treating vanadium electrolyte production wastewater is proposed to address these problems. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a method for treating vanadium electrolyte production wastewater.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] In a first aspect, in one embodiment of the present invention, a method for treating vanadium electrolyte production wastewater is provided, the method comprising the following steps:

[0007] Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction is completed, the clear liquid containing organic matter in the upper layer of the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower slurry is discharged to a membrane concentration tank.

[0008] A purified solution is obtained by catalytic oxidation of a clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank.

[0009] The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0010] The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0011] As a further aspect of the present invention, the micro-reduction and neutralization precipitation treatment includes:

[0012] Add a reducing agent at 0.5%–1.0% of the total mass of vanadium and chromium under aeration, react for 5–10 minutes, add an alkaline solution to adjust the pH to 7.2–7.5, adjust the aeration rate and continue the reaction for 30–45 minutes to make the concentration of vanadium and chromium less than 0.5 mg / L, while allowing the suspended organic matter containing extractant and oil in the wastewater to float to the surface, and let it stand for 1–1.5 hours.

[0013] As a further embodiment of the present invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system.

[0014] As a further embodiment of the present invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0015] As a further aspect of the present invention, a purified solution containing organic matter is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution, comprising:

[0016] The stir bar speed of the high-potential catalytic oxidation reactor is 300-360 rpm, and the degradation time is 30-45 min.

[0017] As a further aspect of the present invention, the high-potential catalytic oxidation reaction cell employs boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.3–0.5cm. The operating voltage is controlled at 2–4V by a regulated power supply, and the current density is 5–10mA / cm². 2 .

[0018] As a further embodiment of the present invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0019] As a further embodiment of the present invention, the flat sheet membrane filtration concentration tank is made of silicon carbide ceramic membrane sheet with a filtration pore size of 0.5-1 μm and a filtration pressure of 0.05-0.1 MPa.

[0020] As a further embodiment of the present invention, the plate and frame filter is a fully automatic filter washing machine with a filtration accuracy of 5-8 μm.

[0021] As a further aspect of the present invention, the purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration apparatus for processing to obtain anhydrous sulfuric acid, comprising:

[0022] During the process, the stirring speed is 160-200 rpm and the evaporation temperature is 95-105℃.

[0023] The technical solution provided by this invention has the following beneficial effects:

[0024] The present invention provides a method for treating vanadium electrolyte production wastewater. This method involves micro-reduction, neutralization and precipitation, microbubble separation of suspended organic matter, catalytic oxidation treatment of organic-containing brine, membrane concentration and filtration of mud-containing wastewater, and evaporation and crystallization of purified wastewater. After the above steps, vanadium and chromium resources are recovered, and high-purity anhydrous sodium sulfate product is obtained. This method solves the problem of difficult treatment or resource utilization of vanadium electrolyte production wastewater, thereby achieving zero discharge of wastewater.

[0025] These or other aspects of the invention will become more apparent from the following description of embodiments. It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0026] 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.

[0027] Figure 1 This is a flowchart illustrating a specific method for treating vanadium electrolyte production wastewater according to an embodiment of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0030] like Figure 1 As shown, the present invention provides a method for treating vanadium electrolyte production wastewater, which includes the following steps:

[0031] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0032] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0033] Add a reducing agent at 0.5%–1.0% of the total mass of vanadium and chromium under aeration, react for 5–10 minutes, add an alkaline solution to adjust the pH to 7.2–7.5, adjust the aeration rate and continue the reaction for 30–45 minutes to make the concentration of vanadium and chromium less than 0.5 mg / L, while allowing the suspended organic matter containing extractant and oil in the wastewater to float to the surface, and let it stand for 1–1.5 hours.

[0034] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.15-0.2 MPa and a bubble size of 10-30 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0035] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0036] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0037] In this embodiment of the invention, the alkaline solution is a 40-42% liquid alkali, which is generated by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0038] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0039] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0040] The stir bar of the high-potential catalytic oxidation reactor rotates at 300-360 rpm, and the degradation time is 30-45 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The purified solution obtained is mixed with membrane concentrated brine after precision filtration.

[0041] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.3–0.5cm. The operating voltage is controlled by a regulated power supply at 2–4V, and the current density is 5–10mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0042] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0043] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0044] The membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0045] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 0.5–1 μm and a filtration pressure of 0.05–0.1 MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0046] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0047] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 5-8 μm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0048] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0049] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0050] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0051] During the process, the stirring speed is 160-200 rpm and the evaporation temperature is 95-105℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0052] It should be noted that step S4, solid-liquid separation, yields anhydrous sodium sulfate with a purity greater than 98.5%, and the condensate is used as washing water for vanadium-chromium sludge.

[0053] This invention addresses the challenges of treating and utilizing vanadium electrolyte production wastewater through micro-reduction, neutralization precipitation, microbubble separation of suspended organic matter, catalytic oxidation of organic-containing brine, membrane concentration and filtration of mud-containing wastewater, and evaporation and crystallization of the purified wastewater. These steps recover vanadium and chromium resources, yielding a high-purity anhydrous sodium sulfate product. This solution aims to achieve zero wastewater discharge by addressing the difficulties in treating and utilizing vanadium electrolyte production wastewater.

[0054] Example 1

[0055] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0056] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0057] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0058] Under aeration, a reducing agent was added at 0.5% of the total mass of vanadium and chromium. The reaction was allowed to proceed for 5 minutes. An alkaline solution was then added to adjust the pH to 7.2. The aeration rate was adjusted and the reaction continued for another 30 minutes to ensure that the concentrations of vanadium and chromium were less than 0.5 mg / L. At the same time, the organic matter containing extractant and oil suspended in the wastewater was allowed to float to the surface. The mixture was then allowed to stand for 1 hour.

[0059] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.15 MPa and a bubble size of 10–30 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0060] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0061] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0062] In this embodiment of the invention, the alkaline solution is a 40-42% liquid alkali, which is generated by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0063] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0064] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0065] The stir bar in the high-potential catalytic oxidation reactor rotates at 300 rpm, and the degradation time is 30 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The resulting purified solution is mixed with membrane concentrated brine after precision filtration.

[0066] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.3cm. The operating voltage is controlled at 2-4V by a regulated power supply, and the current density is 5mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0067] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0068] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0069] In this embodiment of the invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0070] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 0.5 μm and a filtration pressure of 0.05 MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0071] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0072] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 5-8 μm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0073] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0074] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0075] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0076] During the process, the stirring speed is 160 rpm and the evaporation temperature is 95℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0077] Example 2

[0078] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0079] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0080] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0081] Under aeration, a reducing agent was added at 1.0% of the total mass of vanadium and chromium. The reaction was allowed to proceed for 10 minutes. An alkaline solution was then added to adjust the pH to 7.5. The aeration rate was adjusted and the reaction continued for another 45 minutes to ensure that the concentrations of vanadium and chromium were less than 0.5 mg / L. At the same time, the organic matter containing extractant and oil suspended in the wastewater was allowed to float to the surface. The mixture was then allowed to stand for 1.5 hours.

[0082] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.2 MPa and a bubble size of 30 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0083] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0084] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0085] In this embodiment of the invention, the alkaline solution is a 42% liquid alkali, which is produced by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0086] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0087] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0088] The stir bar in the high-potential catalytic oxidation reactor rotates at 360 rpm, and the degradation time is 45 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The purified solution obtained is mixed with membrane concentrated brine after precision filtration.

[0089] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.5cm. The operating voltage is controlled at 4V by a regulated power supply, and the current density is 10mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0090] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0091] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0092] In this embodiment of the invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0093] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 1µm and a filtration pressure of 0.1MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0094] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0095] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 5-8 μm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0096] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0097] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0098] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0099] During the process, the stirring speed is 200 rpm and the evaporation temperature is 105℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0100] Example 3

[0101] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0102] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0103] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0104] Under aeration, a reducing agent was added at 0.6% of the total mass of vanadium and chromium. The reaction was allowed to proceed for 6 minutes. An alkaline solution was added to adjust the pH to 7.25. The aeration rate was adjusted and the reaction continued for 33 minutes to ensure that the concentrations of vanadium and chromium were less than 0.5 mg / L. At the same time, the organic matter containing extractant and oil suspended in the wastewater was allowed to float to the surface. The mixture was then allowed to stand for 1.1 hours.

[0105] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.16 MPa and a bubble size of 15 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0106] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0107] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0108] In this embodiment of the invention, the alkaline solution is a 40.5% liquid alkali, which is generated by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0109] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0110] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0111] The stir bar in the high-potential catalytic oxidation reactor rotates at 310 rpm, and the degradation time is 33 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The resulting purified solution is mixed with membrane concentrated brine after precision filtration.

[0112] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.35cm. The operating voltage is controlled at 2.5V by a regulated power supply, and the current density is 6mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0113] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0114] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0115] In this embodiment of the invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0116] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 0.6 μm and a filtration pressure of 0.06 MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0117] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0118] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 5-8 μm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0119] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0120] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0121] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0122] During the process, the stirring speed is 170 rpm and the evaporation temperature is 98℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0123] Example 4

[0124] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0125] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0126] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0127] Under aeration, a reducing agent was added at 0.9% of the total mass of vanadium and chromium. The reaction was allowed to proceed for 9 minutes. An alkaline solution was then added to adjust the pH to 7.45. The aeration rate was adjusted and the reaction continued for another 42 minutes to ensure that the concentrations of vanadium and chromium were less than 0.5 mg / L. At the same time, the organic matter containing extractant and oil suspended in the wastewater was allowed to float to the surface. The mixture was then allowed to stand for 1.4 hours.

[0128] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.19 MPa and a bubble size of 25 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0129] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0130] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0131] In this embodiment of the invention, the alkaline solution is a 41.5% liquid alkali, which is generated by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0132] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0133] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0134] The stir bar in the high-potential catalytic oxidation reactor rotates at 350 rpm, and the degradation time is 42 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The purified solution obtained is mixed with membrane concentrated brine after precision filtration.

[0135] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.45cm. The operating voltage is controlled by a regulated power supply at 3.5V, and the current density is 9mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0136] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0137] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0138] In this embodiment of the invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0139] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 0.9 μm and a filtration pressure of 0.09 MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0140] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0141] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 8µm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0142] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0143] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0144] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0145] During the process, the stirring speed is 190 rpm and the evaporation temperature is 102℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0146] Example 5

[0147] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0148] S1. Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction treatment is completed, the upper layer of clear liquid containing organic matter in the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower layer of slurry is discharged to a membrane concentration tank.

[0149] In this embodiment of the invention, the micro-reduction and neutralization precipitation treatment includes:

[0150] Under aeration, a reducing agent was added at 0.75% of the total mass of vanadium and chromium. The reaction was allowed to proceed for 7 minutes. An alkaline solution was then added to adjust the pH to 7.4. The aeration rate was adjusted and the reaction continued for another 28 minutes to ensure that the concentrations of vanadium and chromium were less than 0.5 mg / L. At the same time, the organic matter containing extractant and oil suspended in the wastewater was allowed to float to the surface. The mixture was then allowed to stand for 1.2 hours.

[0151] In this embodiment of the invention, the microbubble reactor is a TV-type high-efficiency dissolved gas system with a working pressure of 0.18 MPa and a bubble size of 20 μm. The gas source used in this process is N2 to ensure that the reaction process is reducing, so as to fully remove vanadium and chromium.

[0152] The bubbles generated by the microbubble reactor carry out emulsified oily organic matter suspended in wastewater and entrained in sediments, and float it to the surface of the wastewater, thus fully separating the organic matter and reducing its impact on subsequent treatment processes and the appearance of the product.

[0153] In this embodiment of the invention, the reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

[0154] In this embodiment of the invention, the alkaline solution is a 41% liquid alkali, which is produced by chlor-alkali ion-exchange membrane electrolysis. It is low in cost, and this concentration reduces the amount of water introduced, thus ensuring the water balance of the system.

[0155] S2. The organic-containing liquid is subjected to catalytic oxidation treatment in a high-potential catalytic oxidation reaction tank to obtain a purified solution.

[0156] In this embodiment of the invention, step S2, catalytic oxidation treatment of the clear liquid containing organic matter in a high-potential catalytic oxidation reaction tank to obtain a purified solution, includes:

[0157] The stir bar in the high-potential catalytic oxidation reactor rotates at 330 rpm, and the degradation time is 38 min. After degradation, the organic matter is completely decomposed, the oil content is less than 0.5 mg / L, and the COD is less than 15 mg / L. The resulting purified solution is mixed with membrane concentrated brine after precision filtration.

[0158] In this embodiment of the invention, the high-potential catalytic oxidation reaction cell uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.4cm. The operating voltage is controlled at 3V by a regulated power supply, and the current density is 7mA / cm². 2 Meanwhile, the high-potential catalytic oxidation reactor is equipped with a gas extraction system at the top, and the collected gas can be sent to the microbubble reactor as supplementary gas.

[0159] S3. The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge.

[0160] In this embodiment of the invention, S3, the mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge, comprising:

[0161] In this embodiment of the invention, the membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

[0162] In this embodiment of the invention, the flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets pressed together, with a filtration pore size of 0.8 μm and a filtration pressure of 0.08 MPa. The advantage of using a flat-sheet membrane filtration concentration tank is that it has a small footprint and high filtration accuracy.

[0163] In this embodiment of the invention, the concentrated slurry is filtered using a plate and frame filter.

[0164] In this embodiment of the invention, the plate and frame filter is a fully automatic filter washing machine from Chengdu Changjie Technology Co., Ltd., with a filtration accuracy of 5-8 μm, made of high-pressure resistant polyvinyl chloride, and the washing process is a counter-current three-stage washing.

[0165] It should be noted that the filtrate consists of Na. + 50-55 g / L, SO4 2- 145~150g / L, Cl - <0.5g / L, V≤0.2mg / L, Cr≤0.1mg / L, Ca<0.01g / L, pH6.5~7.0.

[0166] S4. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

[0167] Step S4 involves feeding the purified solution and filtrate into a mixing and then feeding them into an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid, including:

[0168] During the process, the stirring speed is 180 rpm and the evaporation temperature is 100℃. The mixture is concentrated until sodium sulfate is saturated, and then cooled to 85℃ to crystallize and precipitate anhydrous sodium sulfate.

[0169] Example 6

[0170] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0171] S1. Vanadium electrolyte production wastewater is fed into a microbubble reactor. Under aeration, sodium metabisulfite reducing agent is added at 1.0% of the total mass of (V+Cr). The reaction is carried out for 10 minutes. Then, 40% liquid alkali is added to adjust the pH to 7.3. Aeration is adjusted to microbubble mode and the reaction is carried out for 45 minutes. Aeration is then stopped and the mixture is allowed to stand for 1.5 hours. The solution is divided into upper, middle and lower layers. The lower layer is vanadium-chromium slurry, the middle layer is the solution after removing organic matter, V and Cr, and the upper layer is oily organic wastewater.

[0172] S2. Oily organic wastewater is scraped into a high-potential catalytic oxidation tank. The power is turned on and the voltage is adjusted to a stable 4V. Degradation takes place for 45 minutes. The clear liquid is analyzed for oil content and COD. The results show that the oil content is 0.2 mg / L and the COD content is 6 mg / L. The degraded brine is then filtered through a 1.0-micron precision filter and sent to a concentrated brine tank.

[0173] S3. The remaining wastewater and slurry from the microbubble reactor are sent to the flat-plate membrane filtration concentration tank. The membrane filtration is started, and the vanadium-chromium sludge is trapped on the membrane surface. The filtrate is sent to the concentrated brine tank through the inner tube. The composition of the obtained filtrate is shown in Table 1. The V content is 0.1 mg / L, Cr < 0.1 mg / L, the salt content is concentrated to a certain extent, reaching about 20%, and the pH is weakly acidic. It can be directly sent to the evaporation concentration device for further concentration.

[0174] Table 1. Composition of brine after flat sheet membrane filtration (g / L)

[0175]

[0176] The sludge trapped on the membrane surface is filtered by plate and frame filter press, washed, and dried at 105℃. Its composition is shown in Table 2. The Cr content reaches about 23%, which can be further purified.

[0177] Table 2. Component analysis results of vanadium-chromium sludge after drying / %

[0178]

[0179] S4. The brine from the concentration tank is pumped into an evaporation and concentration device, where it is further concentrated to saturation at 100℃~105℃, so that Na... +When the content reaches 120-130 g / L, it is discharged into the DBT crystallizer, 0.2% sodium sulfate seed crystals are added, the stirring speed is controlled at 180 rpm, the temperature is gradually reduced to 85℃ and kept at this temperature for 2 hours, and finally centrifugation is used to obtain high-purity anhydrous sodium sulfate. After drying, its indicators are shown in Table 3, which meet the Class II superior grade of the anhydrous sodium sulfate product standard.

[0180] Table 3. Parameters of anhydrous sodium sulfate after drying

[0181]

[0182] Example 7

[0183] A method for treating wastewater from vanadium electrolyte production includes the following steps:

[0184] S1. Vanadium electrolyte production wastewater is fed into a microbubble reactor. Under aeration, sodium metabisulfite reducing agent is added at 0.6% of the total mass of (V+Cr). The reaction is carried out for 10 minutes. Then, 40% liquid alkali is added to adjust the pH to 7.5. The aeration is adjusted to microbubble mode and the reaction is carried out for 30 minutes. Aeration is then stopped and the mixture is allowed to stand for 1.0 h. The solution is divided into upper, middle and lower layers. The lower layer is vanadium-chromium slurry, the middle layer is the solution after removing organic matter, V and Cr, and the upper layer is oily organic wastewater.

[0185] S2. Oily organic wastewater is scraped into a high-potential catalytic oxidation tank. The power is turned on and the voltage is adjusted to a stable 3V. Degradation takes 45 minutes.

[0186] The clarified liquid was analyzed for oil content and COD, with results showing an oil content of 0.5 mg / L and a COD content of 12 mg / L. The degraded brine was then filtered through a 1.0-micron precision filter before being sent to a concentrated brine tank.

[0187] S3. Send the remaining wastewater and slurry from the microbubble reactor to the flat-plate membrane filtration thickening tank, start membrane filtration, and the vanadium-chromium-containing sludge is...

[0188] The filtrate is retained on the membrane surface and sent to the concentrated brine tank through the inner tube. The composition of the obtained filtrate is shown in Table 4. The V content is 0.6 mg / L, the Cr content is 0.3 mg / L, the salt content is concentrated to a certain extent, reaching about 20%, and the pH is weakly acidic. It can be directly sent to the evaporation and concentration device for further concentration.

[0189] Table 4. Composition of brine after flat sheet membrane filtration (g / L)

[0190]

[0191] The sludge trapped on the membrane surface is filtered by plate and frame filter press, washed, and dried at 105℃. Its composition is shown in Table 5. The Cr content reaches about 23%, which can be further purified.

[0192] Table 5. Component analysis results of vanadium-chromium sludge after drying / %

[0193]

[0194] S4. The brine from the concentration tank is pumped into an evaporation and concentration device, where it is further concentrated to saturation at 100℃~105℃, so that Na... + When the content reaches 120-130 g / L, it is discharged into the DBT crystallizer, 0.2% sodium sulfate seed crystals are added, the stirring speed is controlled at 180 rpm, the temperature is gradually reduced to 85℃ and kept at this temperature for 2 hours, and finally centrifugation is used to obtain high-purity anhydrous sodium sulfate. After drying, its indicators are shown in Table 6, which meet the Class II superior grade of the anhydrous sodium sulfate product standard.

[0195] Table 6. Parameters of anhydrous sodium sulfate after drying

[0196]

[0197] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for treating wastewater from vanadium electrolyte production, characterized in that, The method includes: Wastewater generated during the vanadium electrolyte production process is fed into a microbubble reactor, where it undergoes micro-reduction and neutralization precipitation treatment. After the reaction is completed, the clear liquid containing organic matter in the upper layer of the microbubble reactor flows into a high-potential catalytic oxidation reaction tank, while the lower slurry is discharged to a membrane concentration tank. The micro-reduction and neutralization precipitation treatment includes: adding a reducing agent at 0.5%–1.0% of the total mass of vanadium and chromium under aeration, reacting for 5–10 minutes, adding an alkaline solution to adjust the pH to 7.2–7.5, adjusting the aeration rate, and continuing the reaction for 30–45 minutes to ensure that the concentration of vanadium and chromium is less than 0.5 mg / L. Simultaneously, the organic matter containing extractant and oil suspended in the wastewater floats to the surface, and the mixture is allowed to stand for 1–1.5 hours. The bubbles generated by the microbubble reactor carry out the emulsified oily organic matter suspended in the wastewater and entrained in the precipitate, and float it to the surface of the wastewater, thus fully separating the organic matter. A purified solution is obtained by catalytic oxidation of a clarified liquid containing organic matter in a high-potential catalytic oxidation reactor. The high-potential catalytic oxidation reactor uses boron-doped diamond (BDD) electrodes with a high oxidation potential of 2.8V and an electrode spacing of 0.3–0.5cm. The operating voltage is controlled at 2–4V by a regulated power supply, and the current density is 5–10mA / cm². 2 ; The mud-containing wastewater is concentrated and filtered through a membrane thickener to obtain filtrate and concentrated slurry. The concentrated slurry is then pressure filtered and washed to obtain vanadium-chromium sludge. The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sodium sulfate.

2. The method for treating vanadium electrolyte production wastewater as described in claim 1, characterized in that, The microbubble reactor is a TV-type high-efficiency dissolved gas system.

3. The method for treating vanadium electrolyte production wastewater as described in claim 2, characterized in that, The reducing agent is any combination of sodium metabisulfite and sodium thiosulfate.

4. The method for treating vanadium electrolyte production wastewater as described in claim 1, characterized in that, A purified solution containing organic matter is obtained by catalytic oxidation treatment of a clear liquid in a high-potential catalytic oxidation reactor, comprising: The stir bar speed of the high-potential catalytic oxidation reactor is 300-360 rpm, and the degradation time is 30-45 min.

5. The method for treating vanadium electrolyte production wastewater as described in claim 1, characterized in that, The membrane concentration tank includes a flat-sheet membrane filtration concentration tank.

6. The method for treating vanadium electrolyte production wastewater as described in claim 5, characterized in that, The flat-sheet membrane filtration concentration tank uses silicon carbide ceramic membrane sheets that are pressed together, with a filtration pore size of 0.5-1 μm and a filtration pressure of 0.05-0.1 MPa.

7. The method for treating vanadium electrolyte production wastewater as described in claim 1, characterized in that, The purified solution and filtrate are fed into a mixing and then sent to an evaporation and concentration unit for processing to obtain anhydrous sulfuric acid. The process includes a stirring speed of 160-200 rpm and an evaporation temperature of 95-105°C.

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