Method for separating vanadium and tungsten from sodium-containing vanadium and tungsten solution and synchronously recovering sodium

Abstract

The invention relates to a method for synchronously separating vanadium and tungsten from a sodium-containing vanadium-tungsten solution and recovering sodium, which comprises the following steps: (1) by taking a mixed solution containing sodium vanadate and sodium tungstate as an anode solution, a sodium hydroxide solution as a cathode solution and a cation exchange membrane and a bipolar membrane as electrolytic diaphragms, carrying out electrolysis, a low-sodium solution containing vanadium and tungsten is obtained at the anode, and a recovered sodium hydroxide solution is obtained at the cathode; (2) mixing a reducing agent and the low-sodium vanadium-tungsten-containing solution, and carrying out heating reduction to obtain a reduced solution; and (3) mixing a first extraction agent and the reduced solution obtained in the step (2), and carrying out first extraction separation to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution. And further separating to obtain an ammonium tungstate solution and a vanadyl sulfate solution. The method is simple and easy to implement, and compared with a traditional vanadium-tungsten separation process, sufficient separation of vanadium and tungsten can be achieved, meanwhile, sodium hydroxide is effectively recycled, and sodium-containing wastewater is prevented from being generated from the source.

Description

Technical Field

[0001] The invention relates to the technical field of efficient separation of vanadium and tungsten, and in particular to a method for separating vanadium and tungsten and simultaneously recovering sodium from a sodium-containing vanadium and tungsten solution. Background Art

[0002] Ammonium tungstate is a white crystalline powder with the molecular formula (NH4) 10 W 12 O 41 ·5H2O, mainly used to make ammonium metatungstate and other tungsten compounds, or used as an additive in the petrochemical industry. Vanadyl sulfate has a molecular formula of VOSO4 and is the main component of the electrolyte of vanadium liquid flow energy storage batteries.

[0003] At present, the process of producing ammonium tungstate / vanadium oxysulfate with waste SCR catalyst as raw material mainly adopts the process of roasting-leaching-extraction separation of vanadium and tungsten-strip extraction-crystallization. Among them, roasting-leaching is mainly based on sodium roasting, and a mixed solution containing sodium tungstate-sodium vanadate is obtained by sodium salt roasting-water leaching or direct alkaline leaching, and then vanadium and tungsten are separated by ion exchange / solvent extraction, and then vanadium / tungsten are enriched by stripping to obtain a vanadium / tungsten solution, and further vanadium / tungsten products are obtained by crystallization. On the one hand, the main problem in separation is that the vanadium and tungsten ions in the leachate are all present in the form of anion groups, and their properties are too close, making it difficult to achieve efficient separation of vanadium and tungsten in the solution through a single selective extraction. On the other hand, the separated sodium is discharged in the form of wastewater, which makes subsequent treatment more difficult.

[0004] The existing technology has the problems of high difficulty in separating vanadium and tungsten and waste of sodium wastewater resources. Therefore, how to achieve efficient and clean separation of vanadium and tungsten and effective recovery of sodium has become a problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for separating vanadium from tungsten and simultaneously recovering sodium in a sodium-containing vanadium-tungstate solution. The method achieves efficient and clean separation of vanadium and tungsten in a sodium vanadate-sodium tungstate mixed solution, while effectively recovering sodium, thereby avoiding the generation of a large amount of sodium-containing wastewater.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for separating vanadium and tungsten from a sodium-containing vanadium and tungsten solution and simultaneously recovering sodium, the method comprising the following steps:

[0008] (1) A mixed solution containing sodium vanadate and sodium tungstate is used as an anode solution, a sodium hydroxide solution is used as a cathode solution, a cation exchange membrane and a bipolar membrane are used as electrolysis diaphragms, and electrolysis is performed to obtain a low-sodium vanadium-containing tungsten solution at the anode and a recovered sodium hydroxide solution at the cathode.

[0009] (2) mixing a reducing agent and the low sodium vanadium-containing tungsten solution, and performing heating reduction to obtain a reduced solution.

[0010] (3) Mixing the first extractant and the reduced solution of step (2), and performing a first extraction separation to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0011] Step (1) of the present invention is to electrolyze the vanadium-containing tungsten solution to achieve the separation of vanadium tungsten and sodium, as well as the effective recovery of sodium hydroxide. The principle of step (1) is as follows: the vanadium-containing tungsten mixed solution and the sodium hydroxide solution are placed in the anode chamber and the cathode chamber respectively, and separated by a cation exchange membrane and a bipolar membrane. Under the action of electrolysis, an oxygen evolution reaction occurs in the anode chamber, and the equation is as follows:

[0012] 4OH - =2H2O+O2+4e -

[0013] The cathode chamber (alkali chamber) undergoes a hydrogen evolution reaction, and the equation is as follows:

[0014] 4H2O+4e - =4OH - +2H2

[0015] Anode Na + Under the action of the electric field, the cation exchange membrane migrates from the anode chamber to the cathode chamber and interacts with the cathode OH - Combined to produce sodium hydroxide. The traditional membrane electrolysis system needs to produce H+ and OH through electrode reaction. - , which inevitably leads to the generation of H2 and O2, resulting in a waste of electrical energy. However, for the bipolar membrane system of the present invention, under the action of the electric field, the bipolar membrane can directly decompose water molecules into H + and OH - , no gas is produced, so compared with the traditional membrane electrolysis system, the consumption of electricity can be greatly reduced. The reaction equation of bipolar membrane water decomposition is as follows:

[0016] H2O=OH - +H +

[0017] As the electrolysis process progresses, the pH of the anode chamber decreases and the WO4 2- Gradually aggregated, HW6O appeared in turn 21 5- 、H2W 12 O 42 10- 、H2W 12 O 40 6- The vanadium ions also gradually aggregated, showing V4O7 2- 、V 10 O28 6- 、H2V 10 O 28 4- When the electrolysis reaches the solution pH of 1-2, the solution in the anode chamber is transferred out and recovered in the cathode chamber to obtain a sodium hydroxide solution by-product.

[0018] Preferably, the mixed solution containing sodium vanadate and sodium tungstate in step (1) is a leaching solution obtained by leaching the spent SCR catalyst with a sodium hydroxide solution, and / or a leaching solution obtained by leaching with water after sodiumization and roasting.

[0019] Preferably, the sodium calcination comprises: mixing the spent SCR catalyst and Na2CO3 for calcination.

[0020] Preferably, the pH value of the mixed solution containing sodium vanadate and sodium tungstate is greater than 7, for example, it may be 7.5, 8, 9, 10, 11, 12, 13 or 14.

[0021] Preferably, the tungsten concentration in the mixed solution containing sodium vanadate and sodium tungstate is 0.1 to 40 g / L, for example, 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L or 40 g / L; the vanadium concentration is 0.1 to 40 g / L, for example, 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L or 40 g / L. g / L, 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L or 40g / L, etc.; sodium concentration is 1-100g / L, for example, it can be 1g / L, 10g / L, 20g / L, 30g / L, 40g / L, 50g / L, 60g / L, 70g / L, 80g / L, 90g / L or 100g / L, etc.

[0022] The present invention preferably contains sodium concentration in the mixed solution of sodium vanadate and sodium tungstate within the above range to ensure that the sodium yield during the electrolysis process is above 92%. Preferably, the tungsten concentration and vanadium concentration in the mixed solution of sodium vanadate and sodium tungstate are within the above range to ensure that the tungsten yield after the extraction and separation process is above 96% and the vanadium yield is above 97%.

[0023] Preferably, the concentration of sodium hydroxide in the sodium hydroxide solution is 0.1-100 g / L, for example, it can be 0.1 g / L, 1 g / L, 10 g / L, 20 g / L, 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L or 100 g / L.

[0024] The present invention preferably has a concentration of sodium hydroxide in the cathode liquid sodium hydroxide solution within the above range, and further improves the sodium yield of the electrolysis while ensuring that the electrolysis can be carried out.

[0025] Preferably, the temperature of the electrolysis in step (1) is 10-80°C, for example, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0026] Preferably, the current density of the electrolysis is 100 to 2000 A / m 2 , for example, it can be 100A / m 2 , 400A / m 2 、800A / m 2 , 1200A / m 2 、1400A / m 2 、1600A / m 2 、1800A / m 2 or 2000A / m 2 wait.

[0027] The present invention preferably sets the electrolysis temperature and current density within the above range, which can improve the migration efficiency of sodium ions, further improve the sodium yield of electrolysis, and reduce the pH value of the low-sodium vanadium-containing tungsten solution obtained at the anode after electrolysis to acidic, so that it can be heated and reduced in step (2).

[0028] Preferably, the electrolysis time of the electrolysis is 0.1 to 10 h, for example, it can be 0.1 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0029] Preferably, the anode used in the electrolysis in step (1) comprises a titanium-based precious metal-plated electrode.

[0030] Preferably, the cathode used in the electrolysis in step (1) comprises a mesh carbon steel electrode, a nickel electrode, a nickel-plated carbon steel electrode or a titanium-based precious metal-plated electrode.

[0031] Preferably, the cation exchange membrane in step (1) comprises a sulfonic acid or sulfonic acid-carboxylic acid composite cation exchange membrane.

[0032] Preferably, the sodium concentration in the low sodium vanadium-containing tungsten solution in step (1) is 0.1-20 g / L, for example, 0.1 g / L, 0.5 g / L, 1 g / L, 5 g / L, 10 g / L, 15 g / L or 20 g / L, etc.; the vanadium concentration is 0.1-10 g / L, for example, 0.1 g / L, 0.5 g / L, 1 g / L, 5 g / L or 10 g / L, etc.; the tungsten concentration is 0.1-50 g / L, for example, 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 20 g / L or 50 g / L, etc.

[0033] Preferably, the sodium concentration in the recovered sodium hydroxide solution is 0.1 to 200 g / L, for example, 0.1 g / L, 5 g / L, 10 g / L, 50 g / L or 200 g / L. In step (2) of the present invention, a reducing agent is added to the vanadium-tungsten mixed solution in the anode chamber, and H2V in the solution is reduced under heating conditions. 10 O 28 4- The pentavalent vanadium anion is converted into a tetravalent vanadium cation VO 2+ .

[0034] Preferably, the heating temperature for the heating reduction in step (2) is 35-90°C, for example, it can be 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, etc.

[0035] In the present invention, the reduction temperature is preferably within the above range to fully convert H2V 10 O 28 4- The pentavalent vanadium ions are fully reduced to tetravalent vanadium ions VO 2+ .

[0036] Preferably, the reducing agent is oxalic acid.

[0037] Preferably, the molar ratio of vanadium to reducing agent in the low-sodium vanadium-containing tungsten solution is 1:1 to 1:2, for example, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8 or 1:2.

[0038] In the present invention, the molar ratio of vanadium to reducing agent in the low sodium vanadium-containing tungsten solution is preferably within the above range, and the H2V 10 O 28 4- The pentavalent vanadium ions are fully reduced to tetravalent vanadium ions VO 2+ .

[0039] Preferably, the heating reduction time is 0.5 to 3 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0040] In step (3) of the present invention, the tungsten anions and vanadium cations in the solution are selectively extracted and separated by an anion extractant to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0041] Preferably, in step (3), the first extractant comprises any one of N235, N1923 or N263, or a combination of at least two of them, wherein typical but non-limiting combinations are a combination of N235 and N1923, a combination of N235 and N263, and a combination of N1923 and N263.

[0042] Preferably, the volume ratio of the first extractant to the low-sodium vanadium-containing tungsten solution is 0.5:1 to 2:1, for example, it can be 0.5:1, 0.7:1, 1:1, 1.5:1 or 2:1.

[0043] Preferably, the temperature of the first extraction is room temperature.

[0044] The present invention realizes the clean separation of vanadium tungsten and sodium and the recovery of sodium hydroxide through a process combining bipolar membrane system electrolysis and extraction.

[0045] After extraction, the vanadium-containing solution of the present invention is subjected to cationic extraction agent to extract and separate vanadium to obtain a vanadium-containing organic phase. The tungsten-containing organic phase is stripped and enriched with ammonia water / ammonium salt solution to obtain an ammonium tungstate solution product. The vanadium-containing organic phase is stripped and enriched directly with sulfuric acid to obtain a vanadyl sulfate solution product.

[0046] Preferably, the method further comprises: mixing the tungsten-containing organic phase with a first stripping solution, and obtaining an ammonium tungstate solution through a first stripping.

[0047] Preferably, the first stripping solution comprises an ammonium salt solution and / or aqueous ammonia.

[0048] Preferably, the ammonium concentration of the first stripping solution is 0.1-5 mol / L, for example, 0.1 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0049] Preferably, the number of stages of the first stripping is 1 to 10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, etc.

[0050] Preferably, the method further comprises: mixing the vanadium-containing aqueous solution with a second extractant, and performing a second extraction separation to obtain a vanadium-containing organic phase.

[0051] Preferably, the second extractant comprises P204 and / or P507.

[0052] Preferably, the volume ratio of the second extractant to the vanadium-containing aqueous solution is 0.5:1 to 2:1, for example, 0.5:1, 0.7:1, 1:1, 1.5:1 or 2:1.

[0053] Preferably, the temperature of the second extraction is room temperature.

[0054] Preferably, the method further comprises: mixing the vanadium-containing organic phase with a second stripping solution, and obtaining a vanadyl sulfate solution through a second stripping.

[0055] Preferably, the second stripping solution is a sulfuric acid solution.

[0056] Preferably, the mass fraction of sulfuric acid in the second stripping solution is 0.1% to 40%, for example, it can be 0.1%, 1%, 10%, 20%, 30% or 40%.

[0057] Preferably, the number of stages of the second stripping is 1 to 10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, etc.

[0058] The invention realizes the short-process preparation of ammonium tungstate solution and vanadyl sulfate solution by back-extraction of tungsten-containing organic phase and vanadium-containing organic phase.

[0059] As a preferred technical solution, the method for separating vanadium and tungsten from a sodium-containing vanadium and tungsten solution and simultaneously recovering sodium in the present invention comprises the following steps:

[0060] (1) A leaching solution with a tungsten concentration of 0.1-40 g / L, a vanadium concentration of 0.1-40 g / L, and a sodium concentration of 1-100 g / L obtained by leaching a waste SCR catalyst with a sodium hydroxide solution and / or sodium-fermented roasting and then water leaching is used as an anode solution, a titanium-based precious metal-plated electrode is used as an anode, a 0.1-100 g / L sodium hydroxide solution is used as a cathode solution, a mesh carbon steel electrode, a nickel electrode or a nickel-plated carbon steel electrode is used as a cathode, a sulfonic acid or sulfonic acid-carboxylic acid composite cation exchange membrane and a bipolar membrane are used as an electrolytic diaphragm, and the reaction mixture is heated to 10 to 80 ° C and 100 to 2000 A / m 2 Electrolysis is performed for 0.1 to 10 hours at a current density to obtain a low-sodium vanadium-containing tungsten solution with a sodium concentration of 0.1 to 20 g / L, a vanadium concentration of 0.1 to 10 g / L, and a tungsten concentration of 0.1 to 50 g / L at the anode, and a recovered sodium hydroxide solution with a sodium concentration of 0.1 to 200 g / L is obtained at the cathode.

[0061] (2) mixing the reducing agent and the low sodium vanadium-containing tungsten solution in a molar ratio of vanadium to reducing agent of 1:1 to 1:2, and performing heating reduction at 35 to 90° C. for 0.5 h to 3 h to obtain a reduced solution.

[0062] (3) Mixing an extractant selected from any one of N235, N1923 or N263 or a combination of at least two of them with the reduced solution of step (2) at a volume ratio of 0.5:1 to 2:1, and performing extraction and separation at room temperature to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0063] The tungsten-containing organic phase is mixed with an ammonium salt solution and / or aqueous ammonia with an ammonium concentration of 0.1 to 5 mol / L, and subjected to 1 to 10 levels of stripping to obtain an ammonium tungstate solution.

[0064] The vanadium-containing aqueous solution is mixed with P204 and / or P507 extractants at a volume ratio of extractant to vanadium-containing aqueous solution of 0.5:1 to 2:1, and the vanadium-containing organic phase is obtained by extraction and separation at room temperature.

[0065] The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 0.1% to 40%, and subjected to 1 to 10 levels of stripping to obtain a vanadyl sulfate solution.

[0066] Compared with the prior art, the present invention has at least the following beneficial effects:

[0067] (1) The method for separating vanadium from tungsten and simultaneously recovering sodium from a sodium-containing vanadium-tungsten solution provided by the present invention realizes the clean separation of vanadium from tungsten and sodium and the recovery of sodium hydroxide, thereby avoiding the generation of sodium-containing wastewater from the source and reducing the pH value of the vanadium-tungsten solution so that it can be directly heated and reduced without adding other acids to adjust the pH value.

[0068] (2) The method for separating vanadium from tungsten and simultaneously recovering sodium in a sodium-containing vanadium-tungsten solution provided by the present invention achieves efficient selective extraction and separation of vanadium and tungsten by changing the presence form of vanadium ions in the solution, wherein the sodium yield is above 92.7%, the vanadium yield is above 96.9%, and the tungsten yield is above 97.2%.

[0069] (3) The method for separating vanadium tungsten and simultaneously recovering sodium from a sodium-containing vanadium tungsten solution provided by the present invention obtains a vanadium oxysulfate solution by direct stripping of a vanadium-containing organic phase, thereby realizing a short-process preparation of vanadium oxysulfate, wherein the vanadium concentration in the vanadium oxysulfate is 0.1 to 90 g / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 This is a process flow chart of the method for separating vanadium and tungsten and simultaneously recovering sodium from a vanadium and tungsten solution provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0071] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0072] Example 1

[0073] This embodiment provides a method for separating vanadium and tungsten from a vanadium and tungsten solution and simultaneously recovering sodium. Figure 1 As shown, the method comprises the following steps:

[0074] (1) A mixed solution of sodium vanadate and sodium tungstate is used as the raw material solution as the anode solution. The anode solution contains: sodium concentration 66g / L, tungsten concentration 19g / L (tungsten in the form of WO4 2- Anion form), vanadium concentration 21g / L (vanadium in the form of V2O7 2-anionic form); titanium-plated platinum electrode as anode, 10g / L sodium hydroxide solution as cathode solution, mesh carbon steel electrode as cathode, DuPont cation exchange membrane and Kerun bipolar membrane as electrolytic diaphragm, at 40℃, 800A / m 2 After electrolysis for 5 hours at the current density, a low-sodium vanadium-containing tungsten solution with a sodium concentration of 4 g / L, a vanadium concentration of 21 g / L, and a tungsten concentration of 19 g / L was obtained at the anode, and a recovered sodium hydroxide solution with a sodium concentration of 71 g / L was obtained at the cathode.

[0075] (2) The reducing agent (oxalic acid) and the low sodium vanadium-containing tungsten solution are mixed in a molar ratio of vanadium to reducing agent of 1:1, and heated for reduction at 80° C. for 2 h to obtain a reduced solution.

[0076] (3) Mixing the N263 extractant and the reduced solution of step (2) in a volume ratio of 1:1 between the N263 extractant and the low sodium vanadium-containing tungsten solution, and performing a first extraction separation at room temperature to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0077] The tungsten-containing organic phase and ammonia water with an ammonium concentration of 2 mol / L are mixed in a volume ratio of 10:1, and an ammonium tungstate solution is obtained through five-stage stripping.

[0078] The vanadium-containing aqueous solution is mixed with the P204 extractant at a volume ratio of 1:1 between the P204 extractant and the vanadium-containing aqueous solution, and the vanadium-containing organic phase is obtained by extraction and separation at room temperature.

[0079] The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 20%, and subjected to five-stage stripping to obtain a vanadyl sulfate solution.

[0080] Example 2

[0081] This embodiment provides a method for separating vanadium and tungsten from a vanadium and tungsten solution and simultaneously recovering sodium. Figure 1 As shown, the method comprises the following steps:

[0082] (1) A mixed solution of sodium vanadate and sodium tungstate was used as the raw material solution as the anode solution. The anode solution contained: sodium concentration 77 g / L, tungsten concentration 29 g / L (tungsten in the form of WO4 2- Anion form), vanadium concentration 8g / L (vanadium in the form of V2O7 2- anionic form); titanium-plated platinum electrode as anode, 15g / L sodium hydroxide solution as cathode solution, titanium-plated platinum electrode as cathode, DuPont cation exchange membrane and Kerun bipolar membrane as electrolytic diaphragm, at 50℃, 1500A / m 2 After electrolysis for 5 hours at the current density, a low-sodium vanadium-containing tungsten solution with a sodium concentration of 14 g / L, a vanadium concentration of 8 g / L, and a tungsten concentration of 29 g / L was obtained at the anode, and a recovered sodium hydroxide solution with a sodium concentration of 79 g / L was obtained at the cathode.

[0083] (2) The reducing agent (oxalic acid) and the low sodium vanadium-containing tungsten solution are mixed in a molar ratio of vanadium to reducing agent of 1:1, and heated for reduction at 70° C. for 2 h to obtain a reduced solution.

[0084] (3) Mixing the N263 extractant and the reduced solution of step (2) in a volume ratio of 1:1 between the N263 extractant and the low sodium vanadium-containing tungsten solution, and performing a first extraction separation at room temperature to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0085] The tungsten-containing organic phase and ammonia water with an ammonium concentration of 2 mol / L are mixed in a volume ratio of 5:1, and an ammonium tungstate solution is obtained through four-stage stripping.

[0086] The vanadium-containing aqueous solution is mixed with the P204 extractant at a volume ratio of 1:1 between the P204 extractant and the vanadium-containing aqueous solution, and the vanadium-containing organic phase is obtained by extraction and separation at room temperature.

[0087] The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 20%, and subjected to five-stage stripping to obtain a vanadyl sulfate solution.

[0088] Example 3

[0089] This embodiment provides a method for separating vanadium and tungsten from a vanadium and tungsten solution and simultaneously recovering sodium. Figure 1 As shown, the method comprises the following steps:

[0090] (1) A mixed solution of sodium vanadate and sodium tungstate is used as the raw material solution as the anode solution. The anode solution contains: sodium concentration 89g / L, tungsten concentration 40g / L (tungsten in the form of WO4 2- Anion form), vanadium concentration 23g / L (vanadium in the form of V2O7 2- anionic form); titanium-plated platinum electrode as anode, 20g / L sodium hydroxide solution as cathode solution, titanium-plated platinum electrode as cathode, DuPont cation exchange membrane and Kerun bipolar membrane as electrolytic diaphragm, at 20℃, 2000A / m 2 After electrolysis for 10 hours at the current density, a low-sodium vanadium-containing tungsten solution with a sodium concentration of 6 g / L, a vanadium concentration of 23 g / L, and a tungsten concentration of 40 g / L was obtained at the anode, and a recovered sodium hydroxide solution with a sodium concentration of 103 g / L was obtained at the cathode.

[0091] (2) The reducing agent (oxalic acid) and the low sodium vanadium-containing tungsten solution are mixed in a molar ratio of vanadium to reducing agent of 1:2, and heated for reduction at 90° C. for 3 h to obtain a reduced solution.

[0092] (3) Mixing the N263 extractant and the reduced solution of step (2) at a volume ratio of 0.5:1 between the N263 extractant and the low sodium vanadium-containing tungsten solution, and performing a first extraction separation at room temperature to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0093] The tungsten-containing organic phase and ammonia water with an ammonium concentration of 2 mol / L are mixed at a volume ratio of 30:1, and an ammonium tungstate solution is obtained through five-stage stripping.

[0094] The vanadium-containing aqueous solution is mixed with the P204 extractant at a volume ratio of 1:1 between the P204 extractant and the vanadium-containing aqueous solution, and the vanadium-containing organic phase is obtained by extraction and separation at room temperature.

[0095] The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 25%, and subjected to seven-stage stripping to obtain a vanadyl sulfate solution.

[0096] Example 4

[0097] This embodiment provides a method for separating vanadium and tungsten from a vanadium and tungsten solution and simultaneously recovering sodium. Figure 1 As shown, the method comprises the following steps:

[0098] (1) A mixed solution of sodium vanadate and sodium tungstate is used as the raw material solution as the anode solution. The anode solution contains: sodium concentration of 100 g / L, tungsten concentration of 28 g / L (tungsten is in the form of WO4 2- Anion form), vanadium concentration 40g / L (vanadium in the form of V2O7 2- anionic form); titanium-plated platinum electrode as anode, 11g / L sodium hydroxide solution as cathode solution, titanium-plated platinum electrode as cathode, DuPont cation exchange membrane and Kerun bipolar membrane as electrolytic diaphragm, at 10℃, 2000A / m 2 After electrolysis for 5 hours at the current density, a low-sodium vanadium-containing tungsten solution with a sodium concentration of 6 g / L, a vanadium concentration of 23 g / L, and a tungsten concentration of 40 g / L was obtained at the anode, and a recovered sodium hydroxide solution with a sodium concentration of 105 g / L was obtained at the cathode.

[0099] (2) The reducing agent (oxalic acid) and the low sodium vanadium-containing tungsten solution are mixed in a molar ratio of vanadium to reducing agent of 1:2, and heated for reduction at 50° C. for 0.5 h to obtain a reduced solution.

[0100] (3) Mixing the N263 extractant and the reduced solution of step (2) in a volume ratio of N263 extractant to the low sodium vanadium-containing tungsten solution of 2:1, and performing a first extraction separation at room temperature to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

[0101] The tungsten-containing organic phase and ammonia water with an ammonium concentration of 2 mol / L are mixed at a volume ratio of 30:1, and an ammonium tungstate solution is obtained through four-stage stripping.

[0102] The vanadium-containing aqueous solution is mixed with the P204 extractant at a volume ratio of 1:1 between the P204 extractant and the vanadium-containing aqueous solution, and the vanadium-containing organic phase is obtained by extraction and separation at room temperature.

[0103] The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 25%, and subjected to seven-stage stripping to obtain a vanadyl sulfate solution.

[0104] Example 5

[0105] In this embodiment, except that a titanium-plated iridium electrode is used as the electrolysis anode, other conditions are the same as those in Embodiment 1.

[0106] Example 6

[0107] In this embodiment, except that a titanium-plated ruthenium electrode is used as the electrolysis anode, other conditions are the same as those in Embodiment 1.

[0108] Example 7

[0109] In this embodiment, except that the sodium concentration in the anolyte is 116 g / L, other conditions are the same as those in Embodiment 1.

[0110] Example 8

[0111] In this embodiment, except that the tungsten concentration in the anolyte is 116 g / L, other conditions are the same as those in Embodiment 1.

[0112] Example 9

[0113] In this embodiment, except that the vanadium concentration in the anode liquid is 49 g / L, other conditions are the same as those in Embodiment 1.

[0114] Example 10

[0115] In this embodiment, except that the concentration of sodium hydroxide in the cathode liquid is 120 g / L, other conditions are the same as those in Example 1.

[0116] Embodiment 11

[0117] In this embodiment, except that the concentration of sodium hydroxide in the cathode liquid is 0.01 g / L, other conditions are the same as those in Example 1.

[0118] In this embodiment, since the concentration of sodium hydroxide in the cathode liquid is too low, the electrolytic separation process cannot be carried out.

[0119] Example 12

[0120] In this embodiment, except that the electrolysis temperature is 90° C., other conditions are the same as those in Embodiment 1.

[0121] Example 13

[0122] The current density of the electrolysis in this embodiment is 80A / m2 Except for this, other conditions are the same as those in Example 1.

[0123] Embodiment 14

[0124] In this embodiment, except that the molar ratio of vanadium to oxalic acid in the low-sodium vanadium-containing tungsten solution is 1:0.5, other conditions are the same as those in Embodiment 1.

[0125] Embodiment 15

[0126] In this example, except that the reduction temperature is 20° C., other conditions are the same as those in Example 1.

[0127] Comparative Example 1

[0128] In this comparative example, except that electrolysis is not used to recover sodium, other conditions are the same as those in Example 1. Since the pH of the mixed solution containing sodium vanadate and sodium tungstate is greater than 7, tetravalent vanadium exists in the form of precipitation when pH is greater than 7, and pentavalent vanadium cannot be fully reduced to tetravalent vanadium.

[0129] Table 1

[0130]

[0131]

[0132] In Table 1, “-” means there is no relevant data.

[0133] (1) It can be seen from Examples 1 to 6 that the present invention can achieve the technical effect of efficient and clean separation of vanadium and tungsten in a vanadium-tungsten solution by combining electrolysis with extraction, while recovering sodium, wherein the sodium yield is above 92.7%, the vanadium yield is above 96.9%, and the tungsten yield is above 97.2%.

[0134] (2) It can be seen from Example 1 and Comparative Example 1 that when electrolytic separation of sodium is not used, the reduction process cannot be carried out because the pH of the mixed solution containing sodium vanadate and sodium tungstate is greater than 7.

[0135] (3) It can be seen from Example 1 and Examples 7 to 9 that when the initial sodium concentration of the anolyte is 116 g / L, compared with the initial sodium concentration of 66 g / L in Example 1, the initial sodium concentration is too high, and the sodium yield is reduced from 92.7% to 82.7%. When the tungsten concentration in the anolyte is 116 g / L, compared with the initial tungsten concentration of 19 g / L in Example 1, the tungsten yield is reduced from 97.5% to 86.5%. When the vanadium concentration in the anolyte is 49 g / L, compared with the initial vanadium concentration of 21 g / L in Example 1, the vanadium yield is reduced from 98.25% to 80.2%. This shows that the present invention controls the initial sodium concentration within the range of 1 to 100 g / L, the tungsten concentration within the range of 0.1 to 40 g / L, and the vanadium concentration within the range of 0.1 to 40 g / L, and can respectively increase the yields of sodium, tungsten and vanadium.

[0136] (4) It can be seen from Example 1 and Examples 10-11 that the cathode solution sodium hydroxide concentration of Example 10 is 120 g / L, and compared with the cathode solution sodium hydroxide concentration of Example 1 being 10 g / L, the sodium yield is reduced from 92.7% to 87.6%. The cathode solution sodium hydroxide concentration of Example 11 is 0.01 g / L, and the cathode solution sodium hydroxide concentration is too low, so the electrolytic separation process cannot be carried out. This shows that the present invention controls the cathode solution sodium hydroxide concentration within the range of 0.1-100 g / L, which can ensure that the electrolysis can be carried out and improve the sodium yield.

[0137] (5) It can be seen from Example 1 and Examples 12 to 13 that the electrolysis temperature of Example 12 is 90°C, compared with the electrolysis temperature of Example 1 being 40°C, the sodium yield is reduced from 92.7% to 86.7%. The current density of Example 13 is 80A / m 2 , compared with the current density of 800A / m 2 , the sodium yield dropped from 92.7% to 91.8% when the current density was too low. This shows that the present invention controls the electrolysis temperature in the range of 10-80°C and the current density in the range of 100-2000A / m 2 within the range of , the sodium yield can be further improved.

[0138] (6) It can be seen from Examples 1 and 14 to 15 that the molar ratio of vanadium to oxalic acid in the low-sodium vanadium-containing tungsten solution of Example 14 is 1:0.5. Compared with the 1:1 reducing agent in Example 1, the vanadium content in ammonium tungstate increases from <0.1% to 6.4%, and the vanadium yield decreases from 98.2% to 68.5%. The reduction temperature of Example 15 is 20°C, which is too low compared with the 80°C reduction temperature in Example 1. The vanadium content in ammonium tungstate increases from <0.1% to 7.8%, and the vanadium yield decreases from 98.2% to 57.2%. This shows that the present invention controls the molar ratio of vanadium to reducing agent in the low-sodium vanadium-containing tungsten solution within the range of 1:1 to 1:2, and the reduction temperature within the range of 35 to 90°C, so as to achieve full separation of vanadium and tungsten and avoid the inclusion of ammonium vanadate impurities in the ammonium tungstate product.

[0139] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for separating vanadium from tungsten and simultaneously recovering sodium from a sodium-containing vanadium-tungsten solution, characterized in that: The method comprises the following steps: (1) using a mixed solution containing sodium vanadate and sodium tungstate as an anode solution, a sodium hydroxide solution as a cathode solution, a cation exchange membrane and a bipolar membrane as electrolysis diaphragms, and performing electrolysis to obtain a low-sodium vanadium-containing tungstate solution at the anode and a recovered sodium hydroxide solution at the cathode; (2) mixing a reducing agent and the low-sodium vanadium-containing tungsten solution, and performing heating reduction to obtain a reduced solution; (3) Mixing the first extractant and the reduced solution of step (2), and performing a first extraction separation to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution.

2. The method according to claim 1, characterized in that: The mixed solution containing sodium vanadate and sodium tungstate in step (1) is a leaching solution obtained by leaching the spent SCR catalyst with a sodium hydroxide solution, or a leaching solution obtained by leaching with water after sodiumization and roasting; Preferably, the sodium calcination comprises: mixing the spent SCR catalyst and Na2CO3 for calcination; Preferably, the mixed solution containing sodium vanadate and sodium tungstate has a tungsten concentration of 0.1 to 40 g / L, a vanadium concentration of 0.1 to 40 g / L, and a sodium concentration of 1 to 100 g / L; Preferably, the pH value of the mixed solution containing sodium vanadate and sodium tungstate is greater than 7; Preferably, the concentration of sodium hydroxide in the sodium hydroxide solution is 0.1-100 g / L.

3. The method according to claim 1 or 2, characterized in that: The temperature of the electrolysis in step (1) is 10 to 80° C. Preferably, the current density of the electrolysis is 100 to 2000 A / m 2 ; Preferably, the electrolysis time of the electrolysis is 0.1 to 10 hours.

4. The method according to any one of claims 1 to 3, characterized in that: The anode used in the electrolysis in step (1) comprises a titanium-based precious metal-plated electrode; Preferably, the cathode used in the electrolysis in step (1) comprises a mesh carbon steel electrode, a nickel electrode or a nickel-plated carbon steel electrode, or a titanium-based precious metal-plated electrode; Preferably, the cation exchange membrane in step (1) comprises a sulfonic acid or sulfonic acid-carboxylic acid composite cation exchange membrane.

5. The method according to any one of claims 1 to 4, characterized in that: In step (1), the sodium concentration of the low sodium vanadium-containing tungsten solution is 0.1-20 g / L, the vanadium concentration is 0.1-10 g / L, and the tungsten concentration is 0.1-50 g / L; Preferably, the sodium concentration in the recovered sodium hydroxide solution is 0.1-200 g / L.

6. The method according to any one of claims 1 to 5, characterized in that: The temperature of the heating reduction in step (2) is 35 to 90° C. Preferably, the reducing agent is oxalic acid; Preferably, the molar ratio of vanadium to reducing agent in the low-sodium vanadium-containing tungsten solution is 1:1 to 1:2; Preferably, the heating reduction time is 0.5 to 3 hours.

7. The method according to any one of claims 1 to 6, characterized in that: Step (3) the first extractant comprises any one of N235, N1923 or N263 or a combination of at least two thereof; Preferably, the volume ratio of the first extractant to the low-sodium vanadium-containing tungsten solution is 0.5:1 to 2:

1.

8. The method according to any one of claims 1 to 7, characterized in that: The method further comprises: mixing the tungsten-containing organic phase with a first stripping solution, and performing a first stripping to obtain an ammonium tungstate solution; Preferably, the first stripping solution comprises an ammonium salt solution and / or aqueous ammonia; Preferably, the ammonium concentration of the first stripping solution is 0.1 to 5 mol / L; Preferably, the number of stages of the first stripping is 1-10.

9. The method according to any one of claims 1 to 8, characterized in that: The method further comprises: mixing the vanadium-containing aqueous solution with a second extractant, and performing a second extraction separation to obtain a vanadium-containing organic phase; Preferably, the second extractant comprises P204 and / or P507; Preferably, the volume ratio of the second extractant to the vanadium-containing aqueous solution is 0.5:1 to 2:1; Preferably, the method further comprises: mixing the vanadium-containing organic phase with a second stripping solution, and obtaining a vanadyl sulfate solution through a second stripping; Preferably, the second stripping solution is a sulfuric acid solution; Preferably, the mass fraction of sulfuric acid in the second stripping solution is 0.1% to 40%; Preferably, the number of stages of the second stripping is 1-10.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) Using a leaching solution with a tungsten concentration of 0.1-40 g / L, a vanadium concentration of 0.1-40 g / L, and a sodium concentration of 1-100 g / L obtained by leaching a waste SCR catalyst with a sodium hydroxide solution and / or sodium-fermented roasting as an anode solution, a titanium-based precious metal-plated electrode as an anode, a 0.1-100 g / L sodium hydroxide solution as a cathode solution, a mesh carbon steel electrode, a nickel electrode or a nickel-plated carbon steel electrode as a cathode, a cation exchange membrane and a bipolar membrane as an electrolytic diaphragm, at 10-80°C and 100-2000 A / m 2 Electrolyze for 0.1 to 10 hours at a current density to obtain a low-sodium vanadium-containing tungsten solution with a sodium concentration of 0.1 to 20 g / L, a vanadium concentration of 0.1 to 10 g / L, and a tungsten concentration of 0.1 to 50 g / L at the anode, and obtain a recovered sodium hydroxide solution with a sodium concentration of 0.1 to 200 g / L at the cathode; (2) mixing the reducing agent and the low sodium vanadium-containing tungsten solution in a molar ratio of vanadium to reducing agent of 1:1 to 1:2, and heating and reducing the mixture at 35 to 90° C. for 0.5 to 3 hours to obtain a reduced solution; (3) mixing the first extractant and the reduced solution of step (2) at a volume ratio of the first extractant to the low sodium vanadium-containing tungsten solution of 0.5:1 to 2:1, performing a first extraction separation to obtain a tungsten-containing organic phase and a vanadium-containing aqueous solution; The tungsten-containing organic phase and the first stripping solution with an ammonium concentration of 0.1 to 5 mol / L are mixed, and subjected to 1 to 10 stages of stripping to obtain an ammonium tungstate solution; The vanadium-containing aqueous solution is mixed with a second extractant at a volume ratio of the second extractant to the vanadium-containing aqueous solution of 0.5:1 to 2:1, wherein the extractant is P204 and / or P507, and a vanadium-containing organic phase is obtained through extraction and separation; The vanadium-containing organic phase is mixed with a sulfuric acid solution with a mass fraction of 0.1% to 40%, and subjected to 1 to 10 levels of stripping to obtain a vanadyl sulfate solution.

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