Method for cleaning and separating vanadium and tungsten through membrane electrolysis

Abstract

The invention relates to a method for cleaning and separating vanadium and tungsten through membrane electrolysis, which comprises the following steps: (1) mixing a vanadium-tungsten-containing solution and a reducing agent, and heating and reducing to obtain a reduced solution; and (2) the reduced solution serves as a raw material solution, an anode solution and a cathode solution are arranged on the two sides of the raw material solution at intervals correspondingly, three-chamber membrane electrolysis is conducted on the raw material solution, a tungsten-containing solution is obtained from an anode, and a vanadium-containing solution is obtained from a cathode. Clean separation of vanadium and tungsten in the solution containing vanadium and tungsten and effective recovery of the vanadyl sulfate and the tungstic acid solution are achieved through the chemical-membrane electrolysis process, the separation process does not generate waste water, meanwhile, the separation process can directly treat the high-concentration solution containing vanadium and tungsten, and therefore the treatment amount of raw materials is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of tungsten product preparation, and in particular to a method for cleaning and separating vanadium and tungsten by membrane electrolysis. Background Art

[0002] At present, it is a big problem to separate vanadium and tungsten from vanadium-containing tungsten acid leaching solution. Traditional separation methods include chemical precipitation, ion extraction, etc., which have problems such as introducing other impurities and generating a large amount of wastewater during the separation process.

[0003] CN111485121A discloses a method for separating vanadium and tungsten from waste catalysts containing vanadium and tungsten by reducing acid leaching, the method comprising the following steps: (1) acid leaching the waste catalyst containing vanadium and tungsten with an organic acid to obtain an organic acid leaching solution, separating the organic acid to obtain an enriched solution; (2) oxidizing the enriched solution, removing impurity elements from the oxidized enriched solution to obtain a purified solution, and then precipitating the purified solution to obtain a recovered product, the recovered product comprising vanadium compounds and tungsten compounds. The method for separating vanadium and tungsten is a chemical precipitation method, and impurity ions will be introduced during the separation process.

[0004] CN107922994A discloses a method for separating vanadium and tungsten, the method comprising: providing an aqueous solution containing vanadium and tungsten; treating the aqueous solution with a reducing agent to reduce pentavalent vanadium; mixing the aqueous solution with an organic solvent to form a loaded organic layer and an aqueous raffinate; and separating the loaded organic layer and the aqueous raffinate, wherein the aqueous raffinate contains about 50% by weight or more of vanadium in the aqueous solution, and wherein the loaded organic layer contains about 50% by weight or more of tungsten in the aqueous solution. The method for separating vanadium and tungsten uses an extraction technique, and when an organic solution is used for extraction, harmful substances may be generated, and it can only separate about 50% by weight of vanadium and tungsten, and the separation efficiency is low.

[0005] Ion exchange membrane separation technology is a clean chemical separation technology that can achieve efficient separation of vanadium and tungsten anions and cations in the solution without introducing other impurity ions, and obtain vanadium and tungsten products respectively. Therefore, it is urgent to establish a vanadium and tungsten clean separation process with ion membrane electrolysis separation as the core to achieve efficient separation of vanadium and tungsten in the leachate and effective recovery of vanadium and tungsten products. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for clean separation of vanadium and tungsten by membrane electrolysis, which realizes the clean separation of vanadium and tungsten in a vanadium-containing tungsten solution and the effective recovery of vanadium oxysulfate and tungstic acid solution through a chemical-membrane electrolysis process. The separation process does not produce wastewater. At the same time, the separation process can directly process high-concentration vanadium-containing tungsten solutions, thereby greatly reducing the processing volume of raw materials.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, the method comprising the following steps:

[0009] (1) mixing a vanadium-containing tungsten solution and a reducing agent, and performing heating reduction to obtain a reduced solution;

[0010] (2) The reduced solution is used as the raw material solution, an anode solution and a cathode solution are respectively arranged on both sides of the raw material solution, and the raw material solution is subjected to three-chamber membrane electrolysis to obtain a tungsten-containing solution at the anode and a vanadium-containing solution at the cathode.

[0011] The present invention firstly reduces all vanadium in the tungsten-vanadium solution to +4 valence by chemical reduction, thereby changing the vanadium ion form in the solution from H2V 10 O 28 4- All anions are converted into VO 2+ Cations are obtained to obtain a raw material solution, and the raw material solution is subjected to three-chamber membrane electrolysis, wherein the raw material solution is separated from the anode solution by an anion exchange membrane, and the raw material solution is separated from the cathode solution by a cation exchange membrane. Under the action of the electric field, vanadium cations in the raw material solution migrate and react with the cathode solution to obtain a vanadium sulfate solution. At the same time, tungsten anions migrate and react with the anode solution to obtain a tungsten-containing solution. After the electrolysis is completed, an acid solution is supplemented in the dilute vanadium tungsten solution and added to the vanadium-containing tungsten solution for separation treatment again. The present invention realizes the clean separation of vanadium and tungsten in the vanadium-containing tungsten solution and the effective recovery of vanadium sulfate and tungstic acid solution through a chemical-membrane electrolysis process. The separation process does not generate wastewater, and the separation process can directly process a high-concentration vanadium-containing tungsten solution, thereby greatly reducing the processing amount of raw materials.

[0012] As a preferred technical solution of the present invention, the vanadium-tungsten-containing solution in step (1) includes a leachate obtained by leaching a waste catalyst in a sulfuric acid or hydrochloric acid system, and / or a leachate obtained by leaching a waste catalyst after roasting.

[0013] Preferably, in the vanadium-containing tungsten solution of step (1), tungsten exists in the form of tungstate, and vanadium exists in the form of vanadate.

[0014] It is worth noting that the tungsten in the vanadium-containing tungsten solution in step (1) may be sodium tungstate and / or tungstic acid, and the vanadium may be sodium vanadate and / or vanadic acid.

[0015] As a preferred technical solution of the present invention, the reducing agent in step (1) includes any one of oxalic acid, sodium nitrite or sulfur dioxide, or a combination of at least two of them, wherein typical but non-limiting combinations include: a combination of oxalic acid and sodium nitrite, a combination of oxalic acid and sulfur dioxide, a combination of sodium nitrite and sulfur dioxide, and a combination of oxalic acid, sodium nitrite and sulfur dioxide.

[0016] Preferably, the ratio of the vanadium-containing tungsten solution and the reducing agent in step (1) is a molar ratio of vanadium to reducing agent of 1:1-1:2, for example, it can be 1:1, 1:1.3, 1:1.5, 1:1.7 or 1:2, but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0017] The present invention can achieve the effect of completely reducing pentavalent vanadium to tetravalent vanadium by limiting the molar ratio of vanadium to reducing agent in the vanadium-containing tungsten solution.

[0018] As a preferred technical solution of the present invention, the temperature of the heating reduction in step (1) is 25-95°C, for example, it can be 25°C, 35°C, 45°C, 55°C, 65°C, 75°C, 85°C or 95°C, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0019] The present invention limits the temperature of heating reduction to 25-95°C. When the temperature of heating reduction is lower than 25°C, pentavalent vanadium in the solution cannot be completely reduced to tetravalent vanadium, which ultimately results in the inability to completely separate vanadium and tungsten; when the temperature of heating reduction is higher than 95°C, it will lead to increased energy consumption.

[0020] Preferably, the heating reduction time in step (1) is 0.5-3 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0021] The present invention can control the reduction of pentavalent vanadium in the solution after reduction by limiting the time of heating reduction. When the reaction time is less than 0.5h, the pentavalent vanadium in the solution cannot be completely reduced to tetravalent vanadium, which ultimately leads to the inability to completely separate vanadium and tungsten. When the reaction time is greater than 3h, unnecessary energy consumption will be increased.

[0022] As a preferred technical solution of the present invention, the anode solution in step (2) includes a tungstic acid solution.

[0023] Preferably, the cathode solution in step (2) is a sulfuric acid solution.

[0024] Preferably, the tungsten concentration in the anode solution is 0.1-5 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] The present invention limits the tungsten concentration in the anode solution to 0.1-5 mol / L. When the tungsten concentration is less than 0.1 mol / L, there are too few conductive ions in the solution, the electrolysis voltage is too high, and the electrolysis system is difficult to operate stably; when the tungsten concentration is greater than 5 mol / L, the tungsten concentration is too high, tungstic acid precipitation will be generated to block the membrane pores, causing the separation process to be affected.

[0026] Preferably, the mass fraction of sulfuric acid in the sulfuric acid solution is 1-40%, for example, 1%, 5%, 10%, 20%, 30% or 40%, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] The present invention limits the mass fraction of sulfuric acid in the sulfuric acid solution to 1-40%. When the mass fraction of sulfuric acid is less than 1%, the solution conductivity is too low, the electrolysis voltage is too large, and the electrolysis system cannot operate continuously and stably; when the mass fraction of sulfuric acid is greater than 40%, the viscosity of the electrolyte increases, and the high-viscosity electrolyte slows down the migration speed of ions, thereby prolonging the reaction time of membrane electrolysis and reducing the separation efficiency. At the same time, high-concentration sulfuric acid will also corrode the cathode material, increasing the cost of equipment maintenance.

[0028] Preferably, the tungsten concentration in the raw material solution is 0.1-100 g / L, for example, it can be 0.1 g / L, 1 g / L, 10 g / L, 30 g / L, 50 g / L, 75 g / L or 100 g / L, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0029] Preferably, the vanadium concentration in the raw material solution is 0.1-30 g / L, for example, it can be 0.1 g / L, 1 g / L, 5 g / L, 10 g / L, 20 g / L or 30 g / L, but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0030] As a preferred technical solution of the present invention, the tungsten-containing solution in step (2) includes a tungstic acid solution.

[0031] Preferably, the tungsten concentration in the tungsten-containing solution in step (2) is 0.1-200 g / L, for example, it can be 0.1 g / L, 10 g / L, 50 g / L, 100 g / L or 200 g / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] Preferably, the vanadium-containing solution in step (2) is a vanadyl sulfate solution.

[0033] Preferably, the vanadium concentration in the vanadyl sulfate solution in step (2) is 0.1-95 g / L, for example, 0.1 g / L, 5 g / L, 20 g / L, 50 g / L or 95 g / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0034] As a preferred technical solution of the present invention, an anion exchange membrane is arranged between the raw material solution and the anode solution in the three-chamber membrane electrolysis in step (2).

[0035] Preferably, a cation exchange membrane is arranged between the raw material solution and the cathode solution in the three-chamber membrane electrolysis in step (2).

[0036] Preferably, the anion exchange membrane comprises a quaternary ammonium salt anion exchange membrane provided by Kerun.

[0037] Preferably, the cation exchange membrane comprises a N-containing cation exchange membrane provided by DuPont or a F-containing cation exchange membrane provided by Asahi Glass.

[0038] As a preferred technical solution of the present invention, the anode electrode in the three-chamber membrane electrolysis in step (2) comprises a ruthenium-plated titanium mesh electrode or a platinum-plated titanium mesh electrode.

[0039] Preferably, the cathode electrode in the three-chamber membrane electrolysis in step (2) comprises any one of a mesh carbon steel electrode, a nickel electrode or a nickel-plated carbon steel electrode.

[0040] As a preferred technical solution of the present invention, the temperature of the three-chamber membrane electrolysis in step (2) is 20-80°C, for example, it can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0041] Preferably, the current density of the three-chamber membrane electrolysis in step (2) is 100-5000A / m 2 , for example, it can be 100A / m 2 , 500A / m 2 , 1000A / m 2 、2000A / m 2 、3000A / m 2 、4000A / m 2 or 5000A / m 2 , but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0042] Preferably, the electrolysis time of the three-chamber membrane electrolysis in step (2) is 1-11 hours, for example, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours or 11 hours, but is not limited to the listed values, and other values ​​not listed in the above numerical range are also applicable.

[0043] As a preferred technical solution of the present invention, the method comprises the following steps:

[0044] (1) mixing a vanadium-containing tungsten solution with a reducing agent at a molar ratio of vanadium to reducing agent of 1:1-1:2 to obtain a mixed solution, heating the mixed solution for reduction at 25-95° C. for 0.5-3 h to obtain a reduced solution having a tungsten concentration of 0.1-100 g / L and a vanadium concentration of 0.1-30 g / L; wherein the reducing agent comprises any one of oxalic acid, sodium nitrite or sulfur dioxide or a combination of at least two thereof;

[0045] (2) using the reduced solution as a raw material solution, arranging an anode solution and a cathode solution on both sides of the raw material solution, respectively, wherein the tungsten concentration in the anode solution is 0.1-5 mol / L, and a quaternary ammonium salt anion exchange membrane is arranged between the raw material solution and the anode solution;

[0046] The cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 1-40%, and a N-containing cation exchange membrane or a F-containing cation exchange membrane is arranged between the raw material solution and the cathode solution;

[0047] At a temperature of 20-80°C and a current density of 100-5000A / m 2 The raw material solution is subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time is 1-11h;

[0048] After the electrolysis is completed, a tungstic acid solution is obtained at the anode and a vanadyl sulfate solution is obtained at the cathode.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] (1) The method for clean separation of vanadium and tungsten by membrane electrolysis provided by the present invention can realize the clean separation of vanadium and tungsten in a vanadium-containing tungsten solution and the effective recovery of vanadyl sulfate and tungstic acid solution through a chemical-membrane electrolysis process without the need for an extraction-ion adsorption process, wherein the recovery rate of tungsten and the purity of tungstic acid can reach more than 99.2%, and the recovery rate of vanadium and the purity of vanadyl sulfate can reach more than 99.1%.

[0051] (2) The separation process of the membrane electrolysis clean separation method of vanadium and tungsten provided by the present invention does not generate wastewater. After the electrolysis is completed, the dilute vanadium tungsten solution can be recycled, thereby avoiding the generation of wastewater from the source.

[0052] (3) Compared with traditional vanadium-tungsten separation processes such as ion exchange and solvent extraction, the membrane electrolysis clean separation method provided by the present invention can directly process high-concentration vanadium-tungsten solutions, thereby greatly reducing the amount of raw material processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a process flow chart for separating vanadium-containing tungsten solution by membrane electrolysis to prepare vanadium-containing solution and tungsten-containing solution. DETAILED DESCRIPTION

[0054] 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.

[0055] Example 1

[0056] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. Figure 1 , the method specifically comprises the following steps:

[0057] (1) Leaching a waste catalyst in 1.5 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 15.8 g / L and the vanadium concentration is 5.6 g / L (in the form of tungstic acid and vanadic acid), and mixing the vanadium-containing tungsten solution with a reducing agent (oxalic acid) at a molar ratio of vanadium to the reducing agent of 1:2 to obtain a mixed solution, and heating the mixed solution at 65° C. for 2 hours to obtain a reduced solution;

[0058] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 1.5 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 30%. The temperature is 40°C and the current density is 1000 A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 5h.

[0059] After the electrolysis is completed, a tungstic acid solution (i.e., a tungsten-containing solution) is obtained at the anode, and a vanadyl sulfate solution (i.e., a vanadium-containing solution) is obtained at the cathode. The raw material solution is converted into a dilute vanadium-tungsten solution, in which the tungsten concentration is 0.05 g / L and the vanadium concentration is 0.04 g / L.

[0060] Example 2

[0061] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, and the method specifically comprises the following steps:

[0062] (1) leaching a waste catalyst in 1.8 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 36.8 g / L and the vanadium concentration is 11.2 g / L, and the vanadium-containing tungsten solution is mixed with a reducing agent (sodium nitrite) at a molar ratio of vanadium to the reducing agent of 1:1.5 to obtain a mixed solution, and the mixed solution is heated and reduced at 55° C. for 2.5 hours to obtain a reduced solution;

[0063] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 1.2 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 25%. The temperature is 60°C and the current density is 1200 A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 4h.

[0064] After the electrolysis is completed, a tungstic acid solution is obtained at the anode, a vanadyl sulfate solution is obtained at the cathode, and the raw material solution is converted into a dilute vanadium tungsten solution, in which the tungsten concentration is 0.23 g / L and the vanadium concentration is 0.11 g / L.

[0065] Example 3

[0066] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, and the method specifically comprises the following steps:

[0067] (1) leaching a waste catalyst in 2 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 96.6 g / L and the vanadium concentration is 24.7 g / L, and the vanadium-containing tungsten solution is mixed with a reducing agent (sulfur dioxide) at a molar ratio of vanadium to the reducing agent of 1:1 to obtain a mixed solution, and the mixed solution is heated and reduced at 90° C. for 3 hours to obtain a reduced solution;

[0068] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 5 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 40%. The temperature is 50°C and the current density is 700A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 11 h.

[0069] After the electrolysis is completed, a tungstic acid solution is obtained at the anode, a vanadyl sulfate solution is obtained at the cathode, and the raw material solution is converted into a dilute vanadium tungsten solution, in which the tungsten concentration is 0.1 g / L and the vanadium concentration is 0.22 g / L.

[0070] Example 4

[0071] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, and the method specifically comprises the following steps:

[0072] (1) leaching a waste catalyst in 1 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 6.9 g / L and the vanadium concentration is 24.7 g / L, and the vanadium-containing tungsten solution is mixed with a reducing agent (oxalic acid) at a molar ratio of vanadium to reducing agent of 1:1 to obtain a mixed solution, and the mixed solution is heated and reduced at 25° C. for 0.5 h to obtain a reduced solution;

[0073] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 0.6 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 20%. The temperature is 20°C and the current density is 400 A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 7h.

[0074] After the electrolysis is completed, a tungstic acid solution is obtained at the anode, a vanadyl sulfate solution is obtained at the cathode, and the raw material solution is converted into a dilute vanadium tungsten solution, in which the tungsten concentration is 0.02 g / L and the vanadium concentration is 0.03 g / L.

[0075] Example 5

[0076] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, and the method specifically comprises the following steps:

[0077] (1) leaching a waste catalyst in 3.2 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 100 g / L and the vanadium concentration is 30 g / L, and the vanadium-containing tungsten solution is mixed with a reducing agent (oxalic acid) at a molar ratio of vanadium to the reducing agent of 1:1 to obtain a mixed solution, and the mixed solution is heated and reduced at 95° C. for 0.5 h to obtain a reduced solution;

[0078] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 5 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 35%. The temperature is 80°C and the current density is 2000A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 1 h.

[0079] After the electrolysis is completed, a tungstic acid solution is obtained at the anode, a vanadyl sulfate solution is obtained at the cathode, and the raw material solution is converted into a dilute vanadium tungsten solution, in which the tungsten concentration is 0.4 g / L and the vanadium concentration is 0.12 g / L.

[0080] Example 6

[0081] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, and the method specifically comprises the following steps:

[0082] (1) leaching a waste catalyst in 2 mol / L sulfuric acid to obtain a vanadium-containing tungsten solution, wherein the tungsten concentration in the vanadium-containing tungsten solution is 1.8 g / L and the vanadium concentration is 0.3 g / L, and the vanadium-containing tungsten solution is mixed with a reducing agent (oxalic acid) at a molar ratio of vanadium to the reducing agent of 1:2 to obtain a mixed solution, and the mixed solution is heated and reduced at 25° C. for 1.5 hours to obtain a reduced solution;

[0083] (2) The reduced solution is used as the raw material solution, and an anode solution and a cathode solution are arranged on both sides of the raw material solution, wherein the anode solution is a tungstic acid solution with a tungsten concentration of 4 mol / L, and the cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 20%. The temperature is 50°C and the current density is 800 A / m 2 The reduced solution was subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time was 6 h.

[0084] After the electrolysis is completed, a tungstic acid solution is obtained at the anode, a vanadyl sulfate solution is obtained at the cathode, and the raw material solution is converted into a dilute vanadium tungsten solution, in which the tungsten concentration is 0.01 g / L and the vanadium concentration is 0.01 g / L.

[0085] Example 7

[0086] This embodiment provides a method for separating vanadium and tungsten by membrane electrolysis. The difference from the embodiment 1 is that the temperature of the heating reduction in step (1) is adjusted to 20°C, and the rest is the same as the embodiment 1.

[0087] Example 8

[0088] This embodiment provides a method for membrane electrolysis cleaning and separation of vanadium and tungsten. The only difference from Embodiment 1 is that the heating reduction time in step (1) is adjusted to 0.3 h, and the rest is the same as Embodiment 1.

[0089] Example 9

[0090] This embodiment provides a method for separating vanadium and tungsten by membrane electrolysis. The only difference from Embodiment 1 is that the tungstic acid solution in step (2) is replaced by water, and the rest is the same as Embodiment 1. Since water cannot react with tungsten ions in the raw material solution to generate corresponding products, the separation of vanadium and tungsten cannot be achieved.

[0091] Example 10

[0092] This embodiment provides a method for separating vanadium and tungsten by membrane electrolysis. The only difference from Embodiment 1 is that the concentration of the tungstic acid solution in step (2) is replaced with 6 mol / L, and the rest is the same as Embodiment 1. Since the initial tungsten concentration in the anode solution is too high, tungsten easily forms a precipitate adsorbed on the membrane surface, resulting in the inability to carry out the electrolysis process, and thus the inability to separate vanadium and tungsten.

[0093] Embodiment 11

[0094] This embodiment provides a method for separating vanadium and tungsten by membrane electrolysis. The only difference from Embodiment 1 is that the sulfuric acid solution in step (2) is replaced by a hydrochloric acid solution of equal mass fraction, and the rest is the same as Embodiment 1. Since hydrochloric acid cannot react with vanadium ions in the raw material solution to generate corresponding products, it is impossible to separate vanadium and tungsten.

[0095] Example 12

[0096] This embodiment provides a method for separating vanadium and tungsten by membrane electrolysis. The difference from Embodiment 1 is that the mass fraction of the sulfuric acid solution in step (2) is adjusted to 50%, and the rest is the same as Embodiment 1.

[0097] Example 13

[0098] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. The only difference from Embodiment 1 is that, except for the electrolysis temperature of the three-chamber membrane electrolysis in step (2) being adjusted to 10°C, the rest is the same as Embodiment 1.

[0099] Embodiment 14

[0100] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis, which is different from the embodiment 1 only in that the electrolysis temperature of the three-chamber membrane electrolysis in step (2) is adjusted to 90°C, and the rest is the same as the embodiment 1. Since the electrolysis temperature is too high, the electrolysis cannot be carried out effectively, and thus the separation and recovery of vanadium and tungsten cannot be achieved.

[0101] Embodiment 15

[0102] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. The difference from Embodiment 1 is that, in addition to adjusting the current density of the three-chamber membrane electrolysis in step (2) to 50 A / m 2 , the rest are the same as in Example 1.

[0103] Example 16

[0104] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. The difference from Embodiment 1 is that the current density of the three-chamber membrane electrolysis in step (2) is adjusted to 6000 A / m 2, and the rest is the same as in Example 1. Since the current density is too large, the electrolysis cannot be carried out effectively, and thus the separation and recovery of vanadium and tungsten cannot be achieved.

[0105] Embodiment 17

[0106] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. The only difference from Embodiment 1 is that, except for the electrolysis time of the three-chamber membrane electrolysis in step (2) being adjusted to 0.5 h, the rest is the same as Embodiment 1.

[0107] Comparative Example 1

[0108] This embodiment provides a method for cleaning and separating vanadium and tungsten by membrane electrolysis. The only difference from Example 1 is that in Example 1, the vanadium-containing tungsten solution is not subjected to heating and reduction treatment, and the rest is the same as Example 1.

[0109] The concentrations of vanadium and tungsten in the solution were quantitatively determined and analyzed by ICP-OES. The purity was calculated as follows: purity of target element in electrolyte = concentration of target element / total concentration of all metal elements. The product recovery rate was calculated as follows: product recovery rate = concentration of target element in electrolyte / concentration of target element in raw material solution.

[0110] According to the above test method and calculation formula, the purity and recovery rate of vanadium and tungsten after membrane electrolysis separation are obtained. The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113] (1) It can be seen from Examples 1-6 that the method for clean separation of vanadium and tungsten by membrane electrolysis provided by the present invention can efficiently and cleanly separate vanadium and tungsten in a vanadium-containing tungsten solution, while ensuring the purity and recovery rate of the vanadium and tungsten products after separation, wherein the recovery rate of tungsten and the purity of tungstic acid can both reach more than 99.2%, and the recovery rate of vanadium and the purity of vanadyl sulfate can both reach more than 99.1%.

[0114] (2) It can be seen from Example 1 and Examples 7-8 that the heating reduction temperature in Example 1 is 65°C, compared with the heating reduction temperature of 20°C in Example 7, the purity of tungstic acid in Example 1 is 99.4%, while the purity of tungstic acid in Example 7 is reduced to 94.4%; the heating reduction time in Example 1 is 2h, compared with the heating reduction time of 0.3h in Example 8, the purity of tungstic acid in Example 1 is 99.4%, while the purity of tungstic acid in Example 8 is reduced to 92.3%. This shows that the present invention can fully reduce pentavalent vanadium in the solution to tetravalent vanadium by controlling the heating reduction temperature at 25-95°C and the heating reduction time at 0.5-3h, thereby achieving efficient separation of vanadium and tungsten, while ensuring that the recovery rate of tungsten after separation and the purity of tungstic acid can reach more than 99.2%, and the recovery rate of vanadium and the purity of vanadyl sulfate can reach more than 99.1%.

[0115] (3) It can be seen from Example 1 and Example 12 that the mass fraction of the initial sulfuric acid solution in the cathode solution in Example 1 is 30%. Compared with the mass fraction of the initial sulfuric acid solution in the cathode solution in Example 12 being 50%, the recovery rate of tungsten in Example 1 is 99.7%, and the recovery rate of vanadium is 99.8%, while the recovery rate of tungsten in Example 12 is 79.4%, and the recovery rate of vanadium is 73.6%. This shows that the present invention can achieve efficient separation of vanadium and tungsten by controlling the mass fraction of the initial sulfuric acid solution in the cathode solution within the range of 1-40%, while ensuring that the recovery rate of tungsten after separation is above 99.2%, and the recovery rate of vanadium is above 99.1%.

[0116] (4) It can be seen from Example 1 and Example 13 that the electrolysis temperature in Example 1 is 40°C. Compared with the electrolysis temperature in Example 13 of 10°C, the recovery rate of tungsten in Example 1 is 99.7%, and the recovery rate of vanadium is 99.8%, while the recovery rate of tungsten in Example 13 is 92.1%, and the recovery rate of vanadium is 92.6%. This shows that the present invention can achieve sufficient recovery of vanadium and tungsten during the electrolysis process by controlling the electrolysis temperature at 20-80°C, ensuring that the recovery rate of tungsten after the electrolysis is above 99.2%, and the recovery rate of vanadium is above 99.1%.

[0117] (5) Combining Example 1 and Example 15, it can be seen that the current density in Example 1 is 1000 A / m 2 , compared with the current density of 50A / m in Example 15 2 In Example 1, the recovery rate of tungsten is 99.7%, and the recovery rate of vanadium is 99.8%, while the recovery rate of tungsten in Example 15 is 80.7%, and the recovery rate of vanadium is 83.8%, which shows that the present invention can achieve the desired effect by controlling the current density in the range of 100-5000A / m 2, which can realize the full recovery of vanadium and tungsten during the electrolysis process, ensuring that the recovery rate of tungsten reaches more than 99.2% and the recovery rate of vanadium reaches more than 99.1% after the electrolysis.

[0118] (6) It can be seen from Example 1 and Example 17 that the electrolysis time in Example 1 is 5 hours, compared with the electrolysis time of 0.5 hours in Example 17. The recovery rate of tungsten in Example 1 is 99.7%, and the recovery rate of vanadium is 99.8%, while the recovery rate of tungsten in Example 17 is 60.2%, and the recovery rate of vanadium is 55.4%. This shows that the present invention can achieve sufficient recovery of vanadium and tungsten during the electrolysis process by controlling the electrolysis time to 1-11 hours, ensuring that the recovery rate of tungsten after the electrolysis is more than 99.2%, and the recovery rate of vanadium is more than 99.1%.

[0119] (7) It can be seen from Example 1 and Comparative Example 1 that in Comparative Example 1, the vanadium-containing tungsten solution was not subjected to heating reduction treatment before electrolysis, so the vanadium in the vanadium-containing tungsten solution could not be reduced to +4 valence, and therefore could not react with the sulfuric acid solution at the cathode to generate vanadium oxysulfate. At the same time, the purity of tungsten acid obtained at the anode was 50.6%. This shows that the present invention can achieve effective separation of vanadium and tungsten by reducing the vanadium-containing tungsten solution and performing three-chamber membrane electrolysis on the reduced solution, and at the same time can ensure the purity and recovery rate of the vanadium and tungsten products after separation, wherein the recovery rate of tungsten and the purity of tungsten acid can both reach more than 99.2%, and the recovery rate of vanadium and the purity of vanadium oxysulfate can both reach more than 99.1%.

[0120] In summary, the present invention electrolyzes the raw material solution through membrane electrolysis, and can achieve clean separation of vanadium and tungsten and effective recovery of vanadyl sulfate and tungstic acid solution through the chemical-membrane electrolysis process; the separation process of the present invention does not produce waste water, and the dilute vanadium tungsten solution can be recycled after the electrolysis is completed, thereby avoiding the generation of waste water from the source; compared with traditional vanadium tungsten separation processes such as ion exchange / solvent extraction, the separation method of the present invention can directly process high-concentration vanadium-containing tungsten solutions, thereby greatly reducing the processing volume of raw materials.

[0121] 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 cleaning and separating vanadium and tungsten by membrane electrolysis, characterized in that: The method comprises the following steps: (1) mixing a vanadium-containing tungsten solution and a reducing agent, and performing heating reduction to obtain a reduced solution; (2) The reduced solution is used as the raw material solution, an anode solution and a cathode solution are respectively arranged on both sides of the raw material solution, and the raw material solution is subjected to three-chamber membrane electrolysis to obtain a tungsten-containing solution at the anode and a vanadium-containing solution at the cathode.

2. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to claim 1, characterized in that: The vanadium-tungsten solution in step (1) includes a leachate obtained by leaching a waste catalyst in a sulfuric acid or hydrochloric acid system, and / or a leachate obtained by leaching a waste catalyst after roasting; Preferably, in the vanadium-containing tungsten solution of step (1), tungsten exists in the form of tungstate, and vanadium exists in the form of vanadate.

3. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to claim 1 or 2, characterized in that: The reducing agent in step (1) comprises any one of oxalic acid, sodium nitrite or sulfur dioxide, or a combination of at least two thereof; Preferably, the molar ratio of vanadium to reducing agent in the vanadium-containing tungsten solution in step (1) is 1:1-1:

2.

4. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 3, characterized in that: The temperature of the heating reduction in step (1) is 25-95° C.; Preferably, the heating reduction time in step (1) is 0.5-3h.

5. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 4, characterized in that: The anode solution in step (2) comprises a tungstic acid solution; Preferably, the cathode solution in step (2) is a sulfuric acid solution; Preferably, the tungsten concentration in the anode solution is 0.1-5 mol / L; Preferably, the mass fraction of sulfuric acid in the sulfuric acid solution is 1-40%; Preferably, the tungsten concentration in the raw material solution is 0.1-100 g / L; Preferably, the vanadium concentration in the raw material solution is 0.1-30 g / L.

6. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 5, characterized in that: The tungsten-containing solution in step (2) includes a tungstic acid solution; Preferably, the tungsten concentration in the tungsten-containing solution in step (2) is 0.1-200 g / L; Preferably, the vanadium-containing solution in step (2) is a vanadyl sulfate solution; Preferably, the vanadium concentration in the vanadyl sulfate solution in step (2) is 0.1-95 g / L.

7. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 6, characterized in that: In step (2), an anion exchange membrane is provided between the raw material solution and the anode solution in the three-chamber membrane electrolysis; Preferably, a cation exchange membrane is provided between the raw material solution and the cathode solution in the three-chamber membrane electrolysis in step (2); Preferably, the anion exchange membrane comprises a quaternary ammonium salt anion exchange membrane; Preferably, the cation exchange membrane comprises a N-containing cation exchange membrane or a F-containing cation exchange membrane.

8. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 7, characterized in that: The anode electrode in the three-chamber membrane electrolysis in step (2) comprises a ruthenium-plated titanium mesh electrode or a platinum-plated titanium mesh electrode; Preferably, the cathode electrode in the three-chamber membrane electrolysis in step (2) comprises any one of a mesh carbon steel electrode, a nickel electrode or a nickel-plated carbon steel electrode.

9. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 8, characterized in that: The temperature of the three-chamber membrane electrolysis in step (2) is 20-80° C. Preferably, the current density of the three-chamber membrane electrolysis in step (2) is 100-5000A / m 2 ; Preferably, the electrolysis time of the three-chamber membrane electrolysis in step (2) is 1-11 h.

10. The method for cleaning and separating vanadium and tungsten by membrane electrolysis according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) mixing a vanadium-containing tungsten solution with a reducing agent at a molar ratio of vanadium to reducing agent of 1:1-1:2 to obtain a mixed solution, and heating the mixed solution for reduction at 25-95° C. for 0.5-3 h to obtain a reduced solution having a tungsten concentration of 0.1-100 g / L and a vanadium concentration of 0.1-30 g / L; The reducing agent comprises any one of oxalic acid, sodium nitrite or sulfur dioxide or a combination of at least two thereof; (2) using the reduced solution as a raw material solution, arranging an anode solution and a cathode solution on both sides of the raw material solution, respectively, wherein the tungsten concentration in the anode solution is 0.1-5 mol / L, and a quaternary ammonium salt anion exchange membrane is arranged between the raw material solution and the anode solution; The cathode solution is a sulfuric acid solution with a sulfuric acid mass fraction of 1-40%, and a N-containing cation exchange membrane or a F-containing cation exchange membrane is arranged between the raw material solution and the cathode solution; At a temperature of 20-80°C and a current density of 100-5000A / m 2 The raw material solution is subjected to three-chamber membrane electrolysis under the conditions of , and the electrolysis time is 1-11h; After the electrolysis is completed, a tungstic acid solution is obtained at the anode and a vanadyl sulfate solution is obtained at the cathode.

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