Method for circulating sulfuric acid in preparation of 3.5-valent vanadyl sulfate through electrolytic method

Abstract

The invention provides a method for circulating sulfuric acid in preparation of 3.5-valent vanadyl sulfate by an electrolytic process, which comprises the following steps: (1) mixing an electrolyzed anode solution and hydrogen peroxide, and synchronously introducing oxygen for oxidation reaction to obtain a peroxy vanadate radical-containing solution; the anode solution after electrolysis contains vanadium cations and sulfate radicals; and (2) extracting the peroxy vanadate radical-containing solution obtained in the step (1) to obtain a sulfuric acid solution. The problem of vanadium accumulation in the anode chamber in the process of preparing the 3.5-valent vanadyl sulfate solution through electrolytic reduction can be effectively solved, and continuous and stable operation of an electrolysis system is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium preparation, and in particular to a method for circulating sulfuric acid in preparing 3.5-valent vanadyl sulfate by electrolysis. Background Art

[0002] 3.5-valent vanadium oxysulfate solution is an important component of all-vanadium liquid flow energy storage battery. In industrial production, the preparation process of 3.5-valent vanadium oxysulfate electrolyte is chemical reduction-electrolytic reduction method. This method first dissolves vanadium pentoxide in sulfuric acid, adds a reducing agent to reduce pentavalent vanadium to tetravalent vanadium, and thus obtains a tetravalent vanadium oxysulfate solution. Then, the tetravalent vanadium oxysulfate solution is reduced to a 3.5-valent vanadium oxysulfate electrolyte by electrolytic reduction.

[0003] At present, the electrolysis method is used to reduce the 4-valent vanadium oxysulfate solution to prepare the 3.5-valent vanadium oxysulfate solution. The electrolysis is divided into an anode chamber and a cathode chamber, wherein the anode chamber is a sulfuric acid solution and the cathode chamber is a 4-valent vanadium oxysulfate solution. As the electrolysis process proceeds, a reduction reaction occurs in the cathode chamber to generate a 3.5-valent vanadium solution. An oxidation reaction occurs in the anode chamber to generate oxygen. During the electrolysis process, the 4-valent vanadium in the cathode chamber will pass through the membrane into the anode chamber, where it will be oxidized to generate 5-valent vanadium. The generated 5-valent vanadium will precipitate in the sulfuric acid system in the form of a precipitate, covering the electrode / blocking the membrane pores, causing the electrolysis process to be unable to operate continuously and stably. Therefore, it is necessary to remove vanadium from the anode chamber solution after electrolysis to inhibit the generation of precipitation and ensure the continuous and stable operation of the electrolysis system.

[0004] To prevent water migration during electrolysis, the sulfuric acid concentration in the anode chamber is the same as that in the cathode chamber. However, since the sulfuric acid concentration in the cathode chamber is ≥2.5 mol / L, vanadium is present in the form of cations at this time, forming an extraction competition relationship with hydrogen ions, making it difficult to achieve selective extraction and separation of vanadium. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing 3.5-valent vanadyl sulfate by electrolysis in a sulfuric acid cycle, converting vanadium cations into anionic forms to avoid the interference of hydrogen ions in the extraction process and achieve selective extraction and separation of vanadium.

[0006] The present invention provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0007] (1) mixing an electrolytically-post-anodic solution and hydrogen peroxide, and simultaneously introducing oxygen to carry out an oxidation reaction, thereby obtaining a peroxyvanadate-containing solution; wherein the electrolytically-post-anodic solution contains vanadium cations and sulfate;

[0008] (2) The peroxyvanadate solution in step (1) is extracted to obtain a sulfuric acid solution.

[0009] It is worth noting that the process of the present invention is derived from the process of preparing 3.5-valent vanadyl sulfate by electrolysis. Specifically, the reduction of 4-valent vanadyl sulfate solution to prepare 3.5-valent vanadyl sulfate solution adopts electrolysis. The electrolysis is divided into an anode chamber and a cathode chamber, wherein the anode chamber is a sulfuric acid solution, and the cathode chamber is a 4-valent vanadyl sulfate solution. As the electrolysis process proceeds, a reduction reaction occurs in the cathode chamber to generate a 3.5-valent vanadium solution. An oxidation reaction occurs in the anode chamber to generate oxygen. During the electrolysis process, the 4-valent vanadium in the cathode chamber will pass through the membrane into the anode chamber, where it will be oxidized to generate 5-valent vanadium. The generated 5-valent vanadium will precipitate in the sulfuric acid system in the form of a precipitate, covering the electrode / blocking the membrane pores, causing the electrolysis process to be unable to operate continuously and stably. Therefore, it is necessary to remove vanadium from the anode chamber solution after electrolysis to inhibit the formation of precipitation and ensure the continuous and stable operation of the electrolysis system. For its schematic diagram, see Figure 1 Therefore, the present invention has developed a process that can realize the recycling and recovery of sulfuric acid in the anode chamber solution and produce ammonium vanadate as a by-product. First, vanadium cations are converted into anion forms by oxygen and hydrogen peroxide to avoid the interference of hydrogen ions in the extraction process, and then vanadium and sulfate are separated by extraction, thereby realizing the recycling and recovery of sulfate and the preparation of ammonium vanadate.

[0010] Preferably, the mass concentration of vanadium in the anode solution after electrolysis is 0.01-25 g / L0.01 g / L, 2 g / L, 5 g / L, 8 g / L, 11 g / L, 13 g / L, 16 g / L, 19.5 g / L, 22 g / L or 25 g / L, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0011] Preferably, the concentration of sulfate in the anode solution after electrolysis is ≥2.5 mol / L, for example, it can be 2.5 mol / L, 2.6 mol / L, 2.7 mol / L, 2.8 mol / L, 2.9 mol / L, 3.0 mol / L, 3.2 mol / L, 3.5 mol / L, 3.8 mol / L, 4.0 mol / L, 4.2 mol / L or 4.5 mol / L, etc.

[0012] Preferably, the temperature of the oxidation reaction is 20-35°C, for example, it can be 20°C, 22°C, 24°C, 25°C, 27°C, 29°C, 30°C, 32°C, 34°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0013] Preferably, the oxidation reaction time is 0.1 to 0.5 h, for example, 0.1 h, 0.15 h, 0.19 h, 0.24 h, 0.28 h, 0.33 h, 0.37 h, 0.42 h, 0.46 h or 0.5 h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0014] Preferably, the oxygen flow rate is 1 ml / min to 15 ml / min, for example, 1 ml / min, 3 ml / min, 5 ml / min, 10 ml / min or 15 ml / min, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0015] The present invention preferably controls the oxygen flow rate within the above range, which can better improve the oxidation effect, not only improve the oxidation effect, but also reduce the excessive use of hydrogen peroxide.

[0016] Preferably, the concentration of the hydrogen peroxide is 10% to 30%, for example, 10%, 15%, 20%, 25% or 30%, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0017] Preferably, the volume ratio of the hydrogen peroxide to the anode solution after electrolysis is 1:10 to 1:50, for example, 1:10, 1:15, 1:20, 1:30, 1:40 or 1:50, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0018] The present invention preferably controls the amount of hydrogen peroxide to be within the above range, which matches the oxygen inlet flow rate, and can oxidize all vanadium cations in the solution into anions, so as to facilitate subsequent extraction and separation.

[0019] When only oxygen is used for oxidation, since peroxyvanadate needs to be generated, the bubble size and oxygen intake amount of oxygen are relatively high, and it is difficult to generate peroxyvanadate; when only hydrogen peroxide is added, in order to achieve complete oxidation of vanadium in the anode chamber solution, an excessive amount of hydrogen peroxide needs to be added, and the presence of excessive hydrogen peroxide is prone to the problem of excessively violent reaction. Therefore, the present invention simultaneously uses oxygen and hydrogen peroxide for oxidation, which can significantly improve the oxidation effect and avoid excessive addition of hydrogen peroxide, thereby facilitating efficient recycling of sulfuric acid.

[0020] Preferably, the extraction system used in the extraction includes a quaternary ammonium salt anion extractant.

[0021] Preferably, the quaternary ammonium salt anion extractant comprises any one of N235, N263 or N1923 or a combination of at least two thereof, wherein typical but non-limiting combinations are a combination of N235 and N263, a combination of N1923 and N263, and a combination of N235 and N1923.

[0022] Preferably, the extraction system used in the extraction further includes a co-extraction agent and a diluent.

[0023] Preferably, the co-extractant comprises n-octanol and / or isooctyl alcohol.

[0024] Preferably, the diluent comprises sulphonated kerosene.

[0025] Preferably, the extraction system used in the extraction comprises, by weight, 5 to 30% of a quaternary ammonium salt anion extractant, 5 to 20% of a co-extractant, and 50 to 90% of a diluent.

[0026] The present invention further preferably uses an extraction system within the above range to better improve the extraction effect.

[0027] Among them, 5-30% quaternary ammonium salt anion extractant can be, for example, 5%, 8%, 11%, 14%, 17%, 19%, 22%, 25%, 28% or 30%, etc., but is not limited to the listed values, and other values ​​not listed within the range are equally applicable; 5-20% co-extractant can be, for example, 5%, 7%, 9%, 10%, 12%, 14%, 15%, 17%, 19% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the range are equally applicable; and 50-90% diluent can be, for example, 50%, 55%, 59%, 64%, 68%, 73%, 77%, 82%, 86% or 90%, etc., but is not limited to the listed values, and other values ​​not listed within the range are equally applicable.

[0028] Preferably, the extraction time is 3 to 15 min, for example, 3 min, 5 min, 6 min, 7 min, 9 min, 10 min, 11 min, 13 min, 14 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] It is worth noting that the extraction temperature of the present invention is room temperature, generally 20-40°C, for example, it can be 20°C, 25°C, 30°C, 32°C, 35°C, 38°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0030] Preferably, the volume ratio of the extraction system to the peroxyvanadate solution in the extraction is 1:1 to 1:5, for example, it can be 1:1, 1.2, 1:1.5, 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.2, 1:3.5, 1:3.8, 1:4, 1:4.5 or 1:5, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] Preferably, an organic phase containing V is also obtained after the extraction.

[0032] Preferably, the method further comprises: stripping the V-containing organic phase, recovering the extraction system and obtaining an ammonium vanadate solution.

[0033] The invention can realize the recovery of the extraction system through back extraction after extraction, and obtain the ammonium vanadate byproduct, and can also improve the utilization rate of vanadium resources.

[0034] Preferably, the stripping agent used in the stripping is aqueous ammonia.

[0035] Preferably, the concentration of the ammonia water is 2-25%, for example, it can be 2%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, 23% or 25%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0036] Preferably, the volume ratio of the stripping agent to the organic phase containing V in the stripping is 1:1 to 1:10. For example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:7, 1:8, 1:9 or 1:10, but is not limited to the listed values, and other values ​​not listed in the range are also applicable.

[0037] Preferably, the stripping temperature is 20-35°C, for example, 20°C, 22°C, 24°C, 25°C, 27°C, 29°C, 30°C, 32°C, 34°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0038] Preferably, the stripping time is 3 to 15 min, for example, 3 min, 5 min, 6 min, 7 min, 9 min, 10 min, 11 min, 13 min, 14 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0039] Preferably, the method comprises the following steps:

[0040] (1) A post-electrolysis anode solution having a mixed concentration of 10 wt% to 30 wt% hydrogen peroxide and a vanadium mass concentration of 0.01 to 25 g / L and a sulfate concentration of ≥ 2.5 mol / L is prepared in a volume ratio of 1:10 to 1:50, and oxygen is introduced at a flow rate of 1 ml / min to 15 ml / min to perform an oxidation reaction at 20 to 35° C. for 0.1 to 0.5 h to obtain a peroxyvanadate solution.

[0041] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 5-30% quaternary ammonium salt anion extractant; 5-20% co-extractant, and 50-90% diluent, the volume ratio of the extraction system to the peroxyvanadate solution is 1:1-1:5 and the time is 3-15 minutes, to obtain a sulfuric acid solution and a V-containing organic phase.

[0042] (3) stripping the V-containing organic phase with 2-25% ammonia water, wherein the volume ratio of ammonia water to the V-containing organic phase is 1:1-1:10, the stripping temperature is 20-35° C., the stripping time is 3-15 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The method of sulfuric acid circulation in the electrolytic preparation of 3.5-valent vanadyl sulfate provided by the present invention can achieve efficient removal of vanadium in a strong acid system, ensuring continuous and stable operation of the 3.5-valent vanadyl sulfate electrolysis process;

[0045] (2) The method of sulfuric acid circulation in the electrolytic preparation of 3.5-valent vanadyl sulfate provided by the present invention can recover a small amount of vanadium in the vanadium-containing sulfuric acid solution in the anode chamber in the form of ammonium vanadate, thereby realizing the reuse of vanadium, wherein the vanadium removal rate is above 99%, the vanadium recovery rate is above 99%, the purity of the sulfuric acid solution is above 99.5wt%, and the purity of the ammonium vanadate solution is above 99.5wt%. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the principle of preparing 3.5-valent vanadyl sulfate solution by electrolytic reduction in the present invention.

[0047] Figure 2 This is a flow chart of the method for circulating sulfuric acid in preparing 3.5-valent vanadyl sulfate by electrolysis provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0049] As a specific embodiment of the present invention, a method for preparing 3.5-valent vanadyl sulfate by electrolysis is provided, such as Figure 2 As shown, the method comprises the following steps:

[0050] (1) A post-electrolysis anode solution containing 10% to 30% hydrogen peroxide and 0.01 to 25 g / L vanadium by mass and 2.5 mol / L sulfate by volume ratio of 1:10 to 1:50 is mixed, and oxygen is introduced at a flow rate of 1 ml / min to 15 ml / min to perform an oxidation reaction at 20 to 35° C. for 0.1 to 0.5 h to obtain a peroxyvanadate solution.

[0051] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 5-30% quaternary ammonium salt anion extractant; 5-20% co-extractant, and 50-90% diluent, the volume ratio of the extraction system to the peroxyvanadate solution is 1:1-1:5 and the time is 3-15 minutes, to obtain a sulfuric acid solution and a V-containing organic phase.

[0052] (3) stripping the V-containing organic phase with 2-25% ammonia water, wherein the volume ratio of ammonia water to the V-containing organic phase is 1:1-1:10, the stripping temperature is 20-35° C., the stripping time is 3-15 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0053] Example 1

[0054] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0055] (1) A 20 wt% hydrogen peroxide solution and a post-electrolysis anode solution having a vanadium mass concentration of 6 g / L and a sulfate concentration of 3.0 mol / L were mixed in a volume ratio of 1:10, and oxygen was simultaneously introduced at a flow rate of 10 ml / min to perform an oxidation reaction at 25° C. (normal temperature) for 0.2 h to obtain a peroxyvanadate solution.

[0056] (2) The peroxyvanadate solution of step (1) is extracted, wherein the extraction system used for the extraction includes 10% N235, 10% n-octanol, and 80% sulfonated kerosene, the extraction temperature is 30°C, the volume ratio of the extraction system to the peroxyvanadate solution is 1:1, and the extraction time is 5 minutes to obtain a sulfuric acid solution and a V-containing organic phase.

[0057] (3) The V-containing organic phase is back-extracted with 10% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:5, the back-extraction temperature is 25° C., the time is 10 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0058] Example 2

[0059] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0060] (1) A 10 wt% hydrogen peroxide solution and a post-electrolysis anode solution having a vanadium mass concentration of 11 g / L and a sulfate concentration of 2.5 mol / L were mixed in a volume ratio of 1:20, and oxygen was simultaneously introduced at a flow rate of 5 ml / min to perform an oxidation reaction at 35° C. (normal temperature) for 0.1 h to obtain a peroxyvanadate solution.

[0061] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 5% N263, 5% n-octanol, and 90% sulfonated kerosene. The extraction temperature is 25°C, the volume ratio of the extraction system to the peroxyvanadate solution is 1:3, and the extraction time is 10 minutes to obtain a sulfuric acid solution and a V-containing organic phase.

[0062] (3) The V-containing organic phase is back-extracted with 5% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:5, the back-extraction temperature is 35° C., the time is 5 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0063] Example 3

[0064] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0065] (1) A 25 wt% hydrogen peroxide solution and a 25 g / L vanadium mass concentration and a 5 mol / L sulfate concentration post-electrolysis anode solution were mixed in a volume ratio of 1:30, and oxygen was simultaneously introduced at a flow rate of 10 ml / min to perform an oxidation reaction at 20° C. (normal temperature) for 0.5 h to obtain a peroxyvanadate solution.

[0066] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 30% N1923, 10% n-octanol, and 60% sulfonated kerosene, the extraction temperature is 35°C, the volume ratio of the extraction system to the peroxyvanadate solution is 1:5, and the extraction time is 15 minutes to obtain a sulfuric acid solution and a V-containing organic phase.

[0067] (3) The V-containing organic phase is back-extracted with 15% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:4, the back-extraction temperature is 20° C., the time is 10 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0068] Example 4

[0069] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0070] (1) A 30 wt% hydrogen peroxide solution and a 3 g / L vanadium mass concentration and a 3 mol / L sulfate ion concentration post-electrolysis anodic solution were mixed in a volume ratio of 1:40, and oxygen was simultaneously introduced at a flow rate of 10 ml / L to carry out an oxidation reaction at 22° C. (normal temperature) for 0.4 h to obtain a peroxyvanadate solution.

[0071] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 5% N235, 20% n-octanol, and 75% sulfonated kerosene. The extraction temperature is 32° C., the volume ratio of the extraction system to the peroxyvanadate solution is 1:2, and the extraction time is 3 min to obtain a sulfuric acid solution and a V-containing organic phase.

[0072] (3) The V-containing organic phase is back-extracted with 2% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:10, the back-extraction temperature is 35° C., the time is 3 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0073] Example 5

[0074] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0075] (1) A 10 wt% hydrogen peroxide solution and a post-electrolysis anode solution having a vanadium mass concentration of 1 g / L and a sulfate concentration of 2.9 mol / L were mixed in a volume ratio of 1:50, and oxygen was simultaneously introduced at a flow rate of 3 ml / min to perform an oxidation reaction at 30° C. (normal temperature) for 0.1 h to obtain a peroxyvanadate solution.

[0076] (2) The peroxyvanadate solution of step (1) is extracted, and the extraction system used for the extraction includes 10% N263, 10% n-octanol, and 80% sulfonated kerosene, the extraction temperature is 30°C, the volume ratio of the extraction system to the peroxyvanadate solution is 1:8, and the extraction time is 10 minutes to obtain a sulfuric acid solution and a V-containing organic phase.

[0077] (3) The V-containing organic phase is back-extracted with 25% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:8, the back-extraction temperature is 32° C., the time is 6 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0078] Example 6

[0079] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid, the method comprising the following steps:

[0080] (1) A mixture of 22 wt% hydrogen peroxide and a post-electrolysis anode solution having a vanadium mass concentration of 7 g / L and a sulfate concentration of 4 mol / L was prepared in a volume ratio of 1:30, and oxygen was introduced at a flow rate of 9 ml / min to perform an oxidation reaction at 32° C. (normal temperature) for 0.2 h to obtain a peroxyvanadate solution.

[0081] (2) The peroxyvanadate solution of step (1) is extracted using an extraction system comprising 15% N235, 15% n-octanol, and 70% sulfonated kerosene, the extraction temperature is 28°C, the volume ratio of the extraction system to the peroxyvanadate solution is 1:4, and the extraction time is 10 min, to obtain a sulfuric acid solution and an organic phase containing V.

[0082] (3) The V-containing organic phase is back-extracted with 10% ammonia water, the volume ratio of ammonia water to the V-containing organic phase is 1:9, the back-extraction temperature is 30° C., the time is 5 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

[0083] Example 7

[0084] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of Embodiment 1 except that the oxygen flow rate is 0.1 ml / min, and will not be described in detail here.

[0085] Example 8

[0086] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of Embodiment 1 except that the oxygen inlet flow rate is relatively high, specifically 20 ml / min, and will not be described in detail here.

[0087] Example 9

[0088] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis in the circulation of sulfuric acid. The method is the same as that of embodiment 1 except that the concentration of hydrogen peroxide is lower, specifically 5 wt %, and will not be described again.

[0089] Example 10

[0090] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis in the circulation of sulfuric acid. The method is the same as that of embodiment 1 except that the concentration of hydrogen peroxide is relatively high, specifically 40 wt %, and will not be described again.

[0091] Embodiment 11

[0092] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid. The method is the same as that of Embodiment 1 except that N235 is replaced by a cationic extractant P204, and will not be described in detail here.

[0093] Example 12

[0094] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of Example 1 except that 10% N235 is replaced by 2% N235 and the rest is adjusted to sulfonated kerosene, which will not be repeated here.

[0095] Embodiment 13

[0096] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of Embodiment 1 except that the extraction system includes 40% N235, 5% n-octanol, and 55% sulfonated kerosene, and will not be described again.

[0097] Embodiment 14

[0098] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of embodiment 1 except that the extraction system includes 10% N235, 2% n-octanol, and 88% sulfonated kerosene, and will not be described again.

[0099] Embodiment 15

[0100] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as that of Embodiment 1 except that the extraction system includes 10% N235, 25% n-octanol, and 65% sulfonated kerosene, and will not be described again.

[0101] Example 16

[0102] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid. The method is the same as that of Embodiment 1 except that the concentration of ammonia water is 30%, and will not be described in detail here.

[0103] Embodiment 17

[0104] This embodiment provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid. The method is the same as that of Embodiment 1 except that the concentration of ammonia water is 1%, and will not be described in detail here.

[0105] Comparative Example 1

[0106] This comparative example provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as Example 1 except that oxygen is not introduced, and will not be described in detail here.

[0107] Comparative Example 2

[0108] This comparative example provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation. The method is the same as Example 1 except that hydrogen peroxide is not added, and will not be described in detail here.

[0109] Comparative Example 3

[0110] This comparative example provides a method for preparing 3.5-valent vanadyl sulfate by electrolysis and circulating sulfuric acid. The method is the same as Example 1 except that step (1) is not performed and the anode solution after electrolysis is directly subjected to steps (2) to (3). The details will not be repeated here.

[0111] The concentration of each element in the solution was quantitatively determined and analyzed by ICP-OES. According to the above test method and calculation formula, the purity and yield were obtained. The vanadium removal rate in the sulfuric acid solution, the vanadium recovery rate in the ammonium vanadate solution, and the purity of the sulfuric acid solution and the ammonium vanadate solution prepared in the above examples and comparative examples are shown in Table 1.

[0112] The test results of the above embodiments and comparative examples are shown in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] From Table 1 we can see that:

[0117] (1) It can be seen from Examples 1 to 6 that the present invention uses an oxidation pretreatment to first convert vanadium cations in the vanadium-containing sulfuric acid solution after electrolysis into peroxyvanadate anions, and then uses an anion extractant extraction-ammonia water stripping process to achieve efficient removal of vanadium from the raw material solution and recovery of vanadium. The sulfuric acid solution after vanadium removal returns to the electrolysis process, and the removed vanadium is recovered in the form of ammonium vanadate, wherein the vanadium removal rate is above 99%, the vanadium recovery rate is above 99%, the purity of the sulfuric acid solution is above 99.5wt%, and the purity of the ammonium vanadate solution is above 99.5wt%;

[0118] (2) It can be seen from Examples 7 to 10 that when oxygen / hydrogen peroxide is excessive, it will not affect the conversion of peroxyvanadate, and the removal rate and recovery rate of vanadium will not be affected, but there will be a problem of waste of oxygen or hydrogen peroxide. When oxygen / hydrogen peroxide is insufficient, vanadium cations cannot be completely converted into peroxyvanadate anions, resulting in reduced removal rate and recovery rate of vanadium;

[0119] (3) By comparing Example 1 and Example 11, it can be seen that when a cationic extractant is used, effective removal of vanadium in the solution cannot be achieved, and a large amount of vanadium accumulates in the solution system;

[0120] (3) It can be seen from Examples 12-15 that when the volume fraction of the extractant / co-extractant is insufficient, effective removal of vanadium from the solution cannot be achieved, and Example 14 has almost no extraction effect. When the extractant / co-extractant is excessive, there is no obvious effect on the removal of vanadium, but it will lead to an increase in the amount of extractant used, which is more expensive;

[0121] (4) It can be seen from Examples 1 and 16-17 that when the concentration of ammonia water is insufficient, effective stripping and enrichment of vanadium cannot be achieved. When the concentration of ammonia water is too high, there is no obvious effect on the stripping and recovery of vanadium, but there is a large amount of waste of ammonia water resources, and the cost is higher.

[0122] (5) Comparative Examples 1-3 show that it is difficult to effectively remove vanadium from the solution when hydrogen peroxide and oxygen are not added simultaneously or when pretreatment is not performed.

[0123] In summary, the present invention proposes a method for preparing 3.5-valent vanadyl sulfate by electrolysis in a sulfuric acid cycle. The present invention first converts vanadium cations in the solution into peroxyvanadate anions by adding hydrogen peroxide and simultaneously introducing oxygen, and then removes vanadium from the vanadium-containing sulfuric acid solution by extraction to obtain a pure sulfuric acid solution that returns to the electrolysis process. The vanadium-containing organic phase obtained after extraction is stripped by ammonia water to achieve vanadium recovery and organic phase regeneration, and the recovered vanadium is stored in the form of ammonium vanadate solution, so that the resource utilization rate is higher.

[0124] The present invention illustrates the detailed features of the present invention through the above embodiments, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the technical features selected by the present invention, addition of auxiliary technical features, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing 3.5-valent vanadyl sulfate by electrolysis with sulfuric acid circulation, characterized in that: The method comprises the following steps: (1) mixing an electrolytically-post-anodic solution and hydrogen peroxide, and simultaneously introducing oxygen to carry out an oxidation reaction, thereby obtaining a peroxyvanadate-containing solution; wherein the electrolytically-post-anodic solution contains vanadium cations and sulfate; (2) The peroxyvanadate solution in step (1) is extracted to obtain a sulfuric acid solution.

2. The method according to claim 1, characterized in that The mass concentration of vanadium in the anode solution after electrolysis is 0.01 to 25 g / L; Preferably, the concentration of sulfate in the anode solution after electrolysis is ≥2.5 mol / L.

3. The method according to claim 1 or 2, characterized in that: The temperature of the oxidation reaction is 20 to 35°C; Preferably, the oxidation reaction time is 0.1 to 0.5 h.

4. The method according to any one of claims 1 to 3, characterized in that: The oxygen inlet flow rate is 1ml / min to 15ml / min; Preferably, the concentration of the hydrogen peroxide is 10wt% to 30wt%; Preferably, the volume ratio of the hydrogen peroxide solution to the anode solution after electrolysis is 1:10 to 1:

50.

5. The method according to any one of claims 1 to 4, characterized in that: The extraction system used in the extraction includes a quaternary ammonium salt anion extractant; Preferably, the quaternary ammonium salt anion extractant includes any one of N235, N263 or N1923, or a combination of at least two of them.

6. The method according to any one of claims 1 to 5, characterized in that: The extraction system used in the extraction further includes a co-extraction agent and a diluent; Preferably, the co-extractant comprises n-octanol and / or isooctyl alcohol; Preferably, the diluent comprises sulphonated kerosene.

7. The method according to any one of claims 1 to 6, characterized in that: According to the mass fraction, the extraction system used in the extraction comprises 5-30% of quaternary ammonium salt anion extractant, 5-20% of co-extractant, and 50-90% of diluent.

8. The method according to any one of claims 1 to 7, characterized in that: The extraction time is 3 to 15 minutes; Preferably, in the extraction, the volume ratio of the extraction system to the peroxyvanadate-containing solution is 1:1 to 1:

5.

9. The method according to any one of claims 1 to 8, characterized in that: After the extraction, an organic phase containing V is also obtained; Preferably, the method further comprises: stripping the V-containing organic phase, recovering the extraction system and obtaining an ammonium vanadate solution; Preferably, the stripping agent used in the stripping is aqueous ammonia; Preferably, the concentration of the ammonia water is 2 to 25%; Preferably, the volume ratio of the stripping agent to the organic phase containing V in the stripping is 1:1 to 1:10; Preferably, the stripping temperature is 20 to 35°C; Preferably, the stripping time is 3 to 15 minutes.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) mixing a hydrogen peroxide solution having a concentration of 10% to 30% and a vanadium mass concentration of 0.01 to 25 g / L and a post-electrolysis anode solution having a sulfate concentration of ≥ 2.5 mol / L in a volume ratio of 1:10 to 1:50, and simultaneously introducing oxygen at a flow rate of 1 ml / min to 15 ml / min to perform an oxidation reaction at 20 to 35° C. for 0.1 to 0.5 h to obtain a peroxyvanadate solution; (2) The peroxyvanadate solution of step (1) is extracted, wherein the extraction system used in the extraction comprises 5-30% quaternary ammonium salt anion extractant; 5-20% co-extractant, and 50-90% diluent, the volume ratio of the extraction system to the peroxyvanadate solution is 1:1-1:5 and the extraction time is 3-15 minutes, to obtain a sulfuric acid solution and a V-containing organic phase; (3) stripping the V-containing organic phase with 2-25% ammonia water, wherein the volume ratio of ammonia water to the V-containing organic phase is 1:1-1:10, the stripping temperature is 20-35° C., the stripping time is 3-15 min, and the extraction system is recovered to obtain an ammonium vanadate solution.

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