A method for regenerating waste vanadium energy storage medium

Abstract

The present invention provides a method for regenerating waste vanadium energy storage media, comprising the following steps: detecting the content of waste vanadium energy storage media elements; adjusting the valence of vanadium to 3.98-4.02 to obtain a vanadium solution; adding pure water or mother liquor to dilute the vanadium solution, adjusting the pH value of the vanadium solution to obtain a pre-extraction solution; performing countercurrent extraction, countercurrent water washing, and countercurrent stripping to obtain a raffinate, a water washing solution, and a high-purity stripping solution; adjusting the high-purity stripping solution to the standard concentration of the vanadium energy storage medium, adjusting the valence through electrolysis, and obtaining a regenerated vanadium energy storage medium; adjusting the pH value of the raffinate and the water washing solution, adding an oxidant or using electrolytic oxidation to oxidize the tetravalent vanadium therein to a pentavalent state, performing ion exchange through a resin, recovering the vanadium in the raffinate and the water washing solution, and obtaining a vanadium post-liquid; crystallizing the vanadium post-liquid to obtain a mother liquor and crystals. The present invention can separate the impurity elements in the vanadium energy storage medium to achieve the purpose of regeneration.

Description

Technical Field

[0001] The invention relates to energy storage medium recovery technology, and in particular to a method for regenerating waste vanadium energy storage medium. Background Art

[0002] All-vanadium liquid flow battery is the most technically mature liquid flow battery at present, and is also a very promising green and environmentally friendly energy storage battery. It does not produce harmful substances during manufacturing, use and disposal. Since its introduction, it has received extensive attention and has developed rapidly both at home and abroad. It can be used as a backup power supply for buildings, airports, and program-controlled switching stations, as a supporting energy storage device for clean power generation systems such as solar energy, to provide power for submarines and ocean-going ships, and for peak load regulation of power grids.

[0003] Vanadium energy storage medium is not only the ion conductor of the battery, but also the storage medium of the battery active material, and is one of the key materials of the all-vanadium liquid flow battery. The all-vanadium liquid flow battery uses vanadium ions of different valence states in the vanadium energy storage medium, that is, the positive electrode vanadium energy storage medium is composed of a mixed solution of tetravalent and pentavalent vanadium ions and acid, and the negative electrode vanadium energy storage medium is composed of a mixed solution of divalent and trivalent vanadium ions and acid. The redox reaction occurs on the electrode surface to complete the mutual conversion of electrical energy and chemical energy, and realize the storage and release of electrical energy. That is, after the battery is charged, the positive electrode material is a pentavalent vanadium ion acid solution, and the negative electrode is a divalent vanadium ion acid solution. After the battery is discharged, the positive and negative electrodes are tetravalent and trivalent vanadium ion acid solutions, respectively.

[0004] During the charging and discharging process of the all-vanadium liquid flow battery, the migration of vanadium ions, the oxidation of divalent vanadium ions in the negative electrode vanadium energy storage medium, and the hydrogen evolution at the negative electrode will lead to the mismatch between the concentration and valence of the positive and negative electrode vanadium energy storage medium, resulting in the failure of the vanadium energy storage medium. In order to restore its function, a certain amount of additives must be added to it. Some impurity elements in the additives will pollute the vanadium energy storage medium. In addition, the material parts that the vanadium energy storage medium contacts will dissolve some impurity elements, which will also pollute the vanadium energy storage medium. Common impurity elements, such as sodium, potassium, iron, chromium, etc., will cause the deterioration of the electrochemical properties of the vanadium energy storage medium, and then lead to the failure of the vanadium energy storage medium. With the large-scale application of all-vanadium liquid flow batteries, a large number of failed vanadium energy storage media will be generated, and the regeneration of waste vanadium energy storage media has begun to become a concern of the all-vanadium liquid flow battery industry.

[0005] The publication number is "CN110994061A", and the name of the invention is "A method for recovering vanadium electrolyte". It describes that the vanadium electrolyte is first charged with a positive electrode or an oxidant is added to adjust the average valence of vanadium in the vanadium electrolyte to not less than 4.9, and then diluted with water to a V2O5 content of less than or equal to 100g / L, and then an alkaline substance is added to adjust the pH of the solution to 2-3, heated and stirred, and precipitated to prepare red vanadium, and finally the obtained red vanadium is dissolved and clarified by adding an alkaline substance, and a precipitant is added and stirred to prepare high-purity ammonium metavanadate AMV. The process flow of the vanadium electrolyte recovery method is complex and the energy consumption is high. The final product is high-purity ammonium metavanadate, not a vanadium energy storage medium. After analysis, the patent is not suitable for the regeneration of waste vanadium energy storage media containing impurity elements.

[0006] The publication number is "CN109360997A", ​​and the invention name is "Regeneration method of spent vanadium electrolyte in sulfuric acid system", which describes adding tetravalent vanadium electrolyte or trivalent vanadium electrolyte and water to spent vanadium electrolyte in sulfuric acid system to obtain regenerated electrolyte. This regeneration method is only applicable to the adjustment of valence state and concentration of vanadium electrolyte, and does not mention the removal of impurity elements in electrolyte. After analysis, this patent is not applicable to the regeneration of waste vanadium energy storage medium containing impurity elements.

[0007] The publication number is "CN107500357A", and the invention name is "Method for preparing vanadium pentoxide". It describes that hydrogen peroxide is first added to the positive and / or negative electrolyte of the vanadium battery, and reacted under the action of ultrasound to oxidize the non-pentavalent vanadium in the electrolyte into pentavalent vanadium, and then the pentavalent vanadium solution is obtained, and the vanadium pentoxide product is obtained after acid adjustment, vanadium precipitation, and acid washing. The final product of the vanadium electrolyte recovery method is vanadium pentoxide, not vanadium energy storage medium. After analysis, this patent is not suitable for the regeneration of waste vanadium energy storage medium containing impurity elements.

[0008] At present, the domestic recycling technology for vanadium energy storage media has complex processes and high energy consumption costs. The final products of the recycling methods are mostly vanadium oxides and vanadates, and there are few references to the regeneration methods of waste vanadium energy storage media containing impurity elements. Therefore, it is of great practical significance to develop a regeneration method with simple processes, low energy consumption costs, and suitable for vanadium energy storage media containing impurity elements. Summary of the invention

[0009] The purpose of the present invention is to propose a method for regenerating waste vanadium energy storage media, in view of the fact that the current regeneration of vanadium energy storage media has complex processes, high energy consumption costs, and the final products of the recovery methods are mostly vanadium oxides and vanadates, and there is little mention of the regeneration method of waste vanadium energy storage media containing impurity elements. The method can separate the impurity elements in the vanadium energy storage medium to achieve the purpose of regeneration.

[0010] To achieve the above object, the technical solution adopted by the present invention is: a method for regenerating waste vanadium energy storage medium, comprising the following steps:

[0011] Step 1. Detecting the vanadium content, vanadium valence and impurity element content (the impurity elements include but are not limited to one or more of sodium, potassium, iron and chromium) of the waste vanadium energy storage medium;

[0012] Step 2: According to the valence of vanadium in the waste vanadium energy storage medium, the valence of vanadium is adjusted to 3.98-4.02 to obtain a vanadium solution (vanadium oxysulfate solution and / or vanadium oxydichloride solution). The specific method is:

[0013] (1) When the valence of vanadium in the waste vanadium energy storage medium is greater than 4.02, a reducing agent is added or electrolytic reduction is performed to adjust the valence of vanadium to 3.98 to 4.02;

[0014] (2) When the valence of vanadium in the waste vanadium energy storage medium is less than 3.98, an oxidant is added or electrolytic oxidation is used to adjust the valence of vanadium to 3.98 to 4.02;

[0015] Step 3. adding pure water or mother liquor to dilute the vanadium solution so that the vanadium content (in terms of V2O5) is 40 to 120 g / L, adding alkaline substances to adjust the pH value of the vanadium solution to 2 to 3, and obtaining a pre-extraction solution;

[0016] Step 4. using the organic phase as an extractant; using pure water as a washing agent for loading the organic phase, using a sulfuric acid solution or a hydrochloric acid solution as a stripping agent, and performing countercurrent extraction, countercurrent water washing, and countercurrent stripping to obtain a raffinate, a water washing solution, and a high-purity stripping solution (vanadium oxysulfate solution and / or vanadium oxychloride solution);

[0017] Step 5. The high-purity stripping solution is adjusted to the standard concentration of the vanadium energy storage medium by using pure water, sulfuric acid or hydrochloric acid, and the valence state is adjusted by electrolysis to obtain the regenerated vanadium energy storage medium; after adding alkaline substances to the raffinate (V2O5<1.0g / L) and the water washing liquid to adjust the pH value to 2-3, an oxidant is added or electrolytic oxidation is used to oxidize the tetravalent vanadium therein to pentavalent, and ion exchange is performed through a resin to recover the vanadium in the raffinate and the water washing liquid to obtain a vanadium rear liquid; a very small amount of vanadium in the raffinate is not extracted and can be further recovered; during the extraction process, a small amount of vanadium will be attached to the organic phase, and these vanadium will enter the water washing liquid during the water washing process, which can also be further recovered.

[0018] The high-purity stripping solution is adjusted to the standard concentration of vanadium energy storage medium using pure water, sulfuric acid or hydrochloric acid. The standard concentration of the energy storage medium is: V = 1.0-3.0 mol / L in the sulfuric acid system vanadium energy storage medium, SO4 2-=4.0~5.0mol / L; V in the hydrochloric acid system vanadium energy storage medium = 2.0~3.0mol / L, Cl - =8.0~10.0mol / L; V in the mixed acid system vanadium energy storage medium =2.0~3.0mol / L, Cl - =7.0~9.0mol / L, SO4 2- =0.4~0.6mol / L. Cl - and SO4 2- If it is insufficient, use sulfuric acid and hydrochloric acid to supplement it. If it is excessive, use pure water to dilute it.

[0019] Step 6. Crystallize the vanadium post-liquid to obtain a mother liquor and crystals. The crystals are sodium sulfate decahydrate and / or sodium chloride. The mother liquor can be recycled, and the sodium sulfate decahydrate and sodium chloride can be used as chemical raw materials after drying.

[0020] Furthermore, the main components and contents of the waste vanadium energy storage medium in step 1 are as follows: the main components of the sulfuric acid system vanadium energy storage medium are V = 1.0 ~ 3.0 mol / L, SO4 2- =4.0~5.0mol / L, impurity elements Na>55mg / L, K>80mg / L, Fe>35mg / L, Cr>5mg / L; the main components of the vanadium energy storage medium in the hydrochloric acid system are V=2.0~3.0mol / L, Cl - =8.0~10.0mol / L, impurity elements Na>400mg / L, K>200mg / L, Fe>100mg / L, Cr>20mg / L; the main components of the vanadium energy storage medium in the mixed acid system are V=2.0~3.0mol / L, Cl - =7.0~9.0mol / L, SO4 2- =0.4~0.6mol / L, impurity elements Na>400mg / L, K>200mg / L, Fe>100mg / L, Cr>20mg / L. As long as one impurity element in the energy storage medium exceeds the standard, it can be identified as waste vanadium energy storage medium.

[0021] Furthermore, the reducing agent in step 2 is one or more of sulfur dioxide, citric acid, glucose, ascorbic acid, oxalic acid, fructose, cellulose and vanadium trioxide.

[0022] Furthermore, the oxidant in step 2 is one or more of hydrogen peroxide, perchloric acid, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peracetic acid, sodium persulfate and vanadium pentoxide.

[0023] Furthermore, the mother liquor in step 3 is the mother liquor in step 6.

[0024] Furthermore, the alkali used in step 3 is one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate.

[0025] Furthermore, the organic phase is used as an extractant, and extraction is performed at a ratio of O / A=0.5-1.0; pure water is used as a detergent for loading the organic phase, and water washing is performed at a ratio of O / A=20-30; 4.0-5.0 mol / L sulfuric acid solution or 7.0-10.0 mol / L hydrochloric acid solution is used as a stripping agent, and stripping is performed at a ratio of O / A=10-15.

[0026] Furthermore, the organic phase in step 4 is a or b, wherein a is P204 and sulfonated kerosene in a mass ratio of 2 to 4:6 to 8, and b is P507 and sulfonated kerosene in a mass ratio of 2 to 4:6 to 8. The P204 is [di(2-ethylhexyl) phosphate], and the P507 is [2-ethylhexylphosphonic acid mono-2-ethylhexyl ester].

[0027] Furthermore, in step 4, the countercurrent extraction is 4 to 6 stages, the countercurrent water washing is 2 to 4 times, and the countercurrent stripping is 3 to 5 stages.

[0028] Furthermore, the oxidant in step 5 is one or more of hydrogen peroxide, perchloric acid, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peracetic acid and sodium persulfate, and the added amount is 0.5 to 1.5 times the total amount of vanadium in the raffinate and the water washing liquid, preferably 0.8 to 1.2 times.

[0029] Furthermore, the resin in step 5 is a leaching resin or a macroporous anion resin, such as Success996, D201, D301, etc. Ion exchange through the resin is to exchange the anion groups on the resin with vanadate, and replace the vanadate on the resin to achieve vanadium adsorption.

[0030] Furthermore, the crystallization in step 6 is liquid cooling crystallization or evaporative crystallization.

[0031] Furthermore, the cooling crystallization temperature in step 6 is less than 10°C, and the evaporation crystallization temperature is greater than 80°C.

[0032] The method for regenerating waste vanadium energy storage medium of the present invention has the following advantages compared with the prior art:

[0033] 1) The present invention can regenerate waste vanadium energy storage media containing impurity elements (potassium, sodium, iron and chromium);

[0034] 2) The waste vanadium energy storage medium regeneration process of the present invention is simple and is suitable for the recovery of waste vanadium energy storage media in different systems such as sulfuric acid system, hydrochloric acid system or mixed acid system;

[0035] 3) The method for regenerating the waste vanadium energy storage medium of the present invention can achieve a vanadium recovery rate in the vanadium electrolyte of greater than 98%;

[0036] 4) The method for regenerating waste vanadium energy storage media of the present invention can achieve no waste generation in the whole process.

[0037] 5) The present invention adjusts the valence of vanadium in the waste vanadium energy storage medium to 3.98-4.02, and reduces it to positive tetravalent vanadium as much as possible, ensuring that the content of tetravalent vanadium accounts for more than 98%, which is easy to extract. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a process flow chart for the regeneration process of waste vanadium energy storage media. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with embodiments:

[0040] Example 1

[0041] This embodiment discloses a method for regenerating waste vanadium energy storage medium, comprising the following steps:

[0042] Step 1, sulfuric acid system vanadium energy storage medium V = 1.6 mol / L, SO4 2- =4.2mol / L, average valence state is 4.8, among which the impurity element Na content is 80mg / L, Fe content is 50mg / L exceeding the standard, and the other impurity elements meet the standard;

[0043] Step 2, charging the vanadium valence in the solution to an average valence of 4.00 by positive electrode charging;

[0044] Step 3, adding water to dilute the solution to a vanadium concentration of 70 g / L, adding sodium hydroxide to adjust the pH value of the vanadium solution to 2-3, and obtaining a pre-extraction solution;

[0045] Step 4, using 30% P204+70% sulfonated kerosene as an organic phase extractant, with a ratio of O / A=0.8 for extraction; using pure water as a detergent for loading the organic phase, with a ratio of O / A=20 for water washing, and 4.2 mol / L sulfuric acid solution as a stripping agent, with a ratio of O / A=15 for stripping, after 4-stage countercurrent extraction, 3 countercurrent water washings, and 4-stage countercurrent stripping, a raffinate, a water washing liquid and a high-purity vanadium oxysulfate solution are obtained;

[0046] Step 5: Adjust the high-purity vanadium oxysulfate solution to the standard concentration of vanadium energy storage medium V = 1.6 mol / L using sulfuric acid and pure water, SO4 2-=4.2mol / L, and the valence state is adjusted to 3.50 by electrolysis to obtain a regenerated sulfuric acid system vanadium energy storage medium, wherein the Na content is 20mg / L, the Fe content is 15mg / L exceeding the standard, and the other impurity elements meet the standard; after the raffinate and the water washing liquid are added with sodium hydroxide to adjust the pH value to 2-3, hydrogen peroxide is added according to 0.8 times the total amount of vanadium in the raffinate and the water washing liquid to oxidize the tetravalent vanadium therein to pentavalent, and the vanadium in the raffinate and the water washing liquid is recovered by the leaching resin Success 996 to obtain a vanadium post-liquid;

[0047] Step 6: Cool the vanadium post-liquid at 5° C. to crystallize to obtain a mother liquor and sodium sulfate decahydrate. The mother liquor can be recycled, and the sodium sulfate decahydrate can be used as a chemical raw material after drying.

[0048] Example 2

[0049] This embodiment discloses a method for regenerating waste vanadium energy storage medium, comprising the following steps:

[0050] Step 1: Hydrochloric acid system vanadium energy storage medium V = 2.4 mol / L, Cl - =9.0mol / L, average valence state is 4.5, among which the impurity element K content is 300mg / L, Cr content is 30mg / L exceeding the standard, and the other impurity elements meet the standard;

[0051] Step 2, charging the vanadium valence in the solution to an average valence of 4.00 by positive electrode charging;

[0052] Step 3, adding water to dilute the solution to a vanadium concentration of 50 g / L, and adding sodium carbonate to adjust the pH value of the vanadium solution to 2-3 to obtain a pre-extraction solution;

[0053] Step 4, using 30% P507 + 70% sulfonated kerosene as an organic phase extractant, with a ratio of O / A = 1.0 for extraction; using pure water as a detergent for loading the organic phase, with a ratio of O / A = 20 for water washing, 9.0 mol / L hydrochloric acid solution as a stripping agent, with a ratio of O / A = 10 for stripping, after 6 levels of countercurrent extraction, 3 countercurrent water washings, and 3 levels of countercurrent stripping, a raffinate, a water washing liquid and a high-purity vanadium dichloride solution are obtained;

[0054] Step 5: Adjust the high-purity vanadium oxychloride solution to the standard concentration of vanadium energy storage medium V = 2.4 mol / L using hydrochloric acid and pure water. -=9.0mol / L, and the valence state is adjusted to 3.50 by electrolysis to obtain a regenerated hydrochloric acid system vanadium energy storage medium, wherein the Na content is 50mg / L, the Fe content is 30mg / L exceeding the standard, and the other impurity elements meet the standard; after the raffinate and the water washing liquid are added with sodium hydroxide to adjust the pH value to 2-3, hydrogen peroxide is added according to 0.8 times the total amount of vanadium in the raffinate and the water washing liquid to oxidize the tetravalent vanadium therein to pentavalent, and the vanadium in the raffinate and the water washing liquid is recovered by a large-pore anion resin D201 to obtain a vanadium rear liquid;

[0055] Step 6: evaporate and crystallize the vanadium post-liquid at 85° C. to obtain a mother liquor and sodium chloride. The mother liquor can be recycled, and the sodium chloride can be used as a chemical raw material after drying.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for regenerating waste vanadium energy storage media, characterized in that: The following steps are involved: Step 1. Detecting the vanadium content, vanadium valence and impurity element content of the waste vanadium energy storage medium; the impurity element is one or more of sodium, potassium, iron and chromium; Step 2: According to the valence of vanadium in the waste vanadium energy storage medium, the valence of vanadium is adjusted to 3.98-4.02 to obtain a vanadium solution. The specific method is: (1) When the valence of vanadium in the waste vanadium energy storage medium is greater than 4.02, a reducing agent is added or electrolytic reduction is performed to adjust the valence of vanadium to 3.98 to 4.02; (2) When the valence of vanadium in the waste vanadium energy storage medium is less than 3.98, an oxidant is added or electrolytic oxidation is used to adjust the valence of vanadium to 3.98 to 4.02; Step 3. adding pure water or mother liquor to dilute the vanadium solution so that the vanadium content is 40-120 g / L, where the vanadium content is calculated as V2O5, adding alkaline substances to adjust the pH value of the vanadium solution to 2-3, and obtaining a pre-extraction solution; Step 4. using the organic phase as an extractant; using pure water as a washing agent for loading the organic phase, using a sulfuric acid solution or a hydrochloric acid solution as a stripping agent, and performing countercurrent extraction, countercurrent water washing, and countercurrent stripping to obtain a raffinate, a water washing solution, and a high-purity stripping solution; Step 5. The high-purity stripping solution is adjusted to the standard concentration of the vanadium energy storage medium by using pure water, sulfuric acid or hydrochloric acid, and the valence state is adjusted by electrolysis to obtain the regenerated vanadium energy storage medium; after the raffinate and the water washing liquid are added with an alkaline substance to adjust the pH value to 2-3, an oxidant is added or electrolytic oxidation is used to oxidize the tetravalent vanadium therein to pentavalent, ion exchange is performed through a resin, and the vanadium in the raffinate and the water washing liquid is recovered to obtain a vanadium rear liquid; Step 6. Crystallizing the vanadium post-liquid to obtain a mother liquor and crystals, wherein the crystals are sodium sulfate decahydrate and / or sodium chloride.

2. The method for regenerating waste vanadium energy storage medium according to claim 1, characterized in that: The reducing agent in step 2 is one or more of sulfur dioxide, citric acid, glucose, ascorbic acid, oxalic acid and vanadium trioxide.

3. The method for regenerating waste vanadium energy storage medium according to claim 1, characterized in that: The oxidant in step 2 is one or more of hydrogen peroxide, perchloric acid, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peracetic acid, sodium persulfate and vanadium pentoxide.

4. The method for regenerating waste vanadium energy storage medium according to claim 1, characterized in that: The alkaline substance used in step 3 is one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate.

5. The method for regenerating waste vanadium energy storage medium according to claim 1, characterized in that: The organic phase is used as the extractant, and the extraction is performed at a ratio of O / A=0.5-1.0; pure water is used as the detergent for loading the organic phase, and the water washing is performed at a ratio of O / A=20-30; 4.0-5.0 mol / L sulfuric acid solution or 7.0-10.0 mol / L hydrochloric acid solution is used as the stripping agent, and the stripping is performed at a ratio of O / A=10-15.

6. The method for regenerating waste vanadium energy storage medium according to claim 1 or 5, characterized in that: In step 4, the organic phase is a or b, wherein a is P204 and sulfonated kerosene in a mass ratio of 2-4:6-8, and b is P507 and sulfonated kerosene in a mass ratio of 2-4:6-8.

7. The method for regenerating waste vanadium energy storage media according to claim 1, characterized in that: The oxidant in step 5 is one or more of hydrogen peroxide, perchloric acid, ammonium persulfate, potassium persulfate, potassium hydrogen persulfate, peracetic acid and sodium persulfate, and the added amount is 0.5 to 1.5 times the total amount of vanadium in the raffinate and the water washing liquid.

8. The method for regenerating waste vanadium energy storage media according to claim 1, characterized in that: The standard concentration of the energy storage medium in step 5 is vanadium energy storage medium V = 1.0-3.0 mol / L in sulfuric acid system, SO4 2- =4.0~5.0mol / L; hydrochloric acid system vanadium energy storage medium V = 2.0~3.0mol / L, Cl - =8.0~10.0mol / L; the main components of the vanadium energy storage medium in the mixed acid system are V=2.0~3.0mol / L, Cl - =7.0~9.0mol / L, SO4 2- =0.4~0.6mol / L.

9. The method for regenerating waste vanadium energy storage media according to claim 1, characterized in that: The resin in step 5 is a leaching resin or a macroporous anion resin.

10. The method for regenerating waste vanadium energy storage media according to claim 1, characterized in that: The crystallization in step 6 is cooling crystallization or evaporation crystallization.

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