Vanadium slag valence state regulation-based vanadyl sulfate electrolyte short-process preparation method and application thereof

Abstract

The invention discloses a short-process preparation method and application of a vanadyl sulfate electrolyte based on vanadium slag valence regulation and control, and belongs to the technical field of vanadium electrolytes. The method comprises the following steps: leaching the vanadium slag by using sulfuric acid to obtain a leaching solution containing low-valence vanadium; extracting vanadium and chromium in the leachate by adopting an amine organic extraction agent; carrying out reverse extraction by using sulfuric acid; the method comprises the following steps of: firstly, extracting and separating vanadium by using a phosphoric acid extracting agent, and finally, carrying out reverse extraction by using sulfuric acid to obtain the vanadium electrolyte which can be used for constructing a VFB-5kW / 10kWh vanadium battery energy storage system. The traditional established thinking that pentavalent vanadium is extracted through vanadium slag oxidation to serve as a vanadium source to prepare the vanadium electrolyte is broken through, the novel technology for extracting the low-valence vanadium solution from the vanadium slag to directly prepare the vanadium electrolyte is provided, the short-process and green novel technology for preparing the vanadium electrolyte from the vanadium slag is constructed, the efficiency of the vanadium electrolyte preparation technology is improved, and the preparation cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of vanadium electrolyte for all-vanadium liquid flow batteries, and specifically relates to a short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation and application thereof. Background Art

[0002] Liquid flow batteries are a highly anticipated large-scale energy storage technology because they can achieve physical isolation between charge and energy storage materials, thus having longer cycle life and higher safety compared to lithium-ion batteries. In addition, its reaction will not cause capacity decay due to the increase in the number of charge and discharge cycles, and can achieve up to tens of thousands of cycles. With its excellent cycle life, high safety, environmental protection characteristics and other advantages, it has become a long-term energy storage technology close to commercial application. However, the current cost of preparing vanadium electrolyte is relatively high, resulting in its cost accounting for too large a proportion of the vanadium battery system. For an all-vanadium liquid flow battery system with an energy storage time of 10 h, the cost of the electrolyte accounts for more than 70% of the total cost, which directly affects the large-scale commercial application of vanadium liquid flow batteries. Therefore, reducing the cost of the electrolyte is an urgent problem to be solved in the promotion and application of all-vanadium liquid flow batteries.

[0003] At present, the common vanadium electrolyte preparation technologies are mainly chemical reduction and electrolysis, and high-purity V2O5 is mostly used as the vanadium source. This also leads to the fact that the price of vanadium electrolyte in vanadium flow batteries is greatly affected by the fluctuation of vanadium price (V2O5). As the main raw material for direct vanadium extraction, the extraction and purification process of vanadium slag is related to the reduction of vanadium electrolyte cost. Vanadium slag has a complex and dense phase structure, in which vanadium mainly exists in the form of FeV2O4 of V(III). At present, industrial methods produce industrial-grade V2O5 as the final product of vanadium extraction. Industrial-grade V2O5 needs to be dissolved again, precipitated and calcined to high-purity V2O5 (purity greater than 99.9%) as the main raw material for preparing vanadium electrolyte. Therefore, the existing vanadium slag oxidation vanadium extraction process is complex, the production process is long, and the price of V2O5 itself as the raw material for producing other vanadium products is high. In order to reduce the preparation cost, in recent years, some researchers have selected vanadium leaching solution as the raw material to prepare electrolyte, in order to avoid the preparation and dissolution process of high-purity V2O5 and simplify the current industrial process. First, some impurity ions are removed by pre-impurity removal, and then V(V) is reduced to low-valent vanadium ions by reduction method. The deep separation of vanadium and impurities is achieved by extraction-stripping method. Finally, the low-valent vanadium electrolyte is obtained after removing the organic phase. However, this method still uses the intermediate product of vanadium slag oxidation to extract vanadium, and it is inevitable that the vanadium needs to be reduced again.

[0004] CN114361549A discloses a method for preparing a vanadium electrolyte for an all-vanadium liquid flow battery. The method reduces high-purity vanadium pentoxide under a reducing gas to obtain a low-valent vanadium oxide. The low-valent vanadium oxide is then mixed with an activator and heated for activation to obtain a vanadium-containing paste electrolyte. Finally, the vanadium paste electrolyte is dissolved by adding water to obtain a vanadium electrolyte. The method still requires vanadium pentoxide as a reactant and needs to be reduced to low-valent vanadium first.

[0005] CN116995285A discloses a method for preparing vanadium electrolyte for all-vanadium liquid flow battery. Ammonium metavanadate and / or ammonium polyvanadate are subjected to reduction calcination with a reducing gas to obtain vanadium oxide, and a mixed sulfuric acid solution and vanadium oxide are subjected to dissolution reaction, and vanadium is adjusted to obtain vanadium electrolyte. This method still requires vanadium pentoxide as a reactant, and needs to be reduced to low-valent vanadium first.

[0006] CN114156516A discloses a method for producing vanadium electrolyte. Sodium vanadate solution is obtained by high-temperature oxidation, sodium roasting and acid leaching; the alkaline solution is acidified to acidity, and then impurities are removed; acid is further added and the solution is reduced to a tetravalent vanadium solution; and then a vanadium sulfate solution is obtained by extraction-stripping. This method not only requires high-temperature oxidation roasting, but also requires impurity removal pretreatment of the leaching solution, and the vanadium valence state still needs to be reduced, and the overall process flow is long.

[0007] In summary, the current preparation of electrolytes mostly requires the reduction of pentavalent vanadium sources through chemical reduction and electrolysis, which has the following problems: 1) The vanadium slag vanadium extraction process requires oxidation treatment, which causes V(V) and Cr(VI) pollution and increases the subsequent processing steps; 2) In the process of vanadium extraction from vanadium slag to vanadium electrolyte preparation, the valence state of vanadium presents a circuitous route of V(III)-V(V)-V(III) / V(IV); 3) Limited by the current vanadium extraction and purification process, the production process of V2O5 raw materials used to produce vanadium electrolytes is lengthy and costly. Therefore, it is very important to seek an economical and green process for preparing high value-added vanadium oxysulfate electrolytes directly from vanadium slag or other vanadium-containing raw materials. This patent develops a high-concentration all-vanadium electrolyte technology for all-vanadium liquid flow batteries based on V(III)-V(III) / V(IV)-V(III) / V(IV) regulated by the valence state of vanadium slag ( Figure 1 ), simplify the preparation process, reduce costs, improve the environmental friendliness of the preparation process, and realize the efficient application of vanadium liquid flow batteries in the field of energy storage. Summary of the invention

[0008] In view of the above-mentioned prior art, the present invention provides a short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation and its application, so as to solve the technical problems of difficulty in preparing vanadium electrolyte and high preparation cost.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is to provide a short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation, comprising the following steps: S1: The vanadium slag is subjected to selective oxidation roasting acid leaching, low temperature sulfation roasting water leaching or autogenous pressure acid leaching to obtain VO 2+ Cr 3+ , Fe 2+ , Mn 2+ Acidic leachate; S2: adjusting the pH value of the acidic leaching solution to 0.5-2.5, then adding a vanadium-chromium extractant to the acidic leaching solution to co-extract vanadium and chromium to obtain a loaded organic phase containing vanadium and chromium; the vanadium-chromium extractant is obtained by mixing an amine organic extractant, 2-octanol and sulfonated kerosene; S3: stripping the loaded organic phase with a sulfuric acid solution to obtain a stripping solution containing vanadium and chromium; S4: adjusting the pH value of the stripping solution to 1.5-2.7, and then adding a phosphoric acid extractant to the stripping solution to extract the vanadium, thereby obtaining a loaded organic phase containing vanadium; S5: stripping the vanadium-containing loaded organic phase with a sulfuric acid solution to obtain a vanadium-rich sulfuric acid solution; S6: Using activated carbon to remove the organic phase in the vanadium-rich sulfuric acid solution to obtain a vanadyl sulfate electrolyte.

[0010] Based on the above technical solution, the present invention can also be improved as follows.

[0011] Further, the preparation of acidic leaching solution from vanadium slag comprises the following steps: The vanadium slag and the sulfuric acid solution were placed in a high-pressure reactor at a material-liquid ratio of 1 g:10 mL, stirred at a rate of 500 rpm for 60 min at 150 °C and 0.7 MPa, and then filtered and the filtrate was collected to obtain the product.

[0012] Further, the amine organic extractant is subjected to an acidification treatment, and the acidification treatment comprises the following steps: An amine organic extractant and a 1 mol / L sulfuric acid solution were mixed in a volume ratio of 2:1, and then stirred at 25 °C for 1 h, and then the liquids were separated and the organic phase was collected to obtain; The amine organic extractant is trioctylamine (TOA), methyl trioctyl ammonium chloride (Aliquat 336), secondary carbon primary amine extractant (N1923) or trioctyldecyl tertiary amine (N235).

[0013] Furthermore, the vanadium-chromium extractant is obtained by mixing the acidified amine organic extractant, 2-octanol and sulfonated kerosene in a volume ratio of 50:5:45; the volume concentration of the amine organic extractant in the leaching solution after the vanadium-chromium extractant is added to S2 is 15%.

[0014] Furthermore, the extraction conditions in S2 are: extraction temperature is 25 °C, the relative O / A is 1, and the extraction time is 10 min; the extraction method is countercurrent extraction, and the extraction stage is two.

[0015] Furthermore, the concentration of the sulfuric acid solution used for stripping in S3 is 4 mol / L; the stripping conditions are: the stripping temperature is 25°C, the O / A ratio is 2, and the stripping time is 10 min; the extraction method is countercurrent stripping, and the number of extraction stages is three.

[0016] Further, the phosphoric acid extractant is di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) or di(2,4,4-trimethylpentyl)phosphonic acid (C272); and the volume concentration of the phosphoric acid extractant in the stripping solution after the phosphoric acid extractant is added to S4 is 20%.

[0017] Furthermore, the extraction conditions in S4 are: extraction temperature is 25 °C, O / A is 1, and extraction time is 30 min.

[0018] Further, the concentration of the sulfuric acid solution used for stripping in S5 is 5 mol / L; the stripping conditions are: stripping temperature is 25° C., the ratio O / A is 6, and the stripping time is 40 min.

[0019] The present invention also discloses the application of a short-process preparation method of a vanadyl sulfate electrolyte based on the regulation of the valence state of vanadium slag in the preparation of a vanadyl sulfate electrolyte for an all-vanadium liquid flow battery.

[0020] The beneficial effects of the present invention are: 1. The present invention adopts a non-high temperature oxidation method to treat vanadium slag, which can not only improve the leaching rate of metal ions such as vanadium and chromium in the vanadium slag, but also leaches vanadium and chromium in a low-valent state, without the need for subsequent reduction operation. Vanadyl sulfate electrolyte can be obtained by extraction and stripping, which simplifies the preparation process and reduces the preparation cost of vanadium electrolyte.

[0021] 2. The present invention uses an acidified organic extractant as an extractant to extract V and Cr in the leachate, which can be separated from Fe and Mn. The process has the advantages of good selectivity, simple process, and easy regeneration of the extractant. In addition, the organic phase after sulfuric acid stripping does not need to be acidified again and can be directly used for extraction circulation. After five cycles, the extraction capacity remains above 95%.

[0022] 3. The oxidation peak current density Ia and reduction peak current density Ic of the vanadium electrolyte prepared by the method of the present invention are 0.0735 A / cm 2 and 0.0436 A / cm 2Its oxidation peak potential and reduction peak potential are 1.15 V and 0.769 V, showing excellent electrochemical performance.

[0023] 4. In the traditional process of preparing vanadium electrolyte using vanadium slag, vanadium slag is subjected to oxidation roasting-leaching-ammonium salt vanadium precipitation-roasting to obtain V2O5, which is then dissolved and reduced to obtain vanadium oxysulfate electrolyte. However, the solubility of V2O5 is very low. At the same time, the vanadium slag roasting process has high energy consumption, the vanadium precipitation process will produce toxic tailings, and the reduction process will significantly increase production costs. The vanadium slag leaching liquid-extraction separation proposed in the present invention directly prepares vanadium oxysulfate electrolyte. This process has low energy consumption, little harm, and a short process. At the same time, it is easy to further comprehensively utilize metal elements such as Cr, Fe and Mn in the vanadium slag, providing a reference for the green utilization of vanadium slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Comparison between the vanadium electrolyte preparation process disclosed in this patent and the existing process; Figure 2 It is a curve diagram showing the effect of acidified organic extractant on the extraction process of leachate at different pH values; Figure 3 It is a curve diagram showing the effect of sulfuric acid concentration on the back extraction process of loaded organic phase; Figure 4 is the extraction isotherm of V; Figure 5 This is a 2-stage countercurrent extraction cascade experiment diagram; Figure 6 This is the result diagram of the investigation on the recycling performance of the extractant; Figure 7 The curve diagram of the effect of the initial pH value of the stripping solution on the extraction process of vanadium; Figure 8 This is the CV curve of vanadium electrolyte.

[0025] Fig. 9 This is a physical picture of the prepared electrolyte being used in an all-vanadium liquid flow battery charging pile. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0027] Example 1: Preparation of low-valent vanadium solution from vanadium slag Vanadium slag with a particle size of less than 74 μm (vanadium content of 9.6%) and a sulfuric acid solution with a concentration of 2 mol / L are placed in a zirconium autoclave at a material-liquid ratio of 1 g: 10 mL; then the autoclave is sealed, and heating and pressurization are started for leaching reaction, the leaching temperature is 150 ℃, the leaching pressure is 0.7 MPa, the stirring speed is 500 rpm, and the leaching time is 60 min. After the leaching is completed, the slurry is cooled and filtered to obtain the leachate and the leaching slag. It is particularly pointed out that the traditional vanadium slag pressure leaching is pressurized oxidation leaching by introducing oxidizing gas; however, in order to prepare low-valent vanadium leaching solution, the present invention does not require additional gas to supplement the pressure, and the pressure of the reaction process is the self-pressure under high-temperature leaching of the aqueous solution system, which belongs to self-pressure acid leaching. In addition, low-valent vanadium leaching solution can also be prepared by low-temperature sulfuric acid roasting water leaching and other methods.

[0028] The main element contents of the prepared leaching solution were analyzed by ICP-OES, and the results are shown in Table 1. The leaching solution was also tested and analyzed, and no pentavalent vanadium was detected. The obtained leaching solution was a low-valent vanadium solution.

[0029] Table 1 Contents of main elements in the leaching solution

[0030] Example 2: Co-extraction and stripping of vanadium and chromium from low-valent vanadium solution Take the above-mentioned leachate, add it to a conical flask, adjust it to a certain pH value with 2 mol / L H2SO4 and 2 mol / L NaOH as the aqueous phase, then add the vanadium-chromium extractant, stir the solution in the conical flask fully under a constant temperature water bath, transfer it to a separatory funnel for static stratification after the reaction is completed, take out the aqueous phase and the loaded organic phase respectively, and measure the volume, and use the stripping agent to strip the loaded organic phase, the operation is similar to the above-mentioned extraction process, and finally analyze the obtained aqueous phase and organic phase. The vanadium-chromium extractant used is an extractant that has a good extraction effect on vanadium-chromium but a poor extraction effect on other metal ions. In the present invention, an amine organic extractant is preferably used, such as trioctylamine (TOA), methyl trioctyl ammonium chloride (Aliquat 336), secondary carbon primary amine extractant (N1923), trioctyl decyl tertiary amine (N235), etc., and in order to improve the extraction effect, the amine organic extractant can be acidified first, and the acidification treatment includes the following steps: Add 10 mL of amine organic extractant to a stoppered conical flask, and then add 1 mol / L sulfuric acid to the conical flask at a volume ratio of 2:1 between the organic phase and the aqueous phase. After standing to release heat, stir in a constant temperature water bath at 25°C for 1 h, then separate the liquids and collect the upper organic phase, which is the acidified amine organic extractant.

[0031] The above extraction process was used to extract the leaching solution. The composition of the vanadium-chromium extractant used was 50 vol.% acidified N1923 + 5 vol.% sec-octanol + 45 vol.% sulfonated kerosene; the extraction conditions were: the concentration of the acidified organic extractant in the leaching solution after adding the extractant was 10 vol.%, the extraction temperature (T) was 25 °C, the phase ratio (O / A) was 1, and the extraction time (t) was 10 min. The effect of different initial pH values ​​of the aqueous phase on the extraction process is shown in Figure 2. Figure 2 As shown in the figure. It can be seen from the figure that when the pH value is 1.7, the extraction rates of V and Cr are 82.5% and 84.6% respectively. Therefore, the initial pH value of the aqueous phase is selected as 1.7 as the optimal initial pH value. After two-stage countercurrent extraction, the extraction rates of V and Cr are both above 98%, and V and Cr in the leaching solution can be basically completely extracted. Then sulfuric acid is added to the above organic phase for stripping to obtain a precipitate containing V (VO 2+ ), Cr (Cr 3+ ) stripping solution. The stripping conditions are: stripping temperature (T) is 25 ℃, phase ratio (O / A) is 2, and stripping time (t) is 10 min. The effect of different sulfuric acid concentrations on the stripping process of V and Cr is shown in Figure 3 As shown in the figure. It can be seen from the figure that with the increase of sulfuric acid concentration, the stripping rates of V and Cr both increase. When the sulfuric acid concentration is 0.5 mol / L, the stripping rates of V and Cr are 13.4% and 18.2%, respectively; when the sulfuric acid concentration increases to 4 mol / L, the stripping rates of V and Cr increase to 63.5% and 67.8%, respectively; the stripping rate increases with the concentration increase, but the acid concentration of the stripping agent should not be too high, because in the subsequent P204 separation of V and Cr process, high acidity is not conducive to the extraction of V; at the same time, the organic phase is easily destroyed when the stripping acid concentration is high.

[0032] The MT graphical method was used to determine the extraction order to improve the separation efficiency of the target metal. Under the conditions of an initial pH value of the aqueous phase of 1.7, an acidified N1923 concentration of 15 vol.%, a temperature of 25 °C, and a time of 10 min, the extraction isotherm of V was obtained by changing the O / A ratio to 1:3, 1:2, 1:1, 2:1, and 3:1. The results are shown in the figure. Figure 4 As shown in the figure, it can be seen that when the operating line O / A is 1, theoretically, after two-stage countercurrent extraction, the extraction rate of V can reach more than 99%. Figure 5This is the result after 6 extraction cycles. The final solution is close to the real two-stage countercurrent raffinate. Each box in the figure represents the reaction process of extracting V and Cr with an acidified extractant. The letters V and L represent fresh leaching solution and fresh extractant, respectively. Each extraction experiment was carried out under the conditions of O / A of 1, temperature of 25 °C, and time of 10 min. After the cycle experiment, the value of outlet L3 was a steady-state value. The data of V, Cr, Fe and Mn in each stage of reaction are listed in Table 2. In the simulated two-stage countercurrent extraction, the extraction rates of V and Cr were all above 98%, while the extraction rates of Fe and Mn were always below 1%. Therefore, after two-stage countercurrent extraction, V and Cr in the leaching solution can be basically completely extracted to achieve separation from Fe and Mn.

[0033] Table 2 Experimental results of simulated two-stage countercurrent extraction

[0034] The process of stripping with sulfuric acid is also an acidification process. Using the organic phase after stripping, five cycles were carried out under the above preferred conditions. The results are as follows Figure 6 As shown in the figure, after five cycles, the extractant still maintains a good extraction effect and does not need to be re-acidified. After one cycle, the extraction rates of V and Cr are 87.4% and 88.2% respectively; after five cycles, the extraction rates of V and Cr are still maintained at 84.2% and 85.1%. After the extraction agent is circulated, the extraction capacity of V and Cr is maintained above 95%, with good cycle performance.

[0035] Example 3: Separation of V and Cr in stripping solution The leaching solution was extracted using the extraction process in Example 2 and the following optimal extraction conditions to obtain a product containing V(VO 2+ ) and Cr (Cr 3+ ) of the loaded organic phase, and then the loaded organic phase was stripped using the stripping process in Example 2 and the following optimal stripping conditions to obtain a loaded organic phase containing V (VO 2+ ) and Cr (Cr 3+ ) stripping solution, the ion concentrations of the main elements are shown in Table 3: Table 3 Main elements and their contents in stripping solution

[0036] Take the above stripping solution, add it to a conical flask, adjust it to a certain pH value with 2 mol / L H2SO4 and 2 mol / L NaOH as the aqueous phase, then add a phosphoric acid extractant (di(2-ethylhexyl) phosphate (P204), 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) or di(2,4,4-trimethylpentyl)phosphonic acid (C272), preferably P204 in the present invention), fully stir the solution in the conical flask under a constant temperature water bath, transfer it to a separatory funnel and let it stand for stratification after the reaction, take out the aqueous phase and the vanadium-loaded organic phase respectively, and measure the volume, and the vanadium-loaded organic phase is stripped with a stripping agent, the operation is similar to the above extraction process, and finally the obtained aqueous phase and organic phase are analyzed. The extraction conditions are: the concentration of the phosphoric acid extractant is 20 vol.%, the extraction temperature (T) is 25 °C, the phase ratio (O / A) is 1, and the extraction time (t) is 30 min. Effects of different initial pH values ​​of stripping solution on the extraction process Figure 7 As shown in the figure, it can be seen that with the increase of pH value, the extraction rate of V and Cr gradually increases. When the pH value is less than 2.1, P204 does not extract Cr, and does not extract Fe in the entire pH range. Therefore, the initial pH of the stripping solution is 2.1 as the optimal pH value. At this time, the extraction rate of V is 98.8%, and the loaded vanadium (VO 2 ) of the organic phase.

[0037] Acidic extractants often use sulfuric acid as a stripping agent, so sulfuric acid is used to strip low-valent V (VO 2+ ) of the organic phase (loaded with vanadium (VO 2 ) organic phase), can directly prepare vanadium sulfate electrolyte. According to the national standard for all-vanadium liquid flow batteries (GB / T37204-2018), the V concentration in the electrolyte is required to be greater than or equal to 76.41 g / L, SO4 2- The concentration is greater than or equal to 2.3 mol / L. In order to meet the requirements, 5 mol / L H2SO4 was selected as the stripping agent. At a temperature of 25 ℃, the optimal process parameters of ratio and time were explored. When the stripping time reaches 40 min, V can be basically stripped completely. At the same time, increasing the ratio can achieve the effect of enriching V. At 40 min, until the ratio O / A increases to 6, more than 99% of V can still be stripped. At this time, the V concentration in the solution reaches 78.42 g / L, which meets the above national standards. Therefore, the preferred stripping time is 40 min and the ratio O / A is 6.

[0038] Example 4: Characterization of vanadium electrolyte The vanadium electrolyte was prepared by the extraction and stripping process in Example 3 and the optimal extraction and stripping conditions. ICP-OES was used to perform full element testing to test the concentration of each ion in the vanadium electrolyte. The results are shown in Table 4, which are compared with the first-grade standard in the national standard for all-vanadium liquid flow batteries (GB / T 37204-2018). The V concentration and the content of other impurity elements met the requirements.

[0039] Table 4 Impurity ion content of vanadium electrolyte prepared by extraction method and national standard first-class product

[0040] In order to better evaluate the electrochemical performance of the prepared vanadium electrolyte, the vanadium electrolyte obtained by extraction method was used as the test group, and the vanadium electrolyte prepared by 99.80% purity vanadyl sulfate and 5 mol / L sulfuric acid solution was used as the control group. The V concentration in the control group was 78.42 g / L, which was the same as the experimental group. Cyclic voltammetry tests were performed on the experimental group and the control group, respectively. The cyclic voltammetry curves are shown in Figure 2. Figure 8 The main data are listed in Table 5. The oxidation peak current density Ia and reduction peak current density Ic of the experimental group are 0.0735 A / cm 2 and 0.0436 A / cm 2 Its oxidation peak potential and reduction peak potential are 1.15 V and 0.769 V, which are roughly the same as the trend of the cyclic voltammetry curve of the prepared vanadium electrolyte, showing similar properties to the electrolyte in the control group.

[0041] Table 5 Figure 8 Characteristic peak data in

[0042] Example 5: Application of Vanadyl Sulfate Electrolyte Relying on the energy comprehensive utilization demonstration platform of Sichuan University, the prepared VOSO4 electrolyte was used in vanadium flow battery charging piles to build a VFB-5kW / 10kWh vanadium battery energy storage system. Fig. 9 After a period of demonstration operation, the vanadium flow battery system showed good stability and high efficiency, and was able to meet the charging needs of electric vehicles.

[0043] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence regulation, characterized in that: The following steps are involved: S1: The vanadium slag is selectively oxidized, roasted, and acid-leached, low-temperature sulphate-roasted, water-leached, or self-pressure acid-leached to obtain VO 2 + Cr 3+ , Fe 2+ , Mn 2+ Acidic leachate; S2: adjusting the pH value of the acidic leaching solution to 0.5-2.5, then adding a vanadium-chromium extractant to the acidic leaching solution to co-extract vanadium and chromium to obtain a loaded organic phase containing vanadium and chromium; the vanadium-chromium extractant is obtained by mixing an amine organic extractant, 2-octanol and sulfonated kerosene; S3: stripping the loaded organic phase with a sulfuric acid solution to obtain a stripping solution containing vanadium and chromium; S4: adjusting the pH value of the stripping solution to 1.5-2.7, and then adding a phosphoric acid extractant to the stripping solution to extract the vanadium, thereby obtaining a loaded organic phase containing vanadium; S5: stripping the vanadium-containing loaded organic phase with a sulfuric acid solution to obtain a vanadium-rich sulfuric acid solution; S6: Using activated carbon to remove the organic phase in the vanadium-rich sulfuric acid solution to obtain a vanadyl sulfate electrolyte.

2. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The preparation of acidic leaching solution from vanadium slag includes the following steps: The vanadium slag and the sulfuric acid solution were placed in a high-pressure reactor at a material-liquid ratio of 1 g:10 mL, stirred at a rate of 500 rpm for 60 min at 150 °C and 0.7 MPa, and then filtered and the filtrate was collected to obtain the product.

3. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The amine organic extractant is subjected to acidification treatment, and the acidification treatment comprises the following steps: An amine organic extractant and a 1 mol / L sulfuric acid solution were mixed in a volume ratio of 2:1, and then stirred at 25 °C for 1 h, and then the liquids were separated and the organic phase was collected to obtain; The amine organic extractant is trioctylamine, methyl trioctyl ammonium chloride, secondary carbon primary amine extractant or trioctyldecyl tertiary amine.

4. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 3 is characterized in that: The vanadium-chromium extractant is obtained by mixing an acidified amine organic extractant, 2-octanol and sulfonated kerosene in a volume ratio of 50:5:45; the volume concentration of the amine organic extractant in the leaching solution after S2 adding the vanadium-chromium extractant is 15%.

5. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The extraction conditions in S2 are: extraction temperature is 25 ℃, the ratio O / A is 1, and the extraction time is 10 min; the extraction method is countercurrent extraction, and the extraction stage is two.

6. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The concentration of the sulfuric acid solution used for stripping in S3 is 4 mol / L; the stripping conditions are: stripping temperature is 25 °C, the ratio O / A is 2, and the stripping time is 10 min; the extraction method is countercurrent stripping, and the number of extraction stages is three.

7. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The phosphoric acid extractant is di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester or di(2,4,4-trimethylpentyl)phosphonic acid; the volume concentration of the phosphoric acid extractant in the stripping solution after the phosphoric acid extractant is added to S4 is 20%.

8. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The extraction conditions in S4 were: extraction temperature of 25 °C, O / A of 1, and extraction time of 30 min.

9. The short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation according to claim 1, characterized in that: The concentration of the sulfuric acid solution used for stripping in S5 is 5 mol / L; the stripping conditions are: stripping temperature is 25 °C, the ratio O / A is 6, and the stripping time is 40 min.

10. Application of the short-process preparation method of vanadyl sulfate electrolyte based on vanadium slag valence state regulation as described in any one of claims 1 to 9 in the preparation of vanadyl sulfate electrolyte for all-vanadium redox flow battery.

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