Method for preparing vanadium concentrated electrolyte and vanadium electrolyte liquid

Abstract

The invention provides a method for preparing a vanadium concentrated electrolyte and a vanadium electrolytic liquid crystal, and the method for preparing the vanadium concentrated electrolytic liquid crystal comprises the following steps: sequentially carrying out valence state adjustment and pH value adjustment on a vanadium-containing solution to obtain an extraction stock solution, and extracting the extraction stock solution and an acidified organic phase to obtain a loaded organic phase, vanadium electrolytic liquid crystals and crystallization mother liquor are obtained through acid pickling, pressurized dissolving of reducing gas, reverse extraction, oil removal, electrolytic reduction, reverse osmosis membrane concentration and cooling crystallization, and after reverse extraction, a no-load organic phase is recycled after being subjected to oxidizing pretreatment. The vanadium-containing solution is adopted as the raw material, the source is wide, high-purity vanadate does not need to be adopted as the raw material, and on the premise that the product quality is guaranteed, the packaging and transportation cost of the vanadium electrolyte is effectively reduced, and the production cost of the vanadium electrolyte is greatly reduced.

Description

Technical Field

[0001] The invention relates to vanadium electrolyte technology, in particular to a method for preparing vanadium concentrated electrolyte and vanadium electrolyte liquid crystal. 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 the manufacturing, use and disposal process. Since its introduction, it has received widespread attention and has developed rapidly both at home and abroad. It is widely used in the energy storage process of wind power generation and solar power generation, and has become the main means of peak shaving and valley regulation.

[0003] Vanadium electrolyte is not only the ion conductor of the battery, but also the storage medium of the battery's active substances. It is one of the key materials of all-vanadium liquid flow batteries. Its production, packaging, and transportation costs account for 20-40% of the cost of all-vanadium liquid flow batteries. As a liquid hazardous chemical, vanadium electrolyte mainly contains vanadium, sulfuric acid, additives and water, of which the water content accounts for about 50%, accounting for most of the packaging and transportation investment of vanadium electrolyte. Therefore, the development of vanadium electrolyte liquid crystals has become the main research and development direction for reducing the packaging and transportation costs of vanadium electrolytes. Vanadium electrolyte liquid crystals have become a key technology for reducing the cost of vanadium batteries.

[0004] There are currently few methods for producing vanadium electrolytic liquid crystals, including:

[0005] The Chinese patent (publication number CN 116404222 B) uses ammonium metavanadate as a raw material, directly prepares low-valent and high-valent vanadium sulfate crystals and precipitations by electrolysis, and then mixes them in proportion to form vanadium electrolytic liquid crystals.

[0006] The Chinese patent (publication number CN 117747898 A) uses VOSO4 solution as raw material, and prepares V2(SO4)3 crystals and a mixture of copper sulfate crystals and VOSO4 crystals through electrolysis, adjustment, and cooling crystallization, and then mixes them in proportion to form a vanadium electrolytic liquid crystal.

[0007] The Chinese patent (publication number CN104934623 B) uses vanadium sulfate, including two or three of vanadium sulfate (II), vanadium sulfate (III), vanadium oxysulfate (IV), and vanadium oxysulfate (V), adds concentrated sulfuric acid, stirs, and solidifies to obtain vanadium electrolytic liquid crystal.

[0008] The above three patent documents all use high-purity vanadate as raw material to obtain sulfate crystals with an average valence of vanadium ions of positive 3.5. However, in the actual industrial production process, the production of high-purity vanadate is generally prepared by removing impurities, repeatedly precipitating and dissolving vanadium-containing solutions, so the processing price of high-purity vanadate is relatively expensive. Summary of the invention

[0009] The purpose of the present invention is to propose a method for preparing a concentrated vanadium electrolyte in order to solve the problem of long process and high cost in preparing a vanadium electrolyte using high-purity vanadate as a raw material. The method uses a vanadium-containing solution as a raw material, which has a wide source and does not require high-purity vanadate as a raw material. Under the premise of ensuring product quality, the method can effectively reduce the packaging and transportation costs of the vanadium electrolyte and greatly reduce the production cost of the vanadium electrolyte.

[0010] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0011] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a vanadium concentrated electrolyte, comprising the following steps:

[0012] Step 1, adjusting the valence state, detecting the valence state of the vanadium-containing solution, if the valence state of V in the vanadium-containing solution is less than 5.0, adding an oxidant to the vanadium-containing solution or using electrolysis to oxidize it to 5.0;

[0013] Step 2, adjusting the pH value, using an acidic substance to adjust the pH value of the vanadium-containing solution to 1.0-2.0, and performing solid-liquid separation to obtain an extract solution;

[0014] Step 3, acidifying the organic phase, using dilute sulfuric acid, dilute hydrochloric acid or dilute phosphoric acid as an acidifying agent to acidify the organic phase;

[0015] Step 4, extraction, subjecting the organic phase and the extract solution to 2 to 6 levels of countercurrent extraction to obtain a loaded organic phase and a raffinate;

[0016] Step 5, acid washing, performing 1 to 3 levels of countercurrent washing on the loaded organic phase and the dilute acid to obtain a washed loaded organic phase and an acid washing solution;

[0017] Step 6, dissolving under pressure, placing the loaded organic phase in a pressurized reactor and introducing reducing gas, the pressure in the reactor is ≤10Mpa, and the pressure is maintained for 10 to 30 minutes; the present invention utilizes the reducing gas (such as SO2) to have a certain solubility in kerosene and 2-octanol to dissolve the reducing gas and improve the utilization rate of the reducing gas; pressurization can increase the solubility of the reducing gas;

[0018] Step 7, stripping, subjecting the loaded organic phase to 2 to 4 levels of countercurrent stripping, wherein the stripping agent is one or more of dilute sulfuric acid, dilute hydrochloric acid and crystallization mother liquor, and after stripping, an empty loaded organic phase, a vanadium oxysulfate solution and / or a vanadium oxychloride solution are obtained;

[0019] Step 8, oxidation pretreatment, the empty organic phase and the oxidizing solution are subjected to 1 to 3 levels of countercurrent washing to obtain a washed empty organic phase and a washing solution, and the washed empty organic phase can be recycled;

[0020] Step 9, deoiling, under the protection of nitrogen or argon inert gas, deoiling the vanadium oxysulfate and / or vanadium oxydichloride solution obtained by stripping to obtain a vanadium oxysulfate solution and / or a vanadium oxydichloride solution;

[0021] Step 10, electrolytic reduction, electrolytically reducing the vanadyl sulfate solution and / or the vanadyl dichloride solution obtained by oil removal to a valence of 3.5 to obtain a sulfuric acid system electrolyte and / or a hydrochloric acid system electrolyte;

[0022] Step 11, reverse osmosis membrane concentration, the sulfuric acid system electrolyte and / or the hydrochloric acid system electrolyte is concentrated by 20-50% (the volume is reduced by 20-50%) through the reverse osmosis membrane to obtain the sulfuric acid system concentrated electrolyte and / or the hydrochloric acid system concentrated electrolyte and pure water, and the pure water can be reused. The present invention utilizes the reverse osmosis membrane concentration technology to achieve vanadium enrichment, thereby increasing the vanadium concentration, and compared with evaporation crystallization, has the advantages of low energy consumption and low cost.

[0023] Furthermore, the vanadium-containing solution is a sodium-treated roasted steel slag leaching solution, a vanadium sulfate solution, a calcified roasted steel slag leaching solution, a stone coal leaching solution, a vanadium sulfate solution or a vanadium-containing petroleum ash leaching solution.

[0024] Furthermore, the vanadium concentration in the vanadium-containing solution is V2O5=0.5-50g / L.

[0025] Furthermore, the oxidant in step 1 is one or more of air, oxygen, hydrogen peroxide, ozone, potassium permanganate, potassium dichromate, potassium chlorate, sodium chlorate, sodium hypochlorite, potassium hypochlorite, sodium perchlorate, potassium perchlorate and perchloric acid.

[0026] Furthermore, the acidic substance in step 2 is one or more of sulfuric acid, hydrochloric acid, oxalic acid, citric acid, acetic acid, formic acid, nitric acid and phosphoric acid.

[0027] Furthermore, the organic phase in step 3 is a mixture of an organic amine extractant, kerosene and a modifier; the organic amine extractant is one or more of N1923, N263, and N235; the modifier is one or more of octanol, n-octanol, tributyl phosphate, trioctyl phosphate and tri-n-octylphosphine oxide; the volume ratio of the amine extractant, kerosene and modifier is 0.5:9:0.5 to 4:5:1.

[0028] Furthermore, the acidification rate of the organic phase in step 3 is 30-60%. Acidification refers to the protonation reaction between the extractant and the acid, such as R3N+H + +Cl -=(R3NH)Cl, which is convenient for anion exchange reaction with anionic groups. The acidification rate refers to the proportion of the extractant participating in the protonation reaction to the extractant.

[0029] Furthermore, the concentration of the dilute sulfuric acid, dilute hydrochloric acid or dilute phosphoric acid in step 3 is 0.5-1.0 mol / L.

[0030] Furthermore, the extraction temperature in step 4 is 20-50°C.

[0031] Furthermore, the pickling temperature in step 5 is 20-50° C., and the dilute acid concentration is 0.03-0.15 mol / L.

[0032] Furthermore, the dilute acid in step 5 is one or more of dilute sulfuric acid, dilute hydrochloric acid or dilute phosphoric acid.

[0033] Furthermore, the reducing gas in step 6 is sulfur dioxide, and the amount of reducing gas added is 1.1 to 1.5 times the molar amount of V2O5 in the loaded organic phase.

[0034] Furthermore, the pressure in the autoclave in step 6 is 3-10Mpa, preferably 5-10Mpa.

[0035] Furthermore, the stripping temperature in step 7 is 40-60°C.

[0036] Furthermore, in step 7, the concentration of the dilute sulfuric acid is 2-4 mol / L, and the concentration of the dilute hydrochloric acid is 4-6 mol / L.

[0037] Furthermore, the oxidizing solution in step 8 is one or more of hydrogen peroxide, potassium permanganate, pentavalent vanadium solution and ferric sulfate.

[0038] Furthermore, the oil removal in step 9 includes: one-stage flotation oil removal, three-stage resin oil removal and two-stage activated carbon oil removal.

[0039] Furthermore, the reverse osmosis membrane stack in step 11 is of 3 to 10 stages, and each stage has 8 to 12 sections.

[0040] Another object of the present invention is to disclose a method for preparing vanadium electrolytic liquid crystals. After preparing a concentrated electrolyte (a sulfuric acid system concentrated electrolyte and / or a hydrochloric acid system concentrated electrolyte) by the above-mentioned method for preparing a vanadium concentrated electrolyte, the concentrated electrolyte is cooled and crystallized at 0 to 10°C, and the electrolytic liquid crystal (a sulfuric acid system electrolytic liquid crystal and / or a hydrochloric acid system electrolytic liquid crystal) and a crystallization mother liquor are obtained by filtering.

[0041] Furthermore, the sulfuric acid system electrolytic liquid crystal and the hydrochloric acid system electrolytic liquid crystal are mixed in proportion to obtain the mixed acid system electrolytic liquid crystal.

[0042] Furthermore, the crystallization mother liquor is returned to step 7 for reuse.

[0043] The method for preparing vanadium concentrated electrolyte and vanadium electrolytic liquid crystal of the present invention comprises the following steps: adjusting the valence state of the vanadium-containing solution and adjusting the pH value in sequence to obtain an extracting stock solution, extracting with an acidified organic phase to obtain a loaded organic phase, acid washing, pressurized dissolution of reducing gas, stripping, degreasing, electrolytic reduction, reverse osmosis membrane concentration, cooling and crystallization to obtain a vanadium electrolytic liquid crystal and a crystallization mother liquor, and recycling the unloaded organic phase after stripping after oxidative pretreatment. Compared with the prior art, it has the following advantages:

[0044] (1) Using vanadium-containing solution as raw material, which has a wide source, effectively reduces the production cost of vanadium electrolytic liquid crystal;

[0045] (2) Compared with the method of first purifying the vanadium-containing raw materials to prepare high-purity vanadium oxides and then dissolving them to prepare electrolytic liquid crystals, the preparation process of the present invention is short, the operation is simple, and it is easy to realize industrialization. It is suitable for the preparation of vanadium electrolytic liquid crystals in different systems such as sulfuric acid system, hydrochloric acid system or mixed acid system;

[0046] (3) The organic amine extractant of the present invention is an anionic extractant and does not extract cations. Most of the metal impurity elements in the vanadium-containing solution are cationic impurities, so they will be separated from the vanadium during the extraction process and remain in the raffinate.

[0047] (4) The single crystallization rate of the vanadium electrolytic liquid crystal prepared by the present invention is greater than 70%, the purity is higher than 99.5%, and the vanadium recovery rate in the whole process is greater than 99%.

[0048] (5) The present invention can effectively reduce the amount of reducing gas (sulfur dioxide) used by pressurized dissolution, thereby increasing the reduction reaction rate during the stripping process.

[0049] (6) The present invention utilizes reverse osmosis membrane concentration technology to achieve vanadium enrichment, thereby increasing the vanadium concentration. Compared with evaporation crystallization, the present invention has the advantages of low energy consumption and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a process flow chart of the method for preparing vanadium electrolytic liquid crystal. DETAILED DESCRIPTION

[0051] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0052] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0053] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0054] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0055] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0056] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0057] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0058] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0059] Example 1

[0060] This embodiment discloses a method for preparing vanadium electrolytic liquid crystal using sodium-treated roasted leaching solution of steel slag with a V=30 g / L content as a raw material, comprising the following steps:

[0061] Step 1: Adjusting the valence state: Detect the valence state of the vanadium-containing solution, add hydrogen peroxide to the sodium roasting leaching solution of vanadium slag with V=30g / L, and oxidize V to a valence of 5.0.

[0062] Step 2, adjusting the pH value: phosphoric acid is used to adjust the pH value of the leaching solution to 1.8, and solid-liquid separation is performed to obtain the extraction stock solution;

[0063] Step 3, acidification of the organic phase. Use 30% sulfuric acid as an acidifier to acidify the organic phase, which facilitates anion exchange reaction with anionic groups, wherein the organic phase composition is N263, kerosene and n-octanol in a volume ratio of 1.5:8:0.5, and the acidification rate is 35%;

[0064] Step 4: Extraction: The acidified organic phase and the extract solution are subjected to four-stage countercurrent extraction at 40° C. to obtain a vanadium-loaded organic phase and a raffinate.

[0065] Step 5, acid washing. The loaded organic phase and 0.08 mol / L dilute sulfuric acid are subjected to three-stage countercurrent washing at 40°C to wash off the aqueous solution (raffinate) on the surface of the organic phase to prevent it from entering the stripping solution and contaminating the stripping solution. The washed loaded organic phase and acid washing solution are obtained.

[0066] Step 6, dissolving under pressure. Place the loaded organic phase in a pressure reactor, calculate the molar amount of V2O5 in the loaded organic phase, introduce sulfur dioxide gas according to the ratio of the molar amount of sulfur dioxide to the molar amount of V2O5 in the loaded organic phase of 1.1, and maintain the pressure in the reactor at 7.5 MPa for 30 minutes to fully dissolve the sulfur dioxide in the loaded organic phase.

[0067] Step 7, stripping. The loaded organic phase and 2 mol / L dilute sulfuric acid solution were subjected to 4-stage countercurrent stripping at 40°C. After stripping, an empty loaded organic phase and a vanadyl sulfate solution were obtained. The amount of sulfur dioxide used for stripping was calculated to be 0.387 t / tV2O5, and the reduction rate was 1.25 t V2O5 / h.

[0068] Step 8, oxidation pretreatment. The empty organic phase and hydrogen peroxide are subjected to three-stage countercurrent washing to wash away residual sulfur dioxide, prevent sulfur dioxide from remaining in the organic phase, and reduce pentavalent vanadium in the pre-extraction solution to tetravalent vanadium to hinder the next extraction. The washed empty organic phase and washing liquid are obtained, and the washed empty organic phase can be recycled.

[0069] Step 9, deoiling: Under nitrogen protection, the vanadium oxysulfate obtained by stripping is subjected to first-stage flotation deoiling, third-stage resin deoiling and second-stage activated carbon deoiling to obtain a deoiled vanadium oxysulfate solution.

[0070] Step 10: electrolytic reduction: The vanadyl sulfate solution obtained by oil removal is electrolytically reduced to a valence of 3.5 to obtain a sulfuric acid system electrolyte.

[0071] Step 11, reverse osmosis membrane concentration. The sulfuric acid system electrolyte is concentrated by 40% through the reverse osmosis membrane to obtain V = 4.5 mol / L sulfuric acid system concentrated electrolyte and pure water, and the pure water can be reused, wherein the reverse osmosis membrane stack is 8 levels, and each level has 10 sections;

[0072] Step 12, cooling and crystallization. Cool the sulfuric acid system concentrated electrolyte at 5°C for crystallization, filter to obtain sulfuric acid system electrolytic liquid crystal and crystallization mother liquor, and reuse the crystallization mother liquor. The single crystallization rate of the crystal is 75%, and the test results are shown in Table 1.

[0073] Table 1 Crystal test results

[0074] K(％) Na (%) Fe (%) Al(％) Mo (%) Mn (%) Ca (%) 0.0010 0.0005 0.0008 0.0005 0.0003 0.0000 0.0004 W(％) Mg (%) B(％) Pb (%) Cu (%) Cr(％) Bi (%) 0.0001 0.0001 0.0001 0.0000 0.0000 0.0003 0.0000 Ti (%) Co (%) Zn (%) Si (%) Ni (%) 0.0000 0.0000 0.0000 0.0010 0.0000

[0075] Example 2

[0076] This embodiment discloses a method for preparing a vanadium electrolytic liquid crystal using a V=50g / L vanadyl sulfate solution as a raw material, comprising the following steps:

[0077] Step 1: Adjusting the valence state: Detect the valence state of the vanadium-containing solution, and introduce ozone into the V=50 g / L vanadyl sulfate solution to oxidize it to a valence state of 5.0.

[0078] Step 2, adjusting the pH value: adjusting the pH value of the vanadium-containing solution to 1.2 with sulfuric acid, and performing solid-liquid separation to obtain an extract solution;

[0079] Step 3, acidification of the organic phase. Use 30% hydrochloric acid as an acidifier to acidify the organic phase, wherein the organic phase composition is N235, kerosene and n-octanol in a volume ratio of 2:7:1, and the acidification rate is 30%;

[0080] Step 4: Extraction: The acidified organic phase and the extract solution are subjected to three-stage countercurrent extraction at 45° C. to obtain a vanadium-loaded organic phase and a raffinate.

[0081] Step 5, acid washing: The loaded organic phase and 0.1 mol / L dilute phosphoric acid were subjected to two-stage countercurrent washing at 40° C. to obtain a washed loaded organic phase and an acid washing solution.

[0082] Step 6, dissolving under pressure. Place the loaded organic phase in a pressure reactor, calculate the molar amount of V2O5 in the loaded organic phase, introduce sulfur dioxide gas according to the ratio of the molar amount of sulfur dioxide to the molar amount of V2O5 in the loaded organic phase of 1.2, and maintain the pressure in the reactor at 6.0 MPa for 20 minutes to fully dissolve the sulfur dioxide in the loaded organic phase.

[0083] Step 7, stripping. The loaded organic phase and 6 mol / L dilute hydrochloric acid solution were subjected to 4-stage countercurrent stripping at 60°C. After stripping, an empty loaded organic phase and a vanadium dichloride solution were obtained. The amount of sulfur dioxide used for stripping was calculated to be 0.422 t / tV2O5, and the reduction rate was 1.31 t V2O5 / h.

[0084] Step 8, oxidation pretreatment: The empty organic phase and pentavalent vanadium solution are subjected to three-stage countercurrent washing to wash away residual sulfur dioxide, thereby obtaining a washed empty organic phase and a washing liquid, and the washed empty organic phase can be recycled.

[0085] Step 9, deoiling: Under nitrogen protection, the vanadium oxychloride solution obtained by stripping is subjected to first-stage flotation deoiling, third-stage resin deoiling and second-stage activated carbon deoiling to obtain a deoiled vanadium oxychloride solution.

[0086] Step 10, electrolytic reduction: The vanadium oxychloride solution obtained by oil removal is electrolytically reduced to a valence of 3.5 to obtain a hydrochloric acid system electrolyte.

[0087] Step 11, reverse osmosis membrane concentration. The hydrochloric acid system electrolyte is concentrated by 30% through the reverse osmosis membrane to obtain V=6.5mol / L hydrochloric acid system concentrated electrolyte and pure water, and the pure water can be reused, wherein the reverse osmosis membrane stack is 6 levels, and each level has 8 sections;

[0088] Step 12, cooling and crystallization. The hydrochloric acid system concentrated electrolyte was cooled and crystallized at 3°C, and the hydrochloric acid system electrolytic liquid crystal and crystallization mother liquor were filtered, and the crystallization mother liquor was reused. The single crystallization rate of the crystal was 73%, and the test results are shown in Table 2.

[0089] Table 2 Crystal test results

[0090] K(％) Na (%) Fe (%) Al(％) Mo (%) Mn (%) Ca (%) 0.0005 0.0002 0.0006 0.0005 0.0005 0.0000 0.0004 W(％) Mg (%) B(％) Pb (%) Cu (%) Cr(％) Bi (%) 0.0002 0.0001 0.0001 0.0000 0.0000 0.0005 0.0000 Ti (%) Co (%) Zn (%) Si (%) Ni (%) 0.0001 0.0000 0.0000 0.0008 0.0000

[0091] Example 3

[0092] This embodiment discloses a method for preparing vanadium electrolytic liquid crystal using V=40g / L steel slag calcification roasting leaching solution as raw material, comprising the following steps:

[0093] Step 1: Adjusting the valence state: Detect the valence state of the vanadium-containing solution, add sodium hypochlorite to the vanadium slag calcification roasting leaching solution with V=40g / L, and oxidize it to a valence of 5.0.

[0094] Step 2, adjusting the pH value: using nitric acid to adjust the pH value of the vanadium-containing solution to 1.0, and performing solid-liquid separation to obtain an extract solution;

[0095] Step 3, acidification of the organic phase. Use 25% sulfuric acid as an acidifier to acidify the organic phase, wherein the organic phase composition is N1923, kerosene and n-octanol in a volume ratio of 3:6:1, and the acidification rate is 50%;

[0096] Step 4: Extraction: The organic phase and the extract solution are subjected to six-stage countercurrent extraction at 50° C. to obtain a vanadium-loaded organic phase and a raffinate.

[0097] Step 5, acid washing: The loaded organic phase and 0.10 mol / L dilute hydrochloric acid were subjected to three-stage countercurrent washing at 50° C. to obtain a washed loaded organic phase and an acid washing solution.

[0098] Step 6, dissolving under pressure. Place the loaded organic phase in a pressure reactor, calculate the molar amount of V2O5 in the loaded organic phase, introduce sulfur dioxide gas at a pressure of 8.0 MPa in the reactor according to the ratio of sulfur dioxide molar amount to V2O5 molar amount in the loaded organic phase of 1.15, maintain the pressure for 15 minutes, and fully dissolve the sulfur dioxide in the loaded organic phase.

[0099] Step 7, stripping. The loaded organic phase and 3.5 mol / L dilute sulfuric acid were subjected to 4-stage countercurrent stripping at 50°C. After stripping, an empty loaded organic phase and a vanadyl sulfate solution were obtained. The amount of sulfur dioxide used for stripping was calculated to be 0.405 t / tV2O5, and the reduction rate was 1.22 t V2O5 / h.

[0100] Step 8, oxidation pretreatment: The empty organic phase and the ferric sulfate solution are subjected to a first-stage countercurrent washing to wash away the residual sulfur dioxide, thereby obtaining a washed empty organic phase and a washing solution, and the washed empty organic phase can be recycled.

[0101] Step 9, deoiling: Under the protection of argon, the vanadyl sulfate solution obtained by stripping is subjected to first-stage flotation deoiling, third-stage resin deoiling and second-stage activated carbon deoiling to obtain a deoiled vanadyl sulfate solution.

[0102] Step 10: electrolytic reduction: The vanadyl sulfate solution obtained by oil removal is electrolytically reduced to a valence of 3.5 to obtain a sulfuric acid system electrolyte.

[0103] Step 11, reverse osmosis membrane concentration. The sulfuric acid system electrolyte is concentrated by 30% through the reverse osmosis membrane to obtain V = 4.8 mol / L sulfuric acid system concentrated electrolyte and pure water, and the pure water can be reused, wherein the reverse osmosis membrane stack is 10 levels, and each level is 10 sections;

[0104] Step 12, cooling and crystallization. The concentrated sulfuric acid system electrolyte was cooled and crystallized at 4°C, and the sulfuric acid system electrolytic liquid crystal and crystallization mother liquor were obtained by filtration, and the crystallization mother liquor was reused. The single crystallization rate of the crystal was 72%, and the test results are shown in Table 3.

[0105] Table 3 Crystal test results

[0106] K(％) Na (%) Fe (%) Al(％) Mo (%) Mn (%) Ca (%) 0.0008 0.0008 0.0004 0.0006 0.0001 0.0000 0.0001 W(％) Mg (%) B(％) Pb (%) Cu (%) Cr(％) Bi (%) 0.0002 0.0004 0.0001 0.0000 0.0000 0.0006 0.0000 Ti (%) Co (%) Zn (%) Si (%) Ni (%) 0.0004 0.0000 0.0000 0.0003 0.0000

[0107] Comparative Example 1

[0108] This embodiment discloses a method for preparing a vanadium electrolytic liquid crystal using a V=50g / L vanadyl sulfate solution as a raw material, comprising the following steps:

[0109] Step 1: Adjusting the valence state: Detect the valence state of the vanadium-containing solution, and introduce ozone into the V=50 g / L vanadyl sulfate solution to oxidize it to a valence state of 5.0.

[0110] Step 2, adjusting the pH value: adjusting the pH value of the vanadium-containing solution to 1.2 with sulfuric acid, and performing solid-liquid separation to obtain an extract solution;

[0111] Step 3, acidification of the organic phase. Use 30% hydrochloric acid as an acidifier to acidify the organic phase, wherein the organic phase composition is N235, kerosene and n-octanol in a volume ratio of 2:7:1, and the acidification rate is 30%;

[0112] Step 4: Extraction: The acidified organic phase and the extract solution are subjected to three-stage countercurrent extraction at 45° C. to obtain a vanadium-loaded organic phase and a raffinate.

[0113] Step 5, acid washing: The loaded organic phase and 0.1 mol / L dilute phosphoric acid were subjected to two-stage countercurrent washing at 40° C. to obtain a washed loaded organic phase and an acid washing solution.

[0114] Step 6, stripping: Calculate the molar amount of V2O5 in the loaded organic phase, introduce sulfur dioxide gas according to the ratio of the molar amount of sulfur dioxide to the molar amount of V2O5 in the loaded organic phase of 4.0, and the pressure in the kettle is normal pressure.

[0115] Step 7: Perform 4-stage countercurrent stripping of the loaded organic phase and 6.0 mol / L dilute hydrochloric acid at 60°C. After stripping, an empty loaded organic phase and a vanadium dichloride solution are obtained. The amount of sulfur dioxide used for stripping is calculated to be 1.408 t / t V2O5, and the reduction rate is 0.67 t V2O5 / h.

[0116] Step 8, oxidation pretreatment: The empty organic phase and pentavalent vanadium solution are subjected to three-stage countercurrent washing to wash away residual sulfur dioxide, thereby obtaining a washed empty organic phase and a washing liquid, and the washed empty organic phase can be recycled.

[0117] Step 9, deoiling: Under nitrogen protection, the vanadium oxychloride solution obtained by stripping is subjected to first-stage flotation deoiling, third-stage resin deoiling and second-stage activated carbon deoiling to obtain a deoiled vanadium oxychloride solution.

[0118] Step 10, electrolytic reduction: The vanadium oxychloride solution obtained by oil removal is electrolytically reduced to a valence of 3.5 to obtain a hydrochloric acid system electrolyte.

[0119] Step 11, cooling and crystallization. Cool the hydrochloric acid system electrolyte at 3°C ​​for crystallization, filter to obtain the hydrochloric acid system electrolyte liquid crystal and crystallization mother liquor, and reuse the crystallization mother liquor. The single crystallization rate of the crystal is 35%, and the test results are shown in Table 4.

[0120] Table 4 Crystal test results

[0121]

[0122]

[0123] The difference between Reference Example 1 and Example 2 is that Reference Example 1 lacks the steps of pressurized dissolution and reverse osmosis concentration. The purpose of pressurized dissolution is to increase the solubility of sulfur dioxide in the loaded organic phase by increasing the pressure in the kettle, increase the sulfur dioxide concentration in the organic phase, and increase the reduction reaction rate. Due to the lack of the step of pressurized dissolution, a large amount of sulfur dioxide gas is volatilized and wasted during the reduction and stripping process of sulfur dioxide gas, and the sulfur dioxide concentration in the organic phase is low, and the reduction reaction rate is slow. It is calculated that the amount of sulfur dioxide in Reference Example 1 is 3.33 times that of Example 2, and the reduction rate in Reference Example 1 is 0.51 times that of Example 2; the purpose of reverse osmosis concentration is to concentrate the electrolyte by membrane concentration to increase the vanadium concentration in the electrolyte before crystallization. Since Reference Example 1 lacks the step of reverse osmosis concentration, the vanadium concentration of the electrolyte before crystallization is 0.88 times that of Example 2, which reduces the crystallization rate of the electrolyte. It is calculated that the crystallization rate of the electrolyte in Reference Example 1 is 2.09 times that of Example 2.

[0124] Comparative Example 2

[0125] This embodiment discloses a method for preparing vanadium electrolytic liquid crystal using V=40g / L steel slag calcification roasting leaching solution as raw material, comprising the following steps:

[0126] Step 1: Adjusting the valence state: Detect the valence state of the vanadium-containing solution, add sodium hypochlorite to the vanadium slag calcification roasting leaching solution with V=40g / L, and oxidize it to a valence of 5.0.

[0127] Step 2, adjusting the pH value: using nitric acid to adjust the pH value of the vanadium-containing solution to 1.0, and performing solid-liquid separation to obtain an extract solution;

[0128] Step 3, acidification of the organic phase. Use 25% sulfuric acid as an acidifier to acidify the organic phase, wherein the organic phase composition is N1923, kerosene and n-octanol in a volume ratio of 3:6:1, and the acidification rate is 50%;

[0129] Step 4: Extraction: The organic phase and the extract solution are subjected to six-stage countercurrent extraction at 50° C. to obtain a vanadium-loaded organic phase and a raffinate.

[0130] Step 5, acid washing: The loaded organic phase and 0.10 mol / L dilute hydrochloric acid were subjected to three-stage countercurrent washing at 50° C. to obtain a washed loaded organic phase and an acid washing solution.

[0131] Step 6, stripping: Calculate the molar amount of V2O5 in the loaded organic phase, introduce sulfur dioxide gas according to the ratio of the molar amount of sulfur dioxide to the molar amount of V2O5 in the loaded organic phase of 4.5, and the pressure in the kettle is normal pressure.

[0132] Step 7: Perform 4-stage countercurrent stripping of the loaded organic phase and 3.5 mol / L dilute sulfuric acid solution at 50°C. After stripping, an empty loaded organic phase and a vanadyl sulfate solution are obtained. The amount of sulfur dioxide used for stripping is calculated to be 1.583 t / tV2O5, and the reduction rate is 0.75 t V2O5 / h.

[0133] Step 8, oxidation pretreatment: The empty organic phase and the ferric sulfate solution are subjected to a first-stage countercurrent washing to wash away the residual sulfur dioxide, thereby obtaining a washed empty organic phase and a washing solution, and the washed empty organic phase can be recycled.

[0134] Step 9, deoiling: Under the protection of argon, the vanadyl sulfate solution obtained by stripping is subjected to first-stage flotation deoiling, third-stage resin deoiling and second-stage activated carbon deoiling to obtain a deoiled vanadyl sulfate solution.

[0135] Step 10: electrolytic reduction: The vanadyl sulfate solution obtained by oil removal is electrolytically reduced to a valence of 3.5 to obtain a sulfuric acid system electrolyte.

[0136] Step 11, cooling and crystallization. The sulfuric acid system electrolyte was cooled and crystallized at 4°C, and the sulfuric acid system electrolyte liquid crystal and crystallization mother liquor were obtained by filtration, and the crystallization mother liquor was recycled. The single crystallization rate of the crystal was 38%, and the test results are shown in Table 5.

[0137] Table 5 Crystal test results

[0138] K(％) Na (%) Fe (%) Al(％) Mo (%) Mn (%) Ca (%) 0.0001 0.0002 0.0006 0.0005 0.0005 0.0010 0.0004 W(％) Mg (%) B(％) Pb (%) Cu (%) Cr(％) Bi (%) 0.0010 0.0008 0.0001 0.0002 0.0000 0.0010 0.0000 Ti (%) Co (%) Zn (%) Si (%) Ni (%) 0.0006 0.0000 0.0010 0.0008 0.0000

[0139] The difference between Reference Example 2 and Example 3 is that Reference Example 2 lacks the steps of pressurized dissolution and reverse osmosis concentration. The purpose of pressurized dissolution is to increase the solubility of sulfur dioxide in the loaded organic phase by increasing the pressure in the kettle, increase the sulfur dioxide concentration in the organic phase, and increase the reduction reaction rate. Due to the lack of the step of pressurized dissolution, a large amount of sulfur dioxide gas is volatilized and wasted during the reduction and stripping process of sulfur dioxide gas, and the sulfur dioxide concentration in the organic phase is low, and the reduction reaction rate is slow. It is calculated that the amount of sulfur dioxide in Reference Example 2 is 3.91 times that of Example 2, and the reduction rate in Reference Example 2 is 0.61 times that of Example 3; the purpose of reverse osmosis concentration is to concentrate the electrolyte by membrane concentration to increase the vanadium concentration in the electrolyte before crystallization. Since Reference Example 2 lacks the step of reverse osmosis concentration, the vanadium concentration of the electrolyte before crystallization is 0.88 times that of Example 3, which reduces the crystallization rate of the electrolyte. It is calculated that the crystallization rate of the electrolyte in Reference Example 1 is 1.89 times that of Example 2.

[0140] 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 preparing a vanadium concentrated electrolyte, characterized in that: The following steps are involved: Step 1, adjusting the valence state, detecting the valence state of the vanadium-containing solution, if the valence state of V in the vanadium-containing solution is less than 5.0, adding an oxidant to the vanadium-containing solution or using electrolysis to oxidize it to 5.0; Step 2, adjusting the pH value, using an acidic substance to adjust the pH value of the vanadium-containing solution to 1.0-2.0, and performing solid-liquid separation to obtain an extract solution; Step 3, acidifying the organic phase, using dilute sulfuric acid, dilute hydrochloric acid or dilute phosphoric acid as an acidifying agent to acidify the organic phase; Step 4, extraction, subjecting the organic phase and the extract solution to 2 to 6 levels of countercurrent extraction to obtain a loaded organic phase and a raffinate; Step 5, acid washing, performing 1 to 3 levels of countercurrent washing on the loaded organic phase and dilute sulfuric acid to obtain a washed loaded organic phase and an acid washing solution; Step 6: dissolving under pressure, placing the loaded organic phase in a pressure reactor and introducing reducing gas, the pressure in the reactor is ≤10Mpa, and the pressure is maintained for 10 to 30 minutes; Step 7, stripping, subjecting the loaded organic phase to 2 to 4 levels of countercurrent stripping, wherein the stripping agent is one or more of dilute sulfuric acid, dilute hydrochloric acid and crystallization mother liquor, and after stripping, an empty loaded organic phase, a vanadium oxysulfate solution and / or a vanadium oxychloride solution are obtained; Step 8, oxidation pretreatment, the empty organic phase and the oxidizing solution are subjected to 1 to 3 levels of countercurrent washing to obtain a washed empty organic phase and a washing solution, and the washed empty organic phase can be recycled; Step 9, deoiling, under the protection of nitrogen or argon inert gas, deoiling the vanadium oxysulfate and / or vanadium oxychloride solution obtained by stripping; Step 10, electrolytic reduction, electrolytically reducing the vanadyl sulfate solution and / or the vanadyl dichloride solution obtained by oil removal to a valence of 3.5 to obtain a sulfuric acid system electrolyte and / or a hydrochloric acid system electrolyte; Step 11, reverse osmosis membrane concentration, the sulfuric acid system electrolyte and / or the hydrochloric acid system electrolyte is concentrated by 20-50% of the volume through the reverse osmosis membrane to obtain sulfuric acid system concentrated electrolyte and / or hydrochloric acid system concentrated electrolyte and pure water, and the pure water can be reused.

2. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The vanadium-containing solution in step 1 is a sodium-treated roasted steel slag leaching solution, a vanadium sulfate solution, a calcified roasted steel slag leaching solution, a stone coal leaching solution, a vanadium sulfate solution or a vanadium-containing petroleum ash leaching solution; And / or, the vanadium concentration in the vanadium-containing solution is V2O5=0.5-50 g / L; And / or, the oxidant is one or more of air, oxygen, hydrogen peroxide, ozone, potassium permanganate, potassium dichromate, potassium chlorate, sodium chlorate, sodium hypochlorite, potassium hypochlorite, sodium perchlorate, potassium perchlorate and perchloric acid.

3. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The acidic substance in step 2 is one or more of sulfuric acid, hydrochloric acid, oxalic acid, citric acid, acetic acid, formic acid, nitric acid and phosphoric acid.

4. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The organic phase in step 3 is a mixture of an organic amine extractant, kerosene and a modifier; the organic amine extractant is one or more of N1923, N263 and N235; the modifier is one or more of octanol, n-octanol, tributyl phosphate, trioctyl phosphate and tri-n-octylphosphine oxide; the volume ratio of the amine extractant, kerosene and modifier is 0.5:9:0.5 to 4:5:1; And / or, the acidification rate of the organic phase in step 3 is 30-60%.

5. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The extraction temperature in step 4 is 20-50° C.; And / or, in step 5, the water washing temperature is 20-50° C., and the dilute sulfuric acid concentration is 0.03-0.15 mol / L.

6. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The reducing gas in step 6 is sulfur dioxide.

7. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The stripping temperature in step 7 is 40-60° C. And / or, the concentration of the dilute sulfuric acid in step 7 is 2-4 mol / L, and the concentration of the dilute hydrochloric acid is 4-6 mol / L.

8. The method for preparing a vanadium concentrated electrolyte according to claim 1, characterized in that: The oxidizing solution in step 8 is one or more of hydrogen peroxide, potassium permanganate, pentavalent vanadium solution and ferric sulfate; The oil removal in step 9 includes: first-stage air flotation oil removal, third-stage resin oil removal and second-stage activated carbon oil removal; And / or, the reverse osmosis membrane stack in step 11 is 3 to 10 stages, and each stage is 8 to 12 sections.

9. A method for vanadium electrolysis of liquid crystals, characterized in that: After preparing the concentrated electrolyte by the method for preparing the concentrated vanadium electrolyte according to any one of claims 1 to 8, the concentrated electrolyte is cooled and crystallized at 0 to 10° C., and filtered to obtain an electrolytic liquid crystal and a crystallization mother liquor.

10. The method for vanadium electrolysis of liquid crystal according to claim 9, characterized in that: The mixed acid system electrolytic liquid crystal is obtained by mixing the sulfuric acid system electrolytic liquid crystal and the hydrochloric acid system electrolytic liquid crystal in proportion.

Images