Method for continuously preparing vanadyl sulfate electrolyte based on nanoemulsion extraction

Abstract

The invention discloses a method for continuously preparing vanadyl sulfate electrolyte based on a nano-emulsion system, which constructs an integrated process of'centrifugal extraction-centrifugal washing-improved packed tower reduction reverse extraction-continuous replica ', thereby realizing efficient extraction of vanadium from a raw material solution, product purity control and recycling of an extraction agent. And finally, a vanadyl sulfate electrolyte product meeting the requirements of national standard first-grade products is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for continuously preparing vanadyl sulfate electrolyte based on nanoemulsion extraction. Background Art

[0002] Currently, the high cost and inefficient preparation process of vanadyl sulfate (VOSO4) electrolyte, a key active material in all-vanadium redox flow batteries, has become a major bottleneck hindering the widespread adoption of this type of energy storage system. Existing methods for preparing vanadyl sulfate electrolytes primarily include chemical synthesis, electrochemical methods, solvent extraction, and intermittent nanoemulsion extraction. Both chemical synthesis and electrochemical methods require highly pure V2O5 as a raw material, requiring complex purification processes and making it difficult to manufacture on a continuous production line. Solvent extraction, on the other hand, requires repeated, multi-stage extractions to achieve the desired extraction rate, similarly making it difficult to manufacture on a continuous production line. Furthermore, these existing preparation methods suffer from high energy consumption, poor safety, the need for high-temperature electrolysis, or the presence of strong reducing agents. Separation efficiency is low, particularly due to inadequate mixing and separation in traditional tower-type extraction units. Ultimately, product purity is limited, impurity ion removal is difficult, and electrolyte performance is compromised. Furthermore, the extraction equipment used in the production process is difficult to recycle, increasing the overall production cost of vanadyl sulfate electrolytes. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for continuously preparing vanadyl sulfate electrolyte based on nanoemulsion extraction, so as to solve the problems of the prior art in preparing vanadyl sulfate electrolyte, such as the inability to achieve continuous production, high energy consumption, poor safety, low product purity, and difficulty in recycling the extractant, resulting in high production costs.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for continuously preparing vanadyl sulfate electrolyte based on nanoemulsion extraction, comprising the following steps: Step 1: Desiliconizing the calcined roasting-acid leaching solution to obtain a desiliconized calcified solution; Step 2: n-heptane, trioctylmethylammonium chloride and isoamyl alcohol are mixed, and an alkaline sodium chloride solution is added to the mixture for saponification to form a nanoemulsion system; Step 3: using a first centrifugal extractor to mix the nanoemulsion system prepared in step 2 with the calcified liquid treated in step 1 to transfer vanadium from the desiliconized calcified liquid to the nanoemulsion to obtain a loaded phase; Step 4: Mixing the loaded phase obtained after the treatment in step 3 with dilute sulfuric acid through a second centrifugal extractor; Step 5: The loaded phase treated in step 4 is fed into an improved packed extraction tower, and SO2 gas is introduced into the improved packed extraction tower to reduce V(V) in the loaded phase to V(IV), and simultaneously stripped into sulfuric acid to form VOSO4 electrolyte; Step 6: The nanoemulsion obtained after the treatment in step 5 is treated with NaOH, H2O2, and alkaline sodium chloride solution in sequence; Step 7: heating the electrolyte treated in step 5 to remove SO2 therein, and filtering to remove organic aggregates to obtain the vanadyl sulfate electrolyte.

[0005] Preferably, in step 1, the desiliconizing agent is a polycarboxylic acid water-reducing agent; wherein the mass ratio of the desiliconizing agent to Si in each liter of the acid leaching solution is (1-2):1.

[0006] Preferably, in step 2, in the nanoemulsion mixed system, calculated by mass percentage, the organic solvent is 50 wt%-70 wt%, the surfactant is 15 wt%-30 wt%, and the co-surfactant is 5 wt%-25 wt%; wherein the organic solvent is one of sulfonated kerosene or n-heptane, the surfactant is one of trioctylmethylammonium chloride or tetraoctylammonium chloride, and the co-surfactant is one of isoamyl alcohol or n-butanol.

[0007] Preferably, in step 3, the flow ratio of the nanoemulsion to the calcification solution is (0.3-3):1, the flow rate of the nanoemulsion is 60 mL / min-240 mL / min, and the rotation speed of the first centrifugal extractor is 3500 r / min-5500 r / min.

[0008] Preferably, in step 4, the loaded phase and the dilute sulfuric acid are mixed at a flow ratio of (0.5-1):1, the speed of the second centrifugal extractor is 3500 r / min-5500 r / min, and the concentration of the dilute sulfuric acid is 0.05 mol / L-2 mol / L.

[0009] Preferably, in step 5, the SO2 gas flow rate is 0.6 L / min-3.0 L / min, the reduction reaction temperature is 20°C-40°C, and the reaction time is 20 min-50 min; the stripping solution is H2SO4 solution with a concentration of 3 mol / L-5 mol / L.

[0010] Preferably, in step 6, the nanoemulsion is sequentially processed with NaOH, H2O2, and alkaline sodium chloride solution by passing through a third centrifugal extractor, a fourth centrifugal extractor, and a fifth centrifugal extractor, respectively; the specific process is as follows: S1: mixing the nanoemulsion after the stripping treatment in step 5 with the NaOH solution and pumping them into a third centrifugal extractor; wherein the concentration of the NaOH solution is 3 mol / L-5 mol / L, the nanoemulsion and the NaOH solution are mixed at an O / A flow ratio of (0.5-1):1, the speed of the third centrifugal extractor is 3500 r / min-5500 r / min, and the flow rate of the stripped nanoemulsion entering the third centrifugal extractor is 60 mL / min-240 mL / min; S2: The nanoemulsion flowing out of S1 enters a fourth centrifugal extractor and is mixed with a H2O2 solution to remove the residual reducing agent in the oil phase; wherein the concentration of the H2O2 solution is 3wt%-30wt%, the flow rate of the hydrogen peroxide solution pumped in is 60 mL / min-240 mL / min, and the rotation speed of the fourth centrifugal extractor is 3500-5500 r / min; S3: The nanoemulsion flowing out of S2 continuously enters the fifth centrifugal extractor to be mixed with the alkaline sodium chloride solution; wherein, the concentrations of NaOH and NaCl in the alkaline sodium chloride solution are 0.5 mol / L-1 mol / L, the flow rate of the alkaline sodium chloride solution is 60 mL / min-240 mL / min, and the rotation speed of the fifth centrifugal extractor is 3500 r / min-5500 r / min. The nanoemulsion finally flowing out of the light phase outlet of the fifth centrifugal extractor is the replicated nanoemulsion and can be reused.

[0011] Preferably, in step 7, the heating treatment temperature is 85°C-95°C, the heating time is 2 h-5 h, and after the electrolyte is cooled, it is filtered with a 0.22 μm water filter membrane at room temperature to remove large-sized organic aggregates remaining in the electrolyte to obtain the vanadyl sulfate electrolyte.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention improves the existing method for preparing vanadyl sulfate electrolyte, achieving the fundamental goal of continuously preparing high-quality vanadyl sulfate electrolyte; by connecting a centrifugal extractor in series with an improved packed extraction tower, full-process continuous production is achieved, significantly increasing production capacity; a nanoemulsion system is constructed to form microemulsion droplets under high-speed centrifugation, greatly increasing the mass transfer area, resulting in a vanadium extraction rate of up to 99.6% and a stripping rate of over 90%, far exceeding traditional tower extraction processes.

[0013] 2. The vanadium concentration in the electrolyte prepared by the present invention reaches 89.3 g / L, and the impurity content strictly meets the first-class product standard of GB / T37204-2018. At the same time, the method of the present invention has low energy consumption and is environmentally friendly. The entire process is carried out at room temperature and normal pressure, without the need for high-temperature calcination or strong reducing agents. Recyclable SO2 gas is used for reduction. The nanoemulsion extractant can be efficiently recycled and reused through a three-step treatment (NaOH, H2O2, and alkaline sodium chloride solution), significantly reducing the cost of the extractant and the emission of organic waste.

[0014] 3. The method of the present invention operates at room temperature and pressure throughout the entire process, without the need for high-temperature calcination or strong reducing agents; SO2 is used as a reducing agent, and waste gas can be recycled and treated to avoid pollution; the extractant is recycled through three-step replication regeneration; the method of the present invention has resource value and can directly process vanadium-containing waste materials such as vanadium slag calcination roasting acid leaching solution without the need for high-purity raw materials, providing an efficient, green and economical industrialization path for the large-scale production of vanadium battery electrolytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The process flow chart of the method of the present invention is shown in FIG.

[0016] Figure 2 It is a structural schematic diagram of the production process system of the present invention.

[0017] Figure 3 It is a structural schematic diagram of the centrifugal extractor of the present invention.

[0018] Figure 4 This is a schematic structural diagram of the improved packed extraction tower of the present invention.

[0019] Figure 5 1 is the infrared spectra of the nanoemulsion at different stages in Example 1.

[0020] Figure 6 Graph showing the particle size distribution of the nanoemulsion at different stages in Example 1.

[0021] Figure 7 This is the Zeta potential diagram of the nanoemulsion at different stages in Example 1.

[0022] In the figure: first centrifugal extractor 1, second centrifugal extractor 2, third centrifugal extractor 3, fourth centrifugal extractor 4, fifth centrifugal extractor 5, upper oil-water separator 6, tower body 7, lower oil-water separator 8, transmission shaft 9, upper bearing 10, heavy phase collecting chamber 11, light phase collecting chamber 12, light phase weir 13, centrifugal extractor light phase outlet 14, centrifugal extractor light phase inlet 15, rotary drum 16, housing 17, lower bearing 18, mechanical seal 19, turbine disc 20, centrifugal extractor heavy phase outlet 21, centrifugal extractor heavy phase inlet 22, heavy phase weir 23, light phase 24, heavy phase 25, mixed phase 26, upper oil-water separator heavy phase inlet 27, glass spring 28, gas redistributor 29, SO2 inlet 30, lower oil-water separator light phase inlet 31, lower oil-water separator heavy phase outlet 32, upper oil-water separator light phase outlet 33, SO2 outlet 34, baffle 35. DETAILED DESCRIPTION

[0023] The present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments derived by persons of ordinary skill in the art based on the present invention are within the scope of protection of the present invention.

[0024] Unless otherwise indicated in specific cases, the numerical ranges listed herein include the upper and lower limits, and all integers and fractions within the range, and are not limited to the specific values ​​listed when defining the range.

[0025] 1. A method for continuous preparation of vanadyl sulfate electrolyte based on nanoemulsion extraction Step 1: Desiliconizing the calcined roasting-acid leaching solution to obtain a desiliconized calcified solution; Step 2: n-heptane, trioctylmethylammonium chloride and isoamyl alcohol are mixed, and an alkaline sodium chloride solution is added to the mixture for saponification to form a nanoemulsion system; Step 3: using a first centrifugal extractor to mix the nanoemulsion system prepared in step 2 with the calcified liquid treated in step 1 to transfer vanadium from the desiliconized calcified liquid to the nanoemulsion to obtain a loaded phase; Step 4: Mixing the loaded phase obtained after the treatment in step 3 with dilute sulfuric acid through a second centrifugal extractor; Step 5: The loaded phase treated in step 4 is fed into an improved packed extraction tower, and SO2 gas is introduced into the improved packed extraction tower to reduce V(V) in the loaded phase to V(IV), and simultaneously stripped into sulfuric acid to form VOSO4 electrolyte; Step 6: The nanoemulsion obtained after the treatment in step 5 is treated with NaOH, H2O2, and alkaline sodium chloride solution in sequence; Step 7: heating the electrolyte treated in step 5 to remove SO2 therein, and filtering to remove organic aggregates to obtain the vanadyl sulfate electrolyte.

[0026] The present invention addresses the technical problems existing in the traditional vanadyl sulfate electrolyte preparation process, namely: the inability to achieve continuous production resulting in low process efficiency, insufficient vanadium recovery rate and difficulty in meeting product purity requirements, reliance on high calcination or strong reducing agent action resulting in high energy consumption and high pollution, high disposable cost of the extraction machine, and difficulty in treating organic waste liquid. The present invention attempts to simultaneously solve these series of technical problems. First, the present invention uses a polycarboxylate water-reducing agent to perform targeted desiliconization pretreatment on the vanadium-containing acid leachate, accurately controls the mass ratio of the desiliconizer to silicon, and eliminates the interference of silicon impurities in the extraction system; then, the present invention constructs a nanoemulsion extraction system, using trioctylmethylammonium chloride as a surfactant, isoamyl alcohol as a co-surfactant, and n-heptane as a solvent to form a high specific surface area emulsion, greatly improving the vanadium extraction efficiency; at the same time, the system integrates a series of centrifugal extractors with an improved packed extraction tower to achieve full-process automated continuous operation, breaking through the bottleneck of continuous production. Then, sulfuric acid is used as the stripping liquid, and SO2 gas is introduced at the same time to simultaneously complete V(V)→V(IV) reduction and deep stripping in the packed tower. Phase separation residues are avoided through the step-by-step stripping and reduction coupling process. Recyclable SO2 gas is used to replace the strong reducing agent to achieve green reduction at room temperature and pressure. More importantly, the present invention designs a three-step extractant replication technology, which realizes the recycling regeneration of the extractant by stripping impurities with NaOH solution, removing residual reducing agent through H2O2 oxidation, and reforming the nanoemulsion structure with alkaline sodium chloride solution (inner aqueous phase).

[0027] Through the aforementioned improvements, the present inventors discovered that the synergistic effect between SO2 reduction and stripping enhances purification efficiency. When SO2 is introduced into the improved packed column, the resulting bubble disturbance unexpectedly enhances mass transfer, resulting in a stripping efficiency exceeding 90%. Simultaneously, the reduction reaction inhibits organic phase coalescence, significantly reducing organic residues in the electrolyte. Furthermore, the nanoemulsion replica constructed by the present invention exhibits long-term stability. The three-step replica process (NaOH-H2O2-alkaline sodium chloride) not only removes impurities but also surprisingly maintains the activity of the extractant, enabling multiple recycling and significantly reducing operating costs. The desiliconizing agent provides implicit protection for the extraction system. When desiliconized with a precisely formulated polycarboxylate water-reducing agent, the desiliconization unexpectedly reduces ineffective surfactant adsorption, improving the stability of the nanoemulsion and achieving an extraction efficiency as high as 99.6%.

[0028] The present invention not only solves the bottleneck of traditional processes that cannot produce continuously through continuous equipment integration and innovation of the nanoemulsion extraction system, but also realizes the use of a replica process to maintain the long-term stability of the nanoemulsion, ultimately achieving an extraction rate of 99.6%, a stripping rate of over 90%, and product purity (V concentration of 89.3 g / L, meeting the national standard for first-class products). The entire process has good application prospects.

[0029] In some embodiments of the present invention, in step 1, the desiliconizing agent is a polycarboxylate superplasticizer; wherein the mass ratio of desiliconizing agent to Si per liter of acid leaching solution is (1-2):1. The method described herein is primarily intended for use with calcified solutions, as the pH of sodium-containing solutions conflicts with the desiliconizing agent employed in this invention, which is inactivated in high pH environments. Therefore, the mass ratio of desiliconizing agent to Si per liter of acid leaching solution can be 1:1, 1.5:1, 2:1, and so on, as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges may be combined with any other ranges.

[0030] In some embodiments of the present invention, in step 2, in the nanoemulsion mixed system, calculated by mass percentage, the organic solvent is 50 wt%-70 wt%, the surfactant is 15 wt%-30 wt%, and the cosurfactant is 5 wt%-25 wt%; wherein the organic solvent is one of sulfonated kerosene or n-heptane, the surfactant is one of trioctylmethylammonium chloride or tetraoctylammonium chloride, and the cosurfactant is one of isoamyl alcohol or n-butanol. For the nanoemulsion mixed system, the amount of organic solvent, surfactant, and cosurfactant should be strictly controlled. If the three substances are not within the range, it may result in insufficient extraction capacity or excessive viscosity of the nanoemulsion, which is not conducive to production. Therefore, the organic solvent can be 50 wt%, 60 wt%, 70 wt%, etc., and all ranges and sub-ranges between the above values; the surfactant can be 15 wt%, 20 wt%, 25 wt%, 30 wt%, etc., and all ranges and sub-ranges between the above values; the co-surfactant can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, etc., and all ranges and sub-ranges between the above values; it should be understood that in the embodiment, any of the above ranges can be combined with any other ranges to ensure that the total amount of the three substances is 100%.

[0031] In some embodiments of the present invention, in step 3, the mixture of the nanoemulsion and the calcified solution is referred to as the loading phase. The flow ratio of the nanoemulsion to the calcified solution is (0.3-3):1, the flow rate of the nanoemulsion is 60 mL / min-240 mL / min, and the speed of the first centrifugal extractor is 3500 rpm-5500 rpm. If any of these parameters are outside the above ranges, the extraction rate may be too low or the nanoemulsion may break. Therefore, the flow ratio of the nanoemulsion to the calcification solution can be 0.3:1, 1:1, 2:1, 3:1, etc., and all ranges and sub-ranges between the above values; the flow rate of the nanoemulsion can be 60 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 240 mL / min, etc., and all ranges and sub-ranges between the above values; the rotation speed of the first centrifugal extractor can be 3500 r / min, 4000 r / min, 4500 r / min, 5000 r / min, 5500 r / min, etc., and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0032] In some embodiments of the present invention, in step 4, the loaded phase and dilute sulfuric acid are mixed at a flow ratio of (0.5-1):1, the second centrifugal extractor is operated at a speed of 3500-5500 r / min, and the concentration of dilute sulfuric acid is 0.05 mol / L-2 mol / L. If the flow ratio is outside this range, it can lead to entrained phase at the outlet, thus affecting product purity. If the speed is outside this range, it can cause demulsification of the loaded phase or entrained phase at the outlet. If the dilute phosphoric acid concentration is outside this range, impurities in the loaded phase may not be completely cleaned or vanadium loss may be excessive. Therefore, the flow ratio of the load phase to the dilute sulfuric acid can be 0.5:1, 1:1, etc., and all ranges and sub-ranges between the above values; the speed of the second centrifugal extractor can be 3500 r / min, 4000 r / min, 4500 r / min, 5000 r / min, 5500 r / min, etc., and all ranges and sub-ranges between the above values; the concentration of the dilute sulfuric acid can be 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 1.5 mol / L, 2 mol / L, etc., and all ranges and sub-ranges between the above values. It should be understood that in embodiments, any of the above ranges can be combined with any other ranges.

[0033] In some embodiments of the present invention, in step 5, the SO2 gas flow rate is 0.6 L / min-3.0 L / min, the reduction reaction temperature is 20°C-40°C, and the reaction time is 20 min-50 min; the stripping solution is an H2SO4 solution with a concentration of 3 mol / L-5 mol / L. In this step, if the various conditions are not within the stated ranges, the reduction efficiency will be reduced. Therefore, the SO2 gas flow rate can be 0.6 L / min, 1.0 L / min, 1.5 L / min, 2.0 L / min, 2.5 L / min, 3.0 L / min, etc., and all ranges and sub-ranges between the above values; the reduction reaction temperature can be 20°C, 25°C, 30°C, 35°C, 40°C, etc., and all ranges and sub-ranges between the above values; the reaction time can be 20 min, 30 min, 40 min, 50 min, etc., and all ranges and sub-ranges between the above values. It should be understood that in the embodiments, any of the above ranges can be combined with any other ranges.

[0034] In some embodiments of the present invention, in step 6, the nanoemulsion is sequentially subjected to nanoemulsion replication treatment with NaOH, H2O2, and alkaline sodium chloride solution in a third centrifugal extractor, a fourth centrifugal extractor, and a fifth centrifugal extractor, respectively. If the treatment conditions are not within the above range, the nanoemulsion replication will fail. The specific process is as follows: S1: mixing the nanoemulsion after the stripping treatment in step 5 with the NaOH solution and pumping them into a third centrifugal extractor; wherein the concentration of the NaOH solution is 3 mol / L-5 mol / L, the nanoemulsion and the NaOH solution are mixed at an O / A flow ratio of (0.5-1):1, the speed of the third centrifugal extractor is 3500 r / min-5500 r / min, and the flow rate of the stripped nanoemulsion entering the third centrifugal extractor is 60 mL / min-240 mL / min; S2: The nanoemulsion flowing out of S1 enters a fourth centrifugal extractor and is mixed with a H2O2 solution to remove the residual reducing agent in the oil phase; wherein the concentration of the H2O2 solution is 3wt%-30wt%, the flow rate of the hydrogen peroxide solution pumped in is 60 mL / min-240 mL / min, and the rotation speed of the fourth centrifugal extractor is 3500-5500 r / min; S3: The nanoemulsion flowing out of S2 continuously enters the fifth centrifugal extractor to be mixed with the alkaline sodium chloride solution; wherein, the concentration of NaOH and NaCl in the alkaline sodium chloride solution is 0.5 mol / L-1 mol / L, the flow rate of the alkaline sodium chloride solution is 60 mL / min-240 mL / min, and the rotation speed of the fifth centrifugal extractor is 3500 r / min-5500 r / min. The nanoemulsion finally flowing out of the light phase outlet of the fifth centrifugal extractor is the replicated nanoemulsion and can be reused.

[0035] In some embodiments of the present invention, in step 7, the heating treatment temperature is 85°C-95°C, the heating time is 2 h-5 h, and after the electrolyte is cooled, it is filtered with a 0.22 μm water filter membrane at room temperature to remove large-sized organic aggregates remaining in the electrolyte to obtain the vanadyl sulfate electrolyte.

[0036] 2. A production process system for continuous preparation of vanadyl sulfate electrolyte based on nanoemulsion extraction The production process system includes a first centrifugal extractor 1, a second centrifugal extractor 2, an improved packed extraction tower, a third centrifugal extractor 3, a fourth centrifugal extractor 4 and a fifth centrifugal extractor 5. Figure 1-2 As shown, the first centrifugal extractor is fluidically connected to the second centrifugal extractor, the second centrifugal extractor is fluidically connected to the improved packed extraction column, the improved packed extraction column is fluidically connected to the third centrifugal extractor, the third centrifugal extractor is fluidically connected to the fourth centrifugal extractor, the fourth centrifugal extractor is fluidically connected to the fifth centrifugal extractor, and the fifth centrifugal extractor is fluidically connected to the first centrifugal extractor.

[0037] The specific process flow is as follows: the desiliconized calcified liquid is pumped into the heavy phase inlet of the first centrifugal extractor, and the nanoemulsion is pumped into the light phase inlet of the first centrifugal extractor. After thorough mixing in the first centrifugal extractor, the extract flows out of the heavy phase outlet of the first centrifugal extractor and is sent to collection tank I. The loaded phase flows out of the light phase outlet of the first centrifugal extractor and is pumped into the light phase inlet of the second centrifugal extractor. Simultaneously, dilute sulfuric acid is pumped into the heavy phase inlet of the second centrifugal extractor, allowing the loaded phase to be washed with dilute sulfuric acid in the second centrifugal extractor. Subsequently, the washing liquid flows out of the heavy phase outlet of the second centrifugal extractor and is sent to collection tank II. The loaded phase flows out of the light phase outlet of the second centrifugal extractor and enters the light phase inlet of the improved packed extraction tower, where it enters the improved packed extraction tower for reduction stripping.

[0038] When the loaded phase flows to the packing layer of the extraction tower, SO2 gas is introduced through the SO2 inlet 30, and the stripping liquid is pumped in from the heavy phase inlet 27 of the upper oil-water separator at the top of the extraction tower to perform reduction stripping. After a period of reaction, a blue vanadium sulfate electrolyte product appears in the lower oil-water separator 8 of the extraction tower. Then, the heavy phase outlet 32 ​​of the lower oil-water separator is opened to collect the product vanadium sulfate electrolyte; a light green transparent stripping nanoemulsion appears in the upper oil-water separator 28 of the extraction tower. After opening the light phase outlet 33 of the upper oil-water separator, the stripping nanoemulsion flows out. Then, the stripping nanoemulsion enters through the light phase inlet of the third centrifugal extractor, and the NaOH solution is pumped in from the heavy phase inlet of the third centrifugal extractor. After the two phases are fully mixed, the nanoemulsion is discharged. The light phase flows out of the third centrifugal extractor through the light phase inlet of the fourth centrifugal extractor, and hydrogen peroxide is pumped in from the heavy phase inlet of the fourth centrifugal extractor; after being fully mixed, the nanoemulsion flows out of the light phase outlet of the fourth centrifugal extractor, enters through the light phase inlet of the fifth centrifugal extractor, and alkaline sodium chloride is pumped in from the heavy phase inlet of the fifth centrifugal extractor; after being fully mixed, the nanoemulsion flowing out of the light phase outlet of the fifth centrifugal extractor is a complex nanoemulsion, which can be pumped back into the light phase inlet of the first centrifugal extractor for repeated recycling.

[0039] In the improved packed extraction tower, its structure is as follows Figure 4As shown, the improved packed extraction tower includes an upper oil-water separator 6, a tower body 7, and a lower oil-water separator 8. The tower body 7 is a vertical packed tower, with its upper end connected to the feed port of the upper oil-water separator 6 and its lower end connected to the feed port of the lower oil-water separator 8. A packing layer is provided within the tower body, filled with glass springs 28 to increase the contact area. Support plates are provided at the upper and lower ends of the packing layer to secure the glass springs 28. An SO2 inlet 30 is provided at the bottom of the packing layer, and a gas distributor is positioned at the SO2 inlet, allowing gas to enter the packing layer evenly through the gas distributor. Simultaneously, under the action of the packing, the gas rises at a relatively uniform rate, fully contacting the liquid phase in the packing layer, and then exits through the SO2 outlet 34. A light phase inlet 31 and a heavy phase outlet 32 ​​for the lower oil-water separator are provided at the bottom of the tower body. An upper light phase outlet 33 and an upper heavy phase inlet 27 for the upper oil-water separator are provided at the top of the tower base. The light phase enters the tower from the bottom through the lower oil-water separator, flows upward through the packing layer, and is separated from the top of the tower through the upper oil-water separator. The heavy phase enters the tower from the top through the upper oil-water separator, flows downward through the packing layer, and is separated from the bottom of the tower through the lower oil-water separator. At the top of the tower, a separation space of a certain height is retained above the light phase outlet, or a gas-liquid separator is installed to capture droplets rising with the gas phase and prevent the liquid phase from being entrained and escaping. If a gas-liquid separator is installed, the liquid phase collected by the gas-liquid separator is re-introduced into the tower. A gas redistributor 29 is also provided in the middle of the tower to evenly redistribute the gas passing through the middle of the tower so that it can evenly enter the upper part of the packing layer.

[0040] In the present invention, the structure of the centrifugal extractor is as follows Figure 3 As shown, the centrifugal extractor comprises a housing 17, a drive shaft 9, an upper bearing 10, a lower bearing 18, a heavy phase inlet 15, a heavy phase collection chamber 11, a heavy phase weir 23, a heavy phase outlet 21, a light phase inlet 15, a light phase collection chamber 12, a light phase weir 13, a light phase outlet 14, a rotating drum 16, a baffle 35, a turbine disc 20, and a mechanical seal 19. The blue portion 25 represents the heavy phase, the yellow portion 24 represents the light phase, and the green portion 26 represents the mixed phase. The centrifugal extractor operates by installing a rotating drum that rotates at high speeds via a motor. Two immiscible liquids of varying densities are injected into the lower housing of the device via a peristaltic pump. The shear forces generated by the rotating drum or blades cause mixing and mass transfer. Subsequently, driven by the strong centrifugal force, the liquids are rapidly separated, achieving efficient separation. This fully utilizes the advantages of the nanoemulsion for single-stage vanadium extraction and high separation efficiency. After the two phases are separated, the heavy phase, i.e., the raffinate or the washing liquid, flows out from a higher outlet, and the light phase, i.e., the loaded nanoemulsion, flows out from a lower outlet.

[0041] 3. Examples and Comparative Examples Example 1 Step 1: Desiliconizing the vanadium-containing acid leaching solution, using a polycarboxylate water-reducing agent as the desiliconizing agent; wherein the mass ratio of the desiliconizing agent to Si per liter of the acid leaching solution is 1:1, and a calcified solution containing 20.4 g / L vanadium is obtained as the raw material.

[0042] Step 2: n-heptane, trioctylmethylammonium chloride and isoamyl alcohol are mixed, and an alkaline sodium chloride solution is added to the mixture for saponification to form a nanoemulsion system; calculated by mass percentage, the organic solvent is 55 wt%, the surfactant is 25 wt%, and the co-surfactant is 20 wt%; wherein the organic solvent is n-heptane, the surfactant is trioctylmethylammonium chloride, and the co-surfactant is isoamyl alcohol.

[0043] Step 3: The first centrifugal extractor was operated at a speed of 4500 rpm, a 1:1 flow ratio between the nanoemulsion and the desiliconized calcified solution, and a feed-liquid flow rate of 100 mL / min. Under these conditions, the raffinate was clear and transparent, with no demulsification or phase separation, and a vanadium extraction yield of 99.61%.

[0044] Step 4: The loaded nanoemulsion was washed with 0.05 mol / L H2SO4 as the washing acid at a flow rate of 100 mL / min. When the second centrifuge speed was 4500 r / min, the washing liquid was clear and transparent, without demulsification and phase separation. The elution rate of vanadium was 3.94%, and the elution rates of other impurity elements were all greater than 50%. The impurity elements can be effectively separated with little vanadium loss.

[0045] Step 5: The stripping solution and loaded nanoemulsion flow ratio was 1:5, the SO2 gas flow rate was 1.0 L / min, and the stripping solution flow rate was 4 mL / min. Under these conditions, the two phases showed a clear color change and good phase separation. The final vanadium stripping yield was 90.52%, and the element contents of the resulting vanadyl sulfate electrolyte met the requirements for first-class products according to the national standard (GB / T 37204-2018).

[0046] Step 6: Perform replication treatment on the nanoemulsion after use in step 5. The specific replication steps are as follows: S1: mixing the nanoemulsion after the stripping treatment in step 5 with the NaOH solution and pumping them into a third centrifugal extractor; wherein the concentration of the NaOH solution is 3 mol / L, the nanoemulsion and the NaOH solution are mixed at an O / A flow ratio of 1:1, the speed of the third centrifugal extractor is 4500 r / min, and the flow rate of the stripped nanoemulsion entering the third centrifugal extractor is 100 mL / min; S2: The nanoemulsion flowing out of S1 enters the fourth centrifugal extractor and mixes with the H2O2 solution to remove the residual reducing agent in the oil phase; wherein the concentration of the H2O2 solution is 3wt%, the flow rate of the hydrogen peroxide solution pumped in is 100 mL / min, and the speed of the fourth centrifugal extractor is 4500 r / min; S3: The nanoemulsion flowing out of S2 continuously enters the fifth centrifugal extractor to be mixed with the alkaline sodium chloride solution; wherein, the NaOH concentration in the alkaline sodium chloride solution is 0.5 mol / L, the flow rate of the alkaline sodium chloride solution pumped in is 100 mL / min, and the rotation speed of the fifth centrifugal extractor is 4500 r / min. The nanoemulsion finally flowing out of the light phase outlet of the fifth centrifugal extractor is the replicated nanoemulsion and can be reused.

[0047] Step 7: The electrolyte treated in step 5 is heated to 95° C. for 3 h to remove SO 2 therein, and organic aggregates are removed by filtration to obtain the vanadyl sulfate electrolyte.

[0048] Table 1 Composition of the continuous preparation of vanadyl sulfate electrolyte in Example 1 (mg / L) V Si Na K Fe Mn Mg Al Ca Cu Cr Ni National standard first-class product <![CDATA[>76.4×10 3 ]]> ＜10 ＜80 ＜100 ＜50 ＜5 ＜30 ＜50 ＜30 ＜1 ＜15 ＜20 National standard second-class product <![CDATA[>76.4×10 3 ]]> Unlimited ＜200 ＜200 ＜200 ＜30 ＜50 ＜80 ＜70 ＜5 ＜30 ＜60 Example 1 <![CDATA[89.3×10 3 ]]> 2.1 6.4 7.8 <0.1 3.4 8.1 <0.1 11.6 <0.1 <0.1 <0.1 During the entire continuous process of Example 1, the structure of the nanoemulsion is not affected. Figure 5 It can be seen that there is no obvious difference in the infrared spectra of the nanoemulsion at different stages, and the absolute values ​​of the zeta potential of the nanoemulsion before and after continuous extraction and after replication are all around 120 mV, which is much greater than 61 mV. This proves that the nanoemulsion system of the present invention always maintains a high thermodynamic stability during the continuous process, and proves that the centrifugation process does not damage the nanoemulsion system of the present invention.

[0049] Example 2 The method was modified based on Example 1, except that in step 4, the concentration of dilute sulfuric acid was 0.05 mol / L. The other steps were identical to those in Example 1. The resulting electrolyte met the national first-class standard.

[0050] Example 3 The method was modified based on Example 1, except that in step 4, the concentration of dilute sulfuric acid was 2 mol / L. The other steps were identical to those in Example 1. The resulting electrolyte met the national first-class standard.

[0051] Example 4 The process was modified based on Example 1, except that in step 3, the rotational speed of the first centrifugal extractor was 3500 r / min. The other steps were identical to those in Example 1. The resulting electrolyte met the national first-class standard.

[0052] Example 5 The process was modified based on Example 1, except that in step 3, the rotational speed of the first centrifugal extractor was 5500 r / min. The other steps were identical to those in Example 1. The resulting electrolyte met the national first-class standard.

[0053] Comparative Example 1 This was modified based on Example 1, except that 0.005 mol / L H2SO4 was used as the washing acid in step 4. The other steps were identical to those in Example 1. During the washing process, the elution rates of the impurity elements were all less than 10%, resulting in excessive concentrations of Mn, Fe, Ca, Mg, and Al in the final electrolyte.

[0054] Comparative Example 2 The process was modified based on Example 1, except that the rotation speed of the centrifugal extractor in step 3 was 3000 r / min. The other steps were identical to those in Example 1. The resulting raffinate contained the load phase, and the extraction yield was only 76.52%.

[0055] Comparative Example 3 This was modified based on Example 1, differing in that 3 mol / L H2SO4 was used as the washing acid in step 4. The remaining steps were identical to those in Example 1. During the washing process, the elution rate of the V element increased to 8.08%, resulting in a low V concentration in the final electrolyte, which failed to meet the national standard for first-class products.

[0056] Comparative Example 4 The process was modified based on Example 1, except that the rotation speed of the centrifugal extractor in step 3 was 6000 r / min. The other steps were identical to those in Example 1. At this point, the load phase showed slight demulsification, and the load phase was entrained in the raffinate.

[0057] 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 the technical solutions. Those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present invention that do not depart from the purpose and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for continuously preparing vanadyl sulfate electrolyte based on nanoemulsion extraction, characterized in that: Here are the steps: Step 1: Desiliconizing the calcined roasting-acid leaching solution to obtain a desiliconized calcified solution; Step 2: n-heptane, trioctylmethylammonium chloride and isoamyl alcohol are mixed, and an alkaline sodium chloride solution is added to the mixture for saponification to form a nanoemulsion system; Step 3: using a first centrifugal extractor to mix the nanoemulsion system prepared in step 2 with the calcified liquid treated in step 1 to transfer vanadium from the desiliconized calcified liquid to the nanoemulsion to obtain a loaded phase; Step 4: Mixing the loaded phase obtained after the treatment in step 3 with dilute sulfuric acid through a second centrifugal extractor; Step 5: The loaded phase treated in step 4 is fed into an improved packed extraction tower, and SO2 gas is introduced into the improved packed extraction tower to reduce V(V) in the loaded phase to V(IV), and simultaneously stripped into sulfuric acid to form VOSO4 electrolyte; Step 6: The nanoemulsion obtained after the treatment in step 5 is treated with NaOH, H2O2, and alkaline sodium chloride solution in sequence; Step 7: heating the electrolyte treated in step 5 to remove SO2 therein, and filtering to remove organic aggregates to obtain the vanadyl sulfate electrolyte.

2. The method according to claim 1, characterized in that In step 1, the desiliconizing agent is a polycarboxylic acid water reducer; wherein the mass ratio of the desiliconizing agent to Si in each liter of the acid leaching solution is (1-2):

1.

3. The method according to claim 1, characterized in that In step 2, in the nanoemulsion mixed system, calculated by mass percentage, the organic solvent is 50 wt%-70 wt%, the surfactant is 15 wt%-30 wt%, and the co-surfactant is 5 wt%-25 wt%; wherein, the organic solvent is one of sulfonated kerosene or n-heptane, the surfactant is one of trioctylmethylammonium chloride or tetraoctylammonium chloride, and the co-surfactant is one of isoamyl alcohol or n-butanol.

4. The method according to claim 1, characterized in that In step 3, the flow ratio of the nanoemulsion to the calcification solution is (0.3-3):1, the flow rate of the nanoemulsion is 60 mL / min-240 mL / min, and the rotation speed of the first centrifugal extractor is 3500 r / min-5500 r / min.

5. The method according to claim 1, characterized in that: In step 4, the loaded phase and the dilute sulfuric acid are mixed at a flow ratio of (0.5-1):1, the speed of the second centrifugal extractor is 3500 r / min-5500 r / min, and the concentration of the dilute sulfuric acid is 0.05 mol / L-2 mol / L.

6. The method according to claim 1, characterized in that In step 5, the SO2 gas flow rate is 0.6 L / min-3.0 L / min, the reduction reaction temperature is 20 ℃-40 ℃, and the reaction time is 20 min-50 min; the stripping solution is H2SO4 solution, and its concentration is 3 mol / L-5 mol / L.

7. The method according to claim 1, characterized in that: In step 6, the nanoemulsion is sequentially processed with NaOH, H2O2, and alkaline sodium chloride solution by passing through a third centrifugal extractor, a fourth centrifugal extractor, and a fifth centrifugal extractor, respectively. The specific process is as follows: S1: mixing the nanoemulsion after the stripping treatment in step 5 with the NaOH solution and pumping them into a third centrifugal extractor; wherein the concentration of the NaOH solution is 3 mol / L-5 mol / L, the nanoemulsion and the NaOH solution are mixed at an O / A flow ratio of (0.5-1):1, the speed of the third centrifugal extractor is 3500 r / min-5500 r / min, and the flow rate of the stripped nanoemulsion entering the third centrifugal extractor is 60 mL / min-240 mL / min; S2: The nanoemulsion flowing out of S1 enters a fourth centrifugal extractor and is mixed with a H2O2 solution to remove the residual reducing agent in the oil phase; wherein the concentration of the H2O2 solution is 3wt%-30wt%, the flow rate of the hydrogen peroxide solution pumped in is 60 mL / min-240 mL / min, and the rotation speed of the fourth centrifugal extractor is 3500-5500 r / min; S3: The nanoemulsion flowing out of S2 continuously enters the fifth centrifugal extractor to be mixed with the alkaline sodium chloride solution; wherein, the concentrations of NaOH and NaCl in the alkaline sodium chloride solution are 0.5 mol / L-1 mol / L, the flow rate of the alkaline sodium chloride solution pumped in is 60 mL / min-240 mL / min, and the rotation speed of the fifth centrifugal extractor is 3500 r / min-5500 r / min. The nanoemulsion finally flowing out of the light phase outlet of the fifth centrifugal extractor is the replicated nanoemulsion and can be reused.

8. The method according to claim 1, characterized in that: In step 7, the heating treatment temperature is 85°C-95°C, the heating time is 2 h-5 h, and after the electrolyte is cooled, it is filtered with a 0.22 μm water filter membrane at room temperature to remove large-sized organic aggregates remaining in the electrolyte to obtain the vanadyl sulfate electrolyte.

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