Method for recovering and preparing vanadium dioxide from vanadium-containing pickle liquor

Abstract

The invention discloses a method for recovering and preparing vanadium dioxide from vanadium-containing pickle liquor, which comprises the following steps of: extracting and separating vanadium by taking the vanadium-containing pickle liquor as a research object and adopting a saponified P204 microemulsion system, and determining an optimal extraction process condition by exploring the influence of parameters such as pH value of the leaching liquor, NaOH addition amount, P204 concentration, extraction phase ratio, extraction time and the like on the vanadium extraction rate; after extraction, washing with deionized water to remove impurities; then, the optimal vanadium reverse extraction process condition is determined by exploring the influence of parameters such as the reverse extraction agent concentration, the reverse extraction ratio and the reverse extraction time on the vanadium reverse extraction rate; and finally, reducing the high-valence vanadium by adopting an H2SO3 solution to prepare hydrated vanadium dioxide, and then filtering, washing and drying to prepare vanadium dioxide, so that efficient enrichment of vanadium is realized, and vanadium dioxide is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of separation and purification of vanadium, and in particular to a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. Background Art

[0002] Vanadium-containing shale is an important vanadium resource, and the vanadium concentration in its acid leaching solution is often low. This characteristic directly limits the feasibility of obtaining the final vanadium product directly through the vanadium precipitation-calcination process. In view of the economic and efficiency issues of direct treatment of low-concentration vanadium-containing leaching solution, vanadium enrichment of such solution has become a key step in vanadium extraction.

[0003] At present, the separation and enrichment methods widely used in industry mainly include ion exchange resin method, solvent extraction method and microemulsion extraction method. The ion exchange resin method is known for its high selectivity and good separation effect. However, this method faces challenges in practical application, such as limited adsorption capacity, large amount of adsorbent required and long separation cycle, which to some extent limits its large-scale application.

[0004] Solvent extraction is favored for its simple operation, rapid reaction, low equipment requirements and good selectivity. However, emulsification is prone to occur during solvent extraction, which not only increases the complexity of the operation, but also often leads to low vanadium extraction efficiency, affecting the purity and recovery rate of the final product.

[0005] In contrast, microemulsion extraction has shown unique advantages. Microemulsion is a thermodynamically stable dispersion system with a large number of nano-scale water balls dispersed in the internal oil phase. These tiny water balls provide a huge specific surface area, equivalent to countless micro-reactors, which greatly promotes the extraction reaction. This structure not only accelerates the reaction rate, but also significantly increases the extraction saturation capacity. In addition, microemulsion extraction is not easy to emulsify and reacts quickly, so it has broad application prospects in the extraction of vanadium.

[0006] In particular, saponified P204 microemulsion system (such as saponified P204 / sulfonated kerosene solution) is a commonly used vanadium extractant with a clear extraction mechanism and high efficiency. 2+ The ions diffuse under the attraction of the extractant molecules and enter the countless nanoscale water cores in the microemulsion. 2+ It is tightly bound to the extractant molecules and extracted to the surface of the amphiphilic molecular membrane of the microemulsion, and then further enters the water core, achieving efficient vanadium enrichment.

[0007] In summary, although the existing separation and enrichment methods have their own advantages and disadvantages, the microemulsion extraction method, with its unique structure and efficient extraction mechanism, shows significant advantages and potential in the extraction of vanadium from vanadium-containing shale acid leaching solution. However, how to control the extraction and stripping reaction conditions to achieve efficient enrichment of vanadium is a technical problem that needs to be solved urgently. Summary of the invention

[0008] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution, by controlling the extraction and stripping reaction conditions to achieve efficient enrichment of vanadium, thereby solving the technical problem that the vanadium concentration in the vanadium-containing acid leaching solution is too low to directly carry out vanadium precipitation-calcination to obtain the final vanadium product.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] A method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution comprises the following steps:

[0011] (1) P204 and sulfonated kerosene are mixed uniformly to obtain a P204 mixed solution, and then a sodium hydroxide solution is added to the obtained P204 mixed solution and stirred to uniformly saponify the P204, and the mixture is allowed to stand for stratification to obtain a supernatant, which is the microemulsion;

[0012] (2) adding sodium hydroxide solution to the vanadium-containing acid leaching solution to adjust the pH to 1.4-2.2;

[0013] (3) fully mixing the vanadium-containing acid leaching solution obtained in step (2) and the microemulsion obtained in step (1) for extraction, standing to separate the layers, wherein the upper layer is the loaded microemulsion and the lower layer is the aqueous phase, and the loaded microemulsion and the aqueous phase are separated;

[0014] (4) After the loaded microemulsion obtained in step (3) and the detergent are fully mixed, the mixture is allowed to stand for separation, wherein the upper layer is the loaded microemulsion after washing and the lower layer is the residual washing liquid, and the loaded microemulsion after washing and the residual washing liquid are separated;

[0015] (5) fully mixing the washed loaded microemulsion obtained in step (4) with the sodium carbonate solution for stripping, and then standing to separate the layers, and the vanadium-rich solution in the lower layer is set aside;

[0016] (6) adding sulfuric acid to the vanadium-rich solution obtained in step (5) to adjust the pH to 1.0-3.0, adding sulfurous acid solution under stirring until the solution turns blue, and then adding NaOH solution to adjust the pH of the solution to 4.0-6.0 to obtain a tetravalent vanadium hydrate precipitate;

[0017] (7) The obtained tetravalent vanadium hydrate precipitate is filtered, washed and dried to obtain vanadium dioxide.

[0018] Furthermore, in step (1), the concentration of the P204 mixed solution is 0.3-0.75 mol / L.

[0019] Furthermore, in the step (1), after the sodium hydroxide solution is added to the P204 mixed solution, the mass proportion of the obtained sodium hydroxide is 1.2 to 2.6 wt.%.

[0020] Furthermore, in step (3), the vanadium-containing acid leaching solution obtained in step (2) and the microemulsion obtained in step (1) are mixed at an extraction phase ratio A / O of 1:1 to 2.

[0021] Furthermore, in step (4), the detergent is deionized water.

[0022] Furthermore, in the step (4), the loaded microemulsion obtained in the step (3) and the detergent are mixed at a detergent ratio O / A of 1:1.

[0023] Furthermore, in the step (5), the washed loaded microemulsion obtained in the step (4) and the sodium carbonate solution are mixed at a stripping phase O / A ratio of 1:1.

[0024] Furthermore, in step (5), the concentration of the sodium carbonate solution is 1 to 2 mol / L.

[0025] Furthermore, the extraction time in step (3) is 2 minutes.

[0026] The present invention takes vanadium-containing acid leaching solution as the research object, adopts a saponified P204 microemulsion system to extract and separate vanadium, and determines the optimal extraction process conditions by exploring the influence of parameters such as the pH value of the leaching solution, the amount of NaOH added, the P204 concentration, the extraction ratio and the extraction time on the vanadium extraction rate; after the extraction, deionized water is used for washing and impurity removal; then, the optimal vanadium stripping process conditions are determined by exploring the influence of parameters such as the stripping agent concentration, the stripping ratio and the stripping time on the vanadium stripping rate; finally, an H2SO3 solution is used to reduce the high-valent vanadium, and by adjusting the pH value of the solution, it is ensured that the vanadium is completely reduced to a tetravalent state and completely precipitated to obtain a hydrated vanadium dioxide precipitate, which is filtered, washed and dried to obtain vanadium dioxide, thereby achieving efficient enrichment of vanadium and obtaining vanadium dioxide.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention achieves efficient recovery of vanadium resources in vanadium-containing acid leaching solution by optimizing the extraction conditions of saponified P204 microemulsion. Under the optimal conditions, the vanadium extraction rate can reach 99.57%, which greatly improves the utilization rate of vanadium resources and reduces resource waste. At the same time, by comparing different washing methods, it is determined that the use of deionized water 1:1 washing can effectively improve the effect of Na2CO3 stripping vanadium. Finally, combined with the optimized stripping conditions, the stripping rate of vanadium reaches 95.30%, further ensuring the efficient recovery of vanadium. In the entire extraction-washing-stripping process, the total recovery rate of vanadium is as high as 93.95%, which significantly improves production efficiency and economic benefits.

[0029] 2. After the stripping solution obtained by the present invention is reduced with H2SO3 solution, a hydrated vanadium dioxide product is successfully obtained. This product is not only of high purity but also of stable quality, meeting the market demand for high-quality vanadium products. Moreover, the method of the present invention not only effectively recovers vanadium resources, but also reduces the discharge of pollutants such as wastewater and waste residue, which is in line with the green and environmentally friendly production concept. At the same time, by efficiently utilizing resources, the production cost is reduced, providing strong support for the sustainable development of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the XRD spectrum of the final vanadium product of the present invention. DETAILED DESCRIPTION

[0031] The specific implementation modes of the present invention are further described in detail below in conjunction with specific examples.

[0032] The numerical ranges in the present invention are understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any intermediate value in the stated value or stated range and any other stated value or intermediate value in the stated range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded in the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art described in the present invention are generally understood. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of conflict with any incorporated document, the content of this specification shall prevail. Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open terms, which means including but not limited to.

[0034] Unless otherwise specified, the experimental methods used in the present invention are all conventional methods.

[0035] Unless otherwise specified, the materials, reagents, etc. used in the present invention can be purchased or synthesized by known methods.

[0036] The quantitative tests in the present invention were all repeated three times, and the results were averaged.

[0037] 1. Implementation

[0038] Example 1

[0039] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution, and the specific steps are as follows:

[0040] Step 1: Preparation of microemulsion

[0041] First, P204 (di(2-ethylhexyl) phosphate) and sulfonated kerosene were mixed and placed in a constant temperature heated magnetic stirrer and stirred evenly to obtain a P204 mixed solution with a concentration of 0.75 mol / L. Then, NaOH solution was added to the P204 mixed solution so that the mass proportion of NaOH was 2.0wt%, and the mixture was stirred evenly to saponify P204. After standing, stratification was observed between the liquid phases, and the upper layer was a clear and transparent supernatant, which was the prepared microemulsion. The microemulsion has good stability and dispersibility, which provides a basis for subsequent extraction experiments.

[0042] Step 2: Extraction experiment

[0043] 8 mol / L NaOH solution was added to the acid leaching solution of vanadium-containing shale to adjust the pH value of the solution to 2. Then, according to the extraction phase ratio (A / O) of 1:1, the acid leaching solution of vanadium-containing shale after adjusting the pH value and the previously prepared microemulsion were measured respectively. The two liquids were added to the separatory funnel successively and gently shaken for 2 minutes to allow the oil phase and the water phase to fully contact. After standing, when the oil phase and the water phase are completely separated again, it can be observed that the color of the lower water phase changes from blue to light and tends to be colorless and transparent. Take the lower water phase (raffinate), filter and dilute it, and use ICP-OES (inductively coupled plasma emission spectrometer) for element concentration analysis. According to the analysis results, the vanadium extraction rate is as high as 99.57%, indicating that the extraction method has excellent vanadium recovery effect. The remaining upper loaded microemulsion is used for washing and stripping experiments.

[0044] Step 3: Washing experiment

[0045] Place the loaded microemulsion after extraction in a separatory funnel, and then add deionized water at a washing phase ratio (A / O) of 1:1. Shake the separatory funnel slightly to allow the oil phase and the water phase to fully contact. After standing, wait for the oil phase and the water phase to completely separate again. At this time, take the loaded microemulsion on the upper layer for subsequent stripping experiments. The washing process effectively removes possible impurities in the microemulsion and improves the effect of subsequent stripping experiments.

[0046] Step 4: Stripping experiment

[0047] The washed loaded microemulsion is placed in a separatory funnel, and a corresponding volume of 1 mol / L Na2CO3 solution is added to the separatory funnel according to a 1:1 stripping ratio (A / O). The separatory funnel is gently shaken to allow the oil phase and the aqueous phase to fully contact. After standing, the oil phase and the aqueous phase are completely separated again. At this time, the lower aqueous phase (vanadium-rich solution) is taken, filtered and diluted, and the vanadium element concentration is analyzed using ICP-OES. According to the analysis results, the stripping rate of vanadium element is 95.30%. This shows that the stripping process effectively releases vanadium from the microemulsion into the aqueous phase, providing a basis for subsequent vanadium precipitation operations.

[0048] Step 5: Vanadium precipitation experiment

[0049] The aqueous phase after stripping is placed in a beaker, and sulfuric acid solution is added to adjust the pH of the solution to 2.0. Then, sulfurous acid solution is added and stirred. At this time, the color of the solution can be observed to change to blue, indicating that the vanadium is reduced to tetravalent vanadium. Next, NaOH solution is added to adjust the pH of the solution to 5.0. In this process, a flocculent precipitate can be observed, which is a hydrate precipitate of tetravalent vanadium. After filtering, washing and drying the precipitate, a vanadium dioxide product with high purity can be obtained.

[0050] Figure 1 FIG. 4 is an XRD spectrum of the final vanadium product. As can be seen from the figure, the present invention produces hydrated vanadium dioxide with a purity of 90.96%.

[0051] Example 2

[0052] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0053] Step 1: Preparation of microemulsion

[0054] The mass proportion of NaOH was modified to 1.6wt.%, and the vanadium extraction rate was 99.01%.

[0055] Step 4: Stripping experiment

[0056] The concentration of Na2CO3 solution was modified to 0.8 mol / L, and the stripping rate of vanadium was 81.15%.

[0057] The comparison table of metal element concentrations during extraction and stripping in this embodiment is shown in Table 1.

[0058] Table 1 Comparison of metal element concentrations during extraction and stripping

[0059]

[0060] Example 3

[0061] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0062] Step 1: Preparation of microemulsion

[0063] The mass proportion of NaOH was modified to 1.2wt.%, and the vanadium extraction rate was 98.72%.

[0064] Step 4: Stripping experiment

[0065] The concentration of Na2CO3 solution was modified to 2 mol / L, and the stripping rate of vanadium element was 93.54%.

[0066] Example 4

[0067] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0068] Step 2: Extraction experiment

[0069] The extraction phase ratio (A / O) was modified to 1:2, and the vanadium extraction rate was 99.85%.

[0070] Step 4: Stripping experiment

[0071] The stripping ratio (A / O) was modified to 2:1, and the stripping rate of vanadium was 50.65%.

[0072] Example 5

[0073] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0074] Step 2: Extraction experiment

[0075] The pH value of the acid leaching solution of vanadium-containing shale was adjusted to 1.6, and the extraction rate of vanadium was 97.73%.

[0076] Step 4: Stripping experiment

[0077] The stripping ratio (A / O) was changed to 1:2, and the stripping rate of vanadium was 43.67%.

[0078] Example 6

[0079] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0080] Step 2: Extraction experiment

[0081] The extraction rate of vanadium was 99.57%.

[0082] Step 4: Stripping experiment

[0083] The concentration of Na2CO3 solution was modified to 1.5 mol / L, and the stripping rate of vanadium element was 94.98%.

[0084] Example 7

[0085] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0086] Step 1: Preparation of microemulsion

[0087] The concentration of P204 mixed solution was modified to 0.45 mol / L.

[0088] Step 2: Extraction experiment

[0089] The extraction rate of vanadium was 95.08%.

[0090] Step 4: Stripping experiment

[0091] The stripping ratio (A / O) was modified to 1:4, and the stripping rate of vanadium was 25.98%.

[0092] Example 8

[0093] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0094] Step 1: Preparation of microemulsion

[0095] The concentration of P204 mixed solution was modified to 0.3 mol / L.

[0096] Step 2: Extraction experiment

[0097] The extraction rate of vanadium was 76%.

[0098] Step 3: Stripping experiment

[0099] The concentration of Na2CO3 solution was modified to 2 mol / L, and the stripping rate of vanadium element was 93.54%.

[0100] Example 9

[0101] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0102] Step 2: Extraction experiment

[0103] The extraction phase ratio (A / O) was modified to 1:4, and the vanadium extraction rate was 99.45%.

[0104] Step 3: Stripping experiment

[0105] The concentration of Na2CO3 solution was modified to 2.5 mol / L, and the stripping rate of vanadium element was 54.14%.

[0106] Example 10

[0107] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0108] Step 2: Extraction experiment

[0109] The 2 minutes was changed to 1 minute, and the extraction rate of vanadium was 87%.

[0110] Step 3: Stripping experiment

[0111] The concentration of Na2CO3 solution was modified to 3 mol / L, and the stripping rate of vanadium element was 51.98%.

[0112] Embodiment 11

[0113] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 2, except that:

[0114] Step 3: Washing experiment

[0115] Use 0.05 mol / L dilute sulfuric acid solution instead of deionized water for washing.

[0116] The stripping rate of vanadium was 56.22%.

[0117] The comparison table of metal element concentrations during extraction and stripping in this embodiment is shown in Table 1.

[0118] Table 1 Comparison of metal element concentrations during extraction and stripping

[0119]

[0120] Example 12

[0121] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0122] Step 1: Preparation of microemulsion

[0123] The mass proportion of NaOH was adjusted to 2.3wt%, and the extraction rate of vanadium was 99.52%.

[0124] Step 3: Stripping experiment

[0125] The stripping rate of vanadium element is 95.11%.

[0126] Example 13

[0127] The present invention provides a method for recovering and preparing vanadium dioxide from a vanadium-containing acid leaching solution. The preparation steps are mainly the same as those in Example 1, except that:

[0128] Step 1: Preparation of microemulsion

[0129] The mass proportion of NaOH was adjusted to 2.6wt%, and the extraction rate of vanadium was 99.12%.

[0130] Step 3: Stripping experiment

[0131] The stripping rate of vanadium element is 94.26%.

[0132] 2. Data Analysis and Conclusion

[0133] (I) Extraction experiment analysis

[0134] 1. Effect of NaOH addition amount in microemulsion

[0135] P204 in unsaponified microemulsion usually exists in the form of dimer H2A2 in non-polar solvents. At this time, the mechanism of extracting vanadium with P204 can be expressed as:

[0136] VO 2+ (a)+2H2A2(o)==VO(HA2)2(o)+2H +

[0137] The extraction reaction is just a simple cation exchange reaction. The hydrogen in the P204 dimer converts the VO 2+ However, as the extraction reaction proceeds in the positive direction, the pH value of the extraction system continues to decrease, and the reaction moves in a direction that is not conducive to the extraction of VO. 2+ The movement of the H2A2 dimer in the microemulsion will result in poor extraction of vanadium. However, saponification can open the dimer H2A2 in advance, which significantly improves the extraction rate of vanadium. The extraction mechanism can be expressed as:

[0138] VO 2+(a)+2Na + A - = = VOA2(o) + 2Na +

[0139] Both ammonia water and NaOH can be used as saponifying agents, but since the amount of ammonia water added during the saponification reaction is difficult to control, NaOH is used to saponify the microemulsion.

[0140] By comparing Examples 1, 2, and 3, it can be seen that as the amount of NaOH added increases, the extraction rate of vanadium gradually increases. If the amount of NaOH added is too low, on the one hand, its effect on improving the extraction rate of vanadium is not good, and on the other hand, part of P204 will dissolve in the water therein, resulting in a waste of P204. When the amount of NaOH added reaches 2wt%, the extraction rate of vanadium reaches 99.57%, achieving the optimal effect. While continuing to increase the amount of NaOH added, the extraction rate of vanadium tends to be stable, but when the amount of NaOH added exceeds 2.3wt%, the extraction rate decreases slightly to 99.52% (Example 12). It can be observed that the extraction process of the microemulsion is difficult to stratify, and the lower aqueous phase after extraction is no longer clear and transparent, and the extraction rate of vanadium is also reduced, so the amount of NaOH added is selected to be 2wt%.

[0141] 2. Influence of P204 concentration

[0142] By comparing Examples 1, 7, and 8, it can be seen that as the concentration of P204 decreases, the extraction rate of vanadium gradually decreases. When the concentration of P204 is 0.3 mol / L, the extraction rate of vanadium is 76%, indicating that the extraction agent P204 is not added enough at this time, and the specific surface area and binding sites of the extraction reaction are insufficient, resulting in a low extraction rate of vanadium. When the concentration of P204 is between 0.3-0.75 mol / L, the extraction rate of vanadium gradually increases. This is mainly because as the concentration of the extractant increases, more nano-scale water balls are dispersed in the oil phase, providing a huge specific surface area, which is equivalent to countless micro-reactors, which can accelerate the extraction reaction rate and increase the saturated capacity of the extraction, so the extraction rate of vanadium continues to increase. And the inventors have found that when the concentration of P204 is higher than 0.75 mol / L, the extraction rate of vanadium remains almost unchanged, indicating that the extraction agent P204 has been added in excess at this time, and increasing the concentration of the extractant will not increase the extraction rate of vanadium. When the concentration of P204 is 0.75 mol / L, the extraction rate of vanadium is as high as 99.57%. Therefore, the extraction experiment was carried out under the condition that the concentration of extractant P204 was 0.75 mol / L.

[0143] 3. Influence of pH value of leachate

[0144] In Example 5, when the pH value of the leachate is adjusted to 1.6, the extraction rate of vanadium is 97.73%, which is lower than 99.57% when the pH value is 2.0 (Example 1). This confirms that the pH value of the leachate has a significant effect on the extraction efficiency. This is because P204 often exists in the form of a dimer (H2A2) in an inert solvent (such as kerosene) and is an acidic extractant. During the extraction process, the acidic extractant releases hydrogen ions, which are transferred to the aqueous phase as the reaction proceeds. Since the vanadium extraction process involves the cation exchange process of metal ions, the presence of hydrogen ions will interfere with this process, thereby inhibiting the extraction process of vanadium. Therefore, the initial pH value of the leachate has a great influence on the extraction of vanadium. If a microemulsion is directly used to extract the vanadium-containing acid leachate, the extraction rate of vanadium is only about 50%, and it will cause a large amount of waste of microemulsion, so it is necessary to adjust the pH value of the leachate. The inventors have also found that as the pH of the leachate increases, the extraction rate of vanadium gradually increases. When the pH of the leachate exceeds 2.0, the growth of the extraction rate of vanadium tends to be slow. When the pH of the leachate reaches around 2.5, it can be observed that the solution changes from blue to black, and some black precipitates are produced. Therefore, the extraction experiment is carried out under the condition of a leachate pH of 2.0, which has the best effect.

[0145] 5. Effect of extraction ratio (A / O)

[0146] Comparing Examples 1, 4, and 9, when the relative A / O is between 1:1 and 1:4, the vanadium extraction rate does not change significantly and remains above 99.00%, because the relative A / O in this range can meet the extraction of vanadium. However, when the relative A / O is less than 1:2, the pH value of the residual liquid after extraction is high, which will lead to the formation of a third phase, making phase separation difficult. It was found in the experiment that when the pH value of the residual liquid after extraction is high, a large amount of floccules will be generated between the oil phase and the water phase, and the phase separation cannot be completely completed after standing for 12 hours. Therefore, the extraction experiment was carried out under the condition of a relative A / O of 1:1.

[0147] 6. Effect of extraction time

[0148] Extraction time is one of the important factors affecting vanadium extraction, and extraction time is very important for industrial production. It reflects the feasibility and production efficiency of the extraction method, so the extraction time is optimized. By comparing Example 3 and Implementation 10, it can be seen that when the extraction time is 1 min, the extraction rate of vanadium is as high as 87%, which shows that the reaction rate of vanadium extraction is very fast. When the extraction time is 2 min, the extraction rate of vanadium is 99.57%, and the two phases are completely separated and clear; and the study found that the extraction rate of vanadium will not increase if the extraction time is extended. Therefore, the preferred extraction time is 2 min for the extraction experiment.

[0149] (II) Washing experiment analysis

[0150] Due to physical adsorption during the extraction reaction, vanadium ions enter the inner water phase, but at the same time, a small amount of metal cations (such as Fe, Mg, Al, etc.) will be absorbed by VO2 in the extraction process. 2+ Enter into the organic phase, in order to reduce the influence of these elements on the subsequent stripping and vanadium precipitation experiments, the loaded organic phase after extraction can be washed to reduce the concentration of these impurity metal ions. By the comparison of Example 2 and Example 11, it can be seen that the elution rate of metal ions in the case of deionized water washing and acid solution washing is not much different, but under the same conditions, deionized water is used to wash the loaded organic phase after extraction, and the stripping rate of vanadium is 81.15%, which is much higher than the stripping rate of vanadium 56.22% after the loaded organic phase after extraction is washed with dilute sulfuric acid solution. Therefore, deionized water is selected to be washed after comprehensive consideration. And it can be seen that when using Na2CO3 solution stripping, most of the impurity metal elements do not enter the stripping solution rich in vanadium, and vanadium is effectively enriched, which illustrates the feasibility of Na2CO3 solution stripping method at the same time.

[0151] (III) Stripping Experiment Analysis

[0152] 1. Influence of Na2CO3 concentration:

[0153] By the comparison of Examples 1, 2, 3, 6, 9, 10, it can be known that when Na2CO3 concentration is lower than 1mol / L, the stripping rate of vanadium increases with Na2CO3 concentration, which is because as the stripping agent concentration increases, the nano-sized balls in the oil phase are more exchanged with the aqueous phase, which can accelerate the reaction rate of stripping; when the stripping agent Na2CO3 concentration is in 1-2mol / L, the stripping rate of vanadium increases with Na2CO3 concentration, and it is found in the experiment that when Na2CO3 concentration is higher than 2mol / L, the pH value of the residual liquid after stripping is higher, a large amount of floccules will be produced between the oil phase and the aqueous phase, and after standing for 3-4h, phase separation cannot be performed completely, and the stripping rate of vanadium element is lower. And when Na2CO3 concentration is controlled at 1mol / L, phase separation can be performed completely in a short time, and the stripping rate of vanadium reaches 95%. Therefore, Na2CO3 concentration is selected to perform stripping experiment under the condition of 1mol / L.

[0154] 2. Effect of stripping ratio (A / O)

[0155] The stripping ratio (A / O) is one of the important factors affecting vanadium stripping. The present invention optimizes the stripping ratio (A / O) by experiments. By comparing Examples 1, 4, 5, and 7, it can be seen that as the stripping ratio A / O increases, the stripping rate of vanadium first shows an upward trend and then a downward trend. When the stripping ratio A / O is between 1:4 and 1:1, the stripping rate of vanadium increases significantly. This is because in this interval, the dosage of the stripping agent is not enough to meet the stripping requirements, and the vanadium cannot be completely returned to the aqueous phase; when the stripping ratio A / O is greater than 1:1, the pH value of the residual liquid after stripping is high, which easily leads to the generation of the third phase, and the time required for phase separation is very long, and it is found in the experiment that the stripping rate of vanadium is low at this time. And when the stripping ratio A / O is controlled near 1:1, the phase separation can be completely completed in a short time, and the two phases are clear and transparent. Therefore, it is preferred to carry out the stripping experiment under the condition that the stripping ratio A / O is 1:1.

[0156] In summary, the optimal extraction conditions of the present invention are: the addition amount of NaOH is 2wt.%, the pH value of the leachate is 2.0, the P204 concentration is 0.75mol / L, the extraction ratio (A / O) is 1:1, and the extraction time is 2 minutes. The extraction rate of vanadium can reach 99.57%. By comparing the stripping effect of vanadium after washing and stripping, it is determined that the washing method is to use deionized water for 1:1 washing. Under this method of washing, Na2CO3 stripping of vanadium can achieve better results. The optimal stripping conditions are: the Na2CO3 concentration is 1mol / L, and the stripping ratio (A / O) is 1:1. The stripping rate of vanadium can reach 95.30%. In the whole process of extraction-washing-stripping, the recovery rate of vanadium can reach 93.95%.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for recovering vanadium dioxide from a vanadium-containing acid leaching solution, characterized in that: The following steps are involved: (1) P204 and sulfonated kerosene are mixed uniformly to obtain a P204 mixed solution, and then a sodium hydroxide solution is added to the obtained P204 mixed solution and stirred to uniformly saponify the P204, and the mixture is allowed to stand for stratification to obtain a supernatant, which is the microemulsion; (2) adding sodium hydroxide solution to the vanadium-containing acid leaching solution to adjust the pH to 1.4-2.2; (3) fully mixing the vanadium-containing acid leaching solution obtained in step (2) and the microemulsion obtained in step (1) for extraction, standing to separate the layers, wherein the upper layer is the loaded microemulsion and the lower layer is the aqueous phase, and the loaded microemulsion and the aqueous phase are separated; (4) After the loaded microemulsion obtained in step (3) and the detergent are fully mixed, the mixture is allowed to stand for separation, wherein the upper layer is the loaded microemulsion after washing and the lower layer is the residual washing liquid, and the loaded microemulsion after washing and the residual washing liquid are separated; (5) fully mixing the washed loaded microemulsion obtained in step (4) with the sodium carbonate solution for stripping, and then standing to separate the layers, and the vanadium-rich solution in the lower layer is set aside; (6) adding sulfuric acid to the vanadium-rich solution obtained in step (5) to adjust the pH to 1.0-3.0, adding sulfurous acid solution under stirring until the solution turns blue, and then adding NaOH solution to adjust the pH of the solution to 4.0-6.0 to obtain a tetravalent vanadium hydrate precipitate; (7) The obtained tetravalent vanadium hydrate precipitate is filtered, washed and dried to obtain vanadium dioxide.

2. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (1), the concentration of the P204 mixed solution is 0.3-0.75 mol / L.

3. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (1), after the sodium hydroxide solution is added to the P204 mixed solution, the mass proportion of the obtained sodium hydroxide is 1.2 to 2.6 wt.%.

4. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (3), the vanadium-containing acid leaching solution obtained in the step (2) and the microemulsion obtained in the step (1) are mixed at an extraction phase ratio A / O of 1:1 to 2.

5. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (4), the detergent is deionized water.

6. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (4), the loaded microemulsion obtained in the step (3) and the detergent are mixed at a detergent phase ratio O / A of 1:

1.

7. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (5), the washed loaded microemulsion obtained in the step (4) and the sodium carbonate solution are mixed at a stripping phase O / A ratio of 1:

1.

8. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: In the step (5), the concentration of the sodium carbonate solution is 1 to 2 mol / L.

9. The method for recovering vanadium dioxide from a vanadium-containing acid leaching solution according to claim 1, characterized in that: The extraction time in step (3) is 2 minutes.

Images