Impurity removal method for acidic vanadium-containing leachate

Abstract

The invention discloses an impurity removal method for an acidic vanadium-containing leachate, which relates to the technical field of metallurgy and comprises the following steps: by taking the acidic vanadium-containing leachate as a raw material, removing impurity elements such as iron, aluminum and magnesium in the acidic vanadium-containing leachate through a chemical method, and then deeply purifying vanadium ions through an ion exchange method by virtue of strongly basic anion exchange resin, and the finally prepared vanadium-containing enriched liquid is low in impurity content. The method is short in technological process, low in reagent cost, good in impurity removal effect, low in vanadium loss rate and easy to industrialize.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, in particular to a method for removing impurities from an acidic vanadium-containing leaching solution. BACKGROUND

[0002] Vanadium is an important strategic metal, which is widely used in the fields of steel, chemical industry, aerospace, etc. With the development of science and technology, the demand for vanadium is increasing; however, the vanadium resources in China are poor, mainly in the form of low-grade stone coal and vanadium-titanium magnetite, which is difficult to extract and has high cost. At present, the methods for extracting vanadium from vanadium-containing resources mainly include fire method and wet method. The fire method has high energy consumption and causes serious pollution; the wet method is relatively environmentally friendly, but has a long process and high cost. In recent years, with the increasingly stringent environmental protection requirements, the wet metallurgy technology has developed rapidly. In the process of extracting vanadium by wet method, the ore is subjected to acid leaching to obtain an acidic vanadium-containing solution. This solution usually has high acidity, low vanadium content, and contains a large amount of impurities such as iron, aluminum, magnesium, etc. If vanadium is directly recovered, the recovery rate of vanadium is low, and the impurities are also relatively high, which not only leads to low product purity, but also causes a large loss of vanadium; therefore, the acidic vanadium-containing solution with high acidity and multiple impurities needs to be subjected to impurity removal treatment.

[0003] At present, the impurity removal steps for the acidic vanadium-containing solution with high acidity and multiple impurities are generally as follows: pH adjustment of vanadium-containing solution-heating-impurity removal-enrichment-vanadium precipitation-washing-heating of ammonium metavanadate alkali solution-pH adjustment-secondary impurity removal-filtration. Therefore, the current vanadium-containing solution impurity removal method has the following disadvantages: (1) the impurity removal effect is relatively single, mainly targeting one or two impurity elements, and the raw material adaptability is weak; for multiple impurity vanadium-containing solutions, multiple impurity removal is required, and the vanadium loss is large; (2) in order to improve the impurity removal rate and vanadium recovery rate, expensive impurity removal or enrichment reagents are used, or large amounts of reagents are used for multiple impurity removal, which are toxic and harmful, and will generate a large amount of wastewater and waste gas; (3) the process route is long, the vanadium recovery rate is low, and the production cost is increased, which is not easy to industrialize.

[0004] To address the aforementioned issues, researchers have employed various technologies. Among existing technologies, Chinese patent CN114477283B discloses a method for the synergistic removal of silicon and chromium from vanadium solutions using zinc ions to prepare high-purity vanadium pentoxide. This method involves adjusting the pH of the vanadium solution to 6-9 by adding sulfuric acid, then adding a reducing agent to obtain a reduced vanadium solution. After adjusting the pH to alkaline, a Zn source is added, followed by vanadium precipitation to obtain high-purity vanadium pentoxide. This patent achieves deep impurity removal from the vanadium solution, reducing the silicon content to below 5 ppm, the zinc residue to below 10 ppm, and the V₂O₅ purity to greater than 99.99%, with minimal vanadium loss. However, the process described in this patent has stringent reaction conditions. The first step requires adjusting the pH to 6-9, which consumes a large amount of alkali for highly acidic vanadium solutions, resulting in a longer reaction time and increased energy consumption. Furthermore, there are risks associated with Zn residue and the need to treat vanadium precipitation wastewater, which will increase treatment costs.

[0005] Chinese patent CN103937998 B discloses a method for preparing low-silicon vanadium pentoxide from a vanadium-chromium-silicon solution. The method uses an amphoteric metal salt as a silicon remover, performs solid-liquid separation to obtain a supernatant, selectively extracts vanadium using a primary amine system to obtain a vanadium-rich organic phase, and then performs back-extraction and vanadium precipitation to obtain low-silicon vanadium pentoxide. Furthermore, chromium in the raffinate is recovered. This patent effectively utilizes resources and recovers both vanadium and chromium. The wastewater generated during the vanadium precipitation process can be returned to the silicon removal step, achieving resource recycling. However, this process has limited raw material adaptability, does not address the treatment of wastewater generated from chromium recovery, and the primary amine extractant is expensive, indicating that costs will continue to increase during subsequent industrialization.

[0006] Chinese patent CN 106244828 B discloses a method for removing impurities from low-acidity vanadium-containing leachate. The method involves first adding potassium sulfate to crystallize and generate potassium alum, then filtering the solution. Next, reducing agents such as iron powder and sodium sulfite are added to obtain a reduced solution. Finally, soluble oxalates and soluble hydrogen oxalate are added as reducing agents to obtain a purified vanadium-containing leachate. This patent can significantly remove impurities such as aluminum and iron. However, this process consumes excessive amounts of potassium sulfate, and the crystallization process is slow, resulting in a long process cycle and high costs. Furthermore, other impurities such as magnesium, chromium, titanium, silicon, and phosphorus in the vanadium-containing leachate cannot be effectively recovered.

[0007] Currently, existing technologies generally only address one specific drawback of vanadium removal methods in high-acidity, high-impurity solution systems. Therefore, a more efficient and low-cost method is needed to solve the above problems, improve vanadium recovery rate, and reduce vanadium loss while removing multiple impurities.

[0008] In view of this, the present invention is proposed. Summary of the Invention

[0009] The purpose of this invention is to provide a method for removing impurities from acidic vanadium-containing leachate. This method combines chemical precipitation and ion exchange to achieve efficient separation of impurity ions such as Fe, Al, Mg, and Ti, and to deeply purify vanadium. The overall impurity removal rate is over 98%, and the loss of vanadium ions is less than 2%.

[0010] This invention is implemented as follows: This invention proposes a method for removing impurities from acidic vanadium-containing leaching solutions, comprising the following steps: adding an oxidant to the acidic vanadium-containing leaching solution, adjusting the pH of the reaction system to 1-2, stirring to carry out an oxidation reaction, allowing the solution to stand after the reaction is completed, and then filtering to obtain the first filtrate; Add alkali solution to the first filtrate to adjust the pH to 2-3, then add precipitant, stir to carry out the first precipitation reaction, let stand after the reaction is complete, and then filter to obtain the second filtrate; Add alkali solution to the second filtrate to adjust the pH to 11-12, then add ammonium phosphate, stir to carry out the second precipitation reaction, let stand after the reaction is completed, and then filter to obtain the third filtrate. The pH of the third filtrate is adjusted to 7-9, and then adsorbed through a strongly basic anion exchange resin. After the vanadium ions are completely adsorbed, the resin is washed, and finally an eluent is added to elute the resin, thus obtaining a vanadium-enriched solution.

[0011] In some preferred embodiments, the impurity element content in the acidic vanadium-containing leachate is: Fe 8-16 g / L, Al 12-20 g / L, Mg 2-7 g / L, Ti 4-12 g / L, Si 1-4 g / L, K≤2 g / L, Na≤2 g / L, and Cr≤0.5 g / L.

[0012] In some preferred embodiments, the oxidant is at least one selected from hydrogen peroxide, sodium chlorate, sodium hypochlorite, and persulfate.

[0013] In some preferred embodiments, the oxidation reaction is carried out at a temperature of 90-120°C, for a reaction time of 30-60 min, and with a stirring speed of 60-180 r / min.

[0014] In some preferred embodiments, the alkaline solution is at least one of sodium hydroxide and ammonia water.

[0015] In some preferred embodiments, the precipitant is at least one of oxalic acid and oxalate, and the concentration of the precipitant is 5%-15%.

[0016] In some preferred embodiments, the temperature of the first precipitation reaction is 20-80°C, the reaction time is 20-60 min, and the stirring speed is 80-200 r / min.

[0017] In some preferred embodiments, the temperature of the second precipitation reaction is 25-50°C, the reaction time is 30-60 min, and the stirring speed is 200-300 r / min.

[0018] In some preferred embodiments, the eluent is at least one of sodium chloride, ammonium chloride, and sodium hydroxide, the concentration of the eluent is 2-4 mol / L, and the volume ratio of the eluent to the strongly basic anion exchange resin is (2-3):1.

[0019] In some preferred embodiments, the component contents in the vanadium-containing enrichment solution are: V 12-14 g / L, Si≤0.4 g / L, Al≤0.05 g / L, Fe≤0.001 g / L, Mg≤0.01 g / L, Cr≤0.01 g / L, Ti≤0.01 g / L, and K≤0.6 g / L.

[0020] The present invention has the following beneficial effects: (1) This invention provides a method for removing impurities from acidic vanadium-containing leachate. This method combines chemical precipitation and ion exchange to achieve efficient separation of impurity ions such as Fe, Al, Mg, and Ti. It has strong raw material adaptability and deeply purifies vanadium. The overall impurity removal rate is over 98%, and the vanadium ion loss is less than 2%.

[0021] (2) The impurity removal method of the present invention does not use toxic and harmful chemical agents. The wastewater generated is mainly acidic and alkaline wastewater, which can be recycled after simple treatment such as neutralization and precipitation. Furthermore, the filter residue after solid-liquid separation can be further recovered for valuable metals.

[0022] (3) The process of this invention is short, the reagent cost is low, the impurity removal effect is good, the vanadium recovery rate is high, and it is easy to industrialize. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] The following is a detailed description of a method for removing impurities from an acidic vanadium-containing leachate.

[0025] This application proposes a method for removing impurities from acidic vanadium-containing leachates, comprising the following steps: An oxidant was added to the acidic vanadium-containing leaching solution, the pH of the reaction system was adjusted to 1-2, and the oxidation reaction was carried out by stirring. After the reaction was completed, the solution was allowed to stand, and then filtered to obtain the first filtrate. Add alkali solution to the first filtrate to adjust the pH to 2-3, then add precipitant, stir to carry out the first precipitation reaction, let stand after the reaction is complete, and then filter to obtain the second filtrate; Add alkali solution to the second filtrate to adjust the pH to 11-12, then add ammonium phosphate, stir to carry out the second precipitation reaction, let stand after the reaction is completed, and then filter to obtain the third filtrate. The pH of the third filtrate is adjusted to 7-9, and then adsorbed through a strongly basic anion exchange resin. After the vanadium ions are completely adsorbed, the resin is washed, and finally an eluent is added to elute the resin, thus obtaining a vanadium-enriched solution.

[0026] The acidic vanadium-containing leachate is obtained by mixing calcined and roasted vanadium-containing clinker with dilute sulfuric acid solution and leaching under normal pressure, followed by solid-liquid separation after leaching. The impurity element content in the acidic vanadium-containing leachate is as follows: Fe 8-16 g / L, Al 12-20 g / L, Mg 2-7 g / L, Ti 4-12 g / L, Si 1-4 g / L, K≤2 g / L, Na≤2 g / L, and Cr≤0.5 g / L.

[0027] In some preferred embodiments, the oxidant is at least one selected from hydrogen peroxide, sodium chlorate, sodium hypochlorite, and persulfate; the oxidation reaction temperature is 90-120°C, the reaction time is 30-60 min, and the stirring speed is 60-180 r / min. Adding an oxidant to the acidic vanadium-containing leachate oxidizes low-valence vanadium ions to high-valence vanadium ions. High-valence vanadium ions more readily form easily separable compounds. Maintaining the pH of the reaction system at 1-2 ensures that the vanadium ions are fully oxidized to the high-valence state (V). 5+ This process inhibits the hydrolysis of vanadium, maintains its solubility and stability, provides a suitable acidic environment for the oxidation reaction, reduces impurity interference, and optimizes solid-liquid separation. The temperature and duration of the oxidation reaction affect the activity of the oxidant and the overall reaction rate, and controlling the stirring speed ensures a thorough oxidation reaction and uniform mixing.

[0028] In some preferred embodiments, the alkaline solution is at least one of sodium hydroxide and ammonia water; when adjusting the pH before the first precipitation reaction, the alkaline solution used is preferably sodium hydroxide or ammonia water; when adjusting the pH before the second precipitation reaction, the alkaline solution used is preferably sodium hydroxide.

[0029] In some preferred embodiments, the precipitant for the first precipitation reaction is at least one of oxalic acid and oxalate, and the concentration of the precipitant is 5%-15%; the temperature of the first precipitation reaction is 20-80°C, the reaction time is 20-60 min, and the stirring speed is 80-200 r / min.

[0030] Oxalic acid is chosen as the precipitant due to its high selectivity. Oxalic acid and its salts have a strong complexing ability for impurity ions such as iron and aluminum, efficiently precipitating them while having minimal impact on vanadium ions. Simultaneously, maintaining the pH of the reaction system at 2-3 allows iron and aluminum to react with oxalic acid or oxalates to form insoluble oxalate precipitates, which are then separated from the solution. Under these conditions, impurity ions are effectively precipitated while avoiding excessive precipitation of vanadium ions, maintaining the solubility of vanadium in the solution and ensuring the effective removal of impurity ions such as iron and aluminum. This significantly improves the purity and recovery rate of vanadium in the solution.

[0031] In some preferred embodiments, the precipitant used in the second precipitation reaction is ammonium phosphate, the temperature of the second precipitation reaction is 25-50°C, the reaction time is 30-60 min, and the stirring speed is 200-300 r / min.

[0032] Ammonium phosphate was chosen as the precipitant because it has a strong complexing ability for impurity ions such as magnesium, effectively precipitating them while having minimal impact on vanadium ions. Simultaneously, maintaining the pH of the reaction system at 11-12 ensures that magnesium ions react with ammonium phosphate to form insoluble magnesium phosphate precipitate, which is then separated from the solution. Under these conditions, magnesium ions are effectively precipitated while large-scale precipitation of vanadium ions is avoided, preserving the dissolved state of vanadium in the solution.

[0033] In some preferred embodiments, the eluent is at least one of sodium chloride, ammonium chloride, and sodium hydroxide, the concentration of the eluent is 2-4 mol / L, and the volume ratio of the eluent to the strongly basic anion exchange resin is (2-3):1.

[0034] Strongly basic anion exchange resins are polymeric materials with quaternary ammonium groups on their surface, enabling them to selectively adsorb anions in solution. These resins exhibit high selectivity for vanadium ions, effectively adsorbing them in complex solution environments while excluding other impurity ions. Under pH 7-9 conditions, vanadium ions are primarily adsorbed as VO3+. - These anions exist in the form of vanadium ions, which are adsorbed by quaternary ammonium groups on the resin and thus separated from the solution. After vanadium ion adsorption is complete, residual impurity ions and other non-target substances on the resin are removed by washing with an eluent to ensure the cleanliness of the resin surface and improve the purity of subsequent eluent steps. At this time, the resin is eluented with an eluent such as sodium chloride, ammonium chloride, or sodium hydroxide. The anions in these eluents (such as Cl⁻, NH₄⁺, etc.) are present in the resin. +(Or OH⁻) has a strong affinity and can competitively displace vanadium ions on the resin, thereby allowing vanadium ions to re-enter the solution. The concentration of the eluent is typically 2-4 mol / L to ensure sufficient ionic strength for effective vanadium ion removal. The volume ratio of eluent to resin is (2-3):1 to ensure adequate contact and removal efficiency.

[0035] In some embodiments of this application, complete adsorption means that the concentration of vanadium ions in the solution flowing out from the lower end of the ion exchange column is the same as the concentration of vanadium ions in the solution flowing in from the upper end.

[0036] In some preferred embodiments, the component contents in the vanadium-containing enrichment solution are: V 12-14 g / L, Si≤0.4 g / L, Al≤0.05 g / L, Fe≤0.001 g / L, Mg≤0.01 g / L, Cr≤0.01 g / L, Ti≤0.01 g / L, and K≤0.6 g / L.

[0037] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0038] Example 1 This embodiment provides a method for removing impurities from acidic vanadium-containing leachate, comprising the following steps: Add 20g of hydrogen peroxide to 1000ml of acidic vanadium-containing leaching solution, adjust the pH of the reaction system to 1.5, and carry out the oxidation reaction at 90℃ and stirring speed of 120r / min for 60min. After the reaction is completed, let it stand for 30min, and then filter to obtain the first filtrate. Add ammonia to the first filtrate to adjust the pH to 2, then add 44g of oxalic acid. Stir at 160r / min for 60min at 60℃ to carry out the first precipitation reaction. After the reaction is complete, let it stand and then filter to obtain the second filtrate. Add sodium hydroxide to the second filtrate to adjust the pH to 11, then add 6g of ammonium phosphate. Stir at 200r / min for 60min at 30℃ to carry out the second precipitation reaction. After the reaction is completed, let it stand and then filter to obtain the third filtrate. The pH of the third filtrate was adjusted to 7, and then adsorbed through a strong base anion exchange resin. After the vanadium ions were completely adsorbed, the resin was washed, and finally, 2 mol / L ammonium chloride eluent was added to elute the resin. The volume ratio of the eluent to the strong base anion exchange resin was 2:1, and the vanadium-enriched solution was obtained.

[0039] The final vanadium-enriched solution contained the following components: V 12.96 g / L, Fe 0.0003 g / L, Mg 0.0004 g / L, Al 0.04 g / L, Ti 0.0005 g / L, Si 0.4 g / L, Cr 0.01 g / L, and K 0.4 g / L. The removal rates were 99.29% for Fe, 99.14% for Mg, 99.07% for Al, and 99.86% for Ti. The vanadium recovery rate was 90.61%, and the vanadium loss was 0.8%.

[0040] Example 2 This embodiment provides a method for removing impurities from acidic vanadium-containing leachate, comprising the following steps: Add 30g of hydrogen peroxide to 1000ml of acidic vanadium-containing leaching solution, adjust the pH of the reaction system to 1.5, and carry out the oxidation reaction at 160r / min for 30min at 100℃. After the reaction is completed, let it stand for 30min, and then filter to obtain the first filtrate. Add ammonia to the first filtrate to adjust the pH to 2.5, then add 34g of oxalic acid. Stir at 180r / min for 45min at 70℃ to carry out the first precipitation reaction. After the reaction is complete, let it stand and then filter to obtain the second filtrate. Add sodium hydroxide to the second filtrate to adjust the pH to 12, then add 8g of ammonium phosphate. Stir at 240r / min for 30min at 45℃ to carry out the second precipitation reaction. After the reaction is completed, let it stand and then filter to obtain the third filtrate. The pH of the third filtrate was adjusted to 8, and then adsorbed through a strong base anion exchange resin. After the vanadium ions were completely adsorbed, the resin was washed, and finally, 3 mol / L ammonium chloride eluent was added to elute the resin. The volume ratio of the eluent to the strong base anion exchange resin was 2:1, and the vanadium-enriched solution was obtained.

[0041] The final vanadium-enriched solution contained the following components: V 14.18 g / L, Fe 0.0002 g / L, Mg 0.0001 g / L, Al 0.015 g / L, Ti 0.0003 g / L, Si 0.2 g / L, Cr 0.004 g / L, and K 0.2 g / L. The removal rates were 99.34% for Fe, 99.27% ​​for Mg, 99.2% for Al, and 99.91% for Ti. The vanadium recovery rate was 93.51%, and the vanadium loss was 0.3%.

[0042] Example 3 This embodiment provides a method for removing impurities from acidic vanadium-containing leachate, comprising the following steps: Add 30g of hydrogen peroxide to 1000ml of acidic vanadium-containing leaching solution, adjust the pH of the reaction system to 2, and carry out the oxidation reaction at 110℃ and stirring speed of 180r / min for 30min. After the reaction is completed, let it stand for 30min, and then filter to obtain the first filtrate. Add ammonia to the first filtrate to adjust the pH to 3, then add 24g of oxalic acid. Stir at 200r / min for 30min at 80℃ to carry out the first precipitation reaction. After the reaction is complete, let it stand and then filter to obtain the second filtrate. Add sodium hydroxide to the second filtrate to adjust the pH to 11, then add 10g of ammonium phosphate. Stir at 280r / min for 45min at 40℃ to carry out the second precipitation reaction. After the reaction is completed, let it stand and then filter to obtain the third filtrate. The pH of the third filtrate was adjusted to 9, and then adsorbed through a strong base anion exchange resin. After the vanadium ions were completely adsorbed, the resin was washed, and finally, 4 mol / L ammonium chloride eluent was added to elute the resin. The volume ratio of the eluent to the strong base anion exchange resin was 2:1, and the vanadium-enriched solution was obtained.

[0043] The final vanadium-enriched solution contained the following components: V 12.71 g / L, Fe 0.0006 g / L, Mg 0.0002 g / L, Al 0.03 g / L, Ti 0.0004 g / L, Si 0.31 g / L, Cr 0.007 g / L, and K 0.5 g / L. The removal rates were as follows: Fe 99.12%, Mg 98.2%, Al 98.54%, Ti 99.79%, vanadium recovery 89.82%, and vanadium loss 1.2%.

[0044] Example 4 This embodiment provides a method for removing impurities from acidic vanadium-containing leachate, comprising the following steps: Add 25g of hydrogen peroxide to 1000ml of acidic vanadium-containing leaching solution, adjust the pH of the reaction system to 2, and carry out the oxidation reaction at 120r / min for 45min at 100℃. After the reaction is completed, let it stand for 30min, and then filter to obtain the first filtrate. Add ammonia to the first filtrate to adjust the pH to 2.5, then add 44g of oxalic acid. Stir at 180r / min for 60min at 60℃ to carry out the first precipitation reaction. After the reaction is complete, let it stand and then filter to obtain the second filtrate. Add sodium hydroxide to the second filtrate to adjust the pH to 11, then add 6g of ammonium phosphate. Stir at 200r / min for 45min at 30℃ to carry out the second precipitation reaction. After the reaction is completed, let it stand and then filter to obtain the third filtrate. The pH of the third filtrate was adjusted to 8, and then adsorbed through a strong base anion exchange resin. After the vanadium ions were completely adsorbed, the resin was washed, and finally, 2 mol / L ammonium chloride eluent was added to elute the resin. The volume ratio of the eluent to the strong base anion exchange resin was 2:1, and the vanadium-enriched solution was obtained.

[0045] The final vanadium-enriched solution contained the following components: V - 13.26 g / L, Fe - 0.0002 g / L, Mg - 0.0002 g / L, Al - 0.26 g / L, Ti - 0.0004 g / L, Si 0.33 g / L, Cr 0.007 g / L, and K 0.32 g / L. The removal rates were 99.33% for Fe, 99.14% for Mg, 98.87% for Al, and 99.89% for Ti. The vanadium recovery rate was 91.22%, and the vanadium loss was 0.6%.

[0046] Example 5 This embodiment provides a method for removing impurities from acidic vanadium-containing leachate, comprising the following steps: Add 20g of hydrogen peroxide to 1000ml of acidic vanadium-containing leaching solution, adjust the pH of the reaction system to 2, and carry out the oxidation reaction at 100℃ and 150r / min for 30min. After the reaction is completed, let it stand for 30min, and then filter to obtain the first filtrate. Add ammonia to the first filtrate to adjust the pH to 3, then add 24g of oxalic acid. Stir at 150r / min for 30min at 80℃ to carry out the first precipitation reaction. After the reaction is complete, let it stand and then filter to obtain the second filtrate. Add sodium hydroxide to the second filtrate to adjust the pH to 11, then add 10g of ammonium phosphate. Stir at 200r / min for 30min at 25℃ to carry out the second precipitation reaction. After the reaction is completed, let it stand and then filter to obtain the third filtrate. The pH of the third filtrate was adjusted to 9, and then adsorbed through a strong base anion exchange resin. After the vanadium ions were completely adsorbed, the resin was washed, and finally, 4 mol / L ammonium chloride eluent was added to elute the resin. The volume ratio of the eluent to the strong base anion exchange resin was 3:1, and the vanadium-enriched solution was obtained.

[0047] The final vanadium-enriched solution contained the following components: V - 12.32 g / L, Fe - 0.0008 g / L, Mg - 0.0004 g / L, Al - 0.07 g / L, Ti - 0.0008 g / L, Si 0.52 g / L, Cr 0.009 g / L, and K 0.81 g / L. The removal rates were 99.08% for Fe, 98.03% for Mg, 98.16% for Al, and 99.56% for Ti. The vanadium recovery rate was 88.54%, and the vanadium loss was 1.5%.

[0048] Comparative Example 1 This comparative example provides a method for removing impurities from an acidic vanadium-containing leaching solution, comprising the following steps: The vanadium-containing acid leaching solution was subjected to ion exchange with the resin at a flow rate of 1 bv / h, and samples were taken for analysis during the process. The process was stopped when the concentration of the vanadium mother liquor flowing out of the lower end of the ion exchange column containing the resin changed very little from the concentration of the vanadium flowing in from the upper end. The resin in the exchange column was repeatedly rinsed with water until the vanadium concentration in the outflowing water dropped below 0.1 g / L, at which point the rinsing was stopped. The resin in the ion exchange column was then eluent with an 8% sodium hydroxide solution at a rate of 2 bv / h. The eluent was collected, and the vanadium concentration was measured. Eluent was stopped when the vanadium concentration was less than 0.1 g / L. The exchange resin was then rinsed with distilled water until neutral.

[0049] The final vanadium-enriched solution had a vanadium ion concentration of <1 g / L.

[0050] Based on the above experimental results, it can be seen that the impurity removal method for acidic vanadium-containing leachate proposed in this invention achieves efficient removal of various impurity ions such as Fe, Mg, Al, and Ti through the synergistic effect of chemical precipitation and ion exchange, and significantly improves the vanadium recovery rate while reducing the vanadium loss rate. Firstly, regarding the impurity removal effect, in Examples 1 to 5, the Fe removal rate reached over 99%, the Mg removal rate was over 98%, the Al removal rate was generally over 98%, and the Ti removal rate generally exceeded 99.5%. In contrast, Comparative Example 1 only used the traditional ion exchange method without introducing a chemical precipitation pretreatment step, resulting in a vanadium ion concentration in the final vanadium-enriched solution being below 1 g / L, indicating that impurities were not effectively removed, thus severely interfering with the selective adsorption of vanadium by the resin.

[0051] Secondly, regarding the purification of vanadium ions, the vanadium recovery rates in Examples 1 to 5 were all between 88.54% and 93.51%, and the vanadium loss rate was controlled below 1.5%. Example 2, in particular, achieved a vanadium recovery rate of 93.51% with a loss rate of only 0.3%, demonstrating excellent vanadium enrichment performance. This is attributed to the fact that the present invention effectively reduces the concentration of interfering ions through a two-step precipitation reaction before ion exchange, thereby improving the resin's selectivity and adsorption efficiency for vanadium. In contrast, Comparative Example 1, due to the lack of a precipitation pretreatment step, resulted in extremely low resin adsorption efficiency and a very low final vanadium concentration, indicating that traditional methods are difficult to achieve efficient enrichment in complex systems.

[0052] Furthermore, the reagents used in this invention are all common and environmentally friendly, conforming to the principles of green chemistry. Simultaneously, the generated wastewater is primarily acidic or alkaline, which can be recycled through neutralization and precipitation, demonstrating excellent environmental friendliness and resource recovery potential. The recyclable characteristics of the filter residue in the embodiments further illustrate that this process has good overall economic benefits and promising industrialization prospects.

[0053] In summary, this invention, through a technical approach combining chemical precipitation and ion exchange, not only achieves synergistic high efficiency in impurity removal and high recovery rate, but also considers environmental friendliness and industrial feasibility, significantly outperforming traditional single ion exchange methods. It realizes the technical advantages of a short process flow, low reagent cost, good impurity removal effect, and high vanadium recovery rate, possessing good promotional value and application prospects.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for removing impurities from an acidic vanadium-containing leachate, characterized in that, The process includes the following steps: adding an oxidant to an acidic vanadium-containing leaching solution, adjusting the pH of the reaction system to 1-2, stirring to carry out the oxidation reaction, allowing the solution to stand after the reaction is complete, and then filtering to obtain the first filtrate. Add alkali solution to the first filtrate to adjust the pH to 2-3, then add precipitant, stir to carry out the first precipitation reaction, let stand after the reaction is completed, and then filter to obtain the second filtrate; Add alkali solution to the second filtrate to adjust the pH to 11-12, then add ammonium phosphate, stir to carry out the second precipitation reaction, let stand after the reaction is completed, and then filter to obtain the third filtrate. The pH of the third filtrate is adjusted to 7-9, and then adsorbed through a strongly basic anion exchange resin. After the vanadium ions are completely adsorbed, the resin is washed, and finally an eluent is added to elute the resin, thus obtaining a vanadium-enriched solution.

2. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The impurity element content in the acidic vanadium-containing leachate is as follows: Fe 8-16 g / L, Al 12-20 g / L, Mg 2-7 g / L, Ti 4-12 g / L, Si 1-4 g / L, K≤2 g / L, Na≤2 g / L, and Cr≤0.5 g / L.

3. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The oxidant is at least one of hydrogen peroxide, sodium chlorate, sodium hypochlorite, and persulfate.

4. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 90-120℃, for a reaction time of 30-60 min, and with a stirring speed of 60-180 r / min.

5. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The alkaline solution is at least one of sodium hydroxide and ammonia water.

6. The method for removing impurities from an acidic vanadium-containing leachate according to claim 1, characterized in that, The precipitant is at least one of oxalic acid and oxalate, and the concentration of the precipitant is 5%-15%.

7. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The temperature of the first precipitation reaction is 20-80℃, the reaction time is 20-60 min, and the stirring speed is 80-200 r / min.

8. The method for removing impurities from an acidic vanadium-containing leachate according to claim 1, characterized in that, The temperature of the second precipitation reaction is 25-50℃, the reaction time is 30-60 min, and the stirring speed is 200-300 r / min.

9. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The eluent is at least one of sodium chloride, ammonium chloride, and sodium hydroxide, the concentration of the eluent is 2-4 mol / L, and the volume ratio of the eluent to the strongly basic anion exchange resin is (2-3):

1.

10. The method for removing impurities from an acidic vanadium-containing leaching solution according to claim 1, characterized in that, The vanadium-enriched solution contains the following components: V 12-14 g / L, Si≤0.4 g / L, Al≤0.05 g / L, Fe≤0.001 g / L, Mg≤0.01 g / L, Cr≤0.01 g / L, Ti≤0.01 g / L, and K≤0.6 g / L.