Method for preparing vanadium pentoxide and vanadium pentoxide

Abstract

The invention discloses a method for preparing vanadium pentoxide from sodium-modified vanadium and chromium leachate and vanadium pentoxide. The method comprises the following steps: adjusting the pH value of the sodium-modified vanadium and chromium leachate until the sodium-modified vanadium and chromium leachate is weakly alkaline; aluminum salt is added into the sodium-modified vanadium and chromium leaching solution so as to carry out silicon removal treatment, and the adding amount of the aluminum salt is determined according to the silicon content in the sodium-modified vanadium and chromium leaching solution; determining the adding amount of a reducing agent according to the chromium content in the first filtrate obtained after silicon removal treatment so as to carry out primary chromium removal treatment; iron salt is added into the second filtrate obtained after primary chromium removal treatment, secondary chromium removal treatment is carried out, and the adding amount of the iron salt is determined according to the chromium content in the second filtrate; and preparing vanadium pentoxide by using the third filtrate obtained after the secondary chromium removal treatment. The method for preparing high-purity vanadium pentoxide through impurity removal of the sodium vanadium chromium leaching solution has the advantages of being high in production efficiency, high in vanadium recovery rate, low in impurity removal cost, short in technological process, high in operability, small in environmental pollution, high in impurity removal efficiency and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vanadium pentoxide, and particularly relates to a method for preparing vanadium pentoxide from sodium vanadium chromium leaching solution and vanadium pentoxide. BACKGROUND

[0002] Currently, the main impurities in the sodium vanadium chromium leaching solution are Si and Cr, and the impurities are usually removed by solvent extraction, chemical precipitation, ion exchange, and static precipitation. The production cost of high-purity vanadium pentoxide is high. Because the production of vanadium pentoxide requires multiple precipitation-dissolution processes, the existing process for preparing high-purity vanadium pentoxide from sodium vanadium chromium leaching solution has the problems of long process flow and high production cost. In addition, the long production process is prone to introduce impurities, and has the defects of high consumption of auxiliary materials, high consumption of energy and power, and large amount of wastewater. SUMMARY

[0003] In view of this, in order to overcome at least one aspect of the above problems, the present application provides a method for preparing vanadium pentoxide from sodium vanadium chromium leaching solution, which comprises the following steps: adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkalinity; adding aluminum salt to the sodium vanadium chromium leaching solution to remove silicon, wherein the amount of aluminum salt added is determined according to the silicon content in the sodium vanadium chromium leaching solution; determining the amount of reducing agent added according to the chromium content in the first filtrate obtained after the silicon removal treatment to perform primary chromium removal treatment; adding iron salt to the second filtrate obtained after the primary chromium removal treatment to perform secondary chromium removal treatment, wherein the amount of iron salt added is determined according to the chromium content in the second filtrate; using the third filtrate obtained after the secondary chromium removal treatment to prepare vanadium pentoxide.

[0004] In some embodiments, adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkalinity further comprises: adding sulfuric acid under stirring to reduce the pH value of the sodium vanadium chromium leaching solution to 8-9.

[0005] In some embodiments, the amount of aluminum salt added to remove silicon is determined according to the silicon content in the sodium vanadium chromium leaching solution, and the method further comprises: determining the amount of aluminum salt added according to the stoichiometric ratio of aluminum in the aluminum salt to silicon in the sodium vanadium chromium leaching solution being 0.6-1.2:1.

[0006] In some embodiments, the method for preparing vanadium pentoxide from sodium vanadium chromium leaching solution further comprises: stirring at 60-70℃ for 1-2h, then standing, and then settling, filtering the first filtrate after 16-36h.

[0007] In some embodiments, the chromium content in the first filtrate obtained after the silicon removal treatment determines the amount of reducing agent to be added, further comprising: The amount of reducing agent to be added is determined according to a stoichiometric ratio of the reducing agent to the chromium in the first filtrate being 1.5-3.5:1.

[0008] In some embodiments, the method for preparing vanadium pentoxide from sodium vanadium-chromium leaching solution further comprises: After stirring for 1-3 hours at a temperature of 50-70°C, the solution is allowed to stand, and after 18-36 hours, the second filtrate is obtained by sedimentation and filtration.

[0009] In some embodiments, the reducing agent is one of sodium pyrosulfite, sodium sulfide, hydrogen sulfide, sodium thiosulfate, and sodium sulfite.

[0010] In some embodiments, the chromium content in the second filtrate determines the amount of iron salt to be added, further comprising: The amount of iron salt to be added is determined according to a stoichiometric ratio of iron in the iron salt to the chromium in the second filtrate being 5-15:1.

[0011] In some embodiments, the method for preparing vanadium pentoxide from sodium vanadium-chromium leaching solution further comprises: After stirring for 1-3 hours at a temperature of 50-80°C, the solution is allowed to stand, and after 18-36 hours, the third filtrate is obtained by sedimentation and filtration.

[0012] Based on the same inventive concept, according to another aspect of the present application, embodiments of the present application also provide a vanadium pentoxide prepared by the method of any one of the above-mentioned embodiments.

[0013] The present application has one of the following beneficial technical effects: the method for preparing high-purity vanadium pentoxide from sodium vanadium-chromium leaching solution provided by the present application has the characteristics of high production efficiency, high vanadium recovery rate, low impurity removal cost, short process flow, strong operability, small environmental pollution, and high impurity removal efficiency, overcomes the problems of long process flow and high production cost in the existing preparation of high-purity vanadium pentoxide from sodium vanadium-chromium leaching solution, and overcomes the defects of long production flow, easy introduction of impurities in the production process, high consumption of auxiliary materials, high energy consumption, and large amount of wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other embodiments according to these drawings without creating any inventive labor.

[0015] Figure 1 A flowchart of a method for preparing vanadium pentoxide from a sodium vanadium chromium leaching solution is provided for an embodiment of the present application. Figure 2 A flowchart of a method for preparing vanadium pentoxide from a sodium vanadium chromium leaching solution is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the present application clearer, further detailed descriptions of embodiments of the present application are provided below with reference to the accompanying drawings.

[0017] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two same-named different entities or different parameters, and "first" and "second" are only used for the convenience of description and should not be understood as a limitation on the embodiments of the present application. Subsequent embodiments will not be described one by one.

[0018] According to one aspect of the present application, an embodiment of the present application proposes a method for preparing vanadium pentoxide from a sodium vanadium chromium leaching solution, as shown in Figure 1 which can include the following steps: S1, adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkalinity; S2, determining the amount of the reducing agent added according to the chromium content in the first filtrate obtained after the silicon removal treatment to perform a first chromium removal treatment; S3, determining the amount of the reducing agent added according to the chromium content in the first filtrate obtained after the silicon removal treatment to perform a first chromium removal treatment; S4, adding an iron salt to the second filtrate obtained after the first chromium removal treatment to perform a second chromium removal treatment, wherein the amount of the iron salt added is determined according to the chromium content in the second filtrate; S5, preparing vanadium pentoxide by using the third filtrate obtained after the second chromium removal treatment.

[0019] The method for preparing high-purity vanadium pentoxide by impurity removal from a sodium vanadium chromium leaching solution provided by the present application has the characteristics of high production efficiency, high vanadium recovery rate, low impurity removal cost, short process flow, strong operability, small environmental pollution, and high impurity removal efficiency, overcomes the problems of long process flow and high production cost in the existing preparation of high-purity vanadium pentoxide from a sodium vanadium chromium leaching solution, and overcomes the defects of long production flow, easy introduction of impurities in the production process, high consumption of auxiliary materials, high energy consumption, and large amount of wastewater.

[0020] In some embodiments, adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkalinity further includes: adding sulfuric acid under stirring to reduce the pH value of the sodium vanadium chromium leaching solution to between 8 and 9.

[0021] In some embodiments, the amount of aluminum salt added for silicon removal is determined according to the silicon content in the sodium vanadium-chromium leaching solution, further comprising: The amount of aluminum salt added is determined according to the stoichiometric ratio of aluminum in the aluminum salt to silicon in the sodium vanadium-chromium leaching solution being 0.6-1.2:1.

[0022] In some embodiments, the method for preparing vanadium pentoxide from the sodium vanadium-chromium leaching solution further comprises: After stirring for 1-2 hours at a temperature of 60-70°C, the solution is allowed to stand, and after 16-36 hours, the first filtrate is obtained by sedimentation and filtration.

[0023] Specifically, as shown in Figure 2 The pH of the vanadium-containing leaching solution is between 9.5 and 10.5, and a certain amount of sulfuric acid is added under stirring conditions to reduce the pH to between 8 and 9, thereby performing silicon removal under weakly alkaline conditions.

[0024] The Si content of the sodium vanadium-chromium leaching solution is then detected, and the amount of aluminum salt added is calculated according to the Si content. This results in a high silicon removal rate, large flocculent particles, fast sedimentation speed, high production efficiency, good purification effect, no introduction of Cl and organic matter pollution, simple equipment, low process requirements, high degree of conformity with industrial production, control of the silicon removal pH value, and the effect of aluminum-silicon co-removal, eliminating the risk of introducing impurities. Preferably, the aluminum salt is aluminum sulfate 18 water, and the stoichiometric ratio of aluminum salt to Si in the leaching solution is n(Al):n(Si)=0.6-1.2:1, the reaction temperature is 60-70°C, the reaction time under stirring conditions is 1-2 hours, and the standing time is 16-36 hours. In this process, the chemical reaction equation is: Al 3+ +HSiO3 - +H2O→Al(OH)3↓+H2SO3↓ Al 3+ +3HSiO3 - →Al(HSiO3)3↓ Al2(SO4)3·18H2O + 3Na2SiO3→ Al2(SiO3)3↓ + 3Na2SO4 + 18H2O Thus, based on the traditional aluminum salt silicon removal process, the pH value for silicon removal is controlled to be between 8 and 9, Al destroys the negative charge on the surface of polysilicic acid, neutralizes the negative ions on the surface of polysilicic acid, promotes the formation of polysilicic acid, improves the silicon removal rate, and the pH value between 8 and 9 is conducive to the hydrolysis of Al 3+ to Al(OH)3 precipitate, achieving the effect of aluminum-silicon co-removal.

[0025] In some embodiments, the amount of reducing agent added is determined according to the chromium content in the first filtrate obtained after silicon removal treatment, further comprising: The amount of the reducing agent is determined according to the stoichiometric ratio of the reducing agent to the chromium in the first filtrate being 1.5-3.5:1.

[0026] In some embodiments, the method for preparing vanadium pentoxide from the sodium vanadium chromium leaching solution further comprises: After stirring for 1-3 hours at a temperature of 50-70°C, the solution is allowed to stand, and after 18-36 hours, the second filtrate is obtained by sedimentation and filtration.

[0027] In some embodiments, the reducing agent is one of sodium pyrosulfite, sodium sulfide, hydrogen sulfide, sodium thiosulfate, and sodium sulfite.

[0028] Specifically, as shown in Figure 2 the silicon-removing solution is allowed to stand, settle, and be filtered, and the filtrate is subjected to a first chromium-removing treatment by adding a reducing agent (sodium pyrosulfite, sodium sulfide, hydrogen sulfide, sodium thiosulfate, sodium sulfite, etc.). Preferably, the reducing agent is sodium pyrosulfite (Na2S2O5), and the stoichiometric ratio of the reducing agent to the chromium in the first filtrate is (reducing agent):(Cr)=1.5-3.5:1, the reaction temperature is 50-70°C, the stirring condition reaction time is 1-3 hours, and the standing time is 18-36 hours. In this process, the chemical reaction equation is: 3Na2S2O5+4Na2CrO4+5H2O→5Na2SO4+4Cr(OH)3↓+4NaOH In this way, a certain amount of reducing agent is added to the silicon-removing sodium vanadium solution, the specific reduction of the reducing agent to hexavalent chromium is utilized, the separation is realized by the extremely weak alkalinity of the precipitation of trivalent chromium under weak alkaline conditions, and the pH value of the solution is controlled to be between 8 and 9. In the alkaline environment, CrO4 2- is relatively strong, VO3 - / HVO4 2- is relatively weak, and therefore SO3 2- preferentially reacts with hexavalent chromium, SO3 2- does not substantially react with pentavalent vanadium, and pentavalent vanadium remains in the solution, so that selective reduction of vanadium and chromium is realized, that is, hexavalent chromium is reduced to trivalent chromium, and pentavalent vanadium remains in the solution. Moreover, in the reaction process, a small amount of reduced tetravalent vanadium is oxidized to pentavalent vanadium by stirring and heating, thereby reducing the loss of vanadium.

[0029] In some embodiments, the amount of the iron salt is determined according to the chromium content in the second filtrate obtained after the first chromium-removing treatment, so as to perform a second chromium-removing treatment, and the method further comprises: The amount of the iron salt is determined according to the stoichiometric ratio of the iron in the iron salt to the chromium in the second filtrate being 5-15:1.

[0030] In some embodiments, the method for preparing vanadium pentoxide from sodium vanadium chromium leaching solution further includes: After stirring for 1 to 3 hours at a temperature of 50℃ to 80℃, the mixture is allowed to stand for 18 to 36 hours, and then settled and filtered to obtain the third filtrate.

[0031] Specifically, such as Figure 2 As shown, the chromium removal solution is allowed to settle and filtered to obtain a second filtrate. Iron salts (ferrous sulfate, ferric sulfate, ferric sulfide, ferrous sulfide, etc.) are added to the second filtrate for a secondary chromium removal treatment. Further addition of iron salts to the second filtrate neutralizes the negatively charged Cr(OH)₄ due to the positive charge on the Fe(OH)₃ surface. - Eliminate Cr 3+ Nucleation barriers are formed, allowing chromium to precipitate further, resulting in a clear, transparent alkaline solution with Fe, Si, Cr, and Al concentrations all less than 0.005 g / L. This solution can be used to prepare ammonium polyvanadate and ammonium metavanadate. Preferably, the stoichiometric ratio of the iron salt to Cr in the silicon removal solution is n(Fe):n(Cr) = 5-15:1. The reaction temperature is 50℃~80℃, the reaction time under stirring is 1~3 h, and the settling time is 18-36 h. The chemical reaction equation for this process is: Fe 3+ +3OH - →Fe(OH)3↓ Fe(OH)3↓+Cr(OH) 4- →[Fe(OH)3•Cr(OH)4]↓ This utilizes the property that iron ions hydrolyze to (FeOH3) under alkaline conditions, resulting in low concentrations of Cr. 3+ Hydrolysis produces soluble mononuclear complexes (such as Cr(OH)). 2+ Cr(OH)2 + ), and when Cr 3+ When the concentration is <0.05 g / L, the supersaturation is insufficient, and the spontaneous nucleation rate decreases. Adding Fe can address this. 3+ The positive charge on the Fe(OH)3 surface neutralizes the negative charge on the Cr(OH)3 surface. 4- This process eliminates nucleation barriers, allowing chromium to precipitate further. Furthermore, stirring and heating during the reaction oxidize a small amount of reduced tetravalent vanadium to pentavalent vanadium, reducing vanadium loss.

[0032] In some embodiments, such as Figure 2 As shown, after a second chromium removal process, a third filtrate is obtained. An alkaline ammonium salt is added to this solution to precipitate vanadium and obtain ammonium metavanadate (AMV). Finally, after drying and calcination, high-purity vanadium pentoxide is obtained.

[0033] Example 1 Take 1 L sodium leaching solution, vanadium concentration is 50.28 g / L, Si content is 1.574 g / L, Cr content is 3.56 g / L, pH value is 10.56; using sulfuric acid to adjust the solution pH to 8.0, heating to 60 DEG C, under stirring conditions, add 11.2 g (nAl:nSi=0.6) aluminum sulfate octadecahydrate, react 1 h, settle 24 h and filter, filtrate heating to 50 DEG C, under stirring conditions, add sodium pyrosulfite, the amount of addition is 4.34 g, namely n (Cr):n (S)=1.5, react 1 h, stand and settle 24 h, clear liquid heating to 50 DEG C, clear liquid chromium content is 0.034 g / L, add 0.65 g of ferric sulfate salt (according to n (Fe):n (Cr)=5), the Si, Cr, Al, Fe content in the solution is 0.005 g / L, 0.004 g / L, 0.004 g / L, 0.003 g / L respectively, the solution is used to obtain ammonium metavanadate (AMV) by using basic ammonium salt vanadium precipitation, high-purity vanadium pentoxide is obtained by drying and calcining, the Si, Cr, Al, Fe content in the product is 0.008%, 0.008%, 0.005%, 0.009% respectively.

[0034] Example 2 Take 1 L sodium leaching solution, vanadium concentration is 50.28 g / L, Si content is 1.574 g / L, Cr content is 3.56 g / L, pH value is 10.56; using sulfuric acid to adjust the solution pH to 8.5, heating to 60 DEG C, under stirring conditions, add 16.8 g (nAl:nSi=0.9) aluminum sulfate octadecahydrate, react 1 h, settle 24 h and filter, filtrate heating to 60 DEG C, under stirring conditions, add sodium pyrosulfite, the amount of addition is 2.62 g, namely n (Cr):n (S)=2.5, react 1 h, stand and settle 24 h, clear liquid heating to 65 DEG C, clear liquid chromium content is 0.034 g / L, add 1.3 g of ferric sulfate salt (according to n (Fe):n (Cr)=10), the Si, Cr, Al, Fe content in the solution is 0.004 g / L, 0.003 g / L, 0.004 g / L, 0.004 g / L respectively, the solution is used to obtain ammonium metavanadate (AMV) by using basic ammonium salt vanadium precipitation, high-purity vanadium pentoxide is obtained by drying and calcining, the Si, Cr, Al, Fe content in the product is 0.007%, 0.006%, 0.004%, 0.009% respectively.

[0035] Example 3 Take 1L sodium leaching solution, vanadium concentration is 50.28g / L, Si content is 1.574g / L, Cr content is 3.56g / L, pH value is 10.56; use sulfuric acid to adjust the solution pH value to 9, heat to 60℃, under stirring condition, add 22.4g (nAl:nSi=1.2) aluminum sulfate octadecahydrate, react for 1h, settle for 24h, filter, heat the filtrate to 70℃, under stirring condition, add sodium pyrosulfite, the adding amount is 1.87g, namely n(Cr):n(S)=3.5, react for 1h, stand for 24h, heat the clear liquid to 80℃, the clear liquid chromium content is 0.034g / L, add 1.96g of ferric sulfate salt (according to n(Fe):n(Cr)=15), the Si, Cr, Al, Fe content in the solution is 0.003g / L, 0.002g / L, 0.005g / L, 0.005g / L respectively, the solution is used to prepare ammonium metavanadate (AMV) by using alkali ammonium salt vanadium precipitation, high-purity vanadium pentoxide is obtained by drying and calcining, the Si, Cr, Al, Fe content in the product is 0.006%, 0.002%, 0.005%, 0.010% respectively.

[0036] Based on the same inventive concept, according to another aspect of the present application, the embodiments of the present application also provide a vanadium pentoxide, which is prepared by the steps of any one of the above embodiments.

[0037] The above is the exemplary embodiments disclosed by the present application, but it should be noted that various changes and modifications can be made without departing from the scope of the embodiments disclosed by the present application defined in the claims. The functions, steps and / or acts of the method claims described herein need not be performed in any particular order. Furthermore, although the elements of the embodiments disclosed by the present application can be described or claimed in individual forms, they can also be understood as plural unless explicitly limited to a single.

[0038] It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that "and / or" as used herein refers to any and all possible combinations of one or more of the associated listed items.

[0039] The above embodiment number of the embodiments disclosed by the present application is only for description, not representing the advantages and disadvantages of the embodiments.

[0040] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to mean that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples; under the idea of the embodiments of the present application, the above embodiments or technical features in different embodiments can also be combined, and there are many other changes of different aspects of the embodiments of the present application as above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made in the spirit and principle of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A method for preparing vanadium pentoxide from a sodium vanadium chromium leaching solution, characterized in that, The method comprises the following steps: adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkaline; adding aluminum salt into the sodium vanadium chromium leaching solution to remove silicon, wherein the amount of aluminum salt is determined according to the silicon content in the sodium vanadium chromium leaching solution; determining the amount of reducing agent according to the chromium content in the first filtrate obtained after the silicon removal treatment to perform primary chromium removal treatment; adding iron salt into the second filtrate obtained after the primary chromium removal treatment to perform secondary chromium removal treatment, wherein the amount of iron salt is determined according to the chromium content in the second filtrate; preparing vanadium pentoxide by using the third filtrate obtained after the secondary chromium removal treatment.

2. The method of claim 1, wherein, The method for adjusting the pH value of the sodium vanadium chromium leaching solution to weak alkaline further comprises the following steps: adding sulfuric acid under stirring to reduce the pH value of the sodium vanadium chromium leaching solution to 8-9.

3. The method of claim 1, wherein, The method for determining the amount of aluminum salt according to the silicon content in the sodium vanadium chromium leaching solution further comprises the following steps: determining the amount of aluminum salt according to the stoichiometric ratio of aluminum in the aluminum salt to silicon in the sodium vanadium chromium leaching solution being 0.6-1.2:

1.

4. The method of claim 3, wherein, The method further comprises the following steps: standing after stirring at 60-70℃ for 1-2h, and then settling and filtering after 16-36h to obtain the first filtrate.

5. The method of claim 1, wherein, The method for determining the amount of reducing agent according to the chromium content in the first filtrate obtained after the silicon removal treatment to perform primary chromium removal treatment further comprises the following steps: determining the amount of reducing agent according to the stoichiometric ratio of the reducing agent to chromium in the first filtrate being 1.5-3.5:

1.

6. The method of claim 5, wherein, The method further comprises the following steps: standing after stirring at 50-70℃ for 1-3h, and then settling and filtering after 18-36h to obtain the second filtrate.

7. The method of claim 5, wherein, The reducing agent is one of sodium pyrosulfite, sodium sulfide, hydrogen sulfide, sodium thiosulfate and sodium sulfite.

8. The method of claim 1, wherein, The method for determining the amount of iron salt according to the chromium content in the second filtrate further comprises the following steps: determining the amount of iron salt according to the stoichiometric ratio of iron in the iron salt to chromium in the second filtrate being 5-15:

1.

9. The method of claim 8, wherein, The method further comprises the following steps: standing after stirring at 50-80℃ for 1-3h, and then settling and filtering after 18-36h to obtain the third filtrate.

10. Vanadium pentoxide characterized in that, The vanadium pentoxide is prepared by using the method according to any one of claims 1-9.

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