A method for clean production of high-purity V2O5

Abstract

The present invention provides a method for clean production of high-purity V2O5, comprising the following steps: step 1, extracting a crude tetravalent vanadium solution containing impurities with a dilute extractant to obtain a loaded organic phase; step 2, stripping the loaded organic phase with a dilute acid stripping agent to obtain a stripping solution; step 3, electrolytically oxidizing the stripping solution to obtain a pentavalent vanadium solution at the anode; step 4, high-temperature precipitation of vanadium from the pentavalent vanadium solution, condensing and recovering the high-temperature steam of the high-temperature precipitation, filtering the precipitation slurry to obtain a hydrated vanadium pentoxide solid and a dilute acid; step 5, drying the hydrated vanadium pentoxide solid, and calcining at a high temperature to obtain vanadium pentoxide. The present invention uses a crude tetravalent vanadium solution containing impurities as a raw material, and prepares a V2O5 product with a purity of more than 99.95% by a method that does not pollute the environment.

Description

Technical Field

[0001] The invention relates to material technology, and in particular to a method for cleanly producing high-purity V2O5. Background Art

[0002] High-purity V2O5 means that the content of various impurities is lower than the ppm level, the total content of vanadium pentoxide is higher than 99.9%, and the content of pentavalent vanadium accounts for more than 99.9% of the total vanadium content.

[0003] The general method of producing vanadium pentoxide in the vanadium industry is through the ammonium salt precipitation method. First, obtain the precipitation of ammonium polyvanadate or ammonium metavanadate, separate the impurities, and then calcine the ammonium polyvanadate or ammonium metavanadate into V2O5. In order to obtain a higher purity, it is usually necessary to repeatedly add alkali to dissolve the ammonium vanadate and then add ammonium salt to precipitate. The problem with this method is that the operation is cumbersome and costly, the ammonium salt wastewater has a high environmental pressure, and ultimately produces a lot of sodium sulfate, which cannot be treated.

[0004] The extraction process of vanadium is to extract vanadium from water using an organic phase, and then strip it to obtain a vanadium salt with a higher purity. Use an alkaline extractant, such as N263 methyltrialkylammonium chloride, to extract pentavalent vanadium, and use sodium hydroxide to strip it to obtain a sodium vanadate solution, which is further precipitated with ammonium vanadate and calcined to obtain vanadium pentoxide. Compared with the traditional process, the pentavalent vanadium extraction process cannot completely get rid of the dependence on the ammonium salt vanadium precipitation process, and the cost reduction is limited. Summary of the invention

[0005] The purpose of the present invention is to propose a method for cleanly producing high-purity V2O5, which is environmentally friendly and can effectively reduce costs, in view of the problems of environmental pollution and high cost in traditional V2O5 production methods.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a method for clean production of high-purity V2O5, comprising the following steps:

[0007] Step 1: extracting the crude tetravalent vanadium solution containing impurities with a dilute extractant to obtain a loaded organic phase;

[0008] Step 2: stripping the loaded organic phase with a dilute acid stripping agent to obtain a stripping solution (the stripping solution includes vanadyl sulfate and sulfuric acid, or vanadyl dichloride and hydrochloric acid);

[0009] Step 3: electrolytically oxidizing the stripping solution to obtain a pentavalent vanadium solution at the anode;

[0010] Step 4: subjecting the pentavalent vanadium solution to high-temperature vanadium precipitation, condensing and recovering the high-temperature steam of the high-temperature vanadium precipitation, and filtering the vanadium precipitation slurry to obtain hydrated vanadium pentoxide solid and dilute acid;

[0011] Step 5: Drying the hydrated vanadium pentoxide solid and calcining at high temperature to obtain vanadium pentoxide.

[0012] Furthermore, the crude tetravalent vanadium solution containing impurities includes one or more of vanadyl sulfate, vanadyl dichloride, vanadyl oxalate and vanadyl citrate.

[0013] Furthermore, in the crude tetravalent vanadium solution in step 1, V=0.1-5.0 mol / L, preferably 0.5-3.0 mol / L.

[0014] Further, the crude tetravalent vanadium solution in step 1 contains SO4 2- =0~8.0mol / L, and / or Cl - =0~8.5mol / L, and / or P=0~0.5mol / L.

[0015] Further, in step 1, other impurity elements in the tetravalent vanadium solution satisfy Na>50mg / L, and / or K>50mg / L, and / or Fe>50mg / L, and / or Mg>50mg / L, and / or Ca>50mg / L, and / or Cr>50mg / L, and / or Mn>50mg / L, and / or Mo>50mg / L, and / or Co>50mg / L, and / or Ni>50mg / L, and / or Al>50mg / L, and / or Si>50mg / L. Further, in step 1, the dilution extractant comprises an extractant and a diluent, the extractant is one or more of P204, P507, Cyanex272, TOPO, TBP, TEBP and sec-octanol, the diluent is kerosene, and the mass ratio of the extractant to the diluent is 5:95 to 50:50, preferably 20:60 to 50:50.

[0016] Furthermore, the volume ratio of the diluted extractant in step 1 to the crude tetravalent vanadium solution containing impurities is 1:5 to 5:1, preferably 1:2 to 3:1.

[0017] Furthermore, the dilute acid stripping agent in step 2 is dilute sulfuric acid or dilute hydrochloric acid, and the volume ratio of the dilute acid stripping agent to the loaded organic phase is 1:15 to 3:1. When the dilute acid stripping agent is dilute sulfuric acid, the stripping solution includes vanadyl sulfate and sulfuric acid; when the dilute acid stripping agent is dilute hydrochloric acid, the stripping solution includes vanadyl dichloride and hydrochloric acid;

[0018] Furthermore, the concentration of the dilute sulfuric acid is 0.1 to 5 mol / L, preferably 0.3 to 3 mol / L, and the concentration of the dilute hydrochloric acid is 0.5 to 10 mol / L, preferably 1.0 to 8.5 mol / L.

[0019] Furthermore, in step 3, the stripping solution is placed in the positive electrode of the vanadium battery, and the negative electrode solution uses a solution with the same vanadium concentration and acid concentration (sulfate concentration or chloride ion concentration) as the stripping solution, and is charged and electrolyzed. At the positive electrode, vanadium is oxidized to pentavalent vanadium, and at the negative electrode, vanadium is reduced to divalent vanadium. After the electrolysis is completed, the positive electrode liquid (pentavalent vanadium solution) is transferred out and entered into step 4.

[0020] Furthermore, the negative electrode solution is recovered by introducing air into the negative electrode solution after electrolysis in step 3 to oxidize the divalent vanadium to trivalent vanadium, and the oxidized negative electrode solution is returned to step 3 as the negative electrode solution.

[0021] Furthermore, the electrolytic oxidation condition in step 3 is a current density of 20 to 500 mA / cm 2 , preferably 100 to 300 mA / cm 2 , constant current electrolysis to 1.55V, then constant voltage electrolysis to 50mA / cm 2 After electrolytic oxidation, the vanadium valence state in the positive electrode solution is pentavalent.

[0022] Furthermore, the temperature of high temperature vanadium precipitation in step 4 is 60-110°C, preferably 90-105°C.

[0023] Furthermore, the dilute acid (dilute sulfuric acid or dilute hydrochloric acid) in step 4 is returned to step 2 as a dilute acid stripping agent, and the dilute acid circulates in the system without being consumed.

[0024] Furthermore, the drying temperature in step 5 is 50-300°C, preferably 90-200°C.

[0025] Furthermore, in step 5, the calcination temperature is 200 to 650° C., preferably 400 to 550° C., and the calcination time is 0.5 to 5 h, preferably 1 to 3 h.

[0026] The working principle of the method for clean production of high-purity V2O5 of the present invention;

[0027] Taking dilute sulfuric acid as the stripping agent as an example, the reaction of the electrolysis process is as follows:

[0028] positive electrode

[0029] 2VOSO4+2H2O=(VO2)2SO4+H2SO4+2e+2H +

[0030] negative electrode

[0031] 2VOSO4+2e+2H + +H2SO4=V2(SO4)3+2H2O

[0032] VOSO4+2e+2H + =VSO4+2H2O

[0033] The reaction of high temperature precipitation of vanadium (precipitation of red vanadium) from pentavalent vanadium solution is as follows:

[0034] 6(VO2)2SO4+7H2O=6V2O5·H2O+6H2SO4

[0035] Taking dilute hydrochloric acid as the stripping agent as an example, the reaction of the electrolysis process is as follows:

[0036] positive electrode

[0037] VOCl2+H2O=VO2Cl+HCl+e+H +

[0038] negative electrode

[0039] VOCl2+e+H + +HCl=VCl3+H2O

[0040] VOCl2+2e+2H + =VCl2+H2O

[0041] The reaction of high temperature precipitation of vanadium (precipitation of red vanadium) from pentavalent vanadium solution is as follows:

[0042] 12VO2Cl+7H2O=6V2O5·H2O+12HCl

[0043] The method for cleanly producing high-purity V2O5 of the present invention has the following advantages compared with the prior art:

[0044] 1) The present invention uses crude tetravalent vanadium solution containing impurities as raw material. The raw material has a wide source and is easy to obtain. The content of impurity elements is relatively low and is almost not limited by impurity elements.

[0045] 2) The purity of the V2O5 product prepared by extraction and stripping in the present invention is as high as 99.95% or more, for example, the elements such as silicon, sodium, potassium, etc. are reduced to less than 10 ppm.

[0046] 3) Compared with the traditional process, the present invention completely avoids the ammonium salt vanadium precipitation process, does not use sodium hydroxide, has low cost, and does not produce sodium sulfate, thus achieving harmlessness and reduction in the production process, which is of great significance for sustainable development and environmental protection.

[0047] 4) The dilute sulfuric acid or dilute hydrochloric acid used in the present invention can be recycled in the system without loss, thus saving production costs and meeting my country's goal of developing a circular economy and energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Flow chart of the method for clean production of high-purity V2O5. DETAILED DESCRIPTION

[0049] The present invention is further described below in conjunction with embodiments:

[0050] Example 1

[0051] This embodiment discloses a method for clean production of high-purity V2O5, the process of which is as follows: Figure 1 As shown, the following steps are included:

[0052] In embodiment 1 of the present invention:

[0053] The crude tetravalent vanadium solution is a crude vanadyl sulfate solution, V = 0.7 mol / L, SO4 2- =1.5mol / L, and its impurity content is shown in Table 1.

[0054] Table 1

[0055]

[0056] Step 1: using P204 [di(2-ethylhexyl) phosphate] as an extractant and sulfonated kerosene as a diluent, the extractant and the diluent are mixed in a ratio of 30:70 as a diluent extractant, and a four-stage countercurrent extraction is performed in a volume ratio of the diluent extractant to the crude vanadium sulfate solution of 1.5:1 to extract tetravalent vanadium from the crude vanadium sulfate solution to obtain a loaded organic phase;

[0057] Step 2: Using 2 mol / L sulfuric acid as a stripping agent, three-stage countercurrent stripping is performed in a volume ratio of 1:5 between the volume of 2 mol / L sulfuric acid and the volume of the organic phase to obtain a mixed solution of 1 mol / L vanadyl sulfate and 1 mol / L sulfuric acid;

[0058] Step 3: Place the mixed solution into the positive electrode of the vanadium battery, and use a solution with the same vanadium concentration and sulfate concentration at the negative electrode. 2 , constant current electrolysis to 1.55V, then constant voltage electrolysis to 50mA / cm 2 Perform charging electrolysis, after electrolytic oxidation, the positive electrode vanadium is oxidized to pentavalent, and the negative electrode vanadium is reduced to trivalent; the positive electrode liquid is transferred out and enters step 4, the negative electrode solution continues to circulate electrolysis, and the vanadium is reduced to divalent in the next electrolysis, and enters step 6;

[0059] Step 4: heating the cathode solution to boiling, condensing and recovering the high-temperature steam to obtain a hydrated vanadium pentoxide precipitate, and filtering the precipitated vanadium pentoxide solid and dilute sulfuric acid;

[0060] Step 5: Dry the hydrated vanadium pentoxide at 105°C, and calcine at 500°C for 1.5h to obtain vanadium pentoxide powder; return the dilute sulfuric acid to step 1 for stripping;

[0061] Step 6: Negative electrode recovery: air is introduced into the negative electrode solution after electrolysis to oxidize the divalent vanadium to trivalent vanadium, and then the solution returns to step 3 to be used as the negative electrode in the electrolysis process.

[0062] The high-purity V2O5 prepared in this embodiment has a V2O5 content of 99.96%, wherein K=0.0001%, Na=0.0003%, Si=0.0003%, and Fe=0.0005%.

[0063] Example 2

[0064] This embodiment discloses a method for clean production of high-purity V2O5, the process of which is as follows: Figure 1 As shown, the following steps are included:

[0065] In Embodiment 2 of the present invention:

[0066] The crude tetravalent vanadium solution is a crude dichlorovanadium solution, V = 1.0 mol / L, Cl - =3.5mol / L, and its impurity content is shown in Table 1.

[0067] Table 1

[0068]

[0069] Step 1: P507 [2-ethylhexyl phosphate mono-2-ethylhexyl ester] is used as an extractant and sulfonated kerosene is used as a diluent. The extractant and the diluent are mixed in a ratio of 40:60 as a diluent extractant. A four-stage countercurrent extraction is performed in a volume ratio of the diluent extractant to the crude vanadyl sulfate solution of 1.5:1 to extract tetravalent vanadium from the crude vanadyl sulfate solution to obtain a loaded organic phase.

[0070] Step 2: using 1.5 mol / L sulfuric acid as a stripping agent, and performing four-stage countercurrent stripping according to a volume ratio of 1:3 between the amount of 1.5 mol / L sulfuric acid and the organic phase to obtain a mixed solution of 0.8 mol / L vanadyl sulfate and 0.7 mol / L sulfuric acid;

[0071] Step 3: Place the mixed solution into the positive electrode of the vanadium battery, and use a solution with the same vanadium concentration and sulfate concentration at the negative electrode. 2 , constant current electrolysis to 1.55V, then constant voltage electrolysis to 50mA / cm 2 Perform charging electrolysis, after electrolytic oxidation, the positive electrode vanadium is oxidized to pentavalent, and at the negative electrode, the vanadium is reduced to trivalent; the positive electrode liquid is transferred out and enters step 4, the negative electrode solution continues to circulate electrolysis, and the vanadium is reduced to divalent during the next electrolysis, and enters step 6;

[0072] Step 4: heating the cathode solution to boiling, condensing and recovering the high-temperature steam to obtain a hydrated vanadium pentoxide precipitate, and filtering the precipitated vanadium slurry to obtain a solid and dilute sulfuric acid;

[0073] Step 5: Dry the hydrated vanadium pentoxide at 120°C, and calcine at 400°C for 2h to obtain vanadium pentoxide powder; return the dilute sulfuric acid to step 1 for stripping;

[0074] Step 6: Negative electrode recovery: air is introduced into the negative electrode solution after electrolysis to oxidize the divalent vanadium to trivalent vanadium, and then the solution returns to step 3 to be used as the negative electrode in the electrolysis process.

[0075] The high-purity V2O5 prepared in this embodiment has a V2O5 content of 99.98%, wherein K=0.0002%, Na=0.0001%, Si=0.0001%, and Fe=0.0006%.

[0076] Example 3

[0077] This embodiment discloses a method for clean production of high-purity V2O5, the process of which is as follows: Figure 1 As shown, the following steps are included:

[0078] In Embodiment 3 of the present invention:

[0079] The crude tetravalent vanadium solution is a mixed solution of crude vanadium oxysulfate and vanadium oxychloride, V = 0.8 mol / L, SO4 2- =1.2mol / L, Cl - =0.6mol / L, and its impurity content is shown in Table 1.

[0080] Table 1

[0081]

[0082] Step 1: using TOPO [tri-n-octylphosphine oxide] as an extractant and sulfonated kerosene as a diluent, mixing the extractant and the diluent in a ratio of 50:50 as a diluent extractant, performing secondary countercurrent extraction in a volume ratio of the diluent extractant to the crude vanadyl sulfate solution of 1:1, extracting tetravalent vanadium from the crude vanadyl sulfate solution, and obtaining a loaded organic phase;

[0083] Step 2: using 4.0 mol / L hydrochloric acid as a stripping agent, and performing five-stage countercurrent stripping according to a volume ratio of 1:6 between the amount of 4.0 mol / L hydrochloric acid and the organic phase; obtaining a mixed solution of 1.8 mol / L vanadium oxychloride and 2.2 mol / L hydrochloric acid;

[0084] Step 3: Place the mixed solution into the positive electrode of the vanadium battery, and use a solution with the same vanadium concentration and sulfate concentration at the negative electrode. 2, constant current electrolysis to 1.55V, then constant voltage electrolysis to 50mA / cm 2 Perform charging electrolysis, after electrolytic oxidation, the positive electrode vanadium is oxidized to pentavalent, and at the negative electrode, the vanadium is reduced to trivalent; the positive electrode liquid is transferred out and enters step 4, the negative electrode solution continues to circulate electrolysis, and the vanadium is reduced to divalent during the next electrolysis, and enters step 6;

[0085] Step 4: heating the cathode solution to boiling, condensing and recovering the high-temperature steam to obtain a hydrated vanadium pentoxide precipitate, and filtering the precipitated vanadium slurry to obtain a solid and dilute hydrochloric acid;

[0086] Step 5: drying the hydrated vanadium pentoxide at 100° C. and calcining at 400° C. for 2 h to obtain vanadium pentoxide powder; the dilute hydrochloric acid is returned to step 1 for stripping;

[0087] Step 6: Negative electrode recovery: air is introduced into the negative electrode solution after electrolysis to oxidize the divalent vanadium to trivalent vanadium, and then the solution returns to step 3 to be used as the negative electrode in the electrolysis process.

[0088] The high-purity V2O5 prepared in this embodiment has a V2O5 content of 99.95%, wherein K=0.0005%, Na=0.0005%, Si=0.0006%, and Fe=0.0002%.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A clean method for producing high purity V 2 O 5 method, It is characterized in that The following steps are involved: Step 1: extracting a crude tetravalent vanadium solution containing impurities with a dilute extractant to obtain a loaded organic phase; the crude tetravalent vanadium solution containing impurities contains one or more of vanadyl sulfate, vanadyl dichloride, vanadyl oxalate and vanadyl citrate; Step 2: stripping the loaded organic phase with a dilute acid stripping agent to obtain a stripping solution; Step 3: electrolytically oxidizing the stripping solution to obtain a pentavalent vanadium solution at the anode; The stripping solution is placed in the positive electrode of the vanadium battery, and the negative electrode solution uses a solution with the same vanadium concentration and acid concentration as the stripping solution, and is charged and electrolyzed. At the positive electrode, the vanadium is oxidized to pentavalent vanadium, and at the negative electrode, the vanadium is reduced to divalent vanadium; air is introduced into the negative electrode solution after electrolysis to oxidize the divalent vanadium to trivalent vanadium, and the oxidized negative electrode solution is returned to step 3 as the negative electrode solution; The conditions for electrolytic oxidation are a current density of 20~500mA / cm 2 , constant current electrolysis to 1.55V, then constant voltage electrolysis to 50mA / cm 2 , after electrolytic oxidation, the vanadium valence state of the cathode solution is pentavalent; Step 4: subjecting the pentavalent vanadium solution to high-temperature vanadium precipitation, condensing and recovering the high-temperature steam of the high-temperature vanadium precipitation, and filtering the vanadium precipitation slurry to obtain hydrated vanadium pentoxide solid and dilute acid; Step 5: Dry the hydrated vanadium pentoxide solid, and calcine at high temperature to obtain vanadium pentoxide, V 2 O 5 The product purity is over 99.95%.

2. The method for cleanly producing high-purity V according to claim 1 2 O 5 method, It is characterized in that The diluted extractant in step 1 includes an extractant and a diluent, the extractant is one or more of P204, P507, Cyanex272, TOPO, TBP, TEBP and 2-octanol, the diluent is kerosene, and the mass ratio of the extractant to the diluent is 5:95~50:

50.

3. The method for cleanly producing high-purity V according to claim 1 2 O 5 method, It is characterized in that The dilute acid stripping agent in step 2 is dilute sulfuric acid or dilute hydrochloric acid, and the volume ratio of the dilute acid stripping agent to the loaded organic phase is 1:15~3:1; the concentration of the dilute sulfuric acid is 0.1~5mol / L, and the concentration of the dilute hydrochloric acid is 0.5~10mol / L.

4. The method for cleanly producing high-purity V according to claim 1 2 O 5 method, It is characterized in that Step 4: The high temperature vanadium precipitation temperature is 60-110°C.

5. The method for cleanly producing high-purity V according to claim 1 2 O 5 method, It is characterized in that In step 5, the calcination temperature is 200-650° C. and the calcination time is 0.5-5 h.

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