SYSTEM FOR EXTRACTING VANADIUM FROM LEACHING SOLUTION CONTAINING VANADIUM CHROMIUM SILICON AND FOR PREPARING VANADIUM PENTOXIDE AND PROCESSING METHOD THEREFOR

Abstract

A system for extracting vanadium from a leaching solution containing vanadium chromium silicon and for preparing vanadium pentoxide, and a method therefor, the system comprising, in sequence: an impurity removal system, an extraction system, a reverse-extraction and vanadium precipitation system, a washing system and a calcining system. The method comprises the following steps: removing silicon in a leaching solution by using a silicon removal agent, extracting most of the vanadium to an organic phase by using centrifugal extraction, reverse-extracting the vanadium of a vanadium-rich organic phase by using a mixed solution containing a basic solution and an ammonium salt, and precipitating ammonium metavanadate to obtain an ammonium metavanadate solid, washing and drying, and then calcining at a certain temperature to obtain a low chromium, low silicon, low aluminum and high-purity vanadium pentoxide product.

Claims

1. A system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide, wherein it comprises an impurity removal system, an extraction system, a strip-extraction and vanadium precipitation system, a washing system and a calcination system in sequence.

2. The system according to claim 1, wherein the impurity removal system comprises a first filter, an impurity removal reaction kettle, an impurity removal liquid standing tank and a second filter which are connected in sequence, with a liquid outlet of the second filter being configured to connect with a feed inlet of the extraction system.

3. The system according to claim 1, wherein the extraction system comprises a centrifugal extractor, a raffinate storage tank and a vanadium-rich organic phase storage tank, with a raffinate outlet of the centrifugal extractor being connected with an inlet of the raffinate storage tank, an organic phase outlet of the centrifugal extractor being connected with an inlet of the vanadium-rich organic phase storage tank, and a discharge outlet of the vanadium-rich organic phase storage tank being configured to connect with a feed inlet of the strip-extraction and vanadium precipitation system.

4. The system according to claim 1, wherein the strip-extraction and vanadium precipitation system comprises a vanadium-rich organic phase washing tank, a strip-extraction and vanadium precipitation kettle and a strip-extracted aqueous phase-solid phase storage tank, with an organic phase outlet of the vanadium-rich organic phase washing tank being connected with an organic phase inlet of the strip-extraction and vanadium precipitation kettle, a liquid-solid mixed phase outlet of the strip-extraction and vanadium precipitation kettle being connected with an inlet of the strip-extracted aqueous phase-solid phase storage tank, and a solid outlet of the strip-extracted aqueous phase-solid phase storage tank being configured to connect with a feed inlet of the washing system.

5. The system according to claim 1, wherein the strip-extraction and vanadium precipitation system comprises an extracted organic phase washing tank, with an organic phase outlet of the strip-extraction and vanadium precipitation kettle being connected with an organic phase inlet of the extracted organic phase washing tank, a liquid outlet of the centrifuge being connected with an aqueous phase inlet of the extracted organic phase washing tank, and an aqueous phase outlet of the extracted organic phase washing tank being connected with an aqueous phase inlet of the vanadium-rich organic phase washing tank.

6. A method for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide, wherein it comprises the steps of: subjecting a vanadium-chromium-silicon-containing leaching solution to impurity removal treatment, extraction treatment, strip-extraction and vanadium precipitation treatment, washing, drying and calcination in sequence so that vanadium pentoxide is obtained.

7. The method according to claim 6, wherein the impurity removal treatment comprises the steps of: adding a desiliconization agent into a filtered leaching solution containing vanadium, chromium and silicon for desiliconization treatment, following the desiliconization treatment, adjusting the pH of the solution, allowing the solution to stand, and filtering again is filtered again so that a stock extract liquid after impurity removal is obtained.

8. The method according to claim 6, wherein the extraction treatment comprises the steps of: (1) adjusting the pH of the stock extract liquid after impurity removal treatment, and then a vanadium-rich organic phase and a raffinate are obtained through centrifugal extraction; (2) after the pH of the raffinate obtained in the step (1) is adjusted, adding a reducing agent for reduction and the pH is adjusted, filtration is conducted, and a solid hydrated chromium oxide is obtained.

9. The method according to claim 6, wherein the strip-extraction and vanadium precipitation treatment comprises the following steps: (a) the vanadium-rich organic phase obtained by the extraction treatment is subjected to strip-extraction and vanadium precipitation treatment by using a stripping agent, and an extracted organic phase and a solid-liquid mixture are obtained; (b) the solid-liquid mixture obtained in the step (a) is subjected to centrifugal separation so that ammonium metavanadate is obtained.

10. The method according to claim 6, wherein the washing is multiple washing with the washing times being 1.

11. The method according to claim 6, wherein the drying temperature is 60 C.-150 C.

12. The method according to claim 6, wherein the vanadium-chromium-silicon-containing leaching solution is any one or a combination of at least two selected from the group consisting of a vanadium-chromium-containing slag leaching solution, a vanadium-containing waste leaching solution, and a vanadium-containing plant wastewater.

13. The system according to claim 4, wherein the washing system comprises a washing liquid storage tank, an ammonium metavanadate washing tank and a centrifuge, with a liquid outlet of the washing liquid storage tank being connected with an aqueous phase inlet of the ammonium metavanadate washing tank, a discharge outlet of the ammonium metavanadate washing tank being connected with a feed inlet of the centrifuge, and a solid discharge outlet of the centrifuge being configured to connect with a feed inlet of the calcination system.

14. The system according to claim 1, wherein the calcination system comprises a drying oven and a calcination furnace which are connected in sequence.

15. The system according to claim 4, wherein the strip-extraction and vanadium precipitation system comprises an extracted organic phase washing tank, with an organic phase outlet of the strip-extraction and vanadium precipitation kettle being connected with an organic phase inlet of the extracted organic phase washing tank, a liquid outlet of the centrifuge being connected with an aqueous phase inlet of the extracted organic phase washing tank, and an aqueous phase outlet of the extracted organic phase washing tank being connected with an aqueous phase inlet of the vanadium-rich organic phase washing tank.

16. The system according to claim 3, wherein the centrifugal extractor is made of any one or a combination of at least two selected from the group consisting of stainless steel, organic glass, glass, and plastic.

17. The system according to claim 6, wherein the calcination furnace is any one or a combination of at least two selected from the group consisting of a fixed bed, a rotary hearth furnace, and a fluidized bed.

18. The method according to claim 11, wherein the desiliconization agent is an aluminum salt and/or a calcium salt.

19. The method according to claim 11, wherein following the desiliconization treatment, the pH of the solution is adjusted to 7-9.

20. The method according to claim 14, wherein in the step (1), the pH of the stock extract liquid after impurity removal treatment is adjusted to be acidic.

21. The method according to claim 14, wherein the centrifugal extraction in the step (1) is multistage centrifugal extraction having a stage number of 1; wherein during the multistage centrifugal extraction, the pH is adjusted before each extraction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0107] FIG. 1 is a schematic structural diagram of a system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide according to the present invention;

[0108] wherein,

[0109] 1 represents the first filter,

[0110] 2 represents impurity removal reaction kettle,

[0111] 3 represents impurity removal liquid standing tank,

[0112] 4 represents the second filter,

[0113] 5 represents centrifugal extractor,

[0114] 6 represents raffinate storage tank,

[0115] 7 represents vanadium-rich organic phase storage tank,

[0116] 8 represents vanadium-rich organic phase washing tank,

[0117] 9 represents strip-extraction and vanadium precipitation kettle,

[0118] 10 represents strip-extracted aqueous phase-solid phase storage tank,

[0119] 11 represents washing liquid storage tank,

[0120] 12 represents ammonium metavanadate washing tank,

[0121] 13 represents centrifuge,

[0122] 14 represents drying oven,

[0123] 15 represents calcination furnace,

[0124] 16 represents extracted organic phase washing tank.

DETAILED DESCRIPTION

[0125] In order to better illustrate the present invention and to facilitate understanding of the technical solutions of the present invention, the present invention will be further described in detail below. However, the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention, and the scope of the present invention is defined by the claims.

[0126] As shown in FIG. 1, the embodiment part of the present invention provides a system for extracting vanadium from a leaching solution containing vanadium, chromium and silicon and preparing vanadium pentoxide, the system comprises an impurity removal system, an extraction system, a strip-extraction and vanadium precipitation system, a washing system and a calcination system in sequence.

[0127] The impurity removal system comprises a first filter 1, an impurity removal reaction kettle 2, an impurity removal liquid standing tank 3 and a second filter 4 which are connected in sequence, with a liquid outlet of the second filter 4 being configured to connect with a feed inlet of the extraction system.

[0128] The extraction system comprises a centrifugal extractor 5, a raffinate storage tank 6 and a vanadium-rich organic phase storage tank 7, with a raffinate outlet of the centrifugal extractor 5 being connected with an inlet of the raffinate storage tank 6, an organic phase outlet of the centrifugal extractor 5 being connected with an inlet of the vanadium-rich organic phase storage tank 7, and a discharge outlet of the vanadium-rich organic phase storage tank 7 being configured to connect with a feed inlet of the strip-extraction and vanadium precipitation system.

[0129] The strip-extraction and vanadium precipitation system comprises a vanadium-rich organic phase washing tank 8, a strip-extraction and vanadium precipitation kettle 9 and a strip-extracted aqueous phase-solid phase storage tank 10, with an organic phase outlet of the vanadium-rich organic phase washing tank 8 being connected with an organic phase inlet of the strip-extraction and vanadium precipitation kettle 9, a liquid-solid mixed phase outlet of the strip-extraction and vanadium precipitation kettle 9 being connected with an inlet of the strip-extracted aqueous phase-solid phase storage tank 10, and a solid outlet of the strip-extracted aqueous phase-solid phase storage tank 10 being configured to connect with a feed inlet of the washing system.

[0130] The washing system comprises a washing liquid storage tank 11, an ammonium metavanadate washing tank 12 and a centrifuge 13, with a liquid outlet of the washing liquid storage tank 11 being connected with an aqueous phase inlet of the ammonium metavanadate washing tank 12, a discharge outlet of the ammonium metavanadate washing tank 12 being connected with a feed inlet of the centrifuge 13, and a solid discharge outlet of the centrifuge 13 being configured to connect with a feed inlet of the calcination system.

[0131] The calcination system comprises a drying oven 14 and a calcination furnace 15 which are connected in sequence.

[0132] The embodiment part of the present invention further provides a method for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide, comprising: a vanadium-chromium-silicon-containing leaching solution is subjected to impurity removal treatment, extraction treatment, strip-extraction and vanadium precipitation treatment, washing, drying and calcination in sequence so that vanadium pentoxide is obtained.

[0133] The impurity removal treatment comprises: a desiliconization agent is added into a filtered leaching solution containing vanadium, chromium and silicon for desiliconization treatment, following the desiliconization treatment, the pH of the solution is adjusted, the solution is allowed to stand, and is filtered again so that a stock extract liquid after impurity removal is obtained.

[0134] The extraction treatment comprises:

[0135] (1) the pH of the stock extract liquid after impurity removal treatment is adjusted, and then a vanadium-rich organic phase and a raffinate are obtained through centrifugal extraction;

[0136] (2) after the pH of the raffinate obtained in the step (1) is adjusted, a reducing agent is added for reduction and the pH is adjusted, filtration is conducted so that a solid hydrated chromium oxide is obtained.

[0137] The strip-extraction and vanadium precipitation treatment comprises the following steps:

[0138] (a) the vanadium-rich organic phase obtained by the extraction treatment is subjected to strip-extraction and vanadium precipitation treatment by using a stripping agent, and an extracted organic phase and a solid-liquid mixture are obtained;

[0139] (b) the solid-liquid mixture obtained in the step (a) is subjected to centrifugal separation so that ammonium metavanadate is obtained.

[0140] The following are typical but non-limitative examples of the present invention:

Example 1

[0141] This example provides a system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide and a processing method therefor:

[0142] The system comprises an impurity removal system, an extraction system, a strip-extraction and vanadium precipitation system, a washing system and a calcination system in sequence.

[0143] The impurity removal system comprises a first filter 1, an impurity removal reaction kettle 2, an impurity removal liquid standing tank 3 and a second filter 4 which are connected in sequence, with a liquid outlet of the second filter 4 being configured to connect with a feed inlet of the extraction system.

[0144] The extraction system comprises a centrifugal extractor 5, a raffinate storage tank 6and a vanadium-rich organic phase storage tank 7, with a raffinate outlet of the centrifugal extractor 5 being connected with an inlet of the raffinate storage tank 6, an organic phase outlet of the centrifugal extractor 5 being connected with an inlet of the vanadium-rich organic phase storage tank 7, and a discharge outlet of the vanadium-rich organic phase storage tank 7 being configured to connect with a feed inlet of the strip-extraction and vanadium precipitation system.

[0145] The strip-extraction and vanadium precipitation system comprises a vanadium-rich organic phase washing tank 8, a strip-extraction and vanadium precipitation kettle 9 and a strip-extracted aqueous phase-solid phase storage tank 10, with an organic phase outlet of the vanadium-rich organic phase washing tank 8 being connected with an organic phase inlet of the strip-extraction and vanadium precipitation kettle 9, a liquid-solid mixed phase outlet of the strip-extraction and vanadium precipitation kettle 9 being connected with an inlet of the strip-extracted aqueous phase-solid phase storage tank 10, and a solid outlet of the strip-extracted aqueous phase-solid phase storage tank 10 being configured to connect with a feed inlet of the washing system.

[0146] The washing system comprises a washing liquid storage tank 11, an ammonium metavanadate washing tank 12 and a centrifuge 13, with a liquid outlet of the washing liquid storage tank 11 being connected with an aqueous phase inlet of the ammonium metavanadate washing tank 12, a discharge outlet of the ammonium metavanadate washing tank 12 being connected with a feed inlet of the centrifuge 13, and a solid discharge outlet of the centrifuge 13 being configured to connect with a feed inlet of the calcination system.

[0147] The calcination system comprises a drying oven 14 and a calcination furnace 15 which are connected in sequence.

[0148] The strip-extraction and vanadium precipitation system comprises an extracted organic phase washing tank 16, with an organic phase outlet of the strip-extraction and vanadium precipitation kettle 9 being connected with an organic phase inlet of the extracted organic phase washing tank 16, a liquid outlet of the centrifuge 13 being connected with an aqueous phase inlet of the extracted organic phase washing tank 16, and an aqueous phase outlet of the extracted organic phase washing tank 16 being connected with an aqueous phase inlet of the vanadium-rich organic phase washing tank 8.

[0149] The processing method of the aforesaid system comprises:

[0150] (1) a vanadium-chromium-silicon-containing leaching solution was filtered by the first filter 1, 250 mL of the leaching solution containing pentavalent vanadium, hexavalent chromium and silicon was sent into the impurity removal reaction kettle 2, heated to 90 C. at constant temperature, 5.86 g of AlCl.sub.3 and 1.547 g of CaO were added thereto for desilicification treatment, the reaction was carried out for 30 min under stirring, the resulting solution was cooled to room temperature, the pH value thereof was adjusted to 8.8 with sulfuric acid, followed by stirring for 5 min, then the solution was sent into an impurity removal liquid standing tank 3 for standing for 60 min, and subjected to centrifugal separation and filtration by the second filter 4, thereby a stock extract liquid after impurity removal was obtained;

[0151] (2) the stock extract liquid after impurity removal was adjusted to a pH value of 4.2 with sulfuric acid, sent into the centrifugal extractor 5 for mixing with a primary amine extractant (containing 10 wt % of JMT, 5 wt % of hexyl acetate and 85 wt % of kerosene) in a ratio of 1:1, the mixture was subjected to centrifugal extraction at 25 C. for 20 minutes so that a chromium-containing raffinate and a vanadium-rich organic phase were obtained; sulfuric acid was added into the chromium-containing raffinate to adjust the pH value to 3, then, to the chromium-containing raffinate, anhydrous sodium sulfite was added in an amount twice of the theoretical amount, after reacting for 30 min, the pH value was adjusted to 7 with NaOH, hydrated chromium oxide was obtained by filtration; the vanadium-rich organic phase was fed into the vanadium-rich organic phase storage tank 7 for later use;

[0152] (3) the vanadium-rich organic phase in the vanadium-rich organic phase storage tank 7 was fed into the vanadium-rich organic phase washing tank 8 to be contacted with the aqueous phase in the vanadium-rich organic phase washing tank for washing and separation, the washed vanadium-rich organic phase was sent into the strip-extraction and vanadium precipitation kettle 9 for strip-extraction and vanadium precipitation with 100 mL of strip-extraction liquid (containing 2 wt % of aqueous ammonia, 0.1 mol/L of NH.sub.4Cl and 0.1 mol/L of NH.sub.4NO.sub.3) under stirring at 50 C. for 30 min, and the mixture was allowed to stand until oil and water were completely separated, thereby an extracted organic phase and a solid-liquid mixture were obtained;

[0153] the extracted organic phase was sent into the extracted organic phase washing tank 16 to be washed and recycled;

[0154] the solid-liquid mixture was sent into the strip-extracted aqueous phase-solid phase storage tank 10, and subjected to separation so that a solid phase and an aqueous phase were obtained;

[0155] (4) the solid phase obtained in the strip-extracted aqueous phase-solid phase storage tank 10 was sent into the ammonium metavanadate washing tank 12 for washing, wherein the washing liquid came from the washing liquid storage tank 11, the washed material was fed into the centrifuge 13 for centrifugal separation so that an ammonium metavanadate solid was obtained, and the obtained ammonium metavanadate solid was oven dried in the drying oven 14 at 50 C., followed by calcination in the calcination furnace 15 at 300 C. for 1.5 h, thereby a brick red product vanadium pentoxide (V.sub.2O.sub.5) was obtained.

[0156] The vanadium pentoxide (V.sub.2O.sub.5) was determined and analyzed to have a purity of 99.9%, a silicon content of 0.004 wt %, an aluminum content of 0.001 wt % and a chromium content of 0.001 wt %.

Example 2

[0157] This example provides a system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide and a processing method therefor:

[0158] The system is the same as that in Example 1.

[0159] The processing method of the aforesaid system comprises:

[0160] (1) a vanadium-chromium-silicon-containing leaching solution was filtered by the first filter 1, 500 mL of the leaching solution containing pentavalent vanadium, hexavalent chromium and silicon was sent into the impurity removal reaction kettle 2, heated to 60 C. at constant temperature, 5.86 g of Al.sub.2(SO.sub.4).sub.3 and 0.751 g of CaCl.sub.2 were added thereto for desilicification treatment, the reaction was carried out for 40 min under stirring, the resulting solution was cooled to room temperature, the pH value thereof was adjusted to 7.7 with sulfuric acid, followed by stirring for 10 min, then the solution was sent into an impurity removal liquid standing tank 3, for standing for 2 h, and subjected to centrifugal separation and filtration by the second filter 4, thereby a stock extract liquid after impurity removal was obtained;

[0161] (2) the stock extract liquid after impurity removal was adjusted to a pH value of 3.6 with sulfuric acid, sent into the centrifugal extractor 5 for mixing with an extractant (containing 15 wt % of TBP, 5 wt % of ethyl p-methylbenzoate and 80 wt % of kerosene) in a ratio of 2:1, the mixture was subjected to centrifugal extraction at 25 C. for 20 minutes so that a chromium-containing raffinate and a vanadium-rich organic phase were obtained; sulfuric acid was added into the chromium-containing raffinate to adjust the pH value to 3.4, then, to the chromium-containing raffinate, anhydrous sodium sulfite was added in an amount 1.03 times of the theoretical amount, after reacting for 40 min, the pH value was adjusted to 7.2 with NaOH, hydrated chromium oxide was obtained by filtration; the vanadium-rich organic phase was fed into the vanadium-rich organic phase storage tank 7 for later use;

[0162] (3) the vanadium-rich organic phase in the vanadium-rich organic phase storage tank 7 was fed into the vanadium-rich organic phase washing tank 8 to be contacted with the aqueous phase in the vanadium-rich organic phase washing tank for washing and separation, the washed vanadium-rich organic phase was sent into the strip-extraction and vanadium precipitation kettle 9 for strip-extraction and vanadium precipitation with 200 mL of strip-extraction liquid (containing 2 wt % of NaOH and 0.3 mol/L of (NH.sub.4).sub.2SO.sub.4) under stirring at 40 C. for 60 min, and the mixture was allowed to stand until oil and water were completely separated, thereby an extracted organic phase and a solid-liquid mixture were obtained;

[0163] the extracted organic phase was sent into the extracted organic phase washing tank 16 to be washed and recycled;

[0164] the solid-liquid mixture was sent into the strip-extracted aqueous phase-solid phase storage tank 10, and subjected to separation so that a solid phase and an aqueous phase were obtained;

[0165] (4) the solid phase obtained in the strip-extracted aqueous phase-solid phase storage tank 10 was sent into the ammonium metavanadate washing tank 12 for washing, wherein the washing liquid came from the washing liquid storage tank 11, the washed material was fed into the centrifuge 13 for centrifugal separation so that an ammonium metavanadate solid was obtained, and the obtained ammonium metavanadate solid was oven dried in the drying oven 14 at 70 C., followed by calcination in the calcination furnace 15 at 400 C. for 2 h, thereby a brick red product vanadium pentoxide (V.sub.2O.sub.5) was obtained.

[0166] The vanadium pentoxide (V.sub.2O.sub.5) was determined and analyzed to have a purity of 99.9%, a silicon content of 0.004 wt %, an aluminum content of 0.001 wt % and a chromium content of 0.001 wt %.

Example 3

[0167] This example provides a system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide and a processing method therefor:

[0168] The system is the same as that in Example 1.

[0169] The processing method of the aforesaid system comprises:

[0170] (1) a vanadium-chromium-silicon-containing leaching solution was filtered by the first filter 1, 1000 mL of the leaching solution containing pentavalent vanadium, hexavalent chromium and silicon was sent into the impurity removal reaction kettle 2, heated to 70 C. at constant temperature, 1.056 g of Al(OH).sub.3 and 0.7 g of CaCl.sub.2 were added thereto for desilicification treatment, the reaction was carried out for 50min under stirring, the resulting solution was cooled to room temperature, the pH value thereof was adjusted to 8.0 with sulfuric acid, followed by stirring for 10 min, then the solution was sent into an impurity removal liquid standing tank 3 for standing for 3 h, and subjected to centrifugal separation and filtration by the second filter 4, thereby a stock extract liquid after impurity removal was obtained;

[0171] (2) the stock extract liquid after impurity removal was adjusted to a pH value of 3.4 with sulfuric acid, sent into the centrifugal extractor 5 for mixing with a primary amine extractant (containing 15 wt % of N1923, 6 wt % of ethyl p-methylbenzoate and 79 wt % of kerosene) in a ratio of 3:1, the mixture was subjected to centrifugal extraction at 20 C. for 30 min so that a chromium-containing raffinate and a vanadium-rich organic phase were obtained; sulfuric acid was added into the chromium-containing raffinate to adjust the pH value to 2.5, then, to the chromium-containing raffinate, anhydrous sodium sulfite was added in an amount 1.2 times of the theoretical amount, after reacting for 30 min, the pH value was adjusted to 8 with NaOH, hydrated chromium oxide was obtained by filtration; the vanadium-rich organic phase was fed into the vanadium-rich organic phase storage tank 7 for later use;

[0172] (3) the vanadium-rich organic phase in the vanadium-rich organic phase storage tank 7 was fed into the vanadium-rich organic phase washing tank 8 to be contacted with the aqueous phase in the vanadium-rich organic phase washing tank for washing and separation, the washed vanadium-rich organic phase was sent into the strip-extraction and vanadium precipitation kettle 9 for strip-extraction and vanadium precipitation with 500 mL of strip-extraction liquid (containing 3 wt % of KOH, 0.1 mol/L of NH.sub.4Cl and 0.3 mol/L of (NH.sub.4).sub.2SO.sub.4) under stirring at 55 C. for 60 min, and the mixture was allowed to stand until oil and water were completely separated, thereby an extracted organic phase and a solid-liquid mixture were obtained;

[0173] the extracted organic phase was sent into the extracted organic phase washing tank 16 to be washed and recycled;

[0174] the solid-liquid mixture was sent into the strip-extracted aqueous phase-solid phase storage tank 10, and subjected to separation so that a solid phase and an aqueous phase were obtained;

[0175] (4) the solid phase obtained in the strip-extracted aqueous phase-solid phase storage tank 10 was sent into the ammonium metavanadate washing tank 12 for washing, wherein the washing liquid came from the washing liquid storage tank 11, the washed material was fed into the centrifuge 13 for centrifugal separation so that an ammonium metavanadate solid was obtained, and the obtained ammonium metavanadate solid was oven dried in the drying oven 14 at 60 C., followed by calcination in the calcination furnace 15 at 500 C. for 2 h, thereby a brick red product vanadium pentoxide (V.sub.2O.sub.5) was obtained.

[0176] The vanadium pentoxide (V.sub.2O.sub.5) was determined and analyzed to have a purity of 99.9%, a silicon content of 0.003 wt %, an aluminum content of 0.008 wt % and a chromium content of 0.006 wt %.

Example 4

[0177] This example provides a system for extracting vanadium from a vanadium-chromium-silicon-containing leaching solution and preparing vanadium pentoxide and a processing method therefor:

[0178] The system is the same as that in Example 1.

[0179] The processing method of the aforesaid system comprises:

[0180] (1) a vanadium-chromium-silicon-containing leaching solution was filtered by the first filter 1, 2000 mL of the leaching solution containing pentavalent vanadium, hexavalent chromium and silicon was sent into the impurity removal reaction kettle 2, heated to 80 C. at constant temperature, 2.5g of NaOH and 14.66 g of Al.sub.2(SO.sub.4).sub.3 were added thereto for desilicification treatment, the reaction was carried out for 60 min under stirring, the resulting solution was cooled to room temperature, the pH value thereof was adjusted to 8.5 with sulfuric acid, followed by stirring for 15 min, then the solution was sent into an impurity removal liquid standing tank 3 for standing for 4 h, and subjected to centrifugal separation and filtration by the second filter 4, thereby a stock extract liquid after impurity removal was obtained;

[0181] (2) the stock extract liquid after impurity removal was adjusted to a pH value of 3.0 with sulfuric acid, sent into the centrifugal extractor 5 for mixing with a primary amine extractant (containing 20 wt % of N1923, 7 wt % of diisopropyl succinate and 73 wt % of kerosene) in a ratio of 4:1, the mixture was subjected to centrifugal extraction at 30 C. for 40 min so that a chromium-containing raffinate and a vanadium-rich organic phase were obtained; sulfuric acid was added into the chromium-containing raffinate to adjust the pH value to 3.5, then, to the chromium-containing raffinate, anhydrous sodium sulfite was added in an amount 1.4 times of theoretical amount, after reacting for 40 min, the pH value was adjusted to 7.5 with NaOH, hydrated chromium oxide was obtained by filtration; the vanadium-rich organic phase was fed into the vanadium-rich organic phase storage tank 7 for later use;

[0182] (3) the vanadium-rich organic phase in the vanadium-rich organic phase storage tank 7 was fed into the vanadium-rich organic phase washing tank 8 to be contacted with the aqueous phase in the vanadium-rich organic phase washing tank for washing and separation, the washed vanadium-rich organic phase was sent into the strip-extraction and vanadium precipitation kettle 9 for strip-extraction and vanadium precipitation with 800 mL of strip-extraction liquid (containing 4 wt % of NaOH, 0.1 mol/L of NH.sub.4Cl and 0.3 mol/L of (NH.sub.4).sub.2CO.sub.3) under stirring at 60 C. for 2 h, and the mixture was allowed to stand until oil and water were completely separated, thereby an extracted organic phase and a solid-liquid mixture were obtained;

[0183] the extracted organic phase was sent into the extracted organic phase washing tank 16 to be washed and recycled;

the solid-liquid mixture was sent into the strip-extracted aqueous phase-solid phase storage tank 10, and subjected to separation so that a solid phase and an aqueous phase were obtained;

[0184] (4) the solid phase obtained in the strip-extracted aqueous phase-solid phase storage tank 10 was sent into the ammonium metavanadate washing tank 12 for washing, wherein the washing liquid came from the washing liquid storage tank 11, the washed material was fed into the centrifuge 13 for centrifugal separation so that an ammonium metavanadate solid was obtained, and the obtained ammonium metavanadate solid was oven dried in the drying oven 14 at 70 C., followed by calcination in the calcination furnace 15 at 450 C. for 2 h, thereby a brick red product of vanadium pentoxide (V.sub.2O.sub.5) was obtained.

[0185] The vanadium pentoxide (V.sub.2O.sub.5) was determined and analyzed to have a purity of 99.9%, a silicon content of 0.001 wt %, an aluminum content of 0.0005 wt % and a chromium content of 0.0002 wt %.

Comparison Example

[0186] This comparison example provides a method for preparing high-purity V.sub.2O.sub.5 from a vanadium-chromium-containing solution, wherein the vanadium-chromium-containing solution used was the same as that in Example 4, and the process steps were carried out according to the method disclosed in CN 100497675A.

[0187] The obtained vanadium pentoxide was determined to have a purity of 99.6%, a silicon content of 0.005 wt %, an aluminum content of 0.001 wt % and a chromium content of <0.001 wt %.

[0188] As can be seen from the combination of the results of Examples 1-4, according to the present invention, through strengthening the processes of removing silicon and aluminum, selective extraction and strip-extraction, vanadium and chromium are deeply separated, so that a high-purity V.sub.2O.sub.5 with a low content of silicon, aluminum and chromium (the silicon content is <0.005 wt %, the aluminum content is <0.001 wt %, the chromium content is <0.001 wt %, and the V.sub.2O.sub.5 content is 99.9%) can be obtained, the quality and value of the product are greatly improved, and the resulting high-purity V.sub.2O.sub.5 can be widely applied to the fields such as catalysts, batteries, aerospace, and electronic elements.

[0189] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention by the above examples, but the present invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above detailed process equipment in order to be implemented. It will be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of the materials for the product of the present invention, and additions of auxiliary ingredients, selections of the specific means and the like, are all within the protection and disclosure scopes of the present invention.