Method for extracting vanadium from vanadium slag crystallized from mother liquor of bayer process

Abstract

The application discloses a method for separating and extracting vanadium from crystallized vanadium slag in a mother liquor of a Bayer process seed, and comprises the following steps: dissolving the vanadium slag in water, adding sodium hydroxide and a vanadium precipitating agent to selectively precipitate vanadium, and filtering to obtain a vanadium precipitation liquid and a vanadium enrichment slag; the vanadium precipitating agent is a barium salt; the vanadium precipitation liquid is subjected to impurity removal through a cooling crystallization or a precipitation method, is filtered, and the filtrate is returned to a vanadium slag dissolving process; the vanadium enrichment slag is subjected to leaching through a leaching agent or is subjected to leaching through a leaching agent after being transformed through an acid solution, is filtered, and vanadium enrichment liquid and leaching slag are obtained; the leaching slag is returned to be used as the vanadium precipitating agent; and the vanadium enrichment liquid is subjected to a vanadium precipitation process to obtain a vanadium product. The strong alkaline vanadium-containing solution obtained after vanadium slag is dissolved does not need to be subjected to neutralization treatment through consumption of additional acid, the operation is simple, vanadium process loss is small, the recovery rate is high, the vanadium precipitating agent and process water can be recycled, waste emission is reduced, environmental protection is facilitated, and the cost is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metallurgy, and particularly relates to extraction of vanadium, and more particularly to a method for extracting vanadium from a vanadium slag crystallized from a mother liquor of a Bayer process seed separation. BACKGROUND

[0002] Vanadium is a kind of important strategic material, which is widely used in steelmaking, non-ferrous alloy, chemical production, energy storage battery and other fields due to its high tensile strength, high hardness and high fatigue resistance. However, due to the lack of high-grade vanadium ore, vanadium is mainly derived from limited resources such as vanadium-titanium magnetite smelting tailings, waste catalysts and stone coal, and the existing vanadium extraction technology has problems such as high cost, serious pollution, long process and low recovery rate.

[0003] Aluminum ore contains rich vanadium resources, especially in the Bayer process of alumina production, the existence of vanadium has potential harm to the seed separation process of sodium aluminate solution. If the vanadium can be extracted, it not only can eliminate the influence on the alumina production process, but also has great significance to improve the economic benefit of China's alumina industry and the international market competitiveness.

[0004] Due to the strong alkalinity of sodium aluminate solution, it is difficult to separate and extract vanadium directly by using traditional extraction method, adsorption method and ion exchange method. On the contrary, chemical precipitation method has great advantages. Patent document CN200610109366.8 proposes a method of adding calcium oxide to the seed separation mother liquor to precipitate vanadium, leaching the precipitate sodium bicarbonate, secondary precipitation of the leaching solution, secondary reverse leaching of the precipitate, and neutralizing and hydrolyzing the leaching solution to prepare vanadium pentoxide. Although the use of lime to precipitate vanadium has low cost, it will cause great loss of aluminum in the mother liquor, poor vanadium precipitation effect, low vanadium content in the slag, and complicated subsequent solution purification and separation process, which is not conducive to industrial promotion. Patent document CN200910243362.2 proposes adding BaO to the seed separation mother liquor to precipitate vanadium, and leaching the vanadium precipitate with sodium carbonate, but in actual situation, the types of impurity ions in the seed separation mother liquor are complex, the composition of the vanadium precipitate is complex and the slag is difficult to be reused, and in addition, the leaching effect of sodium carbonate is not ideal.

[0005] Currently, crystallization method is generally used in industry to remove vanadium from the Bayer process. The anions in sodium aluminate solution will form Na7M2F·19H2O (M = VO4 3- , PO4 3- , AsO4 3-) form, in addition, part of Na2C2O4, Na2CO3, Na2SO4 and other impurities are precipitated synchronously, this method is mature, the equipment is simple, and the vanadium slag with high vanadium content can be obtained for further vanadium extraction, which is called the Bayer process seed separation mother liquor crystallization vanadium slag. The existing process for treating the Bayer process seed separation mother liquor crystallization vanadium slag usually is: adding acid for neutralization treatment, then removing impurities, and then obtaining vanadium product through vanadium precipitation. The process has the problems of large vanadium loss in the impurity removal process, low purity of the vanadium precipitation product, large acid consumption in acid-base neutralization, difficult utilization of the generated wastewater containing a large amount of sodium sulfate and ammonium sulfate, and the generated ammonium sulfate-sodium sulfate crystalline mixture through evaporation crystallization is listed as a dangerous solid waste in China and must be further treated before being disposed. SUMMARY

[0006] The purpose of the present application is to provide a method for extracting vanadium from the Bayer process seed separation mother liquor crystallization vanadium slag, which does not need to consume a large amount of acid for neutralization and has low cost, good vanadium precipitation effect, and recyclable vanadium precipitation agent and process water.

[0007] To achieve the above purpose, the present application provides the following specific technical solutions.

[0008] A method for extracting vanadium from the Bayer process seed separation mother liquor crystallization vanadium slag, comprising the following steps:

[0009] Step S1, dissolving the vanadium slag in water, adding sodium hydroxide and a vanadium precipitation agent to selectively precipitate vanadium, and filtering to obtain a vanadium precipitation solution and a vanadium enrichment residue; the vanadium precipitation agent is a barium salt;

[0010] Step S2, removing impurities from the vanadium precipitation solution by cooling crystallization or precipitation method, filtering, and returning the filtrate to step S1;

[0011] Step S3, leaching the vanadium enrichment residue with a leaching agent or leaching the vanadium enrichment residue after transformation by an acid solution, filtering, and obtaining a leaching residue and a vanadium enrichment solution; the leaching agent is at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium sulfate, sodium bisulfate, ammonium sulfate, and ammonium bisulfate;

[0012] Step S4, returning the leaching residue of step S3 to step S1 as a vanadium precipitation agent; and obtaining a vanadium product and a vanadium precipitation solution from the vanadium precipitation process through the vanadium enrichment solution of step S3, and returning the vanadium precipitation solution to step S3.

[0013] Further, as a preferred solution, in step S1, the solid-liquid ratio of the vanadium slag and water is 1:1-10 g / mL, and the dissolution temperature is 25-100 DEG C.

[0014] Further, as a preferred solution, in step S1, the concentration of sodium hydroxide in the solution is 1-25 wt% after adding sodium hydroxide.

[0015] Further, as a preferred solution, in step S1, the precipitant barium salt is added in a molar ratio of Ba / V of 1-5:1.

[0016] Further, as a preferred solution, in step S2, the cooling crystallization impurity removal process is stirring at 25-50°C for 0.5-12h to precipitate and separate out the impurity sodium salt; and filtering to obtain a crystallized post-liquid and crystallized residue, and returning the crystallized post-liquid to step S1 for dissolving the vanadium residue.

[0017] Further, as a preferred solution, in step S2, the precipitation impurity removal process is adding a precipitant to the post-vanadium precipitation liquid, and filtering to obtain a post-impurity removal liquid and impurity removal residue; and the precipitant is at least one of calcium oxide, calcium hydroxide, and calcium chloride.

[0018] As a further preferred solution, the precipitant is added in a molar ratio of Ca / impurity anion of 1-5:1, and the impurity anion includes at least one of PO4 3- , AsO4 3- , C2O4 2- , CO3 2- , SO4 2- , F - .

[0019] Further, as a preferred solution, the precipitant barium salt in step S1 is barium carbonate or barium sulfate.

[0020] Further, when the precipitant barium salt in step S1 is barium carbonate, in step S3, the vanadium enrichment residue is directly leached with a leaching agent, and the specific leaching process is adding a leaching agent solution in a solid-liquid ratio (1:1-30) g / mL to the vanadium enrichment residue, stirring, and filtering to obtain a vanadium enrichment liquid and barium salt; and the leaching agent is at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

[0021] When the precipitant in step S1 is barium sulfate, in step S3, the vanadium enrichment residue is leached with a leaching agent after being transformed by an acid solution, and the specific process is adding an acid solution in a liquid-solid ratio (1:1-10) g / mL to the vanadium enrichment residue, stirring, and filtering to obtain a transformed post-liquid and transformed residue; and adding a leaching agent solution in a solid-liquid ratio (1:1-30) g / mL to the transformed residue, stirring, and filtering to obtain a vanadium enrichment liquid and barium salt; and the leaching agent is at least one of sodium sulfate, sodium bisulfate, ammonium sulfate, and ammonium bisulfate. +

[0022] Further, the barium salt obtained in step S3 is returned to step S1 as a vanadium precipitation agent.

[0023] ​Further, as a preferred solution, the vanadium precipitation process of step S4 is at least one of weakly alkaline ammonium salt vanadium precipitation, weakly acidic ammonium salt vanadium precipitation, and acidic ammonium salt vanadium precipitation.

[0024] Further, the specific process of the weakly alkaline ammonium salt vanadium precipitation is: adding ammonium salt or ammonia water into the vanadium-rich solution according to a NH3 / V molar ratio of 1-5:1, controlling the pH of the solution system at 7.5-9.5 by carbon dioxide or ammonia water, stirring and reacting, and performing solid-liquid separation to obtain ammonium metavanadate crystals and post-vanadium precipitation liquid.

[0025] Further, the specific process of the weakly acidic ammonium salt vanadium precipitation is: adding ammonium salt or ammonia water into the vanadium-rich solution according to a NH3 / V molar ratio of 0.1-1:1, controlling the pH of the system at 4-6 and the temperature at 20-40℃ by acid or ammonia water, stirring and reacting, and performing solid-liquid separation to obtain ammonium polyvanadate crystals and post-vanadium precipitation liquid.

[0026] Further, the specific process of the acidic ammonium salt vanadium precipitation is: adding ammonium salt or ammonia water into the vanadium-rich solution according to a NH3 / V molar ratio of 0.1-1:1, controlling the pH of the system at 2-3 and the temperature at 60-100℃ by sulfuric acid solution or ammonia water, stirring and reacting, and performing solid-liquid separation to obtain ammonium polyvanadate crystals and post-vanadium precipitation liquid.

[0027] Further, the ammonium salt is at least one of ammonium sulfate and ammonium bisulfate.

[0028] The technical solution provided by the present application has the following obvious beneficial effects:

[0029] (1) The present application does not need to consume a large amount of acid for neutralization and pH adjustment, and the vanadium is basically not lost.

[0030] (2) The present application realizes selective separation and enrichment of vanadium in the vanadium-containing solution by means of mutual transformation between insoluble compounds and using a vanadium precipitant, and the vanadium recovery rate is greater than 95%; and the vanadium precipitant can be regenerated and returned to the vanadium precipitation process after leaching of the vanadium-rich residue, and is recycled, which greatly reduces the raw material cost.

[0031] (3) The post-vanadium precipitation liquid of the present application can be returned to the vanadium residue dissolution step after impurity removal, realizing the recycling of sodium, ammonia and process water, and greatly reducing the discharge of wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The process flow chart for extracting vanadium from the mother liquor crystallization vanadium residue of the Bayer process is used for the embodiments of the present application. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all terms used in the present invention, including technical terms and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The terms used in the present invention should be interpreted only as the meaning of the terms commonly used by one of ordinary skill in the art and should not be interpreted in an ideal or excessively formal sense unless otherwise defined.

[0035] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present invention can be purchased on the market or prepared by existing methods.

[0036] Figure 1 The process flow diagram used for the following examples.

[0037] Example 1

[0038] The process of the present example is as follows:

[0039] Step (1): Take 1000g vanadium slag (Na2O 22.43%, V 8.56%, P 1.64%, As 1.18%, F 1.96%, Al2O3 1.32%) and add water to 10L, stir at 95℃ for 4h.

[0040] Step (2): Add barium carbonate according to the Ba / V molar ratio of 1.4:1, and add sodium hydroxide according to the target concentration of 5%, stir at 100℃ for 5h, so that the vanadium in it is selectively precipitated, and the vanadium precipitation rate reaches 96.41%. The filtrate and the vanadium enrichment slag are obtained, and the vanadium precipitation rate reaches 96.41%.

[0041] Step (3): The obtained vanadium precipitation liquid is precipitated at 20℃ for 12h to precipitate impurity sodium salt, and the crystallized liquid and the crystallized slag are obtained by filtration, and the crystallized liquid is returned to step (1) for the dissolution of vanadium slag.

[0042] Step (4): The vanadium enrichment slag is added to a 150g / L sodium bicarbonate solution according to the solid-liquid ratio of 1:5 g / mL, stirred at 60℃ for 1h, and the filtrate and the leaching residue are obtained, and the leaching residue is returned to the vanadium precipitation.

[0043] Step (5): The obtained vanadium enrichment liquid is added with ammonium bicarbonate according to the NH3 / V molar ratio of 1, stirred at room temperature for 3h, and then filtered to separate the ammonium metavanadate crystal and the vanadium precipitation liquid. The recovery rate of vanadium is 78.56%.

[0044] Ammonium metavanadate is calcined at 500℃ for 2h to obtain vanadium pentoxide product containing 99.3% vanadium, and the vanadium precipitation liquid is returned to step (4).

[0045] Example 2

[0046] The process of this example is as follows:

[0047] Step (1): 200 g of vanadium residue (Na2O 30.16%, V 10.15%, P 2.16%, As 1.87%, F 2.35%, C 5.22%) was placed in 1 L of water and dissolved by stirring at 95°C.

[0048] Step (2): Barium carbonate was added in a Ba / V molar ratio of 2:1, and sodium hydroxide was added in a solution with a sodium hydroxide concentration of 40 g / L, and stirring was carried out at 95°C for 4 h to selectively precipitate vanadium, and a vanadium precipitation residue and a vanadium-enriched residue were obtained by filtration, and the vanadium precipitation rate reached 98.21%.

[0049] Step (3): The obtained vanadium precipitation residue was added to the vanadium precipitation residue in a Ca / (1.5×AsO4 3- +C2O4 2- + CO3 2- + SO4 2- + 0.5×F - ) molar ratio of 1.5:1, and stirring was carried out at 60°C for 3 h, and a vanadium precipitation residue and a vanadium-enriched residue were obtained by filtration, and the vanadium precipitation residue was returned for use in dissolving vanadium residue;

[0050] Step (4): The obtained vanadium-enriched residue was added to 100 g / L of ammonium bicarbonate solution in a solid-liquid ratio of 1:20 g / mL, and stirring was carried out at 70°C for 0.5 h, and a vanadium-enriched solution and a leaching residue were obtained by filtration, and the leaching residue was returned for use in vanadium precipitation, and the vanadium-enriched solution was used for the production of vanadium products.

[0051] Step (5): The obtained vanadium-enriched solution was passed through carbon dioxide to adjust the pH of the leaching solution to 7.5, and then ammonium bicarbonate was added in an NH3 / V molar ratio of 3, and stirring was carried out at room temperature for 3 h, and ammonia water was added to control the pH of the solution to maintain it at about 8.0, and then ammonium metavanadate crystals and a vanadium precipitation residue were obtained by filtration and separation, and the recovery rate of vanadium was 92.5%.

[0052] Ammonium metavanadate was calcined at 500°C for 2 h to obtain a vanadium pentoxide product containing 99.56% vanadium, and the vanadium precipitation residue was returned to step (4).

[0053] Example 3

[0054] The process of this example is as follows:

[0055] Step (1): 250 g of vanadium residue (Na2O 25.16%, V 9.15%, P 5.5%, As 4.87%, F 3.35%) was placed in 1 L of water and dissolved by stirring at 95°C.

[0056] Step (2): Barium sulfate was added in a Ba / V molar ratio of 1.7:1, and sodium hydroxide was added in a target concentration of 240 g / L of the solution, and stirring was carried out at 95°C for 6h to selectively precipitate vanadium, and a vanadium precipitation residue and a vanadium-enriched residue were obtained by filtration, and the vanadium precipitation rate reached 99.17%.

[0057] Step (3): The obtained vanadium precipitation residue was stirred at 25°C for 8h to precipitate and separate out impurity sodium salt, and a crystallization residue and a crystallization residue were obtained by filtration, and the crystallization residue was returned to the vanadium residue dissolution process.

[0058] Step (4): The obtained vanadium-enriched residue was added to a H + / V molar ratio of 2:1 sulfuric acid solution in a solid-liquid ratio of 1:4 g / mL, and stirring was carried out at 25°C for 5h, and a transformation residue and a transformation residue were obtained by filtration, and the transformation residue was returned to the transformation process after adding concentrated sulfuric acid, and the obtained transformation residue was added to a 150 g / L sodium sulfate solution in a solid-liquid ratio of 1:4 g / mL, and leaching was carried out by stirring at 90°C for 2h, and a vanadium-enriched liquid and a leaching residue were obtained by filtration, and the leaching residue was returned to the vanadium precipitation process.

[0059] Step (5): The obtained vanadium-enriched liquid was added to sulfuric acid to adjust the pH value of the leaching liquid to 5.0, and then ammonium sulfate was added in an NH3 / V molar ratio of 0.5, and stirring was carried out at 40°C for 5h, and then ammonium polyvanadate crystals and a vanadium precipitation residue were obtained by filtration separation, and the vanadium recovery rate was 98.43%; ammonium polyvanadate was calcined at 500°C for 2h to obtain a vanadium content of 97.24% vanadium pentoxide product, and the vanadium precipitation residue was returned to step (4).

[0060] Example 4

[0061] The process of this example is as follows:

[0062] Step (1): 500g of vanadium residue (Na2O 35.16%, V 5.15%, P 3.5%, As 2.87%, F 1.35%, Al2O31.45%) was placed in 3L water and dissolved by stirring at 95°C.

[0063] Step (2): Barium sulfate was added in a Ba / V molar ratio of 1.5:1, and sodium hydroxide was added in a target concentration of 200 g / L of the solution, and stirring was carried out at 95°C for 6h to selectively precipitate vanadium, and a vanadium precipitation residue and a vanadium-enriched residue were obtained by filtration, and the vanadium precipitation rate reached 98.97%.

[0064] Step (3): The obtained vanadium precipitation residue was stirred at 25°C for 8h to precipitate and separate out impurity sodium salt, and a crystallization residue and a crystallization residue were obtained by filtration, and the crystallization residue was returned to the vanadium residue dissolution process;

[0065] Step (4): The obtained vanadium-enriched residue was added to a H+ The transformation liquid and the transformation residue are obtained by stirring for 5 h at 25℃ in a sulfuric acid solution with a NH3 / V molar ratio of 1:1, the transformation liquid is returned to the transformation after adding concentrated sulfuric acid, the transformation residue is added into a 50 g / L ammonium sulfate solution with a solid-liquid ratio of 1:20 g / mL, and leaching is carried out at 70℃ for 1 h, and then the vanadium enrichment liquid and the leaching residue are obtained by filtration, and the leaching residue is returned for vanadium precipitation.

[0066] Step (5): the vanadium enrichment liquid is added into sulfuric acid to adjust the pH value of the leaching liquid to 2.5, then ammonium sulfate is added according to a NH3 / V molar ratio of 0.3, stirring is carried out at 90℃ for 5 h, then the polyacid ammonium crystal and the vanadium precipitation liquid are obtained by filtration, the recovery rate of vanadium is 99.13%, the ammonium polyvanadate is calcined at 500℃ for 2 h to obtain a vanadium content of 99.74% vanadium pentoxide product, and the vanadium precipitation liquid is returned to step (4).

[0067] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A process for the extraction of vanadium from a vanadium crystallized slag from a Bayer process seed mother liquor, characterized in that, The method comprises the following steps: Step S1, dissolving vanadium slag in water, adding sodium hydroxide and vanadium precipitating agent to selectively precipitate vanadium, and filtering to obtain vanadium precipitation solution and vanadium enrichment slag; the vanadium precipitating agent is barium sulfate; Step S2, removing impurities from the vanadium precipitation solution by cooling crystallization or precipitation method, filtering, and returning the filtrate to step S1; Step S3, transforming the vanadium enrichment slag with an acid solution, then leaching with a leaching agent, filtering, and obtaining leaching residue and vanadium enrichment liquid; the leaching agent is at least one of sodium sulfate, sodium bisulfate, ammonium sulfate, and ammonium bisulfate; Step S4, returning the leaching residue of step S3 to step S1 as a vanadium precipitating agent; and obtaining vanadium products and vanadium precipitation solution through a vanadium precipitation process, and returning the vanadium precipitation solution to step S3.

2. The process for extraction of vanadium from the crystallization of vanadium slag from the mother liquor of the Bayer process according to claim 1, characterized in that, In step S1, the solid-liquid ratio of vanadium slag to water is 1:1-10 g / mL, and the dissolution temperature is 25-100°C.

3. The process for extraction of vanadium from vanadium slag crystallized from the mother liquor of the Bayer process according to claim 1, characterized in that, In step S1, sodium hydroxide is added to make the concentration of sodium hydroxide in the solution 1-25wt%; in step S1, the amount of precipitating agent barium sulfate is added according to a Ba / V molar ratio of 1-5:

1.

4. The process for extraction of vanadium from vanadium slag crystallized from the mother liquor of the Bayer process according to claim 1, characterized in that, In step S2, the process of removing impurities from the vanadium precipitation solution by cooling crystallization is stirring at 25-50°C for 0.5-12h to crystallize and precipitate sodium salt impurities; filtering to obtain a crystallization solution and crystallization residue, and returning the crystallization solution to step S1 for dissolving vanadium slag.

5. The process for extraction of vanadium from crystallized vanadium slag from mother liquor of Bayer process as claimed in claim 1 wherein, In step S2, the process of removing impurities from the vanadium precipitation solution by precipitation method is adding a precipitating agent to the vanadium precipitation solution, and filtering to obtain a purified solution and impurity removal residue; the precipitating agent is at least one of calcium oxide, calcium hydroxide, and calcium chloride.

6. The process for extraction of vanadium from the crystallization of vanadium slag from the mother liquor of the Bayer process according to claim 5, characterized in that, The precipitant is added in an amount of 1 to 5:1 molar ratio of Ca to at least one of PO4 3- , AsO4 3- , C2O4 2- , CO3 2- , SO4 2- , F - .

7. The method according to claim 1, wherein the vanadium extraction method from the vanadium slag crystallized from the Bayer process seed separation mother liquor is characterized in that, In step S3, the vanadium-rich slag is transformed by an acid solution and then leached by a leaching agent. The specific process is as follows: according to the solid-liquid ratio (1:1~10) g / mL, H + is added into the vanadium-rich slag, stirring, and then the transformed solution and the transformed slag are obtained by filtration; according to the solid-liquid ratio (1:1~30) g / mL, the leaching agent solution is added into the transformed slag, stirring, and then the vanadium-rich solution and the barium salt are obtained by filtration.

8. The process for extraction of vanadium from vanadium slag crystallized from the mother liquor of the Bayer process according to any one of claims 1 to 7, characterized in that, The vanadium precipitation process of step S4 is at least one of weak alkaline ammonium salt vanadium precipitation, weak acid ammonium salt vanadium precipitation, and acid ammonium salt vanadium precipitation.

9. The method according to claim 8, wherein the vanadium extraction method from the vanadium slag crystallized from the Bayer process seed separation mother liquor is characterized in that, The specific process of the weak alkaline ammonium salt vanadium precipitation is adding ammonium salt to the vanadium enrichment liquid according to a NH3 / V molar ratio of 1-5:1, controlling the pH of the solution system at 7.5-9.5 by carbon dioxide or ammonia water, stirring and reacting, and solid-liquid separation to obtain ammonium metavanadate crystals and vanadium precipitation solution; The specific process of the weak acid ammonium salt vanadium precipitation is adding ammonium salt to the vanadium enrichment liquid according to a NH3 / V molar ratio of 0.1-1:1, controlling the pH of the system at 4-6 by acid or ammonia water, controlling the temperature at 20-40°C, stirring and reacting, and solid-liquid separation to obtain ammonium polyvanadate crystals and vanadium precipitation solution; The specific process of the acid ammonium salt vanadium precipitation is adding ammonium salt to the vanadium enrichment liquid according to a NH3 / V molar ratio of 0.1-1:1, controlling the pH of the system at 2-3 by sulfuric acid solution or ammonia water, controlling the temperature at 60-100°C, stirring and reacting, and solid-liquid separation to obtain ammonium polyvanadate crystals and vanadium precipitation solution.

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