Preparation method of high-density ammonium metavanadate

Abstract

The application belongs to the technical field of wet vanadium extraction, and particularly relates to a preparation method of high-density ammonium metavanadate. The preparation method of high-density ammonium metavanadate comprises the following steps: a, heating vanadium sodium liquid, and stirring and dissolving by adding soluble ammonium salt; b, adjusting the pH value of the mixed solution in step a; c, implementing step-by-step cooling on the mixed solution in step b, and precipitating and crystallizing ammonium metavanadate; and d, filtering and washing the precipitated slurry to obtain high-density ammonium metavanadate. Compared with the prior art, the preparation method of high-density ammonium metavanadate provided in the application scheme does not introduce a surfactant; by controlling the precipitation and crystallization process of ammonium metavanadate, high-density ammonium metavanadate can be obtained, and the whole process is simple and convenient for production implementation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wet vanadium extraction, and particularly relates to a preparation method of high-density ammonium metavanadate. BACKGROUND

[0002] Ammonium metavanadate is a white crystalline powder, slightly soluble in cold water, soluble in hot water and dilute ammonia water, and turns into vanadium pentoxide when burned in the air. It is mainly used for chemical reagents, catalysts, battery materials, etc., and can also be used for preparing vanadium pentoxide.

[0003] The production method of ammonium metavanadate is usually as follows: vanadium slag is subjected to sodiumization roasting and water immersion to obtain a vanadium-containing leaching solution, the vanadium solution is subjected to purification and impurity removal, the pH is adjusted to 7.0-9.0 to make vanadium exist in the form of metavanadate anions, and then an ammonium salt is added to obtain ammonium metavanadate precipitation. In industrial production, in order to improve production efficiency, an excessive amount of ammonium salt is often added to the vanadium solution, and the vanadium is completely precipitated in a short time. In this way, the precipitation reaction of vanadium is greatly supersaturated, and the density of the obtained ammonium metavanadate is small, being 0.4-0.7 g / cm 3 When the ammonium metavanadate powder is treated in the workshop, a large amount of dust is inevitably generated, especially when vanadium oxide is produced by calcination, the ammonium metavanadate is decomposed by heat, the agglomerates are pulverized, and the dust is difficult to control, which seriously endangers the environment and the health of the workshop workers. In addition, in the high-temperature vanadium alloy smelting process, the density and particle size of the ammonium metavanadate are too small, and the vanadium compounds are severely volatilized, which causes the actual proportion of the alloy components to deviate from the formula proportion, and affects the performance of the alloy. The ammonium metavanadate with large particle size and high density can ensure the accurate control of the formula proportion of the alloy components, and therefore it is of great significance to produce the ammonium metavanadate with high density.

[0004] According to the related literature, a Chinese invention patent with the authorization announcement number CN110963528B discloses a spherical high-density ammonium metavanadate, a preparation method and use thereof, and the following steps are given: the vanadium-containing solution and the ammonium sulfate solution are heated to 40-60 DEG C respectively; the vanadium-containing solution and the ammonium sulfate solution are simultaneously added to a stirred reactor, the reactor is a cylindrical reactor, a plurality of baffles are symmetrically arranged on the inner side wall of the cylindrical reactor, and the baffles extend along the radial direction; the ratio of the liquid inlet speed of the vanadium-containing solution to the liquid inlet speed of the ammonium sulfate solution is 1-3:1; an alkaline substance is added to the mixed solution to adjust the pH of the solution to 8-10, the solution is filtered, and the solid is washed with water and dried to obtain the spherical high-density ammonium metavanadate. The scheme prepares the spherical ammonium metavanadate with high density, and the density can be as high as 1.2 g / cm 3 The above.

[0005] Chinese invention patent CN106430305B discloses a method for producing high-density ammonium metavanadate. The main steps are: (1) adding an additive (selected from sodium ions, potassium ions, magnesium ions, or PAM) to a vanadium-containing solution beforehand; (2) heating the solution; (3) adding an ammonium salt to obtain ammonium metavanadate precipitate; (4) cooling to ensure complete vanadium precipitation; and (5) drying. The ammonium metavanadate produced by this method is a perfect single crystal with coarse particles and a loose packing density exceeding 1 g / cm³. 3 This can effectively prevent dust problems during operation. The non-patent literature "Preparation and Characterization of Ammonium Metavanadate with High Density (Pei Yanchun. Shanxi Chemical Industry, 2022(5): 7-9)" also reports the preparation of a high density ammonium metavanadate with a density of 1.06 g / cm³ from sodium vanadate solution using PAM and soluble ammonium salt. 3 Process technology for ammonium metavanadate.

[0006] Chinese Patent CN104973626B discloses a method for preparing high-purity ammonium metavanadate from vanadium sodium solution. The proposed steps are: (1) mixing polyvinyl alcohol, soluble ammonium salt, and vanadium sodium solution; after the soluble ammonium salt dissolves, adjusting the pH of the resulting mixture to neutral or weakly alkaline, and reacting at this pH; (2) separating the reacted mixture into solid and liquid phases, and drying the separated solid. This invention provides a method for preparing high-purity ammonium metavanadate from vanadium sodium solution by adding the surfactant polyvinyl alcohol and soluble ammonium salt to the vanadium sodium solution to precipitate ammonium metavanadate, achieving a vanadium precipitation rate of over 99% and a density of 1.5 g / cm³ for the prepared ammonium metavanadate. 3 And its purity is as high as 99.5%.

[0007] In summary, existing high-density ammonium metavanadate preparation processes mostly use sodium vanadium chloride solution as raw material. Some processes employ special reaction vessels to control the material reaction process, but many rely on the addition of additives (sodium ions, potassium ions, magnesium ions, PAM, or polyacrylamide) to obtain high-density ammonium metavanadate. These processes are relatively complex, requiring precise control of the additive content and demanding high operational skill levels. Therefore, existing technologies still require improvement. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention proposes a method for preparing high-density ammonium metavanadate, thereby solving the problem of complex processes in the preparation of existing high-density ammonium metavanadate.

[0009] A method for preparing high-density ammonium metavanadate includes the following steps:

[0010] a. Heat the sodium vanadium solution and add soluble ammonium salt while stirring to dissolve;

[0011] b. Adjust the pH value of the mixed solution in step a;

[0012] c. segmentally cooling the mixed solution of step b to precipitate ammonium metavanadate;

[0013] d. filtering and washing the precipitated slurry to obtain high-density ammonium polyvanadate.

[0014] Further, the heating temperature of the sodium vanadate solution in step a is 60-80 DEG C.

[0015] Further, the soluble ammonium salt in step a is at least one of ammonium sulfate, ammonium chloride, ammonium oxalate, ammonium carbonate and ammonium bicarbonate.

[0016] Further, the amount of the soluble ammonium salt in step a is 2.0-5.0 times the mass of TV in the sodium vanadate solution.

[0017] Further, any one of sulfuric acid, hydrochloric acid and oxalic acid is used to adjust the acidity in step b.

[0018] Further, the pH value of the mixed solution is adjusted to 8.0-10.0 in step b.

[0019] Further, the segmental cooling in step c is divided into two steps, in the first step, the temperature of the mixed solution is reduced to 50-60 DEG C at a first cooling rate to make ammonium metavanadate grains precipitate from the solution, in the second step, the temperature of the mixed solution is reduced to 5-15 DEG C at a second cooling rate to make the grains grow and precipitate completely, wherein the second cooling rate is greater than the first cooling rate.

[0020] Further, the first cooling rate is 0.1-0.5 DEG C / min and the second cooling rate is 1.0-5.0 DEG C / min in step c.

[0021] Further, the precipitation time is 3-5 h in step c.

[0022] Further, the wastewater obtained by precipitation in step c can be returned to the leaching process for preparing the sodium vanadate solution.

[0023] The present application has the advantages that: the present application provides a preparation method of high-density ammonium metavanadate, which does not introduce surfactant compared with the prior art; high-density ammonium metavanadate can be obtained by controlling the precipitation and crystallization process of ammonium metavanadate, effectively solving the problem of high chromium content in ammonium polyvanadate prepared from sodium vanadate solution. The whole process is simple and easy to produce. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flowchart of the preparation method of high-density ammonium metavanadate is shown. DETAILED DESCRIPTION

[0025] It should be understood that the embodiments of the application shown in the example embodiments are only illustrative. Although only a few embodiments are described in detail in the present application, those skilled in the art can easily appreciate that various modifications are possible without departing from the teachings of the subject matter of the present application. Accordingly, all such modifications should be included within the scope of the present application. Other substitutions, modifications, changes and omissions can be made to the design, operating conditions and parameters of the following example embodiments without departing from the spirit of the present application.

[0026] As shown in Figure 1 The embodiment of the present application provides a preparation method of high-density ammonium metavanadate, comprising the following steps:

[0027] a. heating sodium vanadate solution and adding soluble ammonium salt to stir and dissolve;

[0028] b. adjusting the pH value of the mixed solution in step a;

[0029] c. implementing staged cooling on the mixed solution in step b to precipitate and crystallize ammonium metavanadate;

[0030] d. filtering and washing the precipitated slurry to obtain high-density ammonium metavanadate.

[0031] The preparation method of high-density ammonium metavanadate provided in the application scheme does not introduce surfactants compared with the prior art; by controlling the precipitation and crystallization process of ammonium metavanadate, high-density ammonium metavanadate can be obtained, effectively solving the problem of high chromium content in ammonium metavanadate prepared from sodium vanadate solution, and the whole process is simple and easy to produce.

[0032] In some embodiments, the heating temperature of sodium vanadate solution in step a is 60-80°C.

[0033] In some embodiments, the soluble ammonium salt in step a refers to at least one of ammonium sulfate, ammonium chloride, ammonium oxalate, ammonium carbonate and ammonium bicarbonate, preferably ammonium sulfate.

[0034] In some embodiments, the amount of soluble ammonium salt in step a is 2.0-5.0 times the mass of TV in sodium vanadate solution (m(ammonium salt) / m(solution TV)=2.0-5.0).

[0035] In some embodiments, any one of sulfuric acid, hydrochloric acid and oxalic acid is used to adjust the acid in step b, preferably sulfuric acid.

[0036] In some embodiments, in step b, the pH value of the mixed solution is adjusted to 8.0-10.0.

[0037] In some embodiments, the temperature reduction in step c is divided into two steps, in the first step, the temperature of the mixed solution is reduced to 50-60℃ at a first temperature reduction rate, so that the ammonium metavanadate grains in the solution are slowly precipitated; in the second step, the temperature of the mixed solution is reduced to 5-15℃ at a second temperature reduction rate, so that the grains grow rapidly and the precipitation is complete; wherein the second temperature reduction rate is greater than the first temperature reduction rate.

[0038] In some embodiments, in step c, the first temperature reduction rate is 0.1-0.5℃ / min, and the second temperature reduction rate is 1.0-5.0℃ / min.

[0039] In some embodiments, in step c, the precipitation time is 3-5h.

[0040] In some embodiments, the wastewater obtained in step c can be returned to the leaching process for preparing sodium vanadate solution, so as to realize recycling and save energy.

[0041] It has been verified that the density of the ammonium metavanadate prepared by the above-mentioned embodiment of the preparation method of high-density ammonium metavanadate is not less than 1.0g / cm 3 , and the purity is as high as 99.2%.

[0042] In order to facilitate understanding, the preparation method of high-density ammonium metavanadate provided in the present scheme can be implemented in the following manner in production: first, the sodium vanadate solution in the qualified liquid tank is pumped into a heating tank and heated to 60-80℃ by steam, then the sodium vanadate solution is punched into an ammonium addition tank at a certain rate, and ammonium sulfate is added and stirred to dissolve at the same time (the rate of the two is controlled so that m((NH4)2SO4) / m(TV)=2.0-5.0); secondly, the solution is punched into an acid addition tank, and sulfuric acid is used to adjust the pH value of the mixed solution to 8.0-10.0; then, the solution is punched into a vanadium precipitation tank, and the ammonium-containing vanadium solution is subjected to stepwise temperature reduction, in the first step, the temperature of the mixed solution is reduced to 50-60℃ at a lower temperature reduction rate (0.1-0.5℃ / min), so that the ammonium metavanadate grains in the solution are slowly precipitated, after crystallization, the temperature of the mixed solution is reduced to 5-15℃ at a higher temperature reduction rate (1.0-5.0℃ / min), so that the grains grow rapidly, and the ammonium metavanadate is completely precipitated after being kept for 3-5h; finally, the precipitated slurry is filtered and washed to obtain high-density ammonium metavanadate.

[0043] The purity of the ammonium metavanadate prepared by the present scheme is more than 99.2%, and the density is higher than 1.0g / cm 3 , which effectively solves the problem of high chromium content in ammonium polyvanadate prepared from sodium vanadate solution, and the operation is simple and easy to implement.

[0044] In order to further compare with the prior art, the present scheme also provides several embodiments for comparison with the prior art, specifically as follows:

[0045] Table 1 Main components of sodium vanadate solution used in the examples and comparative examples -1

[0046]

[0047] Comparative Example:

[0048] First, 400 mL of sodium vanadate solution was measured, heated to 70°C in a water bath, and 53.51 g of ammonium sulfate was added and stirred to dissolve (m((NH4)2SO4) / m(TV) = 3.5); second, the pH value of the mixed solution was adjusted to 9.0 using sulfuric acid; then, the ammonium-added sodium vanadate solution was subjected to cooling, and the temperature of the mixed solution was reduced to 10°C at a conventional cooling rate (1.0°C / min) and kept for 4 h; finally, the precipitate slurry was filtered and washed to obtain ammonium metavanadate, the purity of the ammonium metavanadate was 98.3%, and the density was 0.85 g / cm 3 .

[0049] Example 1 of the present application:

[0050] First, 400 mL of sodium vanadate solution was measured, heated to 70°C in a water bath, and 53.51 g of ammonium sulfate was added and stirred to dissolve (m((NH4)2SO4) / m(TV) = 3.5); second, the pH value of the mixed solution was adjusted to 9.0 using sulfuric acid; then, the ammonium-added sodium vanadate solution was subjected to cooling, and the temperature of the mixed solution was reduced to 10°C at a conventional cooling rate (1.0°C / min) and kept for 4 h; finally, the precipitate slurry was filtered and washed to obtain ammonium metavanadate, the purity of the ammonium metavanadate was 98.3%, and the density was 0.85 g / cm 3 .

[0051] Example 2 of the present application:

[0052] First, 400 mL of sodium vanadate solution was measured, heated to 70°C in a water bath, and 53.51 g of ammonium sulfate was added and stirred to dissolve (m((NH4)2SO4) / m(TV) = 3.5); second, the pH value of the mixed solution was adjusted to 9.0 using sulfuric acid; then, the ammonium-added sodium vanadate solution was subjected to cooling, and the temperature of the mixed solution was reduced to 10°C at a conventional cooling rate (1.0°C / min) and kept for 4 h; finally, the precipitate slurry was filtered and washed to obtain ammonium metavanadate, the purity of the ammonium metavanadate was 98.3%, and the density was 0.85 g / cm 3 .

[0053] Embodiment 3 of the present application:

[0054] First, 500 mL of sodium vanadate solution is measured, heated to 60 DEG C in a water bath, and 38.22 g of ammonium sulfate is added and stirred to dissolve (m((NH4)2SO4) / m(TV) = 2.0);Second, the pH value of the mixed solution is adjusted to 10.0 using sulfuric acid;Then, the ammonium-added sodium vanadate solution is subjected to staged cooling, the temperature of the mixed solution is reduced to 50 DEG C at a lower cooling rate (0.1 DEG C / min) in the first step, so that ammonium metavanadate crystals are slowly precipitated from the solution, and after crystallization, the temperature of the mixed solution is reduced to 15 DEG C at a higher cooling rate (1.0 DEG C / min), and the solution is kept for 5 h to make the ammonium metavanadate precipitate completely;Finally, the precipitate slurry is filtered and washed to obtain ammonium metavanadate, the purity of the ammonium metavanadate is 99.2%, and the density is 1.09 g / cm 3 .

[0055] In summary, the preparation method of high-density ammonium metavanadate provided by the present application has higher purity and greater density of the obtained ammonium metavanadate compared with the method for preparing high-density ammonium metavanadate used in the comparative example.

[0056] The above description is only the preferred embodiments of the present application, and is not intended to limit the scope of the present application;If the present application is modified or replaced without departing from the spirit and scope of the present application, it should be covered in the protection scope of the claims of the present application.

Claims

1. A method for preparing high-density ammonium metavanadate, characterized in that, Includes the following steps: a. Heat the sodium vanadium solution and add soluble ammonium salt while stirring to dissolve; b. Adjust the pH value of the mixed solution in step a; c. Perform segmented cooling on the mixed solution from step b to precipitate and crystallize ammonium metavanadate; The segmented cooling process consists of two steps. The first step involves lowering the temperature of the mixed solution to 50-60°C at a first cooling rate, causing ammonium metavanadate crystals to precipitate in the solution. The second step involves lowering the temperature of the mixed solution to 5-15°C at a second cooling rate, allowing the crystals to grow and precipitate completely. The second cooling rate is greater than the first cooling rate. The first cooling rate is 0.1-0.5°C / min, and the second cooling rate is 1.0-5.0°C / min. d. The precipitated slurry is filtered and washed to obtain high-density ammonium metavanadate.

2. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, In step a, the heating temperature of the sodium vanadium solution is 60~80℃.

3. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, The soluble ammonium salt mentioned in step a refers to at least one of ammonium sulfate, ammonium chloride, ammonium oxalate, ammonium carbonate, and ammonium bicarbonate.

4. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, In step a, the amount of soluble ammonium salt used is 2.0 to 5.0 times the mass of TV in the vanadium sodium solution.

5. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, In step b, any one of sulfuric acid, hydrochloric acid, or oxalic acid is used for acid adjustment.

6. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, In step b, adjust the pH of the mixed solution to 8.0~10.

0.

7. The method for preparing high-density ammonium metavanadate according to claim 1, characterized in that, The sedimentation time in step c is 3-5 hours.

8. The method for preparing high-density ammonium metavanadate according to claim 2, characterized in that, The wastewater obtained from precipitation in step c can be returned to the leaching process for preparing sodium vanadium solution.

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