A method for preparing high-purity sodium metavanadate

Abstract

The application discloses a method for preparing high-purity sodium metavanadate, which comprises the following steps: (1) preparing a sodium hydroxide solution by taking sodium hydroxide and water; (2) adding vanadium pentoxide into the sodium hydroxide solution to dissolve, obtaining a first mixed solution, and then performing first temperature rising and first stirring; (3) adjusting the PH value of the first mixed solution to 8.5-10 by adding vanadium pentoxide or sodium hydroxide, obtaining a second mixed solution, and then performing second temperature rising and second stirring; (4) filtering the second mixed solution at a certain temperature, adding a flocculating agent into the filtrate, obtaining a third mixed solution, and then performing first temperature falling and third stirring; and (5) filtering the third mixed solution, allowing the filtrate to be static crystallization, drying the crystals to obtain sodium metavanadate, and the obtained filtrate can be reused. The method can prepare high-purity sodium metavanadate, and the produced wastewater solution can be recycled.

Description

TECHNICAL FIELD

[0001] The application relates to the vanadium chemical industry field, in particular to a method for preparing high-purity sodium metavanadate. BACKGROUND

[0002] Sodium metavanadate can be used for chemical reagents, catalysts, drying agents, mordants, manufacturing ammonium metavanadate or medical photography, plant inoculation and corrosion inhibitors. Generally, sodium metavanadate is prepared by using ammonium metavanadate as raw material, dissolving sodium hydroxide, sodium carbonate or sodium bicarbonate under certain conditions, and preparing by adjusting pH value with sulfuric acid; or using sodium vanadate solution as raw material, precipitating sodium polyvanadate solid under low acidity, and then adjusting pH value and heating to prepare.

[0003] Chinese patent CN200910265893.1 discloses a method for preparing sodium metavanadate, which comprises the following steps: a. adjusting the pH value of sodium extraction vanadium leaching solution to 1.1-1.6 with inorganic acid, and then heating to 90 DEG C to boiling, keeping for 60-90 minutes to generate sodium polyvanadate solid; b. adding sodium hydroxide solution to the obtained sodium polyvanadate solid, and stirring the solid-liquid mixture to make the pH value of the solution in the solid-liquid mixture 8-8.5; c. heating the solid-liquid mixture to 90 DEG C to boiling to generate sodium metavanadate solid. In the above method, the obtained sodium polyvanadate solid is precipitated under strong acid condition, dissolved with sodium hydroxide, adjusted to a certain pH range, and heated to 90 DEG C to boiling to generate sodium metavanadate solid. The sodium extraction vanadium leaching solution is obtained by adding at least one of sodium carbonate, sodium chloride and sodium sulfate to at least one of vanadium slag and stone coal, converting the multivalent vanadium into water-soluble pentavalent vanadium sodium salt by roasting, and then water leaching the roasting product to obtain the sodium extraction vanadium leaching solution. The above patent method needs to use sodium vanadate solution as raw material, adjust pH value with sulfuric acid or sodium hydroxide, precipitate sodium polyvanadate solid, adjust pH value and heat to prepare, and waste water pollution is easy to occur.

[0004] Therefore, it is of great significance to develop a method for preparing high-purity sodium metavanadate, recycle the generated waste water solution, save resources and avoid environmental pollution. SUMMARY

[0005] The application aims to provide a method for preparing high-purity sodium metavanadate, which uses vanadium pentoxide as raw material, obtains high-purity sodium metavanadate by using vanadium pentoxide or sodium hydroxide as pH value regulator, recycles the generated waste water solution, saves resources and avoids environmental pollution.

[0006] In order to achieve the above-mentioned application purposes, the application provides a method for preparing high-purity sodium metavanadate, which comprises the following steps:

[0007] Step (1): preparing sodium hydroxide solution;

[0008] Step (2): adding vanadium pentoxide to dissolve in sodium hydroxide solution to obtain first mixed solution, then performing first temperature rising and first stirring;

[0009] Step (3): adjusting PH value of first mixed solution to 8.5-10 by adding vanadium pentoxide or sodium hydroxide to obtain second mixed solution, then performing second temperature rising and second stirring;

[0010] Step (4): filtering second mixed solution at certain temperature, adding flocculating agent to filtrate to obtain third mixed solution, then performing first temperature falling and third stirring;

[0011] Step (5): filtering third mixed solution, precipitating crystal by static, drying crystal to obtain sodium metavanadate, and filtrate can be reused as sodium hydroxide solution of step (1).

[0012] The method for preparing sodium metavanadate provided by the application uses vanadium pentoxide as raw material, adjusts PH value by vanadium pentoxide or sodium hydroxide, and the generated waste water can be recycled, which is energy-saving and environment-friendly.

[0013] In the application, the sodium hydroxide is of analytical purity, and the content is more than 96wt%.

[0014] According to the method for preparing high-purity sodium metavanadate, preferably, in step (1), the mass-volume ratio of sodium hydroxide to water is 30-45g:100ml; more preferably, the mass-volume ratio of sodium hydroxide to water is 35-40g:100ml. The concentration of the above-mentioned sodium hydroxide solution is conducive to improving the purity of the generated sodium metavanadate.

[0015] According to the method for preparing high-purity sodium metavanadate, preferably, in step (2), the mass ratio of sodium hydroxide to vanadium pentoxide in the sodium hydroxide solution is 1:2-3.5; more preferably, the mass ratio of sodium hydroxide to vanadium pentoxide in the sodium hydroxide solution is 1:2.2-3. The mass ratio of the above-mentioned sodium hydroxide to vanadium pentoxide is conducive to improving the purity of the generated sodium metavanadate.

[0016] According to the method for preparing high-purity sodium metavanadate, preferably, the temperature of the first temperature rising is 50-100℃; more preferably, in step (2), the temperature of the first temperature rising is 60-80℃.

[0017] Preferably, the temperature of the second temperature rising in the step (3) is 85-100 DEG C; more preferably, the temperature of the second temperature rising in the step (3) is 90-100 DEG C.

[0018] Preferably, the time of the second stirring in the step (3) is 10-60 min; more preferably, the time of the second stirring in the step (3) is 20-40 min.

[0019] Preferably, the temperature of the second mixture filtering in the step (4) is 70-95 DEG C; more preferably, the temperature of the second mixture filtering in the step (4) is 80-95 DEG C.

[0020] Preferably, the flocculating agent in the step (4) is polyacrylamide, and the mass of the polyacrylamide and the volume of the filtrate are in the ratio of 0.01-0.1 g:100 ml; more preferably, the mass of the polyacrylamide and the volume of the filtrate are in the ratio of 0.01-0.05 g:100 ml.

[0021] Preferably, the temperature of the first temperature falling in the step (4) is 50-80 DEG C, and the stirring time is 10-60 min; more preferably, the temperature of the first temperature falling in the step (4) is 60-70 DEG C, and the stirring time is 30-60 min.

[0022] Preferably, the purity of the vanadium pentoxide in the step (2) is not less than 99 wt%; more preferably, the purity of the vanadium pentoxide in the step (2) is not less than 99.5 wt%. The vanadium pentoxide with the above-mentioned purity is beneficial to improve the purity of the generated sodium metavanadate.

[0023] The beneficial effects of the present application are:

[0024] The method for preparing high-purity sodium metavanadate provided by the present application uses vanadium pentoxide as raw material, uses vanadium pentoxide or sodium hydroxide as pH value regulator, and the generated waste water can be recycled as sodium hydroxide solution, so that the environment is avoided from being polluted and energy is saved.

[0025] In the more preferable technical scheme of the present application, the purity of the generated sodium metavanadate is as high as 99.95% or above. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail in combination with specific embodiments.

[0027] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two same name different entities or different parameters, and the "first" and "second" are only for the convenience of description, and should not be understood as the limitation of the embodiments of the present application, and the subsequent embodiments will not be described one by one.

[0028] The main raw materials used in the following embodiments are shown in Table 1:

[0029] Table 1 Main raw material composition

[0030]

[0031] Example 1

[0032] (1) First, weigh 70g of sodium hydroxide, add 200ml of water to prepare a sodium hydroxide solution;

[0033] (2) Add 154g of vanadium pentoxide to the sodium hydroxide solution according to the mass ratio of sodium hydroxide to vanadium pentoxide of 1:2.2 to obtain a first mixed solution, stir and heat to 60℃, and measure the pH value to be 10.5;

[0034] (3) Use vanadium pentoxide as a pH adjuster, use 2g of vanadium pentoxide to adjust the pH value to 10 to obtain a second mixed solution, continue to heat to 90℃ and stir for 20min;

[0035] (4) Filter at 80℃, the flocculant is polyacrylamide, and then add 0.02g of polyacrylamide to the filtrate according to the mass ratio of polyacrylamide to the volume of the filtrate of 0.01g:100ml to obtain a third mixed solution, and cool to 60℃ and stir for 30min;

[0036] (5) Filter the third mixed solution through static and filtration, dry the filtered crystals to obtain 189.18g of sodium metavanadate, and return the filtrate to step (1) for recycling.

[0037] The obtained sodium metavanadate is detected, and the purity of the sodium metavanadate is measured to be 99.95wt%.

[0038] Examples 2-6

[0039] Examples 2-6 have the same steps as example 1, and the process parameters are shown in the following table:

[0040]

[0041]

[0042] The sodium metavanadate obtained from examples 2-6 is detected, and the purity of the sodium metavanadate is measured as 99.96wt%, 99.96wt%, 99.96wt%, 99.97wt%, and 99.97wt%, respectively. From the above data, it can be seen that, by using the preparation method of the present application, not only can the wastewater be recycled to avoid environmental pollution and save energy and reduce emissions, but also sodium metavanadate with a purity higher than 99.95wt% can be obtained.

[0043] The inventors of the present application found in the research and development process that, using vanadium pentoxide and sodium hydroxide as raw materials, and adopting the self-adjusting acid principle, the purity of the obtained sodium metavanadate is most ideal when the pH of the second mixed solution is controlled in the range of 8.5-10, that is, if the pH of the first mixed solution is already in the range of 8.5-10, the acid-base adjustment can be omitted, such as examples 3, 4 and 6.

[0044] It should be particularly pointed out that each component or step in each of the above embodiments can be crossed, replaced, added, deleted, and therefore, the combinations formed by these reasonable permutations and combinations should also belong to the protection scope of the present application, and the protection scope of the present application should not be limited to the above-mentioned embodiments.

[0045] The above is an exemplary embodiment disclosed by the present application, and the sequence of the above-mentioned embodiments disclosed by the present application is only for description, not representing the advantages and disadvantages of the embodiments. However, it should be noted that the discussion of any of the above embodiments is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples, and various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps and / or actions of the method claims described herein do not need to be performed in any specific order. In addition, although the elements disclosed in the embodiments of the present application can be described or claimed in singular form, they can also be understood as plural unless explicitly limited to singular.

[0046] Those skilled in the art should understand that the discussion of any of the above embodiments is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including claims) is limited to these examples; under the idea of the embodiments of the present application, the technical features of the above embodiments or different embodiments can also be combined, and there are many other changes of different aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principles of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A method for preparing high purity sodium metavanadate, characterized by, The method comprises the following steps: Step (1): preparing a sodium hydroxide solution with sodium hydroxide and water; Step (2): dissolving vanadium pentoxide in the sodium hydroxide solution, wherein the mass ratio of sodium hydroxide to vanadium pentoxide in the sodium hydroxide solution is 1:(2-3.5), to obtain a first mixed solution, and then performing first temperature rising and first stirring; Step (3): adjusting the PH value of the first mixed solution to 8.5-10 by adding vanadium pentoxide or sodium hydroxide to obtain a second mixed solution, and then performing second temperature rising and second stirring; Step (4): filtering the second mixed solution at a certain temperature, adding polyacrylamide as a flocculating agent to the filtrate, wherein the mass ratio of polyacrylamide to the volume of the filtrate is 0.01-0.1 g:100 ml, to obtain a third mixed solution, and then performing first temperature dropping and third stirring; Step (5): filtering the third mixed solution, performing static crystallization, drying the crystals to obtain sodium metavanadate, and returning the obtained filtrate to Step (1) for reuse as water; In Step (2), the first temperature rising is performed at a temperature of 50-100℃; In Step (3), the second temperature rising is performed at a temperature of 85-100℃; In Step (4), the filtering of the second mixed solution is performed at a temperature of 70-95℃.

2. The method of claim 1, wherein the sodium metavanadate has a purity of 99.99% or more. In Step (1), the mass ratio of sodium hydroxide to the volume of water is 30-45 g:100 ml.

3. The method of claim 1, wherein the sodium metavanadate has a purity of 99.99% or more. In Step (3), the second stirring is performed for 10-60 min.

4. The method of claim 1, wherein the sodium metavanadate has a purity of 99.99% or more. In Step (4), the first temperature dropping is performed at a temperature of 50-80℃, and the stirring is performed for 10-60 min.

5. The method of claim 1, wherein the sodium metavanadate has a purity of 99.99% or more. In Step (2), the purity of vanadium pentoxide is not less than 99 wt%. In Step (3), the second stirring is performed for 10-60 min. In Step (4), the first temperature dropping is performed at a temperature of 50-80℃, and the stirring is performed for 10-60 min. In Step (2), the purity of vanadium pentoxide is not less than 99 wt%.

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