A method for preparing sodium metavanadate from sodium vanadate solution

Abstract

The invention discloses a method for preparing sodium metavanadate by a sodium vanadate solution, comprising the steps of: (1): sodium vanadate solution, after purification and impurity removal, obtains a sodium vanadate purification solution; (2): sodium vanadate purification solution is adjusted to pH value to 5-6 with vanadium pentoxide to obtain a mixed solution; (3): mixed solution is heated for reaction, and in the reaction process, the pH value is adjusted to 7-8.5 by adding sodium vanadate purification solution, stirred, and a reaction solution is obtained; (4): reaction solution is subjected to cooling filtration, and crystals are precipitated through static precipitation, and sodium metavanadate is obtained by drying the crystals. The preparation method of the present invention, using sodium vanadate solution as raw material to react with vanadium pentoxide, adopts sodium vanadate purification solution to adjust pH value, then passes through cooling filtration, stands and precipitates crystals, and dries to obtain sodium metavanadate, the method does not introduce inorganic acid, does not introduce alkali, is conducive to the precipitation of sodium metavanadate crystals, can obtain sodium metavanadate with relatively high purity, and the preparation technology is simple.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of sodium metavanadate, and in particular to a method for preparing sodium metavanadate from a sodium vanadate solution. Background Art

[0002] Sodium metavanadate can be used in chemical reagents, catalysts, drying agents, mordants, the manufacture of ammonium metavanadate or medical photography, plant inoculation and corrosion inhibitors.

[0003] Chinese patent CN200910265893.1 discloses a method for preparing sodium metavanadate, comprising the following steps: a. adjusting the pH of a sodium-containing vanadium extraction leachate to 1.1-1.6 with an inorganic acid, then heating the solution to 90°C until boiling and maintaining the solution for 60-90 minutes to produce a sodium polyvanadate solid; b. adding a sodium hydroxide solution to the resulting sodium polyvanadate solid and stirring the resulting solid-liquid mixture until the pH of the solution in the solid-liquid mixture is 8-8.5; c. heating the solid-liquid mixture to 90°C until boiling to produce a sodium metavanadate solid. In the above method, the sodium polyvanadate solid is precipitated under strong acid conditions, dissolved with sodium hydroxide, adjusted to a certain pH range, and heated to 90°C until boiling to produce a sodium metavanadate solid. The sodium-based vanadium extraction leachate 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 a water-soluble pentavalent sodium salt via roasting, and then leaching the roasted product in water to obtain the sodium-based vanadium extraction leachate. This patented method requires adjusting the pH with sulfuric acid, introducing impurities such as sulfate ions, resulting in the presence of sodium sulfate in the resulting sodium metavanadate. This affects the purity of the sodium metavanadate, necessitating further purification to obtain qualified sodium metavanadate, and the preparation process is complex. Summary of the Invention

[0004] The present invention aims to provide a method for preparing sodium metavanadate from a sodium vanadate solution. The method comprises the following steps: reacting a sodium vanadate solution with vanadium pentoxide as a raw material, adjusting the pH value with a purified sodium vanadate solution, cooling and filtering the solution, standing the solution to precipitate crystals, and drying the solution to obtain sodium metavanadate. The method does not introduce inorganic acid or alkali, is conducive to the precipitation of sodium metavanadate crystals, and can obtain sodium metavanadate with relatively high purity.

[0005] In order to achieve the above object of the invention, the present invention provides a method for preparing sodium metavanadate from a sodium vanadate solution, comprising the following steps:

[0006] Step (1): Purifying and removing impurities from the sodium vanadate solution to obtain a purified sodium vanadate solution;

[0007] Step (2): adjusting the pH value of the purified sodium vanadate solution to 5-6 with vanadium pentoxide to obtain a mixed solution;

[0008] Step (3): heating the mixed solution to react, adjusting the pH value to 7-8.5 by adding sodium vanadate purification solution during the reaction, stirring, and obtaining a reaction solution;

[0009] Step (4): cooling the reaction solution and filtering it, allowing it to stand for precipitation of crystals, and drying the crystals to obtain sodium metavanadate.

[0010] Sodium vanadate is a chemical with the molecular formula Na₃VO₄. It is soluble in water, insoluble in ethanol, and toxic. In the present invention, sodium vanadate solution refers to any aqueous solution containing sodium vanadate obtained by any process; preferably, the sodium vanadate solution is the leachate obtained from the sodium extraction process during vanadium slag extraction.

[0011] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (1), the sodium vanadate solution is a leachate from a vanadium slag sodiumization vanadium extraction process, and the silicon content in the sodium vanadate solution is 0.5-2.5 g / L, and the phosphorus content is 0.05-0.15 g / L.

[0012] In the present invention, the sodiumization vanadium extraction process of vanadium slag comprises: adding at least one of sodium carbonate, sodium chloride and sodium sulfate to at least one of vanadium slag and stone coal, converting multivalent vanadium into water-soluble pentavalent sodium salt of vanadium by roasting, and then leaching the roasted product in water to obtain a sodiumization vanadium extraction leachate.

[0013] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (1), the pH of the sodium vanadate solution is 9.0-11.

[0014] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (1), the purification and impurity removal comprises: removing the silicon content in the sodium vanadate solution by adding an alkaline impurity remover under stirring conditions.

[0015] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (1), the alkaline impurity remover is sodium metaaluminate, and the mass ratio of the sodium metaaluminate to the silicon in the sodium vanadate solution is 2-2.5:1.

[0016] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (1), the temperature for purification and impurity removal is 70-90° C., preferably, the temperature for purification and impurity removal is 75-85° C. Preferably, the stirring time is 30-60 min.

[0017] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (3), the temperature is raised to 90° C. until boiling.

[0018] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (3), the reaction time is 1-1.5 h.

[0019] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (3), the stirring time is 30-60 min.

[0020] According to the method for preparing sodium metavanadate from a sodium vanadate solution of the present invention, preferably, in step (4), the temperature of the cooling filtration is 70-80°C.

[0021] The beneficial effects of the present invention are:

[0022] The method for preparing sodium metavanadate of the present invention uses a sodium vanadate solution as a raw material, adopts a self-reaction polymerization of the sodium vanadate solution and vanadium pentoxide, then uses a purified sodium vanadate solution to adjust the pH value, then cools and filters, stands to precipitate crystals, and dries the crystals to obtain sodium metavanadate. The method does not introduce inorganic acid or alkali, has a simple process, and is easy to obtain sodium metavanadate with high purity. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0024] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. Subsequent embodiments will not explain this one by one.

[0025] The main raw materials used in the following examples are shown in Table 1:

[0026] Table 1 Main raw material ingredients

[0027]

[0028] Example 1

[0029] Example 1 The steps for preparing sodium metavanadate are as follows:

[0030] Step (1): 300 ml of the sodium vanadate solution obtained in the vanadium slag sodiumization vanadium extraction process is stirred at 78° C. for 30 minutes using sodium metaaluminate as an impurity remover to obtain a purified sodium vanadate solution after purification and impurity removal; wherein the contents of the components in the sodium vanadate solution are shown in Table 1, the alkaline impurity remover is sodium metaaluminate, and the mass ratio of sodium metaaluminate to silicon in the sodium vanadate solution is 2:1.

[0031] Step (2): adjusting the pH value of the purified sodium vanadate solution to 5 with vanadium pentoxide to obtain a mixed solution;

[0032] Step (3): heating the mixed solution to 90° C. and reacting for 1 hour; measuring the pH value to be 5.5 using a high-temperature resistant acidity meter; adjusting the pH value to 7 by adding sodium vanadate purification solution; stirring for 30 minutes to obtain a reaction solution;

[0033] Step (4): The reaction solution was cooled to 70° C. and filtered. Crystals were precipitated after standing. The crystals were dried to obtain 31.8 g of sodium metavanadate. The purity of the sodium metavanadate was 99.85 wt %.

[0034] Example 2

[0035] Example 2 The steps for preparing sodium metavanadate are as follows:

[0036] Step (1): 500 ml of the sodium vanadate solution obtained in the vanadium slag sodiumization vanadium extraction process is stirred at 80° C. for 45 minutes using sodium metaaluminate as an impurity remover to obtain a purified sodium vanadate solution after purification and impurity removal; wherein the contents of the components in the sodium vanadate solution are shown in Table 1, the alkaline impurity remover is sodium metaaluminate, and the mass ratio of sodium metaaluminate to silicon in the sodium vanadate solution is 2.2:1.

[0037] Step (2): adjusting the pH value of the purified sodium vanadate solution to 5.5 with vanadium pentoxide to obtain a mixed solution;

[0038] Step (3): heating the mixed solution to 93° C. and reacting for 1.2 h. The pH value was measured to be 5.6 using a high-temperature resistant acidity meter. The pH value was adjusted to 8 by adding sodium vanadate purification solution, and stirred for 60 min to obtain a reaction solution.

[0039] Step (4): The reaction solution was cooled to 76° C. and filtered. Crystals were precipitated after standing. The crystals were dried to obtain 82.2 g of sodium metavanadate, which contained 99.90 wt % of sodium metavanadate.

[0040] Example 3

[0041] Example 3 The steps for preparing sodium metavanadate are as follows:

[0042] Step (1): 1000 ml of the sodium vanadate solution obtained in the vanadium slag sodiumization vanadium extraction process is stirred at 82° C. for 60 minutes using sodium metaaluminate as an impurity remover to obtain a purified sodium vanadate solution after purification and impurity removal; wherein the contents of the components in the sodium vanadate solution are shown in Table 1, the alkaline impurity remover is sodium metaaluminate, and the mass ratio of sodium metaaluminate to silicon in the sodium vanadate solution is 2.5:1.

[0043] Step (2): adjusting the pH value of the purified sodium vanadate solution to 6 with vanadium pentoxide to obtain a mixed solution;

[0044] Step (3): heating the mixed solution to boiling and reacting for 1.5 hours, measuring the pH value with a high-temperature resistant acidity meter to be 5.5, adjusting the pH value to 6.5 by adding sodium vanadate purification solution, stirring for 60 minutes, and obtaining a reaction solution;

[0045] Step (4): The reaction solution was cooled to 80° C. and filtered. After standing, crystals were precipitated. The crystals were dried to obtain 233.3 g of sodium metavanadate, which contained 99.91 wt % of sodium metavanadate.

[0046] As can be seen from the above examples, the preparation method of the present invention does not introduce either acid or base. It uses a sodium vanadate solution and vanadium pentoxide as raw materials, and sodium vanadate and vanadium pentoxide are reacted under acidic conditions (pH 5-6) to produce polysodium vanadate, and then the pH is adjusted to 7-8.5 with a sodium vanadate purification solution to obtain sodium metavanadate with high purity.

[0047] It should be pointed out in particular that the various components or steps in the above-mentioned embodiments can be cross-linked, replaced, added, or deleted with each other. Therefore, the combinations formed by these reasonable permutations and combinations should also fall within the scope of protection of the present invention, and the scope of protection of the present invention should not be limited to the embodiments.

[0048] The above are exemplary embodiments disclosed in the present invention. The order in which the above embodiments of the present invention are disclosed is for description only and does not represent the pros and cons 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 disclosed in the embodiments of the present invention (including the claims) is limited to these examples. Various changes and modifications may be made without departing from the scope defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless expressly limited to the singular.

[0049] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples. Within the spirit of the embodiments of the present invention, the technical features of the above embodiments or different embodiments may be combined, and there are many other variations of the different aspects of the embodiments of the present invention described above, which are not provided in detail for the sake of clarity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included within the scope of protection of the embodiments of the present invention.

Claims

1. A method for preparing sodium metavanadate from a sodium vanadate solution, characterized in that: The steps include: Step (1): Purifying and removing impurities from the sodium vanadate solution to obtain a purified sodium vanadate solution; Step (2): adjusting the pH value of the purified sodium vanadate solution to 5-6 with vanadium pentoxide to obtain a mixed solution; Step (3): heating the mixed solution to react, adjusting the pH value to 7-8.5 by adding sodium vanadate purification solution during the reaction, stirring, and obtaining a reaction solution; Step (4): cooling the reaction solution and filtering it, allowing it to stand for precipitation of crystals, and drying the crystals to obtain sodium metavanadate.

2. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 1, wherein In the step (1), the sodium vanadate solution is the leachate in the sodium vanadium extraction process, and the silicon content in the sodium vanadate solution is 0.5-2.5 g / L, and the phosphorus content is 0.05-0.15 g / L.

3. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 1, wherein In the step (1), the pH of the sodium vanadate solution is 9.0-11.

4. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 2, wherein In the step (1), the purification and impurity removal comprises: removing the silicon content in the sodium vanadate solution by adding an alkaline impurity remover under stirring conditions.

5. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 4, wherein In the step (1), the alkaline impurity remover is sodium metaaluminate, and the mass ratio of the sodium metaaluminate to the silicon in the sodium vanadate solution is 2-2.5:

1.

6. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 4, wherein In the step (1), the temperature for purification and impurity removal is 70-90°C.

7. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 1, wherein In the step (3), the temperature is raised to 90°C until boiling.

8. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 5, wherein: In the step (3), the reaction time is 1-1.5h.

9. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 1, wherein In the step (3), the stirring time is 30-60 min.

10. The method for preparing sodium metavanadate from a sodium vanadate solution according to claim 1, wherein: In the step (4), the temperature of the cooling filtration is 70-80°C.

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