Device for preparing ammonium polyvanadate by continuously crystallizing sodium vanadate solution

Abstract

The utility model discloses a device for preparing ammonium polyvanadate by continuously crystallizing a sodium vanadate solution. The device comprises a premixing tank, a liquid storage tank, a reaction kettle and a filter press, the premixing tank is provided with a sodium vanadate solution inlet, an ammonium sulfate inlet and a sulfuric acid inlet, an outlet of the premixing tank is communicated with an inlet of the liquid storage tank, an outlet of the liquid storage tank is communicated with an inlet of the reaction kettle, and an outlet of the reaction kettle is communicated with an inlet of the filter press; the reaction kettle is provided with a heating structure and a sulfuric acid inlet. According to the device, the pre-mixing tank is independently arranged, the process in the pre-mixing tank is controlled in the use process, so that no crystal precipitate is generated in the pre-mixed vanadium liquid, and the crystallization process is performed in the reaction kettle through the transition of the liquid storage tank, so that the stability of the ammonium polyvanadate crystallization process can be improved, and the particle size of the ammonium polyvanadate can be increased to reduce the cleaning difficulty; the stability and purity of the ammonium polyvanadate in the crystallization process are improved, and meanwhile the particle size of the ammonium polyvanadate is increased.

Description

TECHNICAL FIELD

[0001] The utility model relates to fine chemical technology field especially a device for preparing ammonium polyvanadate by continuous crystallization of sodium vanadate solution. BACKGROUND

[0002] Ammonium polyvanadate (English name: Ammonium Polyvanadate, molecular formula (NH4) 2V6O 16 In the industrial production of ammonium polyvanadate, vanadium slag obtained by converter steelmaking of vanadium-containing molten iron is usually used as raw material, vanadium-containing leaching solution is obtained by sodium roasting-water immersion, and ammonium polyvanadate is obtained by separating vanadium from sodium vanadate solution by ammonium salt precipitation method.

[0003] In the late 20th century, foreign scientists proposed a variety of vanadium precipitation processes, and the representative methods are as follows: Pakhomov et al. used dilute sulfuric acid to treat ammonium polyvanadate, and separated the generated vanadic acid precipitate from the mother liquor (U.S. Pat. No. 3728442). Nasyrov et al. treated sodium vanadate solution with ammonium sulfate under the condition of pH value of 4-6, prepared ammonium sodium decavanadate precipitate, dissolved in hot water, added sulfuric acid to generate ammonium polyvanadate precipitate, and reduced the sodium impurity content (U.S. Pat. No. 4039582).

[0004] At present, the ammonium polyvanadate production process commonly used in industry is indirect acid ammonium salt vanadium precipitation. Sodium vanadate solution uses ammonium sulfate as the source of ammonium ion, reacts under acidic and high temperature conditions to obtain ammonium polyvanadate crystal precipitate, and ammonium polyvanadate is obtained after filtration and drying; the process includes: injecting clear sodium vanadate solution, ammonium sulfate, and concentrated sulfuric acid into the reaction kettle in turn, adjusting the pH value of the mixed vanadium solution to 1.9-2.1, boiling the solution in the reaction kettle for 20-30 min, and then performing solid-liquid separation to obtain ammonium polyvanadate after washing and drying. One inherent disadvantage of this method is that when the end point pH value of the solution is 1.9-2.0, a small amount of reddish-brown precipitate is generated and adheres to the wall of the reaction kettle, resulting in low vanadium conversion rate, and the sodium impurity content in ammonium polyvanadate increases due to the falling of the reddish-brown precipitate. Another disadvantage is that the vanadium concentration in sodium vanadate solution is low (≤35 g / kg H2O), the amount of wastewater generated per ton of vanadium is large (40 m 3 Waste water / tV2O5), and the energy consumption of the production process such as heating and pumping increases. In addition, according to this method, the mixed vanadium solution after adding ammonium sulfate and concentrated sulfuric acid is directly heated by steam in the vanadium precipitation process, ammonium polyvanadate bursts into nucleus, resulting in difficult filtration and washing, and the amount of washing wastewater increases; in the drying process, impurities in the crystallization mother liquor remain inside the ammonium polyvanadate crystal, affecting the quality of the downstream vanadium product, and waste may also be generated.

[0005] In recent years, in view of the problems existing in the above process, domestic scientific and technological workers have put forward to improve the process, for example, the method and device for improving the quality stability of ammonium polyvanadate disclosed in the public number CN117602671A add ammonium sulfate solid and sulfuric acid to the preheated acid vanadium liquid in turn, overflow to multiple parallel vanadium precipitation tanks, improve the quality stability of ammonium polyvanadate product. The public number CN102502823A discloses a preparation method of high tap density ammonium polyvanadate, ammonium polyvanadate seed and a small amount of ammonium sulfate are added to the weak acid vanadium liquid at 60-90 DEG C, after adding sulfuric acid, the temperature is raised to 90-95 DEG C, part of ammonium polyvanadate precipitate is generated, by adding ammonium sulfate, the content of Na2O impurity is reduced, and the particle size of ammonium polyvanadate is increased; but the consumption of ammonium sulfate is large, and the operation process is complex. The public number CN115072778A discloses a continuous reaction and crystallization process of ammonium polyvanadate, seed is added to the weak acid vanadium liquid, dilute sulfuric acid is added to adjust the pH value of the slurry to control the reaction and crystallization rate, and uniform particle size ammonium polyvanadate is obtained. The public number CN114229893A discloses a preparation method of ammonium polyvanadate, the mixed solution of sodium vanadate and ammonium sulfate is passed through an acid adjusting reactor with a partition to prevent local over-acidification from causing bad material; but a large amount of sodium decavanadate precipitate is generated in the first and second acid adjusting zones, which blocks the acid adjusting reactor and is mixed into the ammonium polyvanadate slurry, so that the process cannot proceed smoothly. Practical new type content

[0006] The technical problem to be solved by the utility model is to provide a device for continuously crystallizing sodium vanadate solution to prepare ammonium polyvanadate, which improves the stability of the ammonium polyvanadate crystallization process.

[0007] In order to solve the above technical problems, the technical scheme adopted by the utility model is: including a premixing tank, a liquid storage tank, a reaction kettle and a filter press; the premixing tank is provided with a sodium vanadate solution inlet, an ammonium sulfate inlet and a sulfuric acid inlet, the outlet of the premixing tank is communicated with the inlet of the liquid storage tank, the outlet of the liquid storage tank is communicated with the inlet of the reaction kettle, and the outlet of the reaction kettle is communicated with the inlet of the filter press; the reaction kettle is provided with a heating structure and a sulfuric acid inlet.

[0008] Further, the filtrate outlet of the filter press is communicated with the ammonium sulfate inlet of the premixing tank.

[0009] Further, a drying machine is further provided; the solid material outlet of the filter press is communicated with the inlet of the drying machine, and the steam outlet of the drying machine is communicated with the ammonium sulfate inlet of the premixing tank.

[0010] Further, the premixing tank is provided with a temperature control structure and a stirring device, the liquid storage tank is provided with a temperature control structure and a stirring device, and the reaction kettle is provided with a heating structure and a stirring device.

[0011] Further, the reaction kettle is a continuous crystallization reaction kettle.

[0012] The beneficial effects produced by the above technical scheme are that: the utility model discloses a separately arranged premixing tank, avoids the generation of crystal precipitation in the premixed mixed vanadium solution by controlling the process in the premixing tank during use, and places the crystallization process in the reaction kettle through the overflow of the liquid storage tank, thereby improving the stability of the ammonium polyvanadate crystallization process and increasing the ammonium polyvanadate granularity to reduce the cleaning difficulty, and not only improves the stability and purity of the ammonium polyvanadate crystallization process, but also increases the ammonium polyvanadate granularity. BRIEF DESCRIPTION OF DRAWINGS

[0013] The utility model will be further explained in detail in combination with the drawings and specific embodiments.

[0014] Figure 1 It is the structural schematic diagram of the utility model.

[0015] In the drawing: premixing tank 1, liquid storage tank 2, reaction kettle 3, filter press 4, drying machine 5. SPECIFIC EMBODIMENT

[0016] Figure 1 As shown, the device for preparing ammonium polyvanadate by crystallizing sodium vanadate solution includes a premixing tank 1, a liquid storage tank 2, a reaction kettle 3 and a filter press 4. The premixing tank 1 is provided with a sodium vanadate solution inlet, an ammonium sulfate inlet and a sulfuric acid inlet at the top and an outlet at the bottom. The sodium vanadate solution inlet is connected to a sodium vanadate solution supply source, the ammonium sulfate inlet is connected to an ammonium sulfate supply source, and the sulfuric acid inlet is connected to a sulfuric acid supply source. The premixing tank 1 is provided with a temperature control structure. The outlet of the premixing tank 1 is connected to the inlet at the top of the liquid storage tank 2, the outlet at the bottom of the liquid storage tank 2 is connected to the inlet at the top of the reaction kettle 3, and the outlet at the bottom of the reaction kettle 3 is connected to the inlet of the filter press 4. The liquid storage tank 2 is provided with a temperature control structure. The reaction kettle 3 is provided with a heating structure, which can be a jacket heating structure or a steam pipe directly connected to the inside of the reaction kettle 3. The reaction kettle 3 is preferably a continuous crystallization reaction kettle. The filtrate outlet of the filter press 4 is connected to the ammonium sulfate inlet of the premixing tank 1. A drying machine 5 is also provided. The solid material outlet of the filter press 4 is connected to the inlet of the drying machine 5, and the steam outlet of the drying machine 5 is connected to the ammonium sulfate inlet of the premixing tank 1. The premixing tank 1, the liquid storage tank 2 and the reaction kettle 3 are all provided with stirring devices.

[0017] Figure 1As shown, the method for preparing ammonium polyvanadate by crystallization of sodium metavanadate solution adopts the device with the above structure, and comprises the following steps: 1) sequentially injecting sodium vanadate solution, ammonium sulfate or ammonium sulfate solution and sulfuric acid into the premixing tank 1, stirring uniformly to obtain mixed vanadium liquid. The vanadium concentration in the sodium vanadate solution is 28-40 g / L, the ammonium sulfate solid or ammonium sulfate solution concentration is 300-450 g / L, and the concentrated sulfuric acid concentration is 90-98 wt%. The ammonium sulfate is added in the mixed vanadium liquid to control the molar ratio of ammonium ion to vanadium to be 0.6-1.2, and the ammonium sulfate is added for 1-10 min. The sulfuric acid is added in the mixed vanadium liquid to control the pH value of the mixed vanadium liquid to be 2.2-2.9, and the sulfuric acid is added for 2-10 min. In the initial stage of adding acid, the generated solid increases with the decrease of pH value. When the pH value decreases to 2.2-2.9, the solid phase is completely dissolved, and the mixed vanadium liquid is red and clear. The temperature in the premixing tank 1 needs to be strictly controlled to reduce the precipitation of bright yellow solid in the mixing process. The solubility of the salt is greatly affected by temperature and is unstable. The residual bright yellow solid leads to too high content of potassium and sodium impurities in the subsequent ammonium polyvanadate precipitation. Therefore, the temperature for premixing in the premixing tank 1 is controlled to be 35-65 ℃ to ensure that no crystal precipitates in the mixed vanadium liquid. The stirring time of the mixed vanadium liquid in the premixing tank 1 is 1-10 min.

[0018] 2) The mixed vanadium liquid is introduced into the liquid storage tank 2 as the continuous crystallizer feed to prevent the temperature in the reaction kettle 3 from rising sharply to cause explosion nucleation. The temperature in the liquid storage tank 2 is maintained at 35-80 ℃.

[0019] 3) The mixed vanadium liquid in the liquid storage tank 2 is continuously injected into the reaction kettle 3, sulfuric acid is added to adjust the pH value to 1.9-2.1 at 92-100 ℃, and the vanadium precipitation reaction is carried out to continuously crystallize. The residence time of the feed liquid is 10-40 min, and the stirring rate is 40-260 r / min to obtain ammonium polyvanadate slurry. The sulfuric acid is preferably dilute sulfuric acid with a concentration of 20-75 wt%.

[0020] 4) The slurry after crystallization in the reaction kettle 3 is sent to the filter press 4 for filtration and washing, and the drying machine 5 for drying to obtain large-particle high-purity ammonium polyvanadate.

[0021] 5) The filtrate of the filter press 4 is returned to the premixing tank 1, and the steam generated by the drying machine 5 is returned to the premixing tank 1.

Claims

1. A device for the continuous crystallization of a sodium vanadate solution to produce ammonium polyvanadate, characterized in that: It includes premixing tank (1), liquid storage tank (2), reaction kettle (3) and filter press (4); the premixing tank (1) is equipped with sodium vanadate solution inlet, ammonium sulfate inlet and sulfuric acid inlet, the outlet of premixing tank (1) is communicated with the inlet of liquid storage tank (2), the outlet of liquid storage tank (2) is communicated with the inlet of reaction kettle (3), the outlet of reaction kettle (3) is communicated with the inlet of filter press (4); the reaction kettle (3) is equipped with heating structure and sulfuric acid inlet.

2. The apparatus for continuous crystallization of sodium vanadate solution for production of ammonium polyvanadate according to claim 1, characterized in that: The filtrate outlet of filter press (4) is communicated with the ammonium sulfate inlet of premixing tank (1).

3. The apparatus for continuous crystallization of sodium vanadate solution for preparation of ammonium polyvanadate according to claim 1, characterized in that: It is also equipped with dryer (5); the solid material outlet of filter press (4) is communicated with the inlet of dryer (5), and the steam outlet of dryer (5) is communicated with the ammonium sulfate inlet of premixing tank (1).

4. The apparatus for continuous crystallization of sodium vanadate solution for preparation of ammonium polyvanadate according to claim 1, characterized in that: The premixing tank (1) is equipped with temperature control structure and stirring device, the liquid storage tank (2) is equipped with temperature control structure and stirring device, and the reaction kettle (3) is equipped with heating structure and stirring device.

5. The apparatus for continuous crystallization of sodium vanadate solution for preparation of ammonium polyvanadate according to any one of claims 1 to 4, characterized in that: The reaction kettle (3) is a continuous crystallization reaction kettle.

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