Niobium oxide and preparation method thereof

Abstract

The invention belongs to the technical field of niobium metallurgy, and particularly relates to niobium oxide and a preparation method thereof. A two-stage neutralization method is adopted, in the first-stage neutralization reaction process, high-concentration ammonia water is added, rapid stirring is controlled, and niobium hydroxide crystal nuclei are rapidly nucleated; in the second-stage neutralization reaction process, the niobium hydroxide continuously and slowly grows on the initial nucleation by adding low-concentration ammonia water and controlling slow stirring, so that the niobium oxide prepared by strictly controlling the nucleation and growth process of the niobium hydroxide and subsequently aging, washing, drying, calcining and screening is large in loose ratio, uniform in morphology and high in yield. The mechanical operation is easy; the preparation method provided by the invention is simple to operate, stable in process and suitable for industrial production and application.

Description

Technical Field

[0001] The invention belongs to the technical field of niobium metallurgy, and in particular relates to niobium oxide and a preparation method thereof. Background Art

[0002] As an important electronic material, niobium oxide has been widely used in the fields of ceramic capacitors, piezoelectric ceramics, thick film capacitors, dielectric materials, magnetic materials and optical materials. In recent years, due to the rapid development of liquid crystal displays, metal oxide targets have also received much attention and have developed rapidly. Among them, niobium oxide targets are important materials for the preparation of anti-reflection and anti-reflection glass (ITO) glass. In addition, niobium oxide targets can also be used to prepare anti-reflection and anti-reflection glass coatings, which can effectively reduce the reflection of the glass itself, increase the transmittance of the glass, and make the colors through the glass brighter and more realistic. Niobium oxide can also be used in solar cells, gas sensors, touch screens, and automotive surface coatings. With the development of the economy, the application fields and industries of niobium oxide have gradually improved, and high-end products have higher and higher requirements for the performance of niobium oxide powder, and physical properties have a great influence on the performance of products. Therefore, there is more demand for high-quality large pine spherical niobium oxide in the application field.

[0003] In the preparation process of niobium oxide, two important processes that affect the physical properties of niobium oxide are neutralization precipitation and drying and calcination. In the neutralization precipitation process, factors such as the type of precipitant, solution concentration, neutralization speed, and neutralization temperature affect the nucleation and growth of crystals, thereby affecting the particle size, bulk ratio, morphology and other properties of the final product.

[0004] At present, the preparation technology adopts the neutralization method of ammonia water, but the morphology of the obtained niobium oxide product is uneven and the bulk ratio is small, which cannot meet the requirements of high-end fields for niobium oxide products. Summary of the invention

[0005] The purpose of the present invention is to provide niobium oxide and a preparation method thereof. The niobium oxide obtained by the preparation method provided by the present invention has a large porosity, uniform morphology, and is easy to mechanically operate. At the same time, the preparation method provided by the present invention has a stable process, which solves the problem of large demand for high-quality niobium oxide in current application fields.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing niobium oxide, comprising the following steps:

[0008] (1) subjecting a fluoroniobic acid solution and aqueous ammonia to a first-stage neutralization reaction to obtain a first-stage neutralization reaction liquid; during the first-stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≥40 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the aqueous ammonia is ≥30 L / min, the mass percentage of the aqueous ammonia is 22-25%, the first-stage neutralization reaction is carried out under stirring, and the stirring speed of the first-stage neutralization reaction is ≥200 r / min; the pH value of the first-stage neutralization reaction liquid is 3-4;

[0009] (2) injecting fluoroniobic acid solution and ammonia water into the neutralization reaction liquid of the first stage simultaneously to carry out a second stage neutralization reaction, so as to obtain a second stage neutralization reaction liquid; during the second stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≤22 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the ammonia water is ≤18 L / min, the mass percentage of the ammonia water is 15-18%, the second stage neutralization reaction is carried out under stirring, the stirring speed of the second stage neutralization reaction is ≤200 r / min, and the stirring speed of the second stage neutralization reaction is less than the stirring speed of the first stage neutralization reaction; the pH value of the second stage neutralization reaction liquid is 9-10;

[0010] (3) aging the second-stage neutralization reaction liquid to obtain an aged neutralization reaction liquid;

[0011] (4) separating the aged neutralization reaction liquid into solid and liquid to obtain a wet niobium hydroxide solid, and washing and drying the wet niobium hydroxide solid in sequence to obtain a dry niobium hydroxide solid;

[0012] (5) calcining and sieving the dry niobium hydroxide solid in sequence to obtain the niobium oxide.

[0013] Preferably, in step (1): the flow rate of the fluoroniobic acid solution is 40 to 50 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is 40 to 60 g / L, and the flow rate of the ammonia water is 30 to 40 L / min;

[0014] The stirring speed of the neutralization reaction in the first stage is 200-260 r / min.

[0015] Preferably, the temperature of the first stage neutralization reaction is 40-45°C.

[0016] Preferably, the first-stage neutralization reaction directly obtains the first-stage initial neutralization reaction liquid; after obtaining the first-stage initial neutralization reaction liquid, it also includes: cooling the first-stage initial neutralization reaction liquid to obtain the first-stage neutralization reaction liquid; the temperature of the first-stage initial neutralization reaction liquid is 40-45°C, the temperature of the first-stage neutralization reaction liquid is 30-35°C, the cooling is carried out under stirring, the stirring speed of the cooling is 200-260r / min, and the time is 30-60min.

[0017] Preferably, in step (2): the flow rate of the fluoroniobic acid solution is 20 to 22 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is 40 to 60 g / L, and the flow rate of the ammonia water is 15 to 18 L / min;

[0018] The stirring speed of the second stage neutralization reaction is 160-200 r / min.

[0019] Preferably, the temperature of the second stage neutralization reaction is 30-35°C.

[0020] Preferably, the aging is carried out under stirring conditions, the stirring speed of the aging is 160 to 200 r / min, and the time is 1 to 1.5 h.

[0021] Preferably, the washing is performed 2 to 6 times, and each washing comprises the following steps: mixing the solid product to be washed with water, and then injecting ammonia water into the mixed system until the pH value of the solution is 9 to 10 to obtain a mixed slurry; stirring and washing the mixed slurry, and then performing solid-liquid separation to obtain a washed solid product; the flow rate of ammonia water used in the washing is 13 to 16 L / min, and the mass percentage of ammonia water is 15 to 22%; the stirring washing time is 30 to 40 min, and the stirring washing speed is 160 to 200 r / min;

[0022] The drying temperature is 90-130°C.

[0023] Preferably, the calcination temperature is 1000-1200°C and the time is 6-9h;

[0024] The mesh sizes of the sieves used in the screening are 100 mesh and 300 mesh, and the screening takes the 100 mesh undersize and the 300 mesh oversize to obtain the niobium oxide.

[0025] The present invention provides niobium oxide prepared by the preparation method described in the above technical solution.

[0026] The present invention provides a method for preparing niobium oxide, comprising the following steps: (1) subjecting a fluoroniobic acid solution and ammonia water to a first-stage neutralization reaction to obtain a first-stage neutralization reaction liquid; during the first-stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≥40 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the ammonia water is ≥30 L / min, the mass percentage of the ammonia water is 22-25%, the first-stage neutralization reaction is carried out under stirring, the stirring speed of the first-stage neutralization reaction is ≥200 r / min; the pH value of the first-stage neutralization reaction liquid is 3-4; (2) injecting the fluoroniobic acid solution and ammonia water into the first-stage neutralization reaction liquid at the same time to carry out a second-stage neutralization reaction to obtain a second-stage neutralization reaction liquid; during the second-stage neutralization reaction: the fluoroniobic acid solution is ≥40 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the mass percentage of the ammonia water is ≥30 L / min, the mass percentage of the ammonia water is 22-25%, the first-stage neutralization reaction is carried out under stirring, the stirring speed of the first-stage neutralization reaction is ≥200 r / min, and the pH value of the first-stage neutralization reaction liquid is 3-4. The flow rate of the second stage neutralization reaction is ≤22L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40g / L, the flow rate of the ammonia water is ≤18L / min, the mass percentage of the ammonia water is 15-18%, the second stage neutralization reaction is carried out under stirring, the stirring speed of the second stage neutralization reaction is ≤200r / min, and the stirring speed of the second stage neutralization reaction is less than the stirring speed of the first stage neutralization reaction; the pH value of the second stage neutralization reaction liquid is 9-10; (3) aging the second stage neutralization reaction liquid to obtain an aged neutralization reaction liquid; (4) separating the aged neutralization reaction liquid into solid and liquid to obtain a wet niobium hydroxide solid, washing and drying the wet niobium hydroxide solid in sequence to obtain a dry niobium hydroxide solid; (5) calcining and sieving the dry niobium hydroxide solid in sequence to obtain the niobium oxide. The present invention adopts a two-stage neutralization method. In the first stage of the neutralization reaction process, high-concentration ammonia water is added and rapid stirring is controlled to rapidly nucleate niobium hydroxide crystal nuclei; in the second stage of the neutralization reaction process, low-concentration ammonia water is added and slow stirring is controlled to slowly grow niobium hydroxide on the initial nucleation. Therefore, the present invention strictly controls the nucleation and growth process of niobium hydroxide, and then undergoes aging, washing, drying, calcining and screening to prepare niobium oxide with large pine ratio, uniform morphology and easy mechanical operation; and the preparation method provided by the present invention is simple to operate, has a stable process, and is suitable for industrial production and application.

[0027] The present invention provides niobium oxide prepared by the preparation method described in the above technical solution. The niobium oxide provided by the present invention has a large pore size, uniform morphology, and is easy to mechanically operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an electron microscope photograph of the niobium oxide product prepared in Example 1 of the present invention;

[0029] Figure 2 This is an electron microscope photograph of the niobium oxide product prepared in Example 2 of the present invention;

[0030] Figure 3 This is an electron microscope photograph of the niobium oxide product prepared in Example 3 of the present invention;

[0031] Figure 4 This is an electron microscope photograph of the niobium oxide product prepared in Comparative Example 1 of the present invention;

[0032] Figure 5 This is an electron microscope photograph of the niobium oxide product prepared in Comparative Example 2 of the present invention;

[0033] Figure 6 This is an electron microscope photograph of the niobium oxide product prepared in Comparative Example 3 of the present invention;

[0034] Figure 7 This is an electron microscope photograph of the niobium oxide product prepared in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0035] The present invention provides a method for preparing niobium oxide, comprising the following steps:

[0036] (1) subjecting a fluoroniobic acid solution and aqueous ammonia to a first-stage neutralization reaction to obtain a first-stage neutralization reaction liquid; during the first-stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≥40 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the aqueous ammonia is ≥30 L / min, the mass percentage of the aqueous ammonia is 22-25%, the first-stage neutralization reaction is carried out under stirring, and the stirring speed of the first-stage neutralization reaction is ≥200 r / min; the pH value of the first-stage neutralization reaction liquid is 3-4;

[0037] (2) injecting fluoroniobic acid solution and ammonia water into the neutralization reaction liquid of the first stage simultaneously to carry out a second stage neutralization reaction, so as to obtain a second stage neutralization reaction liquid; during the second stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≤22 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the ammonia water is ≤18 L / min, the mass percentage of the ammonia water is 15-18%, the second stage neutralization reaction is carried out under stirring, the stirring speed of the second stage neutralization reaction is ≤200 r / min, and the stirring speed of the second stage neutralization reaction is less than the stirring speed of the first stage neutralization reaction; the pH value of the second stage neutralization reaction liquid is 9-10;

[0038] (3) aging the second-stage neutralization reaction liquid to obtain an aged neutralization reaction liquid;

[0039] (4) separating the aged neutralization reaction liquid into solid and liquid to obtain a wet niobium hydroxide solid, and washing and drying the wet niobium hydroxide solid in sequence to obtain a dry niobium hydroxide solid;

[0040] (5) calcining and sieving the dry niobium hydroxide solid in sequence to obtain the niobium oxide.

[0041] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0042] The present invention conducts a first-stage neutralization reaction of a fluoroniobic acid solution and ammonia water to obtain a first-stage neutralization reaction liquid; during the first-stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≥40L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40g / L, the flow rate of the ammonia water is ≥30L / min, the mass percentage of the ammonia water is 22-25%, the first-stage neutralization reaction is carried out under stirring, and the stirring speed of the first-stage neutralization reaction is ≥200r / min; the pH value of the first-stage neutralization reaction liquid is 3-4. In the present invention, the fluoroniobic acid solution is preferably an aqueous solution of fluoroniobic acid. The flow rate of the fluoroniobic acid solution is preferably 40-50L / min, specifically 50L / min, 45L / min or 40L / min in the embodiment. The mass concentration of fluoroniobic acid in the fluoroniobic acid solution is preferably 40-60g / L, specifically 40g / L, 50g / L or 60g / L in the embodiment. The flow rate of the ammonia water is preferably 30-40 L / min, and is specifically 40 L / min, 35 L / min or 30 L / min in the embodiment. The mass percentage of the ammonia water is 22-25%, and is specifically 22%, 23%, 23% or 25% in the embodiment. The stirring speed of the neutralization reaction in the first stage is preferably 200-260 r / min, and is specifically 240 r / min, 220 r / min or 200 r / min in the embodiment. The temperature of the neutralization reaction in the first stage is preferably 40-45°C, and is specifically 42-44°C, 40-43°C or 42-45°C in the embodiment. The pH value of the neutralization reaction liquid in the first stage is specifically 3.

[0043] In the present invention, the first stage neutralization reaction directly obtains the first stage initial neutralization reaction liquid; after obtaining the first stage initial neutralization reaction liquid, the present invention preferably further comprises: cooling the first stage initial neutralization reaction liquid to obtain the first stage neutralization reaction liquid; the temperature of the first stage initial neutralization reaction liquid before cooling is the temperature of the first stage neutralization reaction. After cooling, the temperature of the first stage neutralization reaction liquid is preferably 30-35°C, specifically 30-32°C, 31-33°C or 32-35°C in the embodiment. The cooling is carried out under stirring, and the stirring speed of the cooling is preferably 200-260r / min, specifically 240r / min, 220r / min or 200r / min in the embodiment, and the time is preferably 30-60min.

[0044] After obtaining the first-stage neutralization reaction liquid, inject fluoroniobic acid solution and ammonia water into the first-stage neutralization reaction liquid at the same time to carry out the second-stage neutralization reaction to obtain the second-stage neutralization reaction liquid; during the second-stage neutralization reaction: the flow rate of the fluoroniobic acid solution is ≤22L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40g / L, the flow rate of the ammonia water is ≤18L / min, the mass percentage of the ammonia water is 15-18%, the second-stage neutralization reaction is carried out under stirring conditions, the stirring speed of the second-stage neutralization reaction is ≤200r / min, and the stirring speed of the second-stage neutralization reaction is less than the stirring speed of the first-stage neutralization reaction; the pH value of the second-stage neutralization reaction liquid is 9-10. In the present invention, the fluoroniobic acid solution is preferably an aqueous solution of fluoroniobic acid. The flow rate of the fluoroniobic acid solution is preferably 20-22L / min, and specifically 20L / min or 22L / min in the embodiment. The mass concentration of fluoroniobic acid in the fluoroniobic acid solution is preferably 40-60 g / L, and specifically 40 g / L, 50 g / L or 60 g / L in the embodiments. The flow rate of the ammonia water is 15-18 L / min, and specifically 15 L / min, 17 L / min or 18 L / min in the embodiments. The mass percentage of the ammonia water is 15-18%, and specifically 15%, 16% or 18% in the embodiments. The stirring speed of the second stage neutralization reaction is 160-200 r / min, and specifically 160 r / min, 180 r / min or 200 r / min in the embodiments. The temperature of the second stage neutralization reaction is preferably 30-35°C, and specifically 30-32°C, 31-33°C or 32-35°C in the embodiments. The pH value of the second stage neutralization reaction liquid is specifically 10.

[0045] After obtaining the second stage neutralization reaction liquid, the second stage neutralization reaction liquid is aged to obtain an aged neutralization reaction liquid. In the present invention, the aging is carried out under stirring, and the stirring speed of the aging is preferably 160 to 200 r / min, and in the embodiment, it is specifically 160 r / min, 180 r / min or 200 r / min. The aging time is preferably 1 to 1.5 h, and in the embodiment, it is specifically 1 h, 1.2 h or 1.5 h.

[0046] After obtaining the aged neutralization reaction liquid, the present invention separates the aged neutralization reaction liquid into solid and liquid to obtain a wet niobium hydroxide solid, and sequentially washes and dries the wet niobium hydroxide solid to obtain a dry niobium hydroxide solid. In the present invention, the number of washings is preferably 2 to 6 times, and specifically 6 times in the embodiment. Each washing preferably includes the following steps: mixing the solid product to be washed with water, and then injecting ammonia water into the mixed system until the pH value of the solution is 9 to 10, specifically 9 in the embodiment, to obtain a mixed slurry; stirring and washing the mixed slurry, and then solid-liquid separation to obtain a washed solid product. In the present invention, the flow rate of ammonia water used for washing is preferably 13 to 16 L / min, and specifically 15 L / min in the embodiment. The mass percentage of ammonia water is preferably 15 to 22%, and specifically 22% in the embodiment. The stirring washing time is preferably 30 to 40 min, and specifically 30 min in the embodiment; the stirring washing speed is preferably 160 to 200 r / min, and specifically 200 r / min in the embodiment. The specific implementation of the drying is preferably drying, and the drying temperature is preferably 90-130°C, and in the embodiment, it is specifically 110°C, 120°C or 100°C. The drying is preferably carried out in an electric heating box. The heat preservation time of the drying is preferably 10-20h, and in the embodiment, it is specifically 14h, 15h or 16h.

[0047] After obtaining the dry niobium hydroxide solid, the present invention sequentially calcines and screens the dry niobium hydroxide solid to obtain the niobium oxide. In the present invention, the calcination is preferably carried out in a calcining furnace, and the calcination temperature is preferably 1000-1200°C, specifically 1100°C or 1000°C in the embodiment; the time is preferably 6-9h, specifically 9h, 8h or 7h in the embodiment. The mesh size of the sieve preferably used for the screening is preferably 100 mesh and 300 mesh, and the screening preferably takes the 100 mesh undersize and the 300 mesh oversize to obtain the niobium oxide.

[0048] The present invention provides niobium oxide prepared by the preparation method described in the above technical solution.

[0049] In the present invention, the morphology of the niobium oxide is spherical, and the niobium-to-sintering ratio of the niobium oxide is ≥1 g / cm 3 , preferably 1 to 1.5 g / cm 3 , specifically 1.5 g / cm 3 , 1.4g / cm 3 or 1.3 g / cm 3 .

[0050] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0051] The fluoroniobic acid solution in the following examples is an aqueous solution of fluoroniobic acid.

[0052] Example 1

[0053] (1) preparing 4000 L of 60 g / L fluoroniobate solution, 3000 L of 22% ammonia water, and 1875 L of 15% ammonia water as raw material solutions;

[0054] (2) Fluoniobic acid solution with a mass concentration of 60g / L and ammonia water with a mass percentage of 22% are added to the neutralization tank by a peristaltic pump, and stirring is started at a stirring speed of 240r / min. Fluoniobic acid solution and ammonia water are added at flow rates of 50L / min and 40L / min, respectively, and the temperature is 42-45°C. The first stage neutralization reaction consumes 1500L of fluoniobic acid solution and 1200L of ammonia water. The pH value of the first stage neutralization reaction solution is 3. Stop adding fluoniobic acid solution and ammonia water, continue stirring for 60min to lower the solution temperature, and obtain the first stage neutralization reaction solution (temperature is 30-32°C). The first stage neutralization reaction is completed.

[0055] After the first stage of neutralization reaction is completed, fluoroniobic acid solution and ammonia water are continuously added to the first stage of neutralization reaction liquid, the stirring speed is 160r / min, the mass percentage of ammonia water is 15%, the flow rates are 20L / min and 15L / min respectively, and the temperature is 30-32°C. The second stage of neutralization reaction consumes 2500L of fluoroniobic acid solution and 1875L of ammonia water. The pH value of the second stage of neutralization reaction solution is 10, and the addition of fluoroniobic acid solution and ammonia water is stopped. The stirring is continued for 1.5h to complete the reaction, and the second stage of neutralization reaction liquid is obtained. Niobium hydroxide precipitate is generated in the second stage of neutralization reaction;

[0056] (3) Washing: After solid-liquid separation of the second-stage neutralization reaction solution (i.e., niobium hydroxide slurry) obtained in step (2), wet niobium hydroxide solid is obtained, and 6m 3 of room temperature pure water, start stirring at a stirring speed of 200r / min. Then add ammonia water with a mass percentage of 22%, and the flow rate of ammonia water addition is 15L / min. The pH value of the test solution is 9, stop adding ammonia water, continue to stir the slurry for 30min, and obtain niobium hydroxide solid after solid-liquid separation. After the first washing is completed, repeat the above washing operation, and after washing 5 times, obtain the washed wet niobium hydroxide solid;

[0057] (4) Drying: The wet niobium hydroxide obtained in step (3) is placed in an electric heating box at a temperature of 100° C. for drying for 14 hours to obtain dry niobium hydroxide;

[0058] (5) Calcination: The dry niobium hydroxide obtained in step (4) is placed in a calcining furnace at a furnace temperature of 1000° C. for a calcining time of 7 h. The obtained niobium oxide is sieved to a mesh size of 100 mesh and 300 mesh. The niobium oxide in the middle layer of 100 mesh to 300 mesh is the final high-bulk ratio niobium oxide product. The bulk ratio of the niobium oxide is 1.5 g / cm2 when the sample is analyzed. 3 .

[0059] Example 2

[0060] (1) preparing 4000 L of fluoroniobate solution with a mass concentration of 50 g / L, 3000 L of ammonia water with a mass percentage of 23%, and 1875 L of ammonia water with a mass percentage of 16% as raw material solutions;

[0061] (2) Fluoniobic acid solution with a mass concentration of 50 g / L and ammonia water with a mass percentage of 23% were added to the neutralization tank by a peristaltic pump, and stirring was started at a stirring speed of 220 r / min. Fluoniobic acid solution and ammonia water were added at a flow rate of 45 L / min and 35 L / min, respectively, and the temperature was 40-43°C. The first stage neutralization reaction consumed 1500 L of fluoniobic acid solution and 1200 L of ammonia water. The pH value of the first stage neutralization reaction solution was 3. The addition of fluoniobic acid solution and ammonia water was stopped, and stirring was continued for 40 minutes to reduce the solution temperature, and the first stage neutralization reaction solution (temperature was 31-33°C) was obtained. The first stage neutralization reaction was completed.

[0062] After the first stage of neutralization reaction is completed, the fluoroniobic acid solution and ammonia water are continuously added to the first stage of neutralization reaction liquid, the stirring speed is 180r / min, the mass percentage of ammonia water is 16%, the flow rates are 22L / min and 17L / min respectively, and the temperature is 31-33°C. The second stage of neutralization reaction consumes 2500L of fluoroniobic acid solution and 1875L of ammonia water. The pH value of the second stage of neutralization reaction solution is tested to be 10, and the addition of fluoroniobic acid solution and ammonia water is stopped. The stirring is continued for 1.2h to complete the reaction, and the second stage of neutralization reaction liquid is obtained. Niobium hydroxide precipitate is formed in the second stage of neutralization reaction.

[0063] (3) Washing: After solid-liquid separation of the second-stage neutralization reaction solution (i.e., niobium hydroxide slurry) obtained in step (2), wet niobium hydroxide solid is obtained, and 6m 3 of room temperature pure water, start stirring at a stirring speed of 200r / min. Then add ammonia water with a mass percentage of 22%, and the flow rate of ammonia water addition is 15L / min. The pH value of the test solution is 9, stop adding ammonia water, continue to stir the slurry for 30min, and obtain niobium hydroxide solid after solid-liquid separation. After the first washing is completed, repeat the above washing operation, and after washing 5 times, obtain the washed wet niobium hydroxide solid;

[0064] (4) Drying: The wet niobium hydroxide obtained in step (3) is placed in an electric heating box at a temperature of 110° C. for drying for 15 hours to obtain dry niobium hydroxide;

[0065] (5) Calcination: The dry niobium hydroxide obtained in step (4) is placed in a calcining furnace at a furnace temperature of 1100° C. for 8 hours. The obtained niobium oxide is sieved to 100 mesh and 300 mesh. The niobium oxide in the middle layer of 100 mesh to 300 mesh is the final high-bulk ratio niobium oxide product. The bulk ratio of the niobium oxide is 1.4 g / cm2 after sample analysis. 3 .

[0066] Example 3

[0067] (1) preparing 4000 L of fluoroniobate solution with a mass concentration of 40 g / L, 3000 L of ammonia water with a mass percentage of 25%, and 1875 L of ammonia water with a mass percentage of 18% as raw material solutions;

[0068] (2) Fluoniobic acid solution with a mass concentration of 40g / L and ammonia water with a mass percentage of 25% are added to the neutralization tank by a peristaltic pump, and stirring is started at a stirring speed of 200r / min. Fluoniobic acid solution and ammonia water are added at a flow rate of 40L / min and 30L / min respectively, and the temperature is 42-45°C. The first stage neutralization reaction consumes 1500L of fluoniobic acid solution and 900L of ammonia water. The pH value of the first stage neutralization reaction solution is 3. Stop adding fluoniobic acid solution and ammonia water, continue stirring for 30min to reduce the solution temperature, and obtain the first stage neutralization reaction solution (temperature is 32-35°C), and the first stage neutralization reaction is completed.

[0069] After the first stage of neutralization reaction is completed, the fluoroniobic acid solution and ammonia water are continuously added to the first stage of neutralization reaction liquid, the stirring speed is 200r / min, the mass percentage of ammonia water is 18%, the flow rates are 22L / min and 18L / min respectively, and the temperature is 32-35°C. The second stage of neutralization reaction consumes 2500L of fluoroniobic acid solution and 1875L of ammonia water. The pH value of the second stage of neutralization reaction solution is 10 when tested. The addition of fluoroniobic acid solution and ammonia water is stopped, and stirring is continued for 1.5h until the reaction is complete to obtain the second stage of neutralization reaction liquid. Niobium hydroxide precipitate is formed in the second stage of neutralization reaction.

[0070] (3) Washing: After solid-liquid separation of the second-stage neutralization reaction solution (i.e., niobium hydroxide slurry) obtained in step (2), wet niobium hydroxide solid is obtained, and 6m 3of room temperature pure water, start stirring at a stirring speed of 200r / min. Then add ammonia water with a mass percentage of 22%, and the flow rate of ammonia water addition is 15L / min. The pH value of the test solution is 9, stop adding ammonia water, continue to stir the slurry for 30min, and obtain niobium hydroxide solid after solid-liquid separation. After the first washing is completed, repeat the above washing operation, and after washing 5 times, obtain the washed wet niobium hydroxide solid;

[0071] (4) Drying: The wet niobium hydroxide obtained in step (3) is placed in an electric heating box at a temperature of 120° C. for drying for 16 hours to obtain dry niobium hydroxide;

[0072] (5) Calcination: The dry niobium hydroxide obtained in step (4) is placed in a calcining furnace at a furnace temperature of 1100° C. for a calcining time of 9 hours. The obtained niobium oxide is sieved to a mesh size of 100 mesh and 300 mesh. The niobium oxide in the middle layer of 100 mesh to 300 mesh is the final high-bulk ratio niobium oxide product. The bulk ratio of the niobium oxide is 1.3 g / cm2 when the sample is analyzed. 3 .

[0073] Comparative Example 1

[0074] (1) preparing a 60 g / L fluoroniobate solution and 22% ammonia water as raw material solutions;

[0075] (2) Fluoniobic acid solution with a mass concentration of 60g / L and ammonia water with a mass percentage of 22% are added to the neutralization tank by a peristaltic pump, and stirring is started at a stirring speed of 240r / min. Fluoniobic acid solution and ammonia water are added at a flow rate of 50L / min and 40L / min respectively, and the temperature is 42-45°C. When the pH value of the neutralization reaction solution is tested to be 10, the addition of fluoniobic acid solution and ammonia water is stopped, and stirring is continued for 1h until the reaction is complete to obtain a neutralization reaction solution, and niobium hydroxide precipitation is generated in the neutralization reaction;

[0076] According to step (3), step (4) and step (5) in Example 1, niobium oxide was obtained, and the bulk ratio of the obtained product was 0.69 g / cm 3 .

[0077] Comparative Example 1 Compared with Example 1, the bulk ratio of the obtained niobium oxide product is significantly reduced by changing the operating method in step (2) in the comparative example.

[0078] Comparative Example 2

[0079] (1) preparing 4000 L of 60 g / L fluoroniobate solution, 3000 L of 22% ammonia water, and 1875 L of 15% ammonia water as raw material solutions;

[0080] (2) Fluoniobic acid solution with a mass concentration of 60g / L and ammonia water with a mass percentage of 22% are added to the neutralization tank by a peristaltic pump, and stirring is started at a stirring speed of 240r / min. Fluoniobic acid solution and ammonia water are added at flow rates of 50L / min and 40L / min, respectively, and the temperature is 55-60°C. The first stage neutralization reaction consumes 1500L of fluoniobic acid solution and 1200L of ammonia water. The pH value of the first stage neutralization reaction solution is 3. Stop adding fluoniobic acid solution and ammonia water, continue stirring for 60min to lower the solution temperature, and obtain the first stage neutralization reaction solution (temperature is 30-32°C). The first stage neutralization reaction is completed.

[0081] After the first stage of neutralization reaction is completed, fluoroniobic acid solution and ammonia water are continuously added to the first stage of neutralization reaction liquid, the stirring speed is 160r / min, the mass percentage of ammonia water is 15%, the flow rate is 20L / min, 15L / min, and the temperature is 30-32°C. The second stage of neutralization reaction consumes 2500L of fluoroniobic acid solution and 1875L of ammonia water. The pH value of the second stage of neutralization reaction solution is 10, and the addition of fluoroniobic acid solution and ammonia water is stopped. The stirring is continued for 1.5h to complete the reaction, and niobium hydroxide precipitate is generated in the second stage of neutralization reaction;

[0082] According to step (3), step (4) and step (5) in Example 1, niobium oxide was obtained, and the bulk ratio of the obtained product was 0.78 g / cm 3 .

[0083] Compared with Example 1, in Comparative Example 2, the temperature of the first stage neutralization reaction in step (2) was changed from 42-45° C. in Example 1 to 55-60° C., and the bulk ratio of the obtained niobium oxide product was significantly reduced.

[0084] Comparative Example 3

[0085] The preparation method is basically the same as that in Example 1, except that: in the first stage of the neutralization reaction in step (2), the flow rates of the fluoroniobic acid solution and the ammonia water are 40 L / min and 50 L / min respectively, and the final bulk ratio of the niobium oxide product is 0.85 g / cm 3 The bulk ratio of the obtained niobium oxide product is significantly reduced.

[0086] Comparative Example 4

[0087] The preparation method is basically the same as that in Example 1, except that: in the second stage of the neutralization reaction in step (2), the flow rates of the fluoroniobic acid solution and the ammonia water are 22 L / min and 25 L / min, respectively, and the bulk ratio of the finally obtained niobium oxide product is 0.75 g / cm 3 The bulk ratio of the obtained niobium oxide product is significantly reduced.

[0088] From the above examples, it can be seen that the preparation method provided by the present invention adopts a two-stage neutralization method. In the first stage of the neutralization reaction process, high-concentration ammonia water is added and rapid stirring is controlled to rapidly nucleate the niobium hydroxide crystal nucleus; in the second stage of the neutralization reaction process, low-concentration ammonia water is added and slow stirring is controlled to allow the niobium hydroxide to continue to grow slowly on the initial nucleus. Therefore, the present invention strictly controls the nucleation and growth process of niobium hydroxide, and then washes, dries, calcines and screens to prepare niobium oxide with a large pine ratio, uniform morphology, and easy mechanical operation; and the preparation method provided by the present invention is simple to operate, has a stable process, and is suitable for industrial production and application.

[0089] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing niobium oxide, characterized in that: The following steps are involved: (1) subjecting the fluoroniobic acid solution and aqueous ammonia to a first-stage neutralization reaction to obtain a first-stage neutralization reaction solution; During the first stage of neutralization reaction: the flow rate of the fluoroniobic acid solution is ≥40 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40 g / L, the flow rate of the ammonia water is ≥30 L / min, the mass percentage of the ammonia water is 22-25%, the first stage of neutralization reaction is carried out under stirring, and the stirring speed of the first stage of neutralization reaction is ≥200 r / min; the pH value of the first stage of neutralization reaction liquid is 3-4; (2) injecting fluoroniobate solution and ammonia water into the first-stage neutralization reaction liquid at the same time to carry out a second-stage neutralization reaction to obtain a second-stage neutralization reaction liquid; During the second stage of neutralization reaction: the flow rate of the fluoroniobic acid solution is ≤22L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is ≥40g / L, the flow rate of the aqueous ammonia is ≤18L / min, the mass percentage of the aqueous ammonia is 15-18%, the second stage of neutralization reaction is carried out under stirring conditions, the stirring speed of the second stage of neutralization reaction is ≤200r / min, and the stirring speed of the second stage of neutralization reaction is less than the stirring speed of the first stage of neutralization reaction; the pH value of the second stage of neutralization reaction liquid is 9-10; (3) aging the second-stage neutralization reaction liquid to obtain an aged neutralization reaction liquid; (4) separating the aged neutralization reaction liquid into solid and liquid to obtain a wet niobium hydroxide solid, and washing and drying the wet niobium hydroxide solid in sequence to obtain a dry niobium hydroxide solid; (5) calcining and sieving the dry niobium hydroxide solid in sequence to obtain the niobium oxide.

2. The preparation method according to claim 1, characterized in that: In step (1), the flow rate of the fluoroniobic acid solution is 40 to 50 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is 40 to 60 g / L, and the flow rate of the ammonia water is 30 to 40 L / min; The stirring speed of the neutralization reaction in the first stage is 200-260 r / min.

3. The preparation method according to claim 1 or 2, characterized in that: The temperature of the first stage neutralization reaction is 40-45°C.

4. The preparation method according to claim 1, characterized in that: The first stage neutralization reaction directly obtains the first stage initial neutralization reaction liquid; After obtaining the first-stage initial neutralization reaction liquid, the method further includes: cooling the first-stage initial neutralization reaction liquid to obtain the first-stage neutralization reaction liquid; The temperature of the initial neutralization reaction liquid in the first stage is 40-45°C, the temperature of the neutralization reaction liquid in the first stage is 30-35°C, the cooling is carried out under stirring, the stirring speed of the cooling is 200-260r / min, and the time is 30-60min.

5. The preparation method according to claim 1, characterized in that: In step (2), the flow rate of the fluoroniobic acid solution is 20 to 22 L / min, the mass concentration of fluoroniobic acid in the fluoroniobic acid solution is 40 to 60 g / L, and the flow rate of the ammonia water is 15 to 18 L / min; The stirring speed of the second stage neutralization reaction is 160-200 r / min.

6. The preparation method according to claim 1 or 5, characterized in that: The temperature of the second stage neutralization reaction is 30-35°C.

7. The preparation method according to claim 1, characterized in that: The aging is carried out under stirring conditions, the stirring speed of the aging is 160-200 r / min, and the time is 1-1.5 h.

8. The preparation method according to claim 1, characterized in that: The washing is performed 2 to 6 times, and each washing comprises the following steps: mixing the solid product to be washed with water, and then injecting ammonia water into the obtained mixed system until the pH value of the solution is 9 to 10 to obtain a mixed slurry; stirring and washing the mixed slurry, and then performing solid-liquid separation to obtain a washed solid product; the flow rate of ammonia water used in the washing is 13 to 16 L / min, and the mass percentage of ammonia water is 15 to 22%; the stirring washing time is 30 to 40 minutes, and the stirring washing speed is 160 to 200 r / min; The drying temperature is 90-130°C.

9. The preparation method according to claim 1, characterized in that: The calcination temperature is 1000-1200°C and the time is 6-9h; The mesh sizes of the sieves used in the screening are 100 mesh and 300 mesh, and the screening takes the 100 mesh undersize and the 300 mesh oversize to obtain the niobium oxide.

10. Niobium oxide prepared by the preparation method according to any one of claims 1 to 9.

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