Preparation method of niobium hydroxide and preparation method of niobium oxalate

Abstract

The invention belongs to the technical field of niobium metallurgy, and particularly relates to a preparation method of niobium hydroxide and a preparation method of niobium oxalate. The invention provides a preparation method of niobium hydroxide, which comprises the following steps: mixing a fluoxyniobic acid solution and a precipitator for precipitation reaction to obtain niobium hydroxide slurry; the precipitator comprises one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is greater than or equal to 9; the niobium hydroxide slurry is aged, and aged niobium hydroxide slurry is obtained; and carrying out solid-liquid separation on the aged niobium hydroxide slurry to obtain a solid product, and sequentially washing and drying the solid product to obtain niobium hydroxide. According to the present invention, the suitable precipitating agent (one or more of ammonia water, liquid ammonia and ammonia gas) is selected to perform the precipitation reaction, and the pH value of the reaction endpoint is controlled so as to achieve the good physical property consistency of the niobium hydroxide product obtained after aging;

Description

Technical Field

[0001] The invention belongs to the technical field of niobium metallurgy, and in particular relates to a method for preparing niobium hydroxide and a method for preparing niobium oxalate. Background Art

[0002] Niobium oxalate is a new type of petroleum catalyst with the advantages of low cost, good catalytic effect, and low environmental pollution, and is known as a "green catalyst". As a catalyst, niobium oxalate has begun to show its advantages in environmental protection, catalytic activity, catalytic cycle, etc., and is widely used. In addition, adding niobium oxalate in the production process of dielectric materials can make electronic components have lower electrical loss, higher magnetic permeability, and smaller size, which can greatly improve the performance of electronic components.

[0003] The related art discloses the use of niobium precursors, such as niobic acid or niobium ethanol, to react with oxalic acid solution to produce niobium oxalate. It is proposed that there are many types of niobium precursors to choose from, including: niobium pentoxide, hydrous niobium oxide, potassium niobate, calcium niobate, potassium fluoroniobate, sodium fluoroniobate, niobium sulfate, niobium acid or niobium alkoxide, etc. However, the niobium oxalate products obtained by the above technology have low purity and poor product quality. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing niobium hydroxide and a method for preparing niobium oxalate. The method provided by the present invention uses niobium hydroxide as a raw material, and the prepared niobium oxalate has high purity and good product quality.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing niobium hydroxide, comprising the following steps:

[0007] The fluorooxyniobate solution and a precipitant are mixed to perform a precipitation reaction to obtain a niobium hydroxide slurry; the precipitant comprises one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is ≥9;

[0008] Aging the niobium hydroxide slurry to obtain aged niobium hydroxide slurry;

[0009] The aged niobium hydroxide slurry is separated into solid and liquid to obtain a solid product, and the solid product is washed and dried in sequence to obtain the niobium hydroxide.

[0010] Preferably, the mass concentration of Nb2O5 converted in the fluoroniobate acid solution is 80 to 200 g / L, calculated as Nb2O5.

[0011] Preferably, the precipitant is calculated based on the converted NH3, and the ratio of the mass of Nb2O5 converted from the fluoroniobate solution to the mass of NH3 converted from the precipitant is 0.9 to 0.95:1.

[0012] Preferably, the precipitant is ammonia water, the mass percentage of which is 15-20%, and the mixing is as follows: adding the ammonia water to the fluoroniobate solution, the flow rate of which is 2-6 m / s. 3 / h.

[0013] Preferably, the precipitation reaction time is 0.4 to 2 hours; the precipitation reaction is carried out under stirring conditions, and the stirring speed of the precipitation reaction is 100 to 150 r / min.

[0014] Preferably, the aging time is 10 to 15 minutes; the aging is carried out under stirring conditions, and the rotation speed of the aging stirring is 80 to 100 r / min.

[0015] Preferably, the reagent used for the water washing is an ammonia solution, and the pH value of the ammonia solution is 10-11.

[0016] Preferably, the drying temperature is 100±10° C. and the drying time is 24 to 36 hours.

[0017] The present invention provides a method for preparing niobium oxalate, comprising the following steps:

[0018] Niobium hydroxide is prepared according to the preparation method described in the above technical scheme;

[0019] Mixing the niobium hydroxide, oxalic acid and water to obtain a mixed solution;

[0020] The mixed solution is cooled and crystallized to obtain the niobium oxalate.

[0021] Preferably, the mixing temperature is 75-85° C., and the mass ratio of oxalic acid to niobium hydroxide is 2-3:1.

[0022] The present invention provides a method for preparing niobium hydroxide, comprising the following steps: mixing a fluoroniobic acid solution and a precipitant for precipitation reaction to obtain niobium hydroxide slurry; the precipitant comprises one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is ≥9; aging the niobium hydroxide slurry to obtain aged niobium hydroxide slurry; solid-liquid separation of the aged niobium hydroxide slurry to obtain a solid product, and sequentially washing and drying the solid product to obtain the niobium hydroxide. The present invention selects a suitable precipitant (one or more of ammonia water, liquid ammonia and ammonia gas) for precipitation reaction, and at the same time, by controlling the pH value at the reaction end point, the niobium hydroxide product obtained after aging has good physical property consistency (good consistency in the present invention means that the niobium hydroxide product has high activity, fast dissolution speed in oxalic acid solution, short dissolution time, small ignition fluctuation, and its impurity content is within 10ppmm, and the ignition is within 1000ppm).

[0023] Furthermore, in the present invention, the drying temperature is 100±10° C. and the drying time is 24 to 36 hours. The preparation method of niobium hydroxide provided by the present invention adopts low-temperature drying, which generally reduces the energy consumption of niobium hydroxide.

[0024] The present invention provides a method for preparing niobium oxalate, comprising the following steps: preparing niobium hydroxide according to the preparation method described in the above technical solution; mixing the niobium hydroxide, oxalic acid and water to obtain a mixed solution; cooling and crystallizing the mixed solution to obtain the niobium oxalate. The niobium hydroxide prepared in the present invention can be quickly dissolved in a hot oxalic acid solution (a solution of oxalic acid and water), and the prepared niobium oxalate has high purity and good product quality. At the same time, the preparation method of niobium oxalate provided by the present invention has a short production cycle and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a physical picture of niobium hydroxide prepared in Example 1 of the present invention;

[0026] Figure 2 This is a physical picture of niobium oxalate prepared using the niobium hydroxide prepared in Example 1 as a raw material. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing niobium hydroxide, comprising the following steps:

[0028] The fluorooxyniobate solution and a precipitant are mixed to perform a precipitation reaction to obtain a niobium hydroxide slurry; the precipitant comprises one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is ≥9;

[0029] Aging the niobium hydroxide slurry to obtain aged niobium hydroxide slurry;

[0030] The aged niobium hydroxide slurry is separated into solid and liquid to obtain a solid product, and the solid product is washed and dried in sequence to obtain the niobium hydroxide.

[0031] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0032] The present invention mixes a fluoroniobic acid solution and a precipitant to perform a precipitation reaction to obtain a niobium hydroxide slurry; the precipitant includes one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is ≥9. In the present invention, the fluoroniobic acid solution is preferably an aqueous solution of fluoroniobic acid. The molar concentration of HF in the fluoroniobic acid solution is ≤7 mol / L based on the acidity of HF acid. The mass concentration of Nb2O5 converted in the fluoroniobic acid solution is preferably 80 to 200 g / L, specifically 80 g / L, 90 g / L or 100 g / L in the embodiment. The precipitant is calculated as converted NH3, and the ratio of the mass of Nb2O5 converted in the fluoroniobic acid solution to the mass of NH3 converted by the precipitant is preferably 0.9 to 0.95:1. The precipitant is preferably ammonia water, and the mass percentage of ammonia water is preferably 15 to 20%. The mixing is preferably: adding the ammonia water into the fluoroniobate solution, and the flow rate of the ammonia water is preferably 2 to 6 m / s. 3 / h, specifically 3m 3 / h or 2m 3 / h. The precipitation reaction time is preferably 0.4 to 2h, and the precipitation reaction time is calculated from the time when the fluoroniobic acid solution and the precipitant come into contact. In a specific embodiment of the present invention, the precipitation reaction time is the time when the fluoroniobic acid solution and the precipitant are mixed. The precipitation reaction is preferably carried out under stirring, and the stirring speed of the precipitation reaction is preferably 100 to 150r / min.

[0033] After obtaining the niobium hydroxide slurry, the present invention ages the niobium hydroxide slurry to obtain aged niobium hydroxide slurry. In the present invention, the aging time is preferably 10 to 15 minutes; the aging is preferably carried out under stirring conditions, and the aging stirring speed is preferably 80 to 100 r / min.

[0034] After obtaining the aged niobium hydroxide slurry, the present invention performs solid-liquid separation of the aged niobium hydroxide slurry to obtain a solid product, and sequentially washes and dries the solid product to obtain the niobium hydroxide. In the present invention, the solid-liquid separation is preferably performed in a plate-frame filter. The reagent used in the water washing is preferably an ammonia solution, and the pH value of the ammonia solution is 10-11. In the present invention, the specific implementation of the water washing is preferably conditioning washing, and the water washing is performed until the fluorine content in the obtained washing liquid is preferably 0.1-0.2 g / L. After the water washing, the present invention preferably performs solid-liquid separation of the washed slurry in a horizontal plate-frame machine to obtain a washed solid product. The present invention preferably dries the washed solid product to obtain the niobium hydroxide. The drying is preferably performed in a drying oven, and the drying temperature is preferably 100±10°C, and in the embodiment, it is specifically 90°C, 100°C or 110°C; the drying time is preferably 24-36h, and in the embodiment, it is specifically 24h, 30h or 36h. After the drying, the present invention preferably crushes and sieves the niobium hydroxide in sequence. The present invention has no special requirements on the specific implementation of the crushing. The sieve used for the sieving is preferably a 40-mesh sieve.

[0035] The niobium hydroxide prepared by the preparation method of the present invention has good consistency. In the present invention, good consistency means that the niobium hydroxide product has high activity, fast dissolution speed in oxalic acid solution, short dissolution time and small fluctuation of burning loss. The impurity content of the niobium hydroxide prepared by the present invention is within 10ppmm, and the burning loss is within 1000ppm.

[0036] The present invention provides a method for preparing niobium oxalate, comprising the following steps:

[0037] Niobium hydroxide is prepared according to the preparation method described in the above technical scheme;

[0038] Mixing the niobium hydroxide, oxalic acid and water to obtain a mixed solution;

[0039] The mixed solution is cooled and crystallized to obtain the niobium oxalate.

[0040] The present invention prepares niobium hydroxide according to the preparation method described in the above technical scheme.

[0041] After obtaining niobium hydroxide, the present invention mixes the niobium hydroxide, oxalic acid and water to obtain a mixed solution. In the present invention, the mixing of the niobium hydroxide, oxalic acid and water preferably includes the following steps: dissolving the oxalic acid solvent in water to obtain an oxalic acid aqueous solution; heating the oxalic acid aqueous solution to obtain a hot oxalic acid solution; dissolving the niobium hydroxide in the hot oxalic acid solution. In the present invention, the mass ratio of the oxalic acid to the niobium hydroxide is preferably 2 to 3:1. The mass ratio of the oxalic acid to the water is preferably 0.6 to 0.7:1. The temperature of the mixing is preferably 75 to 85°C, specifically 80°C in the embodiment. In the present invention, the temperature of the mixing is the temperature of the hot oxalic acid solution. In a specific embodiment of the present invention, the time for the niobium hydroxide to dissolve in the hot oxalic acid solution is preferably 15 to 20 minutes, indicating that the niobium hydroxide prepared by the present invention can be quickly dissolved in the hot oxalic acid solution.

[0042] After obtaining the mixed solution, the present invention cools the mixed solution for crystallization to obtain the niobium oxalate. In the present invention, the cooling crystallization preferably includes: passing cooling water into the mixed solution, and the temperature of the cooling water is preferably 20°C. The cooling crystallization obtains a crystallization liquid; the present invention preferably separates the crystallization liquid into a solid-liquid separation to obtain a crystalline solid product; and the crystalline solid product is dried to obtain the niobium oxalate. In the present invention, the drying is specifically drying, and the drying temperature is preferably 80 to 100°C.

[0043] The yield of niobium oxalate prepared by the present invention is 45-50%, and the purity is ≥99%, and in the embodiment, it is 99-99.5%.

[0044] 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.

[0045] Example 1

[0046] (1) Place 1.2 m 3 Add pure water to a 200 g / L (converted niobium oxide) fluoroniobate solution to dilute it to a 80 g / L niobium oxide concentration, and start stirring.

[0047] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 3m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0048] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation through a plate and frame to obtain a filter cake. The filter cake is used as 36m 3 Washing with an ammonia solution (pH 10-11) until the fluorine content of the solution is adjusted to 0.1-0.2 g / L, and then pumping into a horizontal plate frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0049] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 90° C. for a drying time of 36 h to obtain dry niobium hydroxide;

[0050] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0051] Example 2

[0052] (1) Place 1.2 m 3 Add pure water to a 200 g / L (converted niobium oxide) fluoroniobate solution to dilute it to a 90 g / L niobium oxide concentration, and start stirring.

[0053] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 3m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0054] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation through a plate and frame to obtain a filter cake. The filter cake is used as 36m 3 Washing with an ammonia solution (pH 10-11) until the fluorine content of the solution is adjusted to 0.1-0.2 g / L, and then pumping into a horizontal plate frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0055] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 100° C. for a drying time of 30 h to obtain dry niobium hydroxide;

[0056] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0057] Example 3

[0058] (1) Place 1.2 m 3 Add pure water to a 200 g / L (converted niobium oxide) fluoroniobate solution to dilute it to a 100 g / L niobium oxide concentration, and start stirring.

[0059] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 2m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0060] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation through a plate and frame to obtain a filter cake. The filter cake is used as 36m 3 Washing with an ammonia solution (pH 10-11) until the fluorine content of the solution is adjusted to 0.1-0.2 g / L, and then pumping into a horizontal plate frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0061] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 110° C. for a drying time of 24 h to obtain dry niobium hydroxide;

[0062] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0063] Comparative Example 1 (Compared with Example 3, the flow rate of ammonia water in step (2) is reduced)

[0064] (1) Place 1.2 m 3 Add pure water to a 200 g / L (converted niobium oxide) fluoroniobate solution to dilute it to a 100 g / L niobium oxide concentration, and start stirring.

[0065] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 0.75m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0066] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation through a plate and frame to obtain a filter cake. The filter cake is used as 36m 3 Washing with an ammonia solution (pH 10-11) until the fluorine content of the solution is adjusted to 0.1-0.2 g / L, and then pumping into a horizontal plate frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0067] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 110° C. for a drying time of 24 h to obtain dry niobium hydroxide;

[0068] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0069] Comparative Example 2 (Compared with Example 2, no dilution treatment was performed before the reaction)

[0070] (1) Place 1.2 m 3 A fluoroniobate solution with a mass concentration of 200 g / L (mass concentration of niobium oxide) was stirred;

[0071] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 3m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0072] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation by a plate and frame to obtain a filter cake, the filter cake is washed with an ammonia solution (pH value is 10-11) and adjusted to a fluorine content of 0.1-0.2 g / L in the solution, and then driven into a horizontal plate and frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0073] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 100° C. for a drying time of 30 h to obtain dry niobium hydroxide;

[0074] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0075] Comparative Example 3 (Comparison with Example 1)

[0076] (1) Place 1.2 m 3 Add pure water to a 200 g / L (converted to niobium oxide) fluoroniobate solution to dilute it to 80 g / L (converted to niobium oxide), start stirring, and heat the niobium solution to 60°C;

[0077] (2) Under continuous stirring at a speed of 100 to 150 r / min, 1.3 ml of 20% ammonia water was slowly injected into the reactor. 3 , the flow rate of ammonia water addition is 3m 3 / h. After the addition of ammonia water is completed, stirring is continued for 10 to 15 minutes at a stirring speed of 80 to 100 r / min to obtain aged niobium hydroxide slurry;

[0078] (3) The aged niobium hydroxide slurry obtained in step (2) is subjected to solid-liquid separation through a plate and frame to obtain a filter cake. The filter cake is used as 36m 3 Washing with an ammonia solution (pH 10-11) until the fluorine content of the solution is adjusted to 0.1-0.2 g / L, and then pumping into a horizontal plate frame for solid-liquid separation to obtain a washed niobium hydroxide filter cake;

[0079] (5) transferring the washed niobium hydroxide filter cake obtained in step (4) into a drying oven for drying at a temperature of 90° C. for a drying time of 36 h to obtain dry niobium hydroxide;

[0080] (6) The dry niobium hydroxide obtained in step (5) is crushed and passed through a 40-mesh sieve.

[0081] The impurities and ignition loss of the niobium hydroxide products prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in the table.

[0082] Table 1 Impurities and loss on ignition of niobium hydroxide products in Examples 1 to 3 and Comparative Examples 1 to 3

[0083] name Ta Cu Fe Sb Sn W Ca Ti Na <![CDATA[F - ]]> Si LOI Example 1 <2 <0.5 1 3.7 1.3 <0.5 <0.5 <0.5 <2 1195 <10 221800 Example 2 <2 <0.5 0.5 2.1 0.5 <0.5 <0.5 <0.5 <2 2669 <10 139300 Example 3 <2 <0.5 1.6 1.5 <0.5 <0.5 <0.5 <0.5 <2 2097 <10 118600 About Billy 1 <2 <0.5 1.5 <1 <0.5 <0.5 <0.5 <0.5 <2 3681 <10 107800 About Billy 2 <2 <0.5 0.5 <1 0.6 <0.5 <0.5 <0.5 <2 1648 <10 157800 About Billy 3 <2 <0.5 0.6 1.1 0.9 <0.5 <0.5 <0.5 <2 1244 <10 164300

[0084] Application Example 1

[0085] The niobium hydroxide prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3 was dissolved in a hot oxalic acid aqueous solution, and a mixed solution was obtained, and then cold water was passed through for cooling and crystallization, and the temperature of the cold water was 20° C. to obtain niobium oxalate, and then the crystals were dried at a temperature of 80-100° C. to finally obtain niobium oxalate. The mass of the niobium hydroxide prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, the temperature of the hot oxalic acid aqueous solution, the mass of oxalic acid in the oxalic acid aqueous solution, the mass of water, the dissolution time, and the yield and purity of the obtained niobium oxalate are shown in Table 2.

[0086] Table 2 Amount of raw materials used and product performance results in Application Example 1

[0087]

[0088] From the data in Table 2, it can be seen that the niobium hydroxide prepared in Examples 1 to 3 of the present invention is used as the preparation method of niobium oxalate, and the purity of the obtained niobium oxalate product is 99% to 99.5%, and the direct yield is 45% to 50%.

[0089] Compared with Example 3, in Comparative Example 1, the flow rate of ammonia water in step (2) in Comparative Example 1 is reduced, the dissolution time of niobium hydroxide is prolonged, and the purity of the final niobium oxalate product is reduced.

[0090] Comparative Example 2 is compared with Example 2. In Comparative Example 2, the fluoroniobic acid solution is not diluted before the reaction, the dissolution time of niobium hydroxide is prolonged, and the purity of the final niobium oxalate product is reduced.

[0091] Compared with Example 1, in Comparative Example 3, the diluted fluoroniobic acid solution was heated to 60° C. before the reaction. In Comparative Example 3, the initial temperature of the fluoroniobic acid solution before neutralization was increased, the dissolution time of niobium hydroxide was prolonged, and the purity of the obtained niobium oxalate product was reduced.

[0092] From the above examples, it can be seen that the method provided by the present invention uses ammonia water (ammonia gas, liquid ammonia) for neutralization, the flow rate and time are easy to control, the physical properties of the produced niobium hydroxide are consistent, and low-temperature drying is performed, which reduces energy consumption overall. The niobium hydroxide prepared in the present invention can be quickly dissolved in hot oxalic acid solution, the production cycle is short, the efficiency is high, and the blank of the niobium precursor production process in the synthesis and production of niobium oxalate is filled.

[0093] 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 hydroxide, characterized in that: The following steps are involved: The fluorooxyniobate solution and a precipitant are mixed to perform a precipitation reaction to obtain a niobium hydroxide slurry; the precipitant comprises one or more of ammonia water, liquid ammonia and ammonia gas, and the pH value of the niobium hydroxide slurry is ≥9; Aging the niobium hydroxide slurry to obtain aged niobium hydroxide slurry; The aged niobium hydroxide slurry is separated into solid and liquid to obtain a solid product, and the solid product is washed and dried in sequence to obtain the niobium hydroxide.

2. The preparation method according to claim 1, characterized in that: The mass concentration of Nb2O5 converted in the fluoroniobate solution is 80 to 200 g / L, calculated as Nb2O5.

3. The preparation method according to claim 1 or 2, characterized in that: The precipitant is calculated based on the converted NH3, and the ratio of the mass of Nb2O5 converted from the fluoroniobate solution to the mass of NH3 converted from the precipitant is 0.9 to 0.95:

1.

4. The preparation method according to claim 1, characterized in that: The precipitant is ammonia water, the mass percentage of which is 15-20%, and the mixing is as follows: adding the ammonia water into the fluoroniobate solution, the flow rate of which is 2-6 m / s. 3 / h.

5. The preparation method according to claim 1, characterized in that: The precipitation reaction time is 0.4 to 2 hours; the precipitation reaction is carried out under stirring conditions, and the stirring speed of the precipitation reaction is 100 to 150 r / min.

6. The preparation method according to claim 1, characterized in that: The aging time is 10 to 15 minutes; the aging is carried out under stirring conditions, and the rotation speed of the aging stirring is 80 to 100 r / min.

7. The preparation method according to claim 1, characterized in that: The reagent used for the water washing is an ammonia solution, and the pH value of the ammonia solution is 10-11.

8. The preparation method according to claim 1, characterized in that: The drying temperature is 100±10° C. and the drying time is 24 to 36 hours.

9. A method for preparing niobium oxalate, characterized in that: The following steps are involved: Niobium hydroxide is prepared according to the preparation method according to any one of claims 1 to 8; Mixing the niobium hydroxide, oxalic acid and water to obtain a mixed solution; The mixed solution is cooled and crystallized to obtain the niobium oxalate.

10. The preparation method according to claim 9, characterized in that: The mixing temperature is 75-85° C., and the mass ratio of the oxalic acid to niobium hydroxide is 2-3:1.

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