CN102442700A

CN102442700A - Method for preparing high-purity spherical niobium oxide through peroxidation precipitation

Info

Publication number: CN102442700A
Application number: CN2011102864033A
Authority: CN
Inventors: 张宗国; 徐忠亭; 张必灵; 张伟宁
Original assignee: GUANGDONG ZHIYUAN NEW MATERIALS CO Ltd
Current assignee: GUANGDONG ZHIYUAN NEW MATERIALS CO Ltd
Priority date: 2011-09-16
Filing date: 2011-09-16
Publication date: 2012-05-09

Abstract

A process for preparing high-purity spherical niobium oxide by peroxidation and precipitation includes such steps as adding hydrogen peroxide H₂O₂Adding the liquid ammonia into the fluoroxyniobate solution H₂NbOF₅In (4), ammonium niobate peroxide (NH) is obtained₄)₃NbO₈Crystallizing, and roasting at a controlled temperature to obtain the niobium oxide with the required phase state and the particle size of 0.3-1 mu m. The ammonium niobate crystal obtained in the precipitation process has no package, no adsorption, no inclusion and easy filtration, so the product has high purity under the same raw material and process conditions; roasting ammonium niobate at 150-1300 ℃ to obtain the fluorine-free niobium oxide, wherein the product is obviously spherical, and has uniform and consistent particles with the particle size of 0.3-1 mu m; according to application requirements, niobium oxide with different phases of alpha, beta and gamma can be obtained by controlling the roasting temperature. The method of the invention omits three procedures of washing, drying and grinding and screening, thereby saving a large amount of manpower, material resources and energy.

Description

Method for preparing high-purity spherical niobium oxide through peroxidation precipitation

Technical Field

The invention relates to a method for preparing spherical niobium oxide, in particular to a method for preparing high-purity spherical niobium oxide by adopting a peroxide precipitation process.

Background

The problem of controlling the optimal granularity of the niobium hydroxide precipitate is a great problem in the manufacturing technology of high-performance functional ceramics, belongs to the research and development of high and new technologies which are mainly supported by the nation, and is an important ring for meeting the requirements of high-capacity laminated ceramic capacitors and tantalum-niobium artificial crystals. The prior preparation process technology comprises the following steps: precipitating fluoroxyniobate solution obtained by solvent extraction with ammonia to obtain amorphous flocculent niobium hydroxide slurry (particle size of 1-3 μm), filtering, washing, and oven dryingAnd drying, roasting and grinding to obtain the niobium pentoxide. The precipitation reaction mechanism is as follows: h₂NbOF₅+5NH₃+4H₂O＝Nb(OH)₅↓+5NH₄F。

The niobium oxide produced by the process technology is divided into three grades according to different purities: namely industrial grade, optical glass grade, high purity grade. The industrial grade product is used for producing metal niobium by carbon reduction or used as a raw material of a ceramic capacitor, and the optical glass grade product is used for producing optical glass; the high-purity product is used for producing lithium niobate single crystals and further processing and manufacturing surface acoustic wave filters or optical communication devices.

The main problems in the existing niobium hydroxide precipitation technology are as follows: (1) the obtained precipitate is amorphous floccule or aggregate, coarse particles and low quality; (2) after precipitation and slurry filtration, the fluorine is washed with a large amount of deionized water, which nevertheless causes problems with the quality of the lithium niobate crystals from time to time. The main reasons for the above problems are:

1. the precipitation mode and the precipitation equipment. The world hydrometallurgy has less research on precipitation modes and precipitation equipment, so that the physical properties such as granularity of a precipitation product are guaranteed to have no mature scientific research results, and the supersaturation degree is not formed according to the material precipitation (1) solution; (2) generating crystal nucleus and growing the crystal nucleus; (3) and (3) designing a precipitation mode and selecting equipment according to a series of objective rules of precipitation growth and aging. Therefore, the product obtained by precipitation has large particles and small density, and is not suitable for the requirements of ceramic capacitor grade products (in 7 months of 1991, the technical society of Tokyo, Japan proposes the requirement of the average particle size of niobium oxide to be 0.32 μm for the first time according to the application of niobium oxide in a large-capacity laminated ceramic capacitor); in addition, the precipitates are easy to aggregate to form 'crystal clusters', and wrap the mother liquor, thereby influencing the purity of the final product.

2. Precipitation of niobium solution (H) with ammonia₂NbOF₅) Desired is NbO₅·NH₂O, ammonia fluoroniobate (NH) which can be practically obtained₄)NbOF₅Difficult to wash and obtain NbO by roasting₂F, thus creating Nb₂O₅Medium fluorine content, high in the drawingWhen the crystal is manufactured, fluorine bubbles are easy to generate, or the crystal is turbid.

Disclosure of Invention

The invention aims to produce spherical high-density and high-purity niobium oxide by adopting a peroxide precipitation technology so as to meet the requirements of a large-capacity laminated ceramic capacitor and an optical-grade lithium niobate single crystal.

According to the aim, the method for preparing the high-purity spherical niobium oxide by the peroxide precipitation is designed, and the method uses hydrogen peroxide H₂O₂Adding the liquid ammonia into the fluoroxyniobate solution H₂NbOF₅In (4), ammonium niobate peroxide (NH) is obtained₄)₃NbO₈Crystallizing, roasting at controlled temperature to obtain niobium oxide in required phase state,

1) putting a certain amount of niobium liquid into a container;

2) according to Nb₂O₅∶H₂O₂Calculating the dosage of 30 percent hydrogen peroxide according to the proportion of 1 mol to 8 mol, adding the hydrogen peroxide into a container and uniformly mixing;

3) introducing ammonia gas into the container until the pH value reaches 8, and realizing the complete precipitation of the niobium mud;

4) filtering the solution and precipitate in the container to obtain ammonium niobate peroxide (NH)₄)₃NbO₈A crystal;

5) ammonium Niobate (NH) peroxide at a temperature of 150-1200 deg.C₄)₃NbO₈Roasting the crystal to respectively obtain alpha, beta and gamma niobium oxides in various phase states; wherein,

nb in niobium solution₂O₅The content of the (b) is 80-150 g/L, and the concentration of the hydrogen peroxide is 30 wt%.

In this case, the particle size of the obtained niobium oxide is 0.3 to 1 μm.

Compared with the prior art, the method of the invention has the advantages that:

1. the ammonium niobate crystal obtained in the precipitation process has no package, no adsorption, no inclusion and easy filtration, so the product has high purity under the same raw material and process conditions.

2. Roasting ammonium niobate at 150-1300 ℃ to obtain fluorine-free niobium oxide, wherein the product is obviously spherical, uniform and consistent in particle size of 0.3-1 mu m; according to application requirements, niobium oxide with different phases of alpha, beta and gamma can be obtained by controlling the roasting temperature.

3. Three procedures of washing, drying and grinding are omitted, and a large amount of manpower, material resources and energy resources are saved.

Detailed Description

The invention aims to solve the problem that the prior art can only use liquid ammonia to precipitate niobium liquid (H)₂NbOF₅) And amorphous flocculent Nb (OH) is obtained₅(Nb₂O₅·NH₂O) precipitates, thereby preparing the niobium oxide product with the granularity of 1-3 mu m, solving the problems of multiple working procedures, complex operation flow and high cost, and providing the method for adopting hydrogen peroxide H₂O₂Precipitating niobium solution H with liquid ammonia₂NbOF₅To obtain ammonium octaoxoniobate (NH)₄)₃NbO₈Crystallizing, filtering and roasting to obtain 0.3-1 micron spherical niobium oxide. The basic scheme of the invention is to use hydrogen peroxide H₂O₂Adding the liquid ammonia into the fluoroxyniobate solution H₂NbOF₅In (4), ammonium niobate peroxide (NH) is obtained₄)₃NbO₈Crystallizing, roasting at controlled temperature to obtain niobium oxide in required phase state,

1) putting a certain amount of niobium liquid into a container;

5) ammonium Niobate (NH) peroxide at a temperature of 150-1300 deg.C₄)₃NbO₈Roasting the crystal to respectively obtain alpha, beta and gamma niobium oxides in various phase states; wherein,

The niobium oxide has the following phase transition temperature: ammonium Niobate (NH) oxide at a temperature of 150 deg.C to 950 deg.C₄)₃NbO₈The temperature of the crystal generating thermal decomposition begins to obtain alpha-phase niobium oxide; obtaining beta-phase niobium oxide at 1100-1150 ℃; the gamma-phase niobium oxide is obtained at temperatures > 1200 ℃.

In this case, the particle size of the obtained niobium oxide is 0.3 to 1 μm. The present invention will be described in more detail with reference to specific examples.

Example (b):

1. calculating the material ratio

Taking 1L of niobium solution containing Nb₂O₅137.5 g/L. Calculate H₂O₂The dosage is as follows: 137.5/226 × 8 ═ 4.16molH₂O₂，

Fold H₂O₂The dosage is as follows: 4.16mol 34g/mol 141.4g/L

Folding by 30% H₂O₂The dosage is as follows: 141.4/0.3 ═ 472ml

Then: 1 liter (Nb)₂O₅137.5g/L) niobium solution H₂O₂472ml

2. Operation of

Taking the concentration as Nb₂O₅Putting 1000ml of 137.5g/L niobium solution into a beaker;

② add 472mlH to the beaker₂O₂(concentration 30%), start stirring;

③ adding NH into the beaker₄OH until the pH value is 8, and completely precipitating;

fourthly, stopping stirring and filtering to obtain (NH)₄)₃NbO₈A crystal;

roasting the crystal in a 10KW muffle furnace for 6 hours, wherein the phase transition temperature is as follows:

150 ℃ C: thermal decomposition; less than 950 ℃ to obtain alpha-Nb₂O₅(ii) a Obtaining beta-Nb at 1100-1150 DEG C₂O₅The temperature is more than 1200 ℃, and the Gamma-Nb is obtained₂O₅To obtain Nb₂O₅The color is uniform and consistent, the whole is spherical, and the granularity is 0.3-1 mu m.

Claims

1. A method for preparing high-purity spherical niobium oxide by peroxidation and precipitation,

the method is to prepare hydrogen peroxide H₂O₂Adding the liquid ammonia into the fluoroxyniobate solution H₂NbOF₅In (4), ammonium niobate peroxide (NH) is obtained₄)₃NbO₈Crystallizing, roasting at controlled temperature to obtain niobium oxide in required phase state,

the method comprises the following specific steps:

1) putting the niobium liquid into a container;

5) ammonium Niobate (NH) peroxide at a temperature of 150-1300 deg.C₄)₃NbO₈The crystal is sintered to respectively obtain alpha, beta and gamma niobium oxides in various phase states;

wherein Nb in the niobium solution₂O₅The content of the (b) is 80-150 g/L, and the concentration of the hydrogen peroxide is 30 wt%.

2. The method for preparing high-purity spherical niobium oxide through peroxidation and precipitation as claimed in claim 1, wherein the particle size of the obtained niobium oxide is 0.3-1 μm.