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CN-122010177-A - Method for preparing ultra-high purity niobium oxide by deep desilication

CN122010177ACN 122010177 ACN122010177 ACN 122010177ACN-122010177-A

Abstract

The invention provides a preparation method of ultra-high purity niobium pentoxide, which has stable process and high efficiency, and aims to realize the reduction of the silicon content to below 3ppm and obtain the ultra-high purity niobium pentoxide by the synergistic effect of directional dissolution and silicon removal and precise filtration and washing.

Inventors

  • Mei Linghan
  • LIANG CHANGMING
  • YE SIHAN

Assignees

  • 江西海协稀有金属材料有限公司

Dates

Publication Date
20260512
Application Date
20260213

Claims (9)

  1. 1. A method for preparing ultra-high purity niobium oxide by deep desilication is characterized by comprising the following steps: S1, drying, crushing and screening the hydrated niobium oxide; S2, mixing the sieved hydrated niobium oxide with deionized water for pulping, injecting a calculated amount of GR-level organic niobium-dissolving reagent for dissolving the hydrated niobium oxide, dissolving and filtering silicon; s3, stirring, heating and dissolving until the niobium feed liquid is clear; s4, filtering the solution by a filter membrane, and filtering out part of insoluble silicon impurities to obtain a primary silicon-niobium removal filtrate; s5, neutralizing the primary silicon-niobium removal filtrate with GR-level ammonia water until the PH value is less than 9, filtering, washing and drying; s6, raising the temperature in a temperature raising section, calcining the dried niobium material to 600 ℃, and preserving the heat for 1h; S7, secondarily crushing the calcined niobium material, and sieving the crushed niobium material by a standard sieve; s8, directionally dissolving and removing silicon, namely mixing the screened niobium oxide with deionized water for pulping, adding a reagent into the slurry for reaction under stirring, and converting silicon impurities into soluble substances; S9, solid-liquid separation and washing, namely, after the reaction is finished, carrying out solid-liquid separation, collecting a filter cake, and washing the filter cake by using hot water until the pH value of a washing liquid is 5.0+/-0.5; s10, dehydration control, namely dehydrating the washed filter cake; S11, drying and crushing, namely drying, crushing and sieving the dehydrated filter cake to obtain an intermediate product.
  2. 2. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein the hydrated niobium oxide is baked niobium hydroxide, and the resistivity of deionized water in step S2 is not less than 18MΩ.cm.
  3. 3. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein the primary desilication of niobium filtrate is ammonia water neutralization to GR grade ammonia water in step S5.
  4. 4. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein the reagent in step S8 is high purity hydrofluoric acid or its dilution.
  5. 5. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 4, wherein the concentration of the high purity hydrofluoric acid is 30% to 50%.
  6. 6. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein the mass concentration of the slurry prepared in the step S8 is 15% to 25%, the reaction temperature is 30 ℃ to 40 ℃ and the reaction time is 2 to 4 hours.
  7. 7. The method of producing ultra-high purity niobium oxide according to claim 1, wherein the stirring speed in the step S3 is 300 r/min to 400 r/min.
  8. 8. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein the temperature of the hot water in step S9 is 45 to 55 ℃.
  9. 9. The method for preparing ultra-high purity niobium oxide by deep desilication of claim 1, wherein in step S10, the filtrate generated by dehydration is detected by adopting a silicon-molybdenum blue spectrophotometry, and no silicon detection is used as a standard for intermediate control qualification.

Description

Method for preparing ultra-high purity niobium oxide by deep desilication Technical Field The invention belongs to the technical field of preparation of high-purity inorganic materials, and particularly relates to a preparation method of ultra-high-purity niobium pentoxide, in particular to a deep silicon removal process through directional chemical dissolution. Background Niobium pentoxide is a key precursor for preparing high-technology materials such as lithium niobate crystals, optical coating films, high-purity targets, special ceramics and the like, and the application has very strict requirements on the purity (especially the silicon content) of the niobium pentoxide, and generally meets the requirements that Nb 2O5 is more than or equal to 99.998 percent and Si is less than or equal to 3ppm and has a good crystal phase structure. At present, the main flow process for industrially producing high-purity Nb 2O5 in large scale is a route of sulfuric acid-hydrofluoric acid decomposition, solvent extraction and ammonia water neutralization, and the process can effectively remove most metal impurities, but because of the complex distribution behavior of silicon in an extraction system, the removal efficiency of silicon impurities (mainly existing in the form of silicon dioxide and silicate) is a bottleneck, and according to the data of high-purity niobium pentoxide (GB/T36246-2018) and industry public data, the Nb 2O5 product produced by optimizing the process has the typical purity of 99.995-99.998 percent and the silicon content generally ranging from 5ppm to 10ppm, and is difficult to meet the requirement of the tip fields such as lithium niobate thin film epitaxial substrates for photonic chips on ultra-high purity. Therefore, developing a purification treatment technology capable of deeply and directionally removing silicon impurities becomes a key for breaking through the bottleneck of the prior art and obtaining the ultra-high purity niobium pentoxide product. Disclosure of Invention Aiming at the technical defect that silicon impurities are not thoroughly removed in the existing high-purity niobium pentoxide preparation process, the invention provides an ultra-high-purity niobium pentoxide preparation method which is stable in process and high in efficiency, and aims to realize the synergistic effect of removing silicon by directional dissolution and removing impurities by precise filtration, reduce the silicon content to below 3ppm and obtain the ultra-high-purity niobium pentoxide. The method for preparing the ultra-high purity niobium oxide by deep desilication comprises the following steps: s1, pretreating raw materials, namely drying, crushing and screening the hydrated niobium oxide. S2, dissolving and removing silicon for the first time, namely mixing the sieved hydrated niobium oxide with deionized water for pulping, injecting a calculated amount of GR-level organic niobium-dissolving reagent for dissolving the hydrated niobium oxide, dissolving and filtering out silicon. S3, stirring, heating and dissolving until the niobium feed liquid is clear. S4, precisely filtering, namely filtering the solution by using a filter membrane, and filtering out part of insoluble silicon impurities to obtain the niobium filtrate for removing silicon once. S5, ammonia water neutralization and primary purification, namely neutralizing the primary desilication niobium filtrate with GR grade ammonia water to pH=9, and then filtering, washing and drying to obtain a primary purification niobium material. S6, calcining, namely heating in a temperature-raising section, calcining the dried niobium material to 600 ℃, and preserving the temperature for 1h. S7, secondary treatment, namely secondary crushing of the calcined niobium material, and screening by a standard screen; S8, directionally dissolving and removing silicon, namely mixing niobium oxide subjected to secondary screening with deionized water for pulping, and adding a fluorine-containing reagent into the slurry under stirring for reaction to convert silicon impurities into soluble substances. S9, solid-liquid separation and washing, namely, after the reaction is finished, solid-liquid separation is carried out, filter cakes are collected, and hot water is used for washing the filter cakes until the pH value of washing liquid is 5.0+/-0.5. S10, dewatering control, namely dewatering the washed filter cake. S11, drying and crushing, namely drying, crushing and sieving a dehydrated filter cake to obtain an intermediate product, namely the high-purity hydrated niobium oxide, and carrying out subsequent treatment to obtain the ultra-high-purity niobium pentoxide. Further, the hydrated niobium oxide is a baked niobium hydroxide. Further, in the step S2, the resistivity of the deionized water is more than or equal to 18M Ω & cm. Further, in step S2, the fluorine-containing reagent is high-purity hydrofluoric acid or a diluted solution thereof, and preferably, th