Method for preparing low-fluorine high-purity tantalum pentoxide

Abstract

This invention discloses a method for preparing low-fluorine, high-purity tantalum pentoxide, relating to the fields of hydrometallurgical processes for tantalum compounds and the preparation of high-purity oxides. The method involves leaching tantalum-containing raw materials using a fluorinated acid system and extracting them with a phosphorus-containing extractant. The tantalum-loaded organic phase is then back-extracted using a fluorine-capturing-complexation-reversal back-extraction system containing ammonium oxalate, ammonium carbonate, ammonia, disodium ethylenediaminetetraacetate, polyethylene glycol 200, and supported fluorine-capturing microspheres. This yields a low-fluorine tantalum-containing back-extraction solution. The solution is then subjected to precipitation, multi-stage washing, drying, and calcination to obtain low-fluorine, high-purity tantalum pentoxide. The supported fluorine-capturing microspheres utilize macroporous adsorption resin microspheres as a carrier, with zirconium-cerium hydroxide active components immobilized through a polydopamine adhesion layer. This allows for simultaneous capture of fluoride ions during back-extraction, reducing fluorine residue in the product, minimizing impurity introduction, and improving product purity and process stability.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical processes for tantalum compounds and the preparation of high-purity oxides, specifically to a method for preparing low-fluorine, high-purity tantalum pentoxide. Background Technology

[0002] Tantalum pentoxide (Ta₂O₅) is an important basic tantalum compound widely used in electronic ceramics, optical glass, single-crystal materials, sputtering targets, catalytic materials, and high-performance capacitor materials. With the development of the electronics, information technology, new energy, and high-end functional materials industries, higher requirements have been placed on the purity, impurity content, particle size distribution, and batch stability of tantalum pentoxide, especially the content of impurities such as fluorine, niobium, iron, silicon, and aluminum, which require strict control. Among these, fluorine impurities easily affect the calcination behavior, crystal phase stability, powder surface activity, and subsequent application performance of tantalum pentoxide, and are one of the key impurities that need to be controlled during the preparation of high-purity tantalum pentoxide.

[0003] Tantalum pentoxide is typically produced from tantalum-containing minerals, tantalum-containing smelting intermediates, or tantalum-containing waste as raw materials. The process involves leaching with a hydrofluoric acid system to form a tantalum-fluorine complex, followed by solvent extraction, back-extraction, precipitation, washing, and calcination. Since tantalum exists primarily as a stable fluorine complex in the hydrofluoric acid system, the tantalum-containing leachate and the tantalum-supported organic phase inevitably contain a large amount of free fluoride ions and complexed fluoride. While conventional aqueous back-extraction systems can achieve phase inversion of tantalum, their ability to simultaneously remove fluoride ions is limited, easily leading to a high fluoride content in the back-extraction solution. Consequently, residual fluoride in the precipitated hydrated tantalum oxide precursor is difficult to completely remove through ordinary washing.

[0004] To reduce fluoride content, existing technologies typically employ methods such as extending washing time, increasing the number of washes, raising calcination temperature, or adding fluoride-precipitating agents like calcium, aluminum, and magnesium salts. However, these methods have significant drawbacks: firstly, simply increasing washing intensity leads to increased water consumption, prolonged treatment cycles, and potential loss of fine powder; secondly, while adding fluoride-precipitating agents can reduce some free fluoride, it easily introduces new metallic impurities, hindering the acquisition of high-purity tantalum pentoxide; furthermore, high-temperature calcination defluorination consumes a lot of energy and may cause powder agglomeration, increased particle size, and decreased activity. Therefore, existing processes struggle to simultaneously achieve efficient tantalum phase inversion, deep fluoride ion removal, low impurity introduction, and product purity stability.

[0005] Therefore, it is necessary to provide a new method for producing low-fluorine, high-purity tantalum pentoxide, which simultaneously achieves tantalum complex phase inversion and fluoride ion capture during the back-extraction process of the tantalum-fluorine complex system, reducing fluorine residue in the back-extraction solution and tantalum precursor, thereby obtaining a tantalum pentoxide product with low fluorine content, high purity, few impurities, and stable process. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the preparation of tantalum pentoxide, such as the difficulty in deeply removing fluoride ions during the process, the high residual fluoride content in the back-extraction solution, the easy introduction of metal impurities by conventional fluoride precipitation methods, the high load of washing and calcination, and the insufficient purity and stability of the product, and to provide a method for preparing low-fluoride, high-purity tantalum pentoxide.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing low-fluorine, high-purity tantalum pentoxide, comprising the following steps: S1. The tantalum-containing raw material is leached through a fluorine-containing system, and after solid-liquid separation, a tantalum-fluorine complex leachate is obtained. The tantalum-fluorine complex leachate is then adjusted to a free fluoride ion concentration of 3.0-8.0 mol / L and a tantalum concentration of 20-120 g / L to obtain the extract.

[0008] S2. Extract the extractant solution using an organic phase containing phosphorus extractant to obtain a tantalum-loaded organic phase; S3. The loaded tantalum organic phase is reacted with the fluorine capture-complexation reverse extraction system to obtain a low-fluorine tantalum-containing back-extraction solution.

[0009] S4. Add a precipitant to the low-fluorine tantalum back-extraction solution to precipitate tantalum in the form of hydrated tantalum oxide precursor. After solid-liquid separation, the low-fluorine tantalum precursor is obtained.

[0010] S5. The low-fluorine tantalum precursor is subjected to multi-stage washing, drying and calcination to obtain low-fluorine high-purity tantalum pentoxide.

[0011] As a preferred technical solution of the present invention, the fluorine capture-complexation reverse extraction system includes a back-extraction solution and solid-supported fluorine capture microspheres dispersed in the back-extraction solution.

[0012] As a preferred embodiment of the present invention, the back-extraction solution is composed of the following raw material components in parts by weight: 100 parts deionized water, 3.0-12.0 parts ammonium oxalate, 1.5-8.0 parts ammonium carbonate, 2.0-10.0 parts ammonia, 0.05-0.50 parts disodium ethylenediaminetetraacetate, and 0.10-0.80 parts polyethylene glycol 200.

[0013] As a preferred embodiment of the present invention, the supported fluorine-capturing microspheres are composed of the following raw material components in parts by weight: 100 parts macroporous adsorption resin microspheres, 0.5-4.0 parts dopamine hydrochloride, 0.3-2.0 parts tris(hydroxymethyl)aminomethane, 15-45 parts zirconium oxychloride, 2-12 parts cerium nitrate, 5-25 parts urea, 150-350 parts anhydrous ethanol, and 200-500 parts deionized water.

[0014] As a preferred technical solution of the present invention, the macroporous adsorption resin microspheres are one or more of D101 type macroporous adsorption resin, AB-8 type macroporous adsorption resin, and HPD-100 type macroporous adsorption resin.

[0015] As a preferred technical solution of the present invention, the low-fluorine high-purity tantalum pentoxide contains a Ta2O5 mass fraction of not less than 99.95%, a fluorine content of not more than 80 ppm, and a loss on ignition of not more than 0.10%.

[0016] After the tantalum-supported organic phase comes into contact with the fluorine capture-complexation-transformation back-extraction system, the ammonium oxalate, ammonium carbonate, and ammonia in the back-extraction solution jointly construct a weakly alkaline complexation-transformation environment. This causes a coordination environment transformation in the tantalum-fluorine complex within the tantalum-supported organic phase. Tantalum, initially stable as a fluorine complex in the organic phase, gradually transforms into a soluble oxalate / carbonate-coordinated tantalum species and enters the aqueous phase. Simultaneously, the supported fluorine-capturing microspheres dispersed in the back-extraction solution, relying on the pore mass transfer effect of the macroporous adsorption resin microspheres and the zirconium-cerium active sites immobilized by the polydopamine adhesion layer on their surface, capture the fluorine released during the back-extraction process. The free fluoride ions and weakly bound fluoride are adsorbed, coordinated, and fixed, reducing the activity of fluoride ions in the aqueous phase, thereby promoting the continued dissociation and phase transformation of the tantalum-fluoride complex. Disodium ethylenediaminetetraacetate has a complexing and shielding effect on trace amounts of impurity metal ions such as iron, aluminum, calcium, and magnesium, reducing impurity co-transfer or subsequent co-precipitation. Polyethylene glycol 200 improves the wetting and dispersibility of the supported fluoride-capturing microspheres in the back-extraction solution and the mass transfer efficiency at the phase interface, thereby achieving efficient transfer of tantalum to the aqueous phase, simultaneous capture of fluoride ions, and synergistic control of impurity ions, so that the resulting low-fluoride tantalum-containing back-extraction solution has low fluoride residue and high tantalum purity.

[0017] As a preferred technical solution of the present invention, in S1, the tantalum-containing raw material is one or more of tantalum-niobium smelting intermediates, tantalum-containing waste residue, and tantalum oxide concentrate; the fluorine-containing system is composed of hydrofluoric acid, sulfuric acid, and deionized water, wherein, by mass, hydrofluoric acid is 20-45 parts, sulfuric acid is 5-25 parts, and deionized water is 30-75 parts; the mass fraction of hydrofluoric acid is 40-49%, and the mass fraction of sulfuric acid is 95-98%; the leaching temperature in S1 is 60-95℃, the leaching time is 2-8h, the liquid-solid mass ratio is 3-10:1, and after leaching, a filter medium with a pore size of 0.22-1.00μm is used for solid-liquid separation to obtain the tantalum-fluorine complex leachate.

[0018] As a preferred embodiment of the present invention, in S2, the phosphorus-containing extractant is one or more of tributyl phosphate, di(2-ethylhexyl)phosphoric acid, and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0019] As a preferred technical solution of the present invention, the organic phase is composed of a phosphorus-containing extractant and a diluent, wherein the volume fraction of the phosphorus-containing extractant in the organic phase is 20-70%.

[0020] As a preferred technical solution of the present invention, the diluent is one or more of sulfonated kerosene, n-heptane, and isoparaffin solvent oil. The volume ratio of the organic phase to the extractant during extraction is 0.5-3.0:1, the extraction temperature is 20-45℃, the single-stage extraction time is 5-30 min, and the number of extraction stages is 1-5.

[0021] As a preferred embodiment of the present invention, the preparation method of the solid-supported fluorine-capturing microspheres includes the following steps:

[0022] A1. The macroporous adsorption resin microspheres were washed sequentially with anhydrous ethanol and deionized water, and then dried at 40-70℃ for 4-12 hours to obtain pretreated resin microspheres.

[0023] A2. Dissolve dopamine hydrochloride and tris(hydroxymethyl)aminomethane in deionized water, adjust the pH to 8.0-9.0, add pretreated resin microspheres, and stir at 20-35℃ for 6-24 hours to form a polydopamine adhesion layer on the surface of the resin microspheres, thus obtaining polydopamine modified resin microspheres.

[0024] A3. Add zirconium oxychloride octahydrate, cerium nitrate hexahydrate and urea to a mixed solvent composed of anhydrous ethanol and deionized water, stir to dissolve, and then add the polydopamine modified resin microspheres. Adjust the initial pH of the system to 4.0-5.5 with dilute ammonia or ammonium bicarbonate aqueous solution, and then reflux or react in a closed system at 88-95℃ for 8-12 hours.

[0025] A4. After the reaction is complete, the solid and liquid are separated. The obtained microspheres are washed with deionized water until the conductivity of the washing solution is not higher than 50 μS / cm, and then dried at 50-80℃ for 6-18h to obtain the solid-supported fluorine capturing microspheres.

[0026] As a preferred embodiment of the present invention, the amount of the solid-supported fluorine-capturing microspheres added to the back-extraction solution is 3-5% of the mass of the back-extraction solution.

[0027] As a preferred technical solution of the present invention, in S3, the volume ratio of the supported tantalum organic phase to the fluorine capture-complexation conversion back-extraction system is 1:0.5-3.0, the contact back-extraction temperature is 20-60℃, the stirring speed is 200-800 r / min, the single-stage back-extraction time is 10-60 min, and the number of back-extraction stages is 1-4. During the back-extraction process, the pH of the aqueous phase is controlled at 7.5-10.5 so that the tantalum in the supported tantalum organic phase is transferred into the aqueous phase, and at the same time, the free fluoride ions are adsorbed and captured by the solid-supported fluorine capture microspheres to obtain the low-fluorine tantalum-containing back-extraction solution.

[0028] As a preferred technical solution of the present invention, in S4, the precipitant is one or more of ammonia water, ammonium carbonate aqueous solution, and ammonium bicarbonate aqueous solution. During the addition of the precipitant, the pH of the system is controlled at 8.0-10.5, the precipitation temperature is 25-70℃, and the precipitation time is 0.5-4h. After the precipitation is completed, an aging treatment is performed at a temperature of 25-70℃ for 1-8h. After solid-liquid separation, the low-fluorine tantalum precursor is obtained.

[0029] As a preferred technical solution of the present invention, in step 5, the multi-stage washing includes deionized water washing, dilute ammonia water washing, and a second deionized water washing; wherein, the mass fraction of dilute ammonia water is 0.1-2.0%, the liquid-solid mass ratio of each stage of washing is 3-15:1, the number of washing cycles for each stage is 2-8, and the washing continues until the fluoride ion concentration in the washing liquid is not higher than 10 mg / L; in step S5, the drying temperature of the low-fluorine tantalum precursor is 80-150℃, the drying time is 4-16h; the calcination temperature is 750-1100℃, the heating rate is 1-10℃ / min, the holding time is 2-8h, and the calcination atmosphere is air or oxygen.

[0030] As a preferred technical solution of the present invention, the obtained low-fluorine high-purity tantalum pentoxide has a Ta2O5 mass fraction of not less than 99.95%, a fluorine content of not more than 80 ppm, and a weight loss on ignition of not more than 0.10%.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This method for producing low-fluorine, high-purity tantalum pentoxide involves introducing a fluorine capture-complexation phase transition back-extraction system, consisting of a back-extraction solution and supported fluorine-capturing microspheres, during the back-extraction stage. This system allows tantalum in the tantalum-loaded organic phase to transition into the aqueous phase within a complexation phase transition environment formed by ammonium oxalate, ammonium carbonate, and ammonia. Simultaneously, the supported fluorine-capturing microspheres capture free fluoride ions and some weakly bound fluoride, thereby reducing the fluorine content in the low-fluorine tantalum-containing back-extraction solution from the source and minimizing fluorine residue in the subsequent precipitation precursor.

[0033] This invention utilizes macroporous adsorption resin microspheres as a carrier and immobilizes the zirconium-cerium hydroxide active component through a polydopamine adhesion layer. This improves the dispersion stability and anti-loss performance of the fluorine-capturing component in the back-extraction system. The zirconium and cerium active sites can form stable coordination or adsorption bonds with fluoride ions, avoiding the problem of introducing a large amount of free metal impurities when conventional fluorine precipitation agents are directly added to the back-extraction or precipitation solution. This helps maintain the high purity of tantalum pentoxide products.

[0034] In the back-extraction solution of this invention, the synergistic effect of ammonium oxalate, ammonium carbonate, and ammonia promotes the transfer of tantalum from the supported organic phase to the aqueous phase and maintains the stability of the tantalum species under suitable pH conditions. Disodium ethylenediaminetetraacetate can complex trace impurity metal ions, reducing the adverse effects of impurities such as iron, aluminum, and silicon on product purity. Polyethylene glycol 200 can improve the wetting and dispersion state of the supported fluorine-capturing microspheres in the back-extraction solution, thereby improving the mass transfer efficiency and fluorine capture uniformity of the back-extraction process.

[0035] This invention achieves efficient tantalum recovery, deep fluorine removal, and impurity control in the same process through a continuous process path of "extraction-fluorine capture and back-extraction-precipitation-multi-stage washing-calcination". This reduces the process burden of relying solely on large-scale washing or high-temperature calcination for defluorination. It has the advantages of mild process conditions, controllable parameters, low fluorine content, high purity, and good batch stability of the product, making it suitable for the industrial preparation of low-fluorine, high-purity tantalum pentoxide. Attached Figure Description

[0036] Figure 1 This is the SEM image of the product obtained in Example 1 of the present invention.

[0037] Figure 2 The XRD patterns are those of the products obtained in Examples 1-4 and Comparative Examples 1-10 of this invention. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the preparation examples, embodiments, and / or comparative examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Preparation Example 1 Preparation of immobilized fluorine-capturing microspheres:

[0040] 1. Raw material components by weight: 100 parts macroporous adsorption resin microspheres, 2.0 parts dopamine hydrochloride, 1.2 parts tris(hydroxymethyl)aminomethane, 30 parts zirconium oxychloride, 6 parts cerium nitrate, 15 parts urea, 250 parts anhydrous ethanol, and 350 parts deionized water.

[0041] The macroporous adsorption resin microspheres are D101 type macroporous adsorption resin microspheres with a particle size of 0.30-1.25mm, and were purchased from Tianjin Yunkai Resin Technology Co., Ltd.

[0042] The zirconium oxychloride is zirconium oxychloride octahydrate.

[0043] The cerium nitrate mentioned is cerium nitrate hexahydrate.

[0044] The conductivity of the deionized water is not higher than 1.0 μS / cm.

[0045] Anhydrous ethanol and deionized water used for washing are not included in the mass fraction of the above reaction feed.

[0046] 2. Preparation method:

[0047] A1. Take 100 parts of macroporous adsorption resin microspheres, add anhydrous ethanol and wash twice, each time for 30 min, with a solid-liquid mass ratio of 1:5; then wash three times with deionized water, each time for 30 min, with a solid-liquid mass ratio of 1:6; after washing, dry at 60℃ for 8 h to obtain pretreated resin microspheres.

[0048] A2. Take 180 parts of deionized water, add 2.0 parts of dopamine hydrochloride and 1.2 parts of tris(hydroxymethyl)aminomethane, stir until completely dissolved, and control the pH of the solution to 8.5. Then add the pretreated resin microspheres obtained in A1, and stir the reaction at 25°C for 12 hours to form a polydopamine adhesion layer on the surface and near the surface of the pores of the macroporous adsorption resin microspheres. After the reaction, the solid and liquid are separated, and the microspheres are washed with deionized water until the washing solution is light-colored to obtain polydopamine modified resin microspheres.

[0049] A3. Mix 250 parts of anhydrous ethanol and 170 parts of deionized water to obtain an ethanol-water mixed solvent. Add 30 parts of zirconium oxychloride octahydrate, 6 parts of cerium nitrate hexahydrate, and 15 parts of urea to the ethanol-water mixed solvent. After stirring and dissolving, add the polydopamine-modified resin microspheres obtained in A2. Adjust the initial pH of the system to 4.8 by slowly adding 2.0% (w / w) dilute ammonia solution, controlling the stirring speed at 400 r / min during the addition. Then, place the system in a reactor equipped with a reflux condenser and reflux at 92℃ for 10 h. During the reaction, urea gradually hydrolyzes to produce ammonium and carbonate / bicarbonate ions, causing the pH of the system to slowly increase. This promotes the in-situ deposition of zirconium and cerium components in the polydopamine adhesion layer and the pores of the macroporous adsorption resin microspheres, forming zirconium-cerium hydroxide active components. After the reaction, a resin microsphere slurry containing zirconium-cerium hydroxide is obtained.

[0050] 250 parts of anhydrous ethanol and 170 parts of deionized water were mixed to obtain an ethanol-water mixed solvent. 30 parts of zirconium oxychloride, 6 parts of cerium nitrate, and 15 parts of urea were added to the ethanol-water mixed solvent. After stirring and dissolving, polydopamine-modified resin microspheres obtained from A2 were added, and the mixture was reacted at 85°C for 8 hours. During the reaction, urea slowly decomposed upon heating, increasing the local alkalinity of the system. This caused the zirconium and cerium components to be deposited and immobilized in situ in the polydopamine adhesion layer and the pores of the macroporous adsorption resin microspheres as zirconium-cerium hydroxide, resulting in a resin microsphere slurry containing zirconium-cerium hydroxide.

[0051] A4. The resin microsphere slurry containing zirconium-cerium hydroxide obtained in A3 was subjected to solid-liquid separation. The obtained microspheres were washed with deionized water at a solid-to-mass ratio of 8:1. Each wash lasted 20 minutes and was repeated until the conductivity of the final wash solution was no higher than 50 μS / cm. Subsequently, the washed microspheres were dried at 70℃ for 12 hours and then sieved to obtain solid-supported fluorine-capturing microspheres.

[0052] Comparative Preparation Example 1

[0053] The preparation of the immobilized fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 2.0 parts of dopamine hydrochloride were replaced with 2.0 parts of polyvinyl alcohol, and the rest remained the same as in Preparation Example 1.

[0054] The polyvinyl alcohol has a degree of alcoholysis of 85.0-89.0% and an acid value of ≤3.0%, and was purchased from Shandong Jichuang Chemical Co., Ltd.

[0055] Comparative Preparation Example 2

[0056] The preparation of the supported fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 6 parts of cerium nitrate were replaced with 6 parts of zirconium oxychloride, and the rest remained the same as in Preparation Example 1.

[0057] Comparative preparation example 3

[0058] The preparation of the supported fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 30 parts of zirconium oxychloride were replaced with 30 parts of aluminum chloride hexahydrate, and the rest remained the same as in Preparation Example 1.

[0059] Comparative preparation example 4

[0060] The preparation of the immobilized fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 15 parts of urea were replaced with 15 parts of ammonia water with a mass fraction of 25%, and the rest remained the same as in Preparation Example 1.

[0061] Comparative preparation example 5

[0062] The preparation of the immobilized fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 100 parts of the D101 type macroporous adsorption resin microspheres were replaced with 100 parts of the 001×7 type strong acid styrene-based cation exchange resin microspheres, and the rest remained the same as in Preparation Example 1.

[0063] The 001×7 type strong acid styrene-based cation exchange resin microspheres have a particle size of 0.315-1.25 mm and were purchased from Piaoyi Pure Resin (Shanghai) Co., Ltd.

[0064] Comparative preparation example 6

[0065] The preparation of the immobilized fluorine-capturing microspheres was carried out by referring to the preparation method in Preparation Example 1, except that 250 parts of anhydrous ethanol in step A3 was replaced with 250 parts of deionized water, and the rest remained the same as in Preparation Example 1. Example 1

[0066] Preparation of low-fluorine, high-purity tantalum pentoxide: 1. Raw material components involved in the preparation process (by weight): In this embodiment, based on 100 parts of tantalum oxide concentrate, the raw material components involved in the preparation process are as follows: The mixture contains 100 parts of tantalum oxide concentrate; 210 parts of hydrofluoric acid (49% by mass); 90 parts of sulfuric acid (98% by mass); 300 parts of deionized water; 50 parts by volume of tributyl phosphate; 50 parts by volume of sulfonated kerosene; 8.0 parts of ammonium oxalate; 4.5 parts of ammonium carbonate; 6.0 parts of ammonia water (25% by mass); 0.20 parts of disodium ethylenediaminetetraacetate; and 0.40 parts of polyethylene glycol 200. The supported fluorine-capturing microspheres obtained in Example 1 were added at an amount of 4.0% of the mass of the back-extraction solution. Precipitation is carried out using 25% ammonia solution, which is 6.5 parts per 100 parts of low-fluorine tantalum back-extraction solution. Use 0.5% dilute ammonia solution for washing, with a liquid-to-solid mass ratio of 8:1 during washing. Use deionized water for washing, with a liquid-to-solid mass ratio of 8:1.

[0067] The tantalum oxide concentrate contains 65% tantalum oxide by mass (calculated as Ta2O5) and has a powder particle size ≤75μm.

[0068] The ammonium oxalate is ammonium oxalate monohydrate.

[0069] The supported fluorine-capturing microspheres are those prepared in Preparation Example 1.

[0070] 2. Preparation method: S1. Take 100 parts of tantalum oxide concentrate and add it to a hydrofluoric acid system consisting of 210 parts of 49% hydrofluoric acid, 90 parts of 98% sulfuric acid, and 300 parts of deionized water, making the liquid-solid mass ratio 6:1. Leach at 85℃ for 5 hours, keeping the system stirred during the leaching process. After leaching, use a 0.45μm pore size filter medium for solid-liquid separation to obtain a tantalum-fluorine complex leachate. Detect the free fluoride ion concentration and tantalum concentration in the obtained tantalum-fluorine complex leachate, and adjust the concentration using the same batch of tantalum-fluorine complex leachate, the same batch of deionized water, and 49% hydrofluoric acid to achieve a free fluoride ion concentration of 5.5 mol / L and a tantalum concentration of 80 g / L, thus obtaining the extract.

[0071] S2. Mix 50 parts by volume of tributyl phosphate and 50 parts by volume of sulfonated kerosene to obtain an organic phase with a phosphorus-containing extractant volume fraction of 50%. Mix the organic phase with the extract solution obtained in S1 at a volume ratio of 1.5:1 and extract at 30°C. The single-stage extraction time is 15 min, and the number of extraction stages is 3. After each extraction stage, allow the phases to separate by standing, and combine the organic phases to obtain a tantalum-loaded organic phase.

[0072] S3. Preparation of the back-extraction solution. Based on 100 parts of deionized water, add 8.0 parts of ammonium oxalate, 4.5 parts of ammonium carbonate, 6.0 parts of 25% ammonia solution, 0.20 parts of disodium ethylenediaminetetraacetate, and 0.40 parts of polyethylene glycol 200 sequentially to the deionized water, stirring until uniformly dissolved to obtain the back-extraction solution. Add the supported fluoride-capturing microspheres obtained in Preparation Example 1 to the back-extraction solution, with the amount of the supported fluoride-capturing microspheres being 4.0% of the mass of the back-extraction solution, to obtain a fluoride capture-complexation conversion back-extraction system. Mix the tantalum-supported organic phase obtained in S2 with the fluoride capture-complexation conversion back-extraction system at a volume ratio of 1:1.5, and perform contact back-extraction at 40°C and 500 r / min. The single-stage back-extraction time is 30 min, and the number of back-extraction stages is 2. During the back-extraction process, control the pH of the aqueous phase to 9.0. After each stage of back-extraction, the mixture is allowed to stand and separate into phases. The aqueous phase is collected and then separated by filtration to obtain a low-fluorine tantalum-containing back-extraction solution.

[0073] S4. Add 25% (w / w) ammonia water as a precipitant to the low-fluorine tantalum-containing back-extraction solution obtained in S3. For every 100 parts of the low-fluorine tantalum-containing back-extraction solution, 6.5 parts of ammonia water are added for precipitation. During the addition process, control the system pH at 9.2, the precipitation temperature at 50℃, and the precipitation time at 2 hours, so that tantalum precipitates as a hydrated tantalum oxide precursor. After precipitation, age at 50℃ for 3 hours, followed by solid-liquid separation to obtain the low-fluorine tantalum precursor.

[0074] S5. The obtained low-fluorine tantalum precursor is subjected to multi-stage washing. The multi-stage washing includes washing with deionized water, washing with 0.5% (w / w) dilute ammonia water, and washing with deionized water again. The liquid-to-solid mass ratio of each washing stage is 8:1, each stage is repeated twice, and each washing lasts for 20 minutes, until the fluoride ion concentration in the final washing solution is no higher than 10 mg / L. The washed low-fluorine tantalum precursor is dried at 120°C for 8 hours to obtain a dried tantalum precursor. Subsequently, the dried tantalum precursor is heated to 950°C at a heating rate of 5°C / min, kept at this temperature in air for 4 hours, and then cooled to obtain low-fluorine high-purity tantalum pentoxide.

[0075] like Figure 1As shown, the tantalum pentoxide product obtained in Example 1 exhibits a loose aggregated structure formed by the accumulation of fine, near-spherical particles under 10,000x SEM. The particle surface is relatively rough, and in some areas, nanoscale primary particles are seen overlapping and forming secondary aggregates. No obvious flaky or blocky impurities or large-sized dense agglomerates formed by melting and sintering are observed. This morphology indicates that after precipitation, washing, drying, and calcination at 950°C, the hydrated tantalum oxide precursor can be transformed into well-dispersed Ta2O5 fine powder. At the same time, a certain degree of particle necking and agglomeration is a normal phenomenon after high-temperature calcination of oxide powder. Example 2

[0076] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that the sulfonated kerosene is replaced with n-heptane, while the rest remains the same as in Example 1. Example 3

[0077] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that tributyl phosphate is replaced with di(2-ethylhexyl)phosphoric acid, and the rest remains the same as in Example 1. Example 4

[0078] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that tributyl phosphate is replaced with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, and the rest remains the same as in Example 1.

[0079] Comparative Examples 1-6

[0080] The preparation of low-fluorine high-purity tantalum pentoxide is carried out by referring to the preparation method of Example 1, except that the solid-supported fluorine trapping microspheres are replaced with the solid-supported fluorine trapping microspheres prepared in Comparative Preparation Examples 1-6, and the rest is the same as in Example 1.

[0081] Comparative Example 7

[0082] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that the supported fluorine-capturing microspheres are replaced with D101 type macroporous adsorption resin microspheres, while the rest remains the same as in Example 1.

[0083] Comparative Example 8

[0084] The preparation of low-fluorine high-purity tantalum pentoxide is carried out by referring to the preparation method of Example 1, except that the amount of solid-supported fluorine-capturing microspheres added is adjusted from 4.0% of the mass of the back-extraction solution to 0.3%, while the rest remains the same as in Example 1.

[0085] Comparative Example 9

[0086] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that 8.0 parts of ammonium oxalate are replaced with 8.0 parts of ammonium chloride, while the rest remains the same as in Example 1.

[0087] Comparative Example 10

[0088] A method for preparing low-fluorine, high-purity tantalum pentoxide is described, referring to the preparation method in Example 1, except that 0.40 parts of polyethylene glycol 200 are replaced with 0.40 parts of glycerol, while the rest remains the same as in Example 1.

[0089] Performance testing: The performance of tantalum pentoxide samples obtained in Examples 1-4 and Comparative Examples 1-10 was tested. Unless otherwise stated, each group of samples was prepared from the same batch of tantalum pentoxide samples, which were gently ground in an agate mortar, passed through a 100-mesh sieve, dried at 105°C for 2 hours, and then cooled to room temperature in a desiccator before use.

[0090] 1. Test of fluoride ion concentration in the back-extraction solution: The low-fluoride, tantalum-containing back-extraction solutions obtained in step S4 of Examples 1-4 and Comparative Examples 1-10 were sampled immediately after separation using supported fluoride trapping microspheres. After sampling, the solution was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) membrane. 2 mL of the initial filtrate was discarded, and the subsequent filtrate was collected as the test solution. The concentration of free fluoride ions in the back-extraction solution was determined using the fluoride ion selective electrode method. Fluoride ion standard solutions of 0.10 mg / L, 0.50 mg / L, 1.00 mg / L, 2.00 mg / L, 5.00 mg / L, and 10.00 mg / L were prepared, and the potential values ​​of each standard solution were measured. A standard curve was plotted with the logarithm of the fluoride ion concentration on the x-axis and the potential value on the y-axis. The correlation coefficient R of the standard curve was calculated. 2 Not less than 0.995. After measuring the potential value of the test liquid, the fluoride ion concentration in the diluted solution is calculated according to the standard curve, and the fluoride ion concentration in the low-fluoride tantalum-containing back-extraction solution is obtained by converting according to the dilution factor. The unit is mg / L, and the data are shown in Table 1.

[0091] 2. Test of fluoride ion concentration in the washing solution: During the multi-stage washing process in step S6, the washing solution was collected after each wash, and the fluoride ion concentration of the last washing solution was measured. Before testing, the washing solution was allowed to stand for 10 minutes, and the supernatant was filtered through a 0.22 μm filter membrane as the test solution. The fluoride ion concentration in the washing solution was determined using the same method as in the "Test of fluoride ion concentration in the back-extraction solution," and the data are shown in Table 1.

[0092] 3. Determination of Fluorine Content in the Obtained Tantalum Pentoxide: The total fluorine content in the obtained tantalum pentoxide sample was determined using a high-temperature hydrolysis-ion chromatography method. 0.1000 g of tantalum pentoxide sample dried at 105℃ was accurately weighed and placed in a quartz boat, which was then placed in the constant-temperature zone of a high-temperature hydrolysis furnace. The furnace temperature was controlled at 1000℃, purified humid air was introduced, the carrier gas flow rate was controlled at 300 mL / min, and the hydrolysis time was 30 min, allowing the fluorine in the sample to be released as volatile fluorine-containing substances and absorbed by the absorbent. The absorbent was a 15 mmol / L sodium hydroxide aqueous solution with a volume of 25.0 mL. After hydrolysis, the absorbent was transferred to a volumetric flask, diluted to 50.0 mL with deionized water, mixed well, and the fluoride ion concentration was determined using an ion chromatograph. A standard curve was established using the fluoride ion standard solution, and the correlation coefficient R of the standard curve was determined. 2 Not less than 0.999. A blank test was conducted simultaneously, and the fluorine content in the sample was calculated using the following formula after subtracting the blank value: Fluorine content / ppm = (C-C0)×V×D / m; In the formula, C is the mass concentration of fluoride ions in the test solution, in mg / L; C0 is the mass concentration of fluoride ions in the blank solution, in mg / L; V is the final volume, in L; D is the dilution factor; and m is the sample mass, in kg. The data are shown in Table 1.

[0093] 4. Determination of Ta₂O₅ mass fraction: The tantalum content in the sample was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the Ta₂O₅ mass fraction was calculated. 0.1000 g of tantalum pentoxide sample dried at 105℃ was accurately weighed and placed in a polytetrafluoroethylene (PTFE) digestion vessel. Nitric acid, hydrofluoric acid, and a small amount of sulfuric acid were added for microwave digestion. After digestion, the solution was transferred to a PTFE beaker, and excess hydrofluoric acid was removed on a low-temperature hot plate. After cooling, the solution was diluted to volume with dilute nitric acid to obtain the test solution. A series of standard solutions were prepared using tantalum standard solutions. The correlation coefficient R of the standard curve was... 2 Not less than 0.999. The tantalum content in the test solution was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the Ta₂O₅ mass fraction was calculated using the following formula: Ta₂O₅ mass fraction / % = C_Ta × V × D × M_Ta₂O₅ / (m × 2M_Ta) × 100%; In the formula, C_Ta is the mass concentration of tantalum in the test solution, in g / L; V is the fixed volume, in L; D is the dilution factor; m is the sample mass, in g; M_Ta2O5 is the molar mass of Ta2O5; M_Ta is the molar mass of Ta, and the data are shown in Table 1.

[0094] 5. Test of loss on ignition: Accurately weigh 1.0000g of tantalum pentoxide sample dried to constant weight at 105℃, denoted as m1, and place it in a pre-weighed high-purity alumina crucible. Place the crucible in a muffle furnace and heat it to 1000℃ at a heating rate of 5℃ / min, hold it at that temperature for 1h, then remove it and cool it to room temperature in a desiccator. Weigh the sample after ignition, denoted as m2. Calculate the loss on ignition using the following formula: Loss on ignition / % = (m1-m2) / m1 × 100%, as shown in Table 1.

[0095] 6. Tantalum Recovery Test: The tantalum content in the tantalum-containing raw material, the extraction solution, the low-fluorine tantalum-containing back-extraction solution, and the final tantalum pentoxide sample were determined. The tantalum content in the tantalum-containing raw material and the final tantalum pentoxide sample was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) after digestion. The tantalum content in the extraction solution and the low-fluorine tantalum-containing back-extraction solution was directly determined after appropriate dilution. The tantalum recovery rate was calculated using the following formula: Tantalum recovery rate / % = m_p × w_p / (m0 × w0) × 100%; In the formula, m_p is the mass of the final tantalum pentoxide sample, in g; w_p is the mass fraction of Ta2O5 in the final tantalum pentoxide sample; m0 is the mass of the tantalum-containing raw material, in g; and w0 is the mass fraction of tantalum oxide in the tantalum-containing raw material, calculated as Ta2O5. The data are shown in Table 1.

[0096] Table 1. Performance test data of the examples and comparative examples

[0097] As shown in Table 1, the tantalum pentoxide samples obtained in Examples 1-4 all exhibited low fluoride ion concentrations in the back-extraction solution, the final washing solution, and the product fluoride content, while maintaining high Ta2O5 mass fraction and tantalum recovery rate. This indicates that the fluoride capture-complexation reverse back-extraction system, composed of ammonium oxalate, ammonium carbonate, ammonia, disodium ethylenediaminetetraacetate, polyethylene glycol 200, and supported fluoride capture microspheres, can synergistically promote the dissociation of tantalum-fluoride complexes and the transfer of tantalum to the aqueous phase during the back-extraction process, while simultaneously reducing the activity of free fluoride ions in the aqueous phase.

[0098] In Comparative Example 1, after replacing dopamine hydrochloride with polyvinyl alcohol, the solidification stability of zirconium-cerium hydroxide on the surface and in the pores of the resin microspheres decreased, resulting in a reduction in the utilization rate of fluorine trapping sites.

[0099] In Comparative Example 2, the lack of cerium component weakened the coordination adsorption synergy between zirconium and cerium active sites.

[0100] In Comparative Example 3, replacing zirconium oxychloride with aluminum chloride hexahydrate reduced the ability to fix fluoride ions and increased the risk of introducing impurities.

[0101] In Comparative Example 4, ammonia was directly used to replace urea, resulting in a faster local deposition process and reduced uniformity of active component distribution.

[0102] After Comparative Example 5 was replaced with strongly acidic cation exchange resin microspheres, the compatibility of the pore mass transfer and back-extraction system decreased.

[0103] In Comparative Example 6, the zirconium-cerium component deposition uniformity was insufficient after the ethanol-water mixed solvent was removed.

[0104] Comparative Example 7 only used D101 type macroporous adsorption resin microspheres, which lacked zirconium-cerium fluorine trapping active sites, resulting in a high fluorine residue.

[0105] In Comparative Example 8, after reducing the amount of immobilized fluorine-capturing microspheres, there were insufficient available capture sites per unit system.

[0106] In Comparative Example 9, after ammonium chloride was used to replace ammonium oxalate, the tantalum complexation and phase inversion ability was weakened, and the tantalum recovery rate decreased significantly.

[0107] In Comparative Example 10, replacing polyethylene glycol 200 with glycerol reduced the wetting and dispersibility of the supported fluorine-capturing microspheres in the back-extraction solution and the interfacial mass transfer efficiency.

[0108] Overall results show that the present invention, through the combination of complexation phase inversion, pore mass transfer, zirconium-cerium active site fixation, polydopamine adhesion and immobilization, and dispersion stabilization, is beneficial to reducing fluorine residue, controlling weight loss on ignition, and maintaining the purity and recovery rate of tantalum pentoxide products.

[0109] Phase analysis of the tantalum pentoxide products obtained in Examples 1-4 and Comparative Examples 1-10 was performed using X-ray diffraction. Cu Kα rays were used for the tests, with a scanning range of 10°-80° and a scanning rate of 5° / min. The test results are as follows: Figure 2 As shown.

[0110] The products obtained in Examples 1-4 exhibit characteristic diffraction peaks corresponding to the standard Ta₂O₅ spectrum at approximately 23°, 29°, 37°, 40°, 50°, 53°, 59°, 65°, and 67° 2θ, and no obvious impurity diffraction peaks are observed, indicating that the main crystalline phase of the products obtained in Examples 1-4 is tantalum pentoxide. Although Comparative Examples 1-10 also possess the main characteristic peaks of Ta₂O₅, weak impurity peaks or abnormal peak shapes deviating from the standard Ta₂O₅ spectrum appear at certain angular positions, indicating that without the use of the fluorine trapping-complexing-conversion reverse extraction system, supported fluorine trapping microspheres, or specific synergistic components specified in this invention, the residual impurities or the degree of crystalline phase purification in the products decrease. Combined with the results of fluorine content, Ta₂O₅ mass fraction, and loss on ignition tests, it can be concluded that the method of this invention can obtain low-fluorine, high-purity tantalum pentoxide products.

[0111] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing low-fluorine, high-purity tantalum pentoxide, characterized in that, Includes the following steps: S1. The tantalum-containing raw material is leached through a hydrofluoric acid system, and after solid-liquid separation, a tantalum-fluorine complex leachate is obtained. The tantalum-fluorine complex leachate is then adjusted to a free fluoride ion concentration of 3.0-8.0 mol / L and a tantalum concentration of 20-120 g / L to obtain the extract. S2. Extract the extractant solution using an organic phase containing phosphorus extractant to obtain a tantalum-loaded organic phase; S3. The supported tantalum organic phase is reacted with the fluorine capture-complexation reverse extraction system to obtain a low-fluorine tantalum-containing back-extraction solution. S4. Add a precipitant to the low-fluorine tantalum-containing back-extraction solution to precipitate tantalum in the form of hydrated tantalum oxide precursor, and obtain the low-fluorine tantalum precursor after solid-liquid separation. S5. The low-fluorine tantalum precursor is subjected to multi-stage washing, drying and calcination to obtain low-fluorine high-purity tantalum pentoxide. The fluorine capture-complexing reverse extraction system includes an extraction solution and solid-supported fluorine capture microspheres dispersed in the extraction solution. The back-extraction solution is composed of the following raw material components in parts by weight: 100 parts deionized water, 3.0-12.0 parts ammonium oxalate, 1.5-8.0 parts ammonium carbonate, 2.0-10.0 parts ammonia water with a mass fraction of 20-28%, 0.05-0.50 parts disodium ethylenediaminetetraacetate, and 0.10-0.80 parts polyethylene glycol 200; The supported fluorine-capturing microspheres are composed of the following raw material components in parts by weight: 100 parts macroporous adsorption resin microspheres, 0.5-4.0 parts dopamine hydrochloride, 0.3-2.0 parts tris(hydroxymethyl)aminomethane, 15-45 parts zirconium oxychloride, 2-12 parts cerium nitrate, 5-25 parts urea, 150-350 parts anhydrous ethanol, and 200-500 parts deionized water; The low-fluorine, high-purity tantalum pentoxide contains a Ta₂O₅ mass fraction of no less than 99.95%, a fluorine content of no more than 80 ppm, and a loss on ignition of no more than 0.10%. The amount of the supported fluoride-capturing microspheres added to the back-extraction solution is 4% of the mass of the back-extraction solution.

2. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, The macroporous adsorption resin microspheres are one or more of the following: D101 type macroporous adsorption resin, AB-8 type macroporous adsorption resin, and HPD-100 type macroporous adsorption resin.

3. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, In S1, the tantalum-containing raw material is one or more of the following: tantalum-niobium smelting intermediate material, tantalum-containing waste residue, and tantalum oxide concentrate; The fluorine-containing system consists of hydrofluoric acid, sulfuric acid, and deionized water, wherein, by mass, hydrofluoric acid comprises 20-45 parts, sulfuric acid comprises 5-25 parts, and deionized water comprises 30-75 parts; the mass fraction of hydrofluoric acid is 40-49%, and the mass fraction of sulfuric acid is 95-98%; the leaching temperature in S1 is 60-95℃, the leaching time is 2-8h, the liquid-solid mass ratio is 3-10:1, and after leaching, solid-liquid separation is performed using a filter medium with a pore size of 0.22-1.00μm to obtain the tantalum-fluorine complexed leachate.

4. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, In S2, the phosphorus-containing extractant is one or more of tributyl phosphate, di(2-ethylhexyl)phosphoric acid, and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester; The organic phase consists of a phosphorus-containing extractant and a diluent, wherein the volume fraction of the phosphorus-containing extractant in the organic phase is 20-70%. The diluent is one or more of sulfonated kerosene, n-heptane, and isoparaffin solvent oil. The volume ratio of the organic phase to the extract is 0.5-3.0:1, the extraction temperature is 20-45℃, the single-stage extraction time is 5-30 min, and the number of extraction stages is 1-5.

5. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, The preparation method of the supported fluorine-capturing microspheres includes the following steps: A1. The macroporous adsorption resin microspheres were washed sequentially with anhydrous ethanol and deionized water, and then dried at 40-70℃ for 4-12 hours to obtain pretreated resin microspheres. A2. Dissolve dopamine hydrochloride and tris(hydroxymethyl)aminomethane in deionized water, adjust the pH to 8.0-9.0, add pretreated resin microspheres, and stir at 20-35℃ for 6-24 hours to form a polydopamine adhesion layer on the surface of the resin microspheres, thus obtaining polydopamine modified resin microspheres. A3. Add zirconium oxychloride octahydrate, cerium nitrate hexahydrate and urea to a mixed solvent composed of anhydrous ethanol and deionized water, stir to dissolve, and then add the polydopamine modified resin microspheres. Adjust the initial pH of the system to 4.0-5.5 with dilute ammonia or ammonium bicarbonate aqueous solution, and then reflux or react in a closed system at 88-95℃ for 8-12 hours. A4. After the reaction is complete, the solid and liquid are separated. The obtained microspheres are washed with deionized water until the conductivity of the washing solution is not higher than 50 μS / cm, and then dried at 50-80℃ for 6-18h to obtain the solid-supported fluorine capturing microspheres.

6. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, In S3, the volume ratio of the supported tantalum organic phase to the fluorine capture-complexation conversion back-extraction system is 1:0.5-3.0, the contact back-extraction temperature is 20-60℃, the stirring speed is 200-800 r / min, the single-stage back-extraction time is 10-60 min, and the number of back-extraction stages is 1-4. During the back-extraction process, the pH of the aqueous phase is controlled at 7.5-10.5 so that the tantalum in the supported tantalum organic phase is transferred into the aqueous phase, and at the same time, free fluoride ions are adsorbed and captured by the solid-supported fluorine capture microspheres to obtain the low-fluorine tantalum-containing back-extraction solution.

7. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, In step S4, the precipitant is one or more of ammonia, ammonium carbonate aqueous solution, and ammonium bicarbonate aqueous solution. During the addition of the precipitant, the pH of the system is controlled at 8.0-10.5, the precipitation temperature is 25-70℃, and the precipitation time is 0.5-4h. After precipitation, an aging treatment is performed at a temperature of 25-70℃ for 1-8h. After solid-liquid separation, the low-fluorine tantalum precursor is obtained.

8. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, In S5, the multi-stage washing includes deionized water washing, dilute ammonia water washing, and a second deionized water washing; wherein the mass fraction of dilute ammonia water is 0.1-2.0%, the liquid-solid mass ratio of each washing stage is 3-15:1, the number of washing stages is 2-8 times, and the washing is continued until the fluoride ion concentration in the washing solution is not higher than 10 mg / L; in S5, the drying temperature of the low-fluoride tantalum precursor is 80-150℃, the drying time is 4-16h; the calcination temperature is 750-1100℃, the heating rate is 1-10℃ / min, the holding time is 2-8h, and the calcination atmosphere is air or oxygen.

9. The method for preparing low-fluorine, high-purity tantalum pentoxide according to claim 1, characterized in that, The obtained low-fluorine high-purity tantalum pentoxide has a Ta2O5 mass fraction of not less than 99.95%, a fluorine content of not more than 80 ppm, and a loss on ignition of not more than 0.10%.

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