A method for preparing a large bulk density tantalum pentoxide by a chemical process

Abstract

The present application relates to non-ferrous metal technical field, specifically to a kind of method for preparing large bulk density of tantalum pentoxide by chemical method, comprising the following steps: (1) adjust acid;(2) heating;(3) heating after fluorotantalate solution is passed into ammonia;(4) second stage ammonia precipitation;(5) static washing;(6) drying, obtain dry tantalum hydroxide;(7) push boat furnace roasting, obtain large bulk density of tantalum pentoxide.The present application uses static continuous washing, without through physical filter pressing, change physical performance parameter.The present application uses push boat furnace static continuous roasting, and the bulk density of tantalum pentoxide grows naturally.The powder of the present application is loose and uniform after roasting, without screening.The present application can efficiently produce the tantalum pentoxide with bulk density greater than 2g / cm 3 .

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-ferrous metals, in particular to a method for preparing large bulk density tantalum pentoxide by chemical method. BACKGROUND

[0002] Tantalum pentoxide is a white metal powder, mainly used in electronic industry, optical glass, lithium tantalate crystal, medicine and other fields.

[0003] At a certain precipitation temperature, the concentration of the precipitant remains unchanged, and the lower the speed of the precipitant during the precipitation process, the lower the solution supersaturation, thereby preparing large bulk tantalum pentoxide, but the production efficiency is low, and it is not suitable for efficient industrial production. The present application uses chemical precipitation method, controls the temperature of fluorotantalate solution system within a certain range, and increases the speed of the precipitant. Although the solution supersaturation will increase, the temperature of the fluorotantalate solution system is controlled within a temperature environment conducive to crystal growth, which can eliminate the influence of the increase of the speed of the precipitant on the increase of the solution supersaturation, thereby efficiently preparing large bulk tantalum pentoxide.

[0004] The method for improving the bulk of tantalum pentoxide prepared by traditional process is based on the addition of crystal seeds during the precipitation process of tantalum hydroxide. The addition of crystal seeds can reduce the primary nucleation process and play a role in inducing nucleation and promoting crystallization. However, according to the theory of precipitation crystallization, only when the particle size of the crystal seeds meets a certain critical size can nucleation be induced, which requires the cultivation of crystal seeds, and the operation is relatively complex. The present application does not need to add crystal seeds, but to keep the acidity of fluorotantalate solution within a certain range, thereby reducing the solution supersaturation, so that the rate of directional arrangement of crystal ions on the crystal nucleus surface is greater than the rate of crystal nucleus aggregation, thereby gradually growing the crystal nucleus.

[0005] In the existing technology, such as the patent "Preparation method of large bulk density tantalum oxide", the preparation of large bulk tantalum pentoxide adopts the method of adding crystal seeds to fluorotantalate solution, precipitating by ammonia neutralization, and repeatedly washing by pressure filtration to remove fluorine and other impurities, to obtain intermediate product tantalum hydroxide. After drying, the rotary tubular furnace is used for calcination at a calcination temperature not higher than 900 DEG C, and then screening is carried out to obtain bulk 1.5-1.8 g / cm 3, impurity content meets the industry standard "Tantalum Pentoxide" YS / T 427-2012 product grade FTa2O5-2 provisions of the tantalum pentoxide. However, the method of producing tantalum pentoxide, due to its washing process by physical means extrusion filter, affects the original bulk density of the powder, and the bulk density is still small and low purity, restricts its application in high purity material preparation, such as high purity tantalum powder, lithium tantalate crystal preparation. In addition, Mitsui Metal Mining Co., Ltd. applied for a patent "acidification tantalum powder and method for producing acidification tantalum powder", which uses ammonia water or ammonia gas slow neutralization precipitation process, the neutralization speed is 1% / hour-5% / hour, if the neutralization speed of the invention is 1% / hour-2% / hour, although the bulk tantalum pentoxide can be produced, the precipitation time is more than 50 hours, even more than 100 hours, the production efficiency is low and not suitable for efficient industrial production. SUMMARY

[0006] The purpose of the present application: the present application adopts chemical precipitation method, by controlling the temperature of fluorotantalate solution system in a certain range, increasing the input speed of precipitant, although the solution supersaturation will increase, but the temperature of fluorotantalate solution system is controlled in an environment temperature which is beneficial to crystal growth, which can eliminate the influence of the increase of supersaturation caused by the increase of the input speed of precipitant, so as to efficiently prepare bulk tantalum pentoxide; compared with the traditional process, the production efficiency is improved, which is suitable for efficient industrial production.

[0007] By keeping the acidity of fluorotantalate solution in a certain range, the solution supersaturation is reduced, so that the directional arrangement rate of crystal ion on the surface of crystal nucleus is greater than the aggregation rate of crystal nucleus, so that the crystal nucleus gradually grows; the washing is carried out in a static continuous leaching mode; there is no physical intervention, the original bulk density of the product is maintained; the dried tantalum hydroxide is loaded into a pure tantalum oxide crucible, and static roasting is carried out by using a push boat furnace, so that the product purity is high; after roasting, the tantalum pentoxide powder is loose and uniform, and does not need to be screened.

[0008] The specific technical scheme of the present application is as follows:

[0009] A method for preparing bulk density tantalum pentoxide by chemical method, comprising the following steps:

[0010] (1) adjust the acid: adding acid to the fluorotantalate solution prepared by extraction separation, and adjusting the acidity of the fluorotantalate solution;

[0011] (2) heating: heating the fluorotantalate solution by passing steam into the fluorotantalate solution;

[0012] (3) first stage ammonia precipitation: under stirring conditions, ammonia gas is passed into the fluorotantalate solution heated in step (2);

[0013] (4) Second stage ammonia precipitation: keeping the stirring speed, continue to pass ammonia into the fluorotantalate solution, to obtain a tantalum hydroxide slurry;

[0014] (5) Static washing: the tantalum hydroxide slurry obtained in step (4) is transferred to a washing tank with filter cloth, hot ammonia water is first passed into the washing tank to wash with ammonia water to remove fluorine, and then hot pure water is passed into the washing tank to wash with pure water to remove ammonia.

[0015] (6) Drying: after washing, the tantalum hydroxide is placed to drain water, and then is loaded into an oil heating vacuum oven or a steam oven to dry, to obtain dry tantalum hydroxide.

[0016] (7) Push boat furnace roasting: the tantalum hydroxide obtained in step (6) is loaded into a pure tantalum oxide crucible and placed in a push boat furnace to roast, to obtain a large bulk density tantalum pentoxide.

[0017] Further, the acid is at least one of hydrofluoric acid or sulfuric acid.

[0018] Further, in step (1), the acidity of the fluorotantalate solution is maintained at 1.3-2 mol / L.

[0019] Further, in step (2), the temperature of the fluorotantalate solution is maintained at 70-80℃.

[0020] Further, in step (3), the stirring speed is 80-90 rpm, the precipitation is to pH 3-4, and the first stage precipitation time is controlled at 0.3-2 hours.

[0021] Further, in step (4), the stirring speed is 80-90 rpm, the precipitation is to pH 8-9, and the second stage precipitation time is controlled at 2-9 hours.

[0022] Further, in step (5), the temperature of the hot ammonia water is 75-80℃, the weight percentage concentration of ammonia in the ammonia water is 1.5-2%, the washing time is 24-36 hours, the temperature of the hot pure water is 75-80℃, and the washing time is 18-24 hours.

[0023] Further, in step (6), the oil heating vacuum oven is used for drying, the drying temperature is 140℃, and the drying time is 16-24 hours.

[0024] Alternatively, in step (6), the steam oven is used for drying, the drying temperature is 100-110℃, and the drying time is 36-48 hours.

[0025] Further, in step (7), the roasting is performed by low-temperature roasting and high-temperature roasting, the low-temperature roasting temperature is set to 350-650 DEG C, the high-temperature roasting temperature is set to 950-1000 DEG C, the low-temperature roasting time is 4-9 hours, and the high-temperature roasting time is 10-20 hours.

[0026] In the present application, the high-purity large bulk density refers to the purity of the tantalum pentoxide meeting the FTa2O5-035 product grade in the industry standard YS / T 547-2007, and the bulk density of the product is greater than 2 g / cm 3 .

[0027] The beneficial effects of the present application are: (1) the present application adopts the chemical precipitation method, by controlling the temperature of the fluorotantalate solution system within a certain range, increasing the input speed of the precipitant, although the solution supersaturation degree will increase, but the temperature of the fluorotantalate solution system is controlled in an environment temperature conducive to crystal growth, which can eliminate the influence of the increase of the input speed of the precipitant on the increase of the supersaturation degree, thereby efficiently preparing large bulk density tantalum pentoxide; (2) the present application does not need to add crystal seeds to promote the growth of crystals, but maintains the acidity of the fluorotantalate solution within a certain range, thereby reducing the solution supersaturation degree, so that the directional arrangement rate of the crystal ions on the crystal nucleus surface is greater than the aggregation rate of the crystal nucleus, thereby gradually growing the crystal nucleus; (3) as known, filter pressing extrusion belongs to physical intervention, and the bulk density is extremely easy to increase through physical intervention, the present application adopts the static continuous washing method for washing without physical intervention, thereby maintaining the original bulk density, particle size and morphology of the product; (4) the dried tantalum hydroxide is loaded into a pure tantalum oxide crucible, and static roasting is adopted by using a push boat furnace, which is different from the agglomeration of the powder in the rotating process in the roasting process of the rotary furnace, the material is loose and not agglomerated after the static roasting of the push boat furnace is completed, and there is no need for screening, the tantalum pentoxide powder is uniform, the product purity can be effectively improved, and the production efficiency is high; (5) the present application has a short process and strong controllability for preparing large bulk density tantalum pentoxide.

[0028] The present application adopts static continuous washing, and there is no need for physical filter pressing to change the physical performance parameters. The present application adopts static continuous roasting by using a push boat furnace, and the bulk density of the tantalum pentoxide is naturally grown. The tantalum pentoxide powder is loose and uniform after roasting, and there is no need for screening. The present application can efficiently produce tantalum pentoxide with a bulk density greater than 2 g / cm 3 . BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a process flow chart of the method for chemically preparing large bulk density tantalum pentoxide according to the present application. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the technical scheme of the application, the technical scheme will be further explained and described through examples.

[0031] Method 1

[0032] (1) Add 1000L of fluorotantalum acid solution to the reaction kettle and start the stirring paddle, and control the stirring paddle speed at 80-90 revolutions per minute.

[0033] (2) Add 50L of analytical reagent hydrofluoric acid to the fluorotantalum acid solution, and check that the fluorotantalum acid solution has an acidity of 2 mol / L and a tantalum pentoxide content of 80g / L.

[0034] (3) Heat the fluorotantalum acid solution to 79.3℃ by passing steam, with a steam pressure of 1-3Kpa, and the steam is passed for 1-3 hours.

[0035] (4) Pass ammonia gas into the fluorotantalum acid solution heated to 79.3℃, and maintain a steady flow of ammonia gas, with the first stage of precipitation being completed at pH=3-4, and the first stage of precipitation taking 1.5 hours.

[0036] (5) Continue to pass ammonia gas into the solution, maintain a steady flow of ammonia gas, and at the same time reduce the ammonia gas flow rate until pH=8-9, and the second stage of precipitation is completed, with the second stage of precipitation taking 8 hours.

[0037] (6) Transfer the above-mentioned precipitated tantalum hydroxide slurry to a leaching tank lined with filter cloth, and wash with hot ammonia water, with the ammonia water temperature being 77℃, the weight percentage concentration of ammonia in the ammonia water being 2%, the washing time being 36 hours, and the hot ammonia water being stopped after 36 hours.

[0038] (7) Wash the above-mentioned leaching tank with hot pure water, with the pure water temperature being 78℃, and the washing time being 24 hours, and the hot pure water being stopped after 24 hours.

[0039] (8) Let the above-mentioned washed tantalum hydroxide slurry stand for 12 hours to fully drain the water.

[0040] (9) Load the above-mentioned water-drained tantalum hydroxide into an oil-heated vacuum oven, with the drying temperature being 140℃, and the drying time being 20 hours.

[0041] (10) Detect the bulk density of the above-mentioned dried tantalum hydroxide, and the bulk density of the tantalum hydroxide is 1.21g / cm 3 .

[0042] (11) Load the above-mentioned tantalum hydroxide into a pure tantalum crucible, and place it in a push boat furnace for calcination, with the calcination temperature being 350℃, the calcination time being 3 hours, the calcination temperature being 650℃, the calcination time being 6 hours, and the calcination temperature being 1000℃, the calcination time being 16 hours.

[0043] (12) The high-purity large bulk density tantalum pentoxide prepared above is analyzed and detected, and the specific analysis and detection data are shown in Table 1.

[0044] Method 2 is implemented

[0045] (1) 1000L of fluorotantalate solution is added to a reaction kettle, and a stirring paddle is turned on, and the stirring paddle is controlled at 80-90 revolutions per minute.

[0046] (2) 35L of analytical reagent hydrofluoric acid is added to the fluorotantalate solution, and the fluorotantalate solution is checked to have an acidity of 1.35 mol / L and a tantalum pentoxide content of 80 g / L.

[0047] (3) Steam is introduced into the fluorotantalate solution to heat it to 80°C, the steam pressure is 1-3 Kpa, and the steam introduction time is 1-3 hours.

[0048] (4) Ammonia gas is introduced into the fluorotantalate solution heated to 80°C, and the ammonia gas is kept smoothly introduced, the first stage of precipitation is completed when the pH is 3-4, and the first stage of precipitation time is 1 hour.

[0049] (5) The ammonia gas is continuously introduced, and the ammonia gas is kept smoothly introduced while the ammonia gas introduction rate is reduced until the pH is 8-9, the second stage of precipitation is completed, and the second stage of precipitation time is 4 hours.

[0050] (6) The tantalum hydroxide slurry prepared above is transferred into a leaching tank paved with filter cloth, and hot ammonia water is added for washing, the temperature of the ammonia water is 78°C, the weight percentage concentration of ammonia in the ammonia water is 2%, the washing time is 36 hours, and the hot ammonia water is stopped after 36 hours.

[0051] (7) Hot pure water is introduced into the leaching tank for washing, the temperature of the pure water is 75°C, the washing time is 24 hours, and the pure water is stopped after 24 hours

[0052] (8) The tantalum hydroxide slurry prepared above is left to stand for 12 hours to fully drain water.

[0053] (9) The tantalum hydroxide drained above is loaded into an oil heating vacuum oven, the drying temperature is 140°C, and the drying time is 20 hours.

[0054] (10) The tantalum hydroxide prepared above is detected for bulk density, and the bulk density of the tantalum hydroxide is 1.07 g / cm 3 .

[0055] (11) The tantalum hydroxide is loaded into a pure tantalum crucible and placed in a push boat furnace for roasting, the roasting temperature is 350°C, the roasting time is 3 hours, the roasting temperature is 650°C, the roasting time is 6 hours, the roasting temperature is 1000°C, and the roasting time is 16 hours.

[0056] (12) The high-purity, large bulk density tantalum pentoxide prepared above is analyzed and detected, and the specific analysis and detection data are shown in Table 1.

[0057] Method 3 is implemented

[0058] (1) 1000L of fluorotantalate solution is added to a reaction kettle, and a stirring paddle is turned on, and the stirring paddle is controlled at a speed of 80-90 revolutions per minute.

[0059] (2) 20L of analytical reagent hydrofluoric acid is added to the fluorotantalate solution, and the acidity of the fluorotantalate solution is checked to be 1.47 mol / L, and the content of tantalum pentoxide is 77.2 g / L.

[0060] (3) Steam is introduced into the fluorotantalate solution to heat it to 76°C, the steam pressure is 1-3 Kpa, and the steam introduction time is 1-3 hours.

[0061] (4) Ammonia gas is introduced into the fluorotantalate solution heated to 76°C, and the ammonia gas is introduced smoothly, the first stage of precipitation is completed when the pH is 3-4, and the first stage of precipitation time is 0.5 hours.

[0062] (5) The ammonia gas is continuously introduced, and the ammonia gas is introduced smoothly, and the ammonia gas introduction rate is reduced until the pH is 8-9, the second stage of precipitation is completed, and the second stage of precipitation time is 3.5 hours.

[0063] (6) The tantalum hydroxide slurry prepared above is transferred to a leaching tank lined with filter cloth, and hot ammonia water is added for washing, the temperature of the ammonia water is 77°C, the weight percentage concentration of ammonia in the ammonia water is 2%, the washing time is 36 hours, and the hot ammonia water is stopped after 36 hours.

[0064] (7) Hot pure water is introduced into the leaching tank for washing, the temperature of the pure water is 76°C, and the washing time is 24 hours, and the washing is stopped after 24 hours

[0065] (8) The tantalum hydroxide slurry prepared above is left to stand for 12 hours to fully drain the water.

[0066] (9) The tantalum hydroxide drained of water is loaded into an oil-heated vacuum oven, the drying temperature is 140°C, and the drying time is 20 hours.

[0067] (10) The tantalum hydroxide prepared above is detected for bulk density, and the bulk density of the tantalum hydroxide is 1.04 g / cm 3 .

[0068] (11) The tantalum hydroxide is loaded into a pure tantalum crucible and placed in a push boat furnace for roasting, the roasting temperature is 350°C, the roasting time is 3 hours, the roasting temperature is 650°C, the roasting time is 6 hours, and the roasting temperature is 1000°C, the roasting time is 16 hours.

[0069] (12) The high-purity, large bulk density tantalum pentoxide prepared according to the technical scheme of the present application is analyzed and detected, and the specific analysis and detection data are shown in Table 1.

[0070] Table 1

[0071]

[0072] As shown in the data in Table 1, the impurities in the high-purity, large bulk density tantalum pentoxide product prepared according to the technical scheme of the present application are superior to the current industry standard, and the bulk density of the product is at least 2.01 g / cm 3 and at most 2.22 g / cm 3 .

[0073] In order to compare the differences in experimental conditions and experimental results between the present application and existing products, the experimental conditions of existing products are shown in the following two patents: patent: JP2005314202A and patent: CN110156082A, and the experimental conditions of the present application are shown in Examples 1, 2 and 3 in Part 4, which have been described in detail. The experimental results are shown in Table 1, and Comparative Example 1 (Example 3 in patent: JP2005314202A), Comparative Example 2 (Example 2 in patent: CN110156082A), and the bulk density experimental data are shown in Table 2.

[0074] Table 2

[0075] Example Method 1 Example Method 2 Example Method 3 Comparative Example 1 Comparative Example 2 Bulk density (g / cm 3 ) 2.22 2.01 2.21 1.77 1.77

[0076] As can be seen from the experimental results in Table 2, the present application can efficiently and conveniently prepare large bulk density, high-purity tantalum pentoxide by chemical method.

[0077] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the present application, and such changes or modifications are equivalent to equivalent embodiments, and are within the scope of the technical scheme.

Claims

1. A method for preparing tantalum pentoxide with high bulk density by chemical method, characterized in that: The steps include: (1) Acid adjustment: adding acid to the fluorotantalate solution obtained by extraction separation to adjust the acidity of the fluorotantalate solution; (2) Heating: passing steam into the fluorotantalate solution to heat the fluorotantalate solution; (3) First stage ammonia precipitation: ammonia gas is introduced into the fluorotantalate solution heated in step (2) under stirring; (4) Second stage ammonia precipitation: maintain the stirring speed and continue to introduce ammonia into the fluorotantalate solution to obtain tantalum hydroxide slurry; (5) Static elution: The tantalum hydroxide slurry obtained in step (4) is transferred to an elution tank covered with a filter cloth. Hot ammonia water is first introduced into the elution tank for ammonia washing and fluorine removal. After the ammonia washing is completed, hot pure water is introduced into the elution tank for pure water washing and ammonia removal. (6) Drying: After washing, the tantalum hydroxide is allowed to stand and drain the water therein, and then dried to obtain dry tantalum hydroxide; (7) Calcination in a push boat furnace: The tantalum hydroxide obtained in step (6) is placed in a pure tantalum oxide crucible and placed in a push boat furnace for calcination to obtain tantalum pentoxide with a high bulk density; In step (1), the acidity of the fluorotantalate solution is maintained at 1.3-2 mol / L; In step (2), the temperature of the fluorotantalate solution is maintained at 70-80°C; In step (3), the stirring speed is 80-90 rpm, and the solution is precipitated to a pH of 3-4. The precipitation time of the first stage is controlled at 0.3-2 hours. In step (4), the stirring speed is 80-90 rpm, and the solution is precipitated to pH 8-9. The second stage precipitation time is controlled at 2-9 hours. In step (7), the calcination is carried out by first calcining at low temperature and then calcining at high temperature. The low temperature calcination temperature is set to 350-650°C, the highest temperature calcination temperature is set to 950-1000°C, the low temperature calcination time is 4-9 hours, and the high temperature calcination time is 10-20 hours.

2. The method for preparing tantalum pentoxide with high bulk density by chemical method according to claim 1, characterized in that: In step (1), the acid is at least one of hydrofluoric acid or sulfuric acid.

3. The method for preparing tantalum pentoxide with high bulk density by chemical method according to claim 1, characterized in that: In step (5), the temperature of the hot ammonia water is 75-80°C, the weight percentage concentration of ammonia in the ammonia water is 1.5-2%, the washing time is 24-36 hours, and the temperature of the hot pure water is 75-80°C, and the washing time is 18-24 hours.

4. The method for preparing tantalum pentoxide with high bulk density by chemical method according to claim 1, characterized in that: In step (6), when drying is performed in an oil-heated vacuum oven, the drying temperature is 140° C. and the drying time is 16-24 hours.

5. The method for preparing tantalum pentoxide with high bulk density by chemical method according to claim 1, characterized in that: In step (6), when a steam oven is used for drying, the drying temperature is 100-110° C. and the drying time is 36-48 hours.

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