High-apparent-density tantalum oxide and preparation method thereof

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to high-apparent-density tantalum oxide and a preparation method thereof. The invention provides a preparation method of high-apparent-density tantalum oxide, which comprises the following steps: adding a urea solution into a fluotantalic acid solution, and carrying out first neutralization reaction to obtain a fluotantalic acid neutralization solution; adding ammonia water into the fluorine tantalic acid neutralization solution, and carrying out a second neutralization reaction to obtain tantalum hydroxide; and calcining the tantalum hydroxide to obtain the high-apparent-density tantalum oxide. According to the present invention, the traditional process is adjusted, the high apparent density tantalum oxide is prepared by using the two-stage neutralization method, the urea is used for neutralization in the first-stage neutralization, the solubility of the urea is high, the dispersion degree of the urea in the solution is good, and the urea is added in the first-stage neutralization so as to form the uniform and fine crystal nucleus without generating the precipitate; and adding ammonia water to slowly neutralize, so that a crystal nucleus slowly grows, and tantalum oxide which is easy to wash and filter, not easy to agglomerate, good in dispersity, regular in crystal form, uniform in morphology and high in loose density is formed.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a tantalum oxide with a high bulk density and a preparation method thereof. Background Art

[0002] Tantalum oxide has good chemical stability and high capacitance performance. It is a wide-bandgap semiconductor and can be used to prepare high-performance capacitors. Tantalum oxide capacitors have high capacitance density, low capacitance leakage current and good temperature stability, so they are widely used in the fields of electronic devices, communication equipment, computers and household appliances. In addition, tantalum oxide also has excellent photocatalytic performance and has broad application prospects in the fields of water treatment, air purification and environmental protection. Therefore, tantalum oxide has important applications in the electronic industry, catalyst field and ceramic industry.

[0003] The traditional preparation method of tantalum oxide commonly uses liquid ammonia, ammonia, etc. for direct neutralization precipitation to obtain tantalum hydroxide, and then obtains tantalum oxide after drying and calcination. However, during the neutralization process, ammonia is prone to volatilization, resulting in uneven neutralization, high local reaction temperature during neutralization, rapid nucleation of tantalum hydroxide particles, small tantalum hydroxide precipitation, and uneven dispersion of tantalum hydroxide, which will also affect the morphology of tantalum oxide, cause agglomeration of tantalum oxide particles, difficult filtration, difficult washing, and low crystallinity, thus directly affecting the purity and quality stability of the product.

[0004] Therefore, there is an urgent need to obtain a tantalum oxide with a high bulk density. Summary of the Invention

[0005] The purpose of the present invention is to provide a tantalum oxide with a high bulk density and a preparation method thereof. The method provided by the present invention can obtain a tantalum oxide with a high bulk density.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a tantalum oxide with a high bulk density, comprising the following steps:

[0008] Adding a urea solution to a fluotantalic acid solution to carry out a first neutralization reaction to obtain a fluotantalic acid neutralization solution;

[0009] Adding ammonia water to the fluotantalic acid neutralization solution to carry out a second neutralization reaction to obtain tantalum hydroxide;

[0010] Calcining the tantalum hydroxide to obtain the tantalum oxide with a high bulk density.

[0011] Preferably, the concentration of Ta2O5 in the fluotantalic acid solution is 40-60 g / L.

[0012] Preferably, the concentration of the urea solution is 80-100 g / L;

[0013] The urea solution is obtained by dissolving urea in water; the purity of the urea is > 99%; the temperature of the water is 80 - 90 °C.

[0014] Preferably, the rate of adding the urea solution is 5 L / min; the time of the first neutralization reaction includes the time of adding the urea solution and the time of continuous reaction after the addition is completed;

[0015] The time of adding the urea solution is 40 - 60 min until the pH value of the system is 3 - 4;

[0016] The time of continuous reaction is 30 - 40 min;

[0017] The first neutralization reaction is carried out under stirring, and the rotation speed of the stirring is 50 - 100 rpm.

[0018] Preferably, the mass concentration of the ammonia water is 8 - 12%.

[0019] Preferably, the rate of adding the ammonia water is 10 L / min; the time of the second neutralization reaction includes the time of adding the ammonia water and the time of continuous reaction after the addition is completed;

[0020] The time of adding the ammonia water is 120 - 180 min until the pH value of the system is 8 - 9;

[0021] The time of continuous reaction is 30 - 40 min;

[0022] The second neutralization reaction is carried out under stirring, and the rotation speed of the stirring is 50 - 100 rpm.

[0023] Preferably, after the second neutralization reaction, it further includes solid-liquid separation of the obtained slurry, and washing and drying of the obtained precipitate.

[0024] Preferably, the washing process is as follows: mixing the precipitate and hot ammonia-containing pure water until the pH value of the system is 8, separating after stirring, and repeating the above operation 3 - 4 times; the temperature of the hot ammonia-containing pure water is 85 - 90 °C; the stirring time is 30 - 45 min;

[0025] The drying temperature is 85 - 120 °C, and the time is 12 - 6 h.

[0026] Preferably, the calcination temperature is 850 - 1100 °C, and the heat preservation time is 8 - 10 h.

[0027] The present invention also provides tantalum oxide with a high bulk specific gravity prepared by the preparation method described above, and the bulk specific gravity of the tantalum oxide is 1.4 - 1.5 g / cm 3 。

[0028] The present invention provides a method for preparing tantalum oxide with a high tap density, comprising the following steps: adding a urea solution to a fluotantalic acid solution to carry out a first neutralization reaction to obtain a neutralized fluotantalic acid solution; adding ammonia water to the neutralized fluotantalic acid solution to carry out a second neutralization reaction to obtain tantalum hydroxide; and calcining the tantalum hydroxide to obtain the tantalum oxide with a high tap density. The present invention makes adjustments to the traditional process and adopts a two-stage neutralization method to prepare tantalum oxide with a high tap density. In the first stage of neutralization, urea is used for neutralization. Urea has a large solubility and good dispersion in the solution. Adding urea in the first stage of neutralization can form uniform and fine crystal nuclei without precipitation; then adding ammonia water for slow neutralization enables the crystal nuclei to grow slowly, forming tantalum oxide that is easy to wash and filter, not prone to agglomeration, has good dispersibility, regular crystal form, uniform morphology, and a high tap density. Detailed implementation manners

[0029] The present invention provides a method for preparing tantalum oxide with a high tap density, comprising the following steps:

[0030] Adding a urea solution to a fluotantalic acid solution to carry out a first neutralization reaction to obtain a neutralized fluotantalic acid solution;

[0031] Adding ammonia water to the neutralized fluotantalic acid solution to carry out a second neutralization reaction to obtain tantalum hydroxide;

[0032] Calcining the tantalum hydroxide to obtain the tantalum oxide with a high tap density.

[0033] In the present invention, a urea solution is added to a fluotantalic acid solution to carry out a first neutralization reaction to obtain a neutralized fluotantalic acid solution.

[0034] In the present invention, the concentration of the urea solution is preferably 80 - 100 g / L, specifically it can be 80 g / L, 90 g / L, 100 g / L; the urea solution is preferably obtained by dissolving urea in water; the purity of the urea is preferably > 99%; the water is preferably pure water; the temperature of the water is preferably 80 - 90 °C.

[0035] In the present invention, the concentration of Ta2O5 in the fluotantalic acid solution is preferably 40 - 60 g / L, specifically it can be 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L.

[0036] In the present invention, the addition rate of the urea solution is preferably 5 L / min; the time of the first neutralization reaction preferably includes the time for adding the urea solution and the time for continuing the reaction after the addition is completed; the time for adding the urea solution is preferably 40 - 60 min, preferably until the pH value of the system is 3 - 4; the time for continuing the reaction is preferably 30 - 40 min; the first neutralization reaction is preferably carried out under stirring, and the stirring speed is preferably 50 - 100 rpm.

[0037] After obtaining the tantalum fluoride neutralization solution, ammonia water is added to the tantalum fluoride neutralization solution in the present invention to carry out a second neutralization reaction to obtain tantalum hydroxide.

[0038] In the present invention, the mass concentration of the ammonia water is preferably 8-12%, specifically it can be 8%, 9%, 10%, 11%, 12%. In the present invention, the addition rate of the ammonia water is preferably 10 L / min; the time of the second neutralization reaction preferably includes the time of adding the ammonia water and the time of continuing the reaction after the addition is completed; the time of adding the ammonia water is preferably 120-180 min, preferably until the pH value of the system is 8-9; the time of continuing the reaction is preferably 30-40 min; the second neutralization reaction is preferably carried out under stirring conditions, and the stirring speed is preferably 50-100 rpm.

[0039] In the present invention, after the second neutralization reaction, it preferably further includes solid-liquid separation of the obtained slurry, and washing and drying of the obtained precipitate. In the present invention, the solid-liquid separation method is preferably pressure filtration. In the present invention, the washing process is preferably as follows: mixing the precipitate and hot ammonia-containing pure water until the pH value of the system is 8, separating after stirring, and repeating the above operation 3-4 times; the temperature of the hot ammonia-containing pure water is preferably 80-90 °C; the stirring time is preferably 30-45 min. In the present invention, the drying temperature is preferably 85-120 °C, and the time is preferably 12-6 h.

[0040] In the present invention, the calcination temperature is preferably 850-1100 °C, specifically it can be 850 °C, 900 °C, 950 °C, 1000 °C, 1050 °C, 1100 °C; the heat preservation time is preferably 8-10 h, specifically it can be 8 h, 9 h, 10 h. In the present invention, the calcination is preferably carried out in a pusher furnace, and the loading amount of tantalum hydroxide in each calcination process is preferably 1.5-2.0 kg / crucible.

[0041] The present invention also provides high-bulk-density tantalum oxide prepared by the preparation method described in the above technical solution, and the bulk density of the tantalum oxide is 1.4-1.5 g / cm 3 。

[0042] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0043] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0044] Example 1

[0045] Add 2500 L of tantalum hexafluoride solution with a concentration of 45 g / L (calculated as Ta2O5) to the reaction tank. Prepare a urea solution with a concentration of 100 g / L using pure water at 90 °C and urea with a purity > 99%. Slowly add the urea solution to the reaction tank at a flow rate of 5 L / min. Start the stirring paddle with a rotation speed of 100 rpm and neutralize to a pH value of 3.5. The neutralization time is 40 minutes (i.e., the addition time of the urea solution). After the addition is completed, continue stirring for 40 minutes to obtain a tantalum hexafluoride neutralization solution;

[0046] Slowly add ammonia water with a concentration of 12% to the tantalum hexafluoride neutralization solution at a flow rate of 10 L / min. The neutralization time is 150 minutes (i.e., the addition time of the ammonia water), and neutralize to a pH value of 8.0. After the addition is completed, continue stirring for 40 minutes to obtain a tantalum hydroxide slurry;

[0047] Filter the tantalum hydroxide slurry into a filter cake and transfer it to a conditioning and washing tank. Use hot ammonia-containing pure water at 85 °C to adjust the pH value of the system to 8.0. Use 3 m 3 of water per tank. Start the stirring paddle, stir for 30 minutes, then pump it into a filter press for filtration. Transfer it back to the conditioning and washing tank again and wash it repeatedly with hot ammonia-containing pure water 3 - 4 times to obtain wet tantalum hydroxide;

[0048] Place the wet tantalum hydroxide evenly and flatly on a tray, then load it into a forced-air electric oven. The drying temperature is 100 °C and the heat preservation time is 12 hours to obtain blocky tantalum hydroxide powder;

[0049] Use a crucible to send the blocky tantalum hydroxide powder to a pusher furnace for calcination. The loading amount of tantalum hydroxide in the crucible is 3 kg / crucible. Control the calcination temperature at 950 °C and the calcination time at 10 hours to obtain tantalum oxide.

[0050] Example 2

[0051] Add 2500 L of tantalum hexafluoride solution with a concentration of 55 g / L (calculated as Ta2O5) to the reaction tank. Prepare a urea solution with a concentration of 100 g / L using pure water at 90 °C and urea with a purity > 99%. Slowly add the urea solution to the reaction tank at a flow rate of 5 L / min. Start the stirring paddle with a rotation speed of 100 rpm and neutralize to a pH value of 4.0. The neutralization time is 40 minutes (i.e., the addition time of the urea solution). After the addition is completed, continue stirring for 40 minutes to obtain a tantalum hexafluoride neutralization solution;

[0052] Slowly add ammonia water with a concentration of 10% to the tantalum hexafluoride neutralization solution at a flow rate of 10 L / min. The neutralization time is 160 minutes (i.e., the addition time of the ammonia water), and neutralize to a pH value of 8.0. After the addition is completed, continue stirring for 40 minutes to obtain a tantalum hydroxide slurry;

[0053] After filtering the tantalum hydroxide slurry into a filter cake, transfer it to a conditioning and washing tank, and adjust the pH value of the system to 8.0 with hot ammonia-containing pure water at a temperature of 85°C. Use 3 m 3 of water per tank, start the stirring paddle, stir for 30 minutes, then pump it into a filter press for filtration. Transfer it back to the conditioning and washing tank again, and repeatedly wash it 3 - 4 times with hot ammonia-containing pure water to obtain wet tantalum hydroxide;

[0054] Place the wet tantalum hydroxide evenly and flatly on a tray, then load it into a forced-air electric heating oven. The drying temperature is 120°C and the heat preservation time is 10 hours to obtain blocky tantalum hydroxide powder;

[0055] Use a crucible to send the blocky tantalum hydroxide powder to a pusher furnace for calcination. The loading amount of tantalum hydroxide in the crucible is 3 kg / crucible. Control the calcination temperature at 1000°C and the calcination time at 10 hours to obtain tantalum oxide.

[0056] Example 3

[0057] Add 2500 L of tantalum hexafluoride solution with a concentration of 40 g / L (calculated as Ta2O5) to a reaction tank. Prepare a urea solution with a concentration of 90 g / L using pure water at a temperature of 90°C and urea with a purity > 99%. Slowly add the urea solution to the reaction tank at a flow rate of 5 L / min, start the stirring paddle with a rotation speed of 100 rpm, neutralize to a pH value of 4.0, and the neutralization time is 50 minutes (i.e., the addition time of the urea solution). After the addition is completed, continue stirring for 40 minutes to obtain a tantalum hexafluoride neutralization solution;

[0058] Slowly add ammonia water with a concentration of 8% to the tantalum hexafluoride neutralization solution at a flow rate of 10 L / min. The neutralization time is 180 minutes (i.e., the addition time of the ammonia water), neutralize to a pH value of 9.0, and continue stirring for 30 minutes after the addition is completed to obtain a tantalum hydroxide slurry;

[0059] After filtering the tantalum hydroxide slurry into a filter cake, transfer it to a conditioning and washing tank, and adjust the pH value of the system to 8.0 with hot ammonia-containing pure water at a temperature of 90°C. Use 3 m 3 of water per tank, start the stirring paddle, stir for 30 minutes, then pump it into a filter press for filtration. Transfer it back to the conditioning and washing tank again, and repeatedly wash it 3 - 4 times with hot ammonia-containing pure water to obtain wet tantalum hydroxide;

[0060] Place the wet tantalum hydroxide evenly and flatly on a tray, then load it into a forced-air electric heating oven. The drying temperature is 95°C and the heat preservation time is 10 hours to obtain blocky tantalum hydroxide powder;

[0061] Use a crucible to send the blocky tantalum hydroxide powder to a pusher furnace for calcination. The loading amount of tantalum hydroxide in the crucible is 3 kg / crucible. Control the calcination temperature at 1100°C and the calcination time at 9 hours to obtain tantalum oxide.

[0062] Performance Test

[0063] The prepared tantalum oxide was tested by a loose bulk density meter, and the test results are shown in Table 1;

[0064] After the prepared tantalum oxide was kept in a muffle furnace at 850 °C for 1 h, its loss on ignition was tested, and the test results are shown in Table 1;

[0065] Table 1 Test results of tantalum oxide obtained in the examples

[0066] Example 1 Example 2 Example 3 <![CDATA[Specific gravity (g / cm 3 )]]> 1.40 1.45 1.48 Ablation amount / % 0.08 0.11 0.15

[0067] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A preparation method of tantalum oxide with a high aspect ratio, characterized in that, It includes the following steps: Adding a urea solution to a tantalum fluoride solution to carry out a first neutralization reaction to obtain a neutralized tantalum fluoride solution; Adding ammonia water to the neutralized tantalum fluoride solution to carry out a second neutralization reaction to obtain tantalum hydroxide; Calcining the tantalum hydroxide to obtain the high-bulk-density tantalum oxide.

2. The preparation method according to claim 1, wherein The concentration of Ta2O5 in the tantalum fluoride solution is 40 - 60 g / L.

3. The preparation method according to claim 2, wherein The concentration of the urea solution is 80 - 100 g / L; The urea solution is obtained by dissolving urea in water; the purity of the urea > 99%; the temperature of the water is 80 - 90 °C.

4. The preparation method according to claim 3, characterized in that, The adding rate of the urea solution is 5 L / min; the time of the first neutralization reaction includes the time for adding the urea solution and the time for continuing the reaction after the addition is completed; The time for adding the urea solution is 40 - 60 min until the pH value of the system is 3 - 4; The time for continuing the reaction is 30 - 40 min; The first neutralization reaction is carried out under stirring, and the stirring speed is 50 - 100 rpm.

5. The preparation method according to claim 1, wherein The mass concentration of the ammonia water is 8 - 12%.

6. The preparation method according to claim 5, wherein The adding rate of the ammonia water is 10 L / min; the time of the second neutralization reaction includes the time for adding the ammonia water and the time for continuing the reaction after the addition is completed; The time for adding the ammonia water is 120 - 180 min until the pH value of the system is 8 - 9; The time for continuing the reaction is 30 - 40 min; The second neutralization reaction is carried out under stirring, and the stirring speed is 50 - 100 rpm.

7. The preparation method according to claim 1, wherein After the second neutralization reaction, it further includes solid-liquid separation of the obtained slurry, and washing and drying of the obtained precipitate.

8. The preparation method according to claim 7, wherein The process of washing is: mixing the precipitate and hot ammonia-containing pure water until the pH value of the system is 8, separating after stirring, and repeating the above operation 3 - 4 times; the temperature of the hot ammonia-containing pure water is 85 - 90 °C; the stirring time is 30 - 45 min; The drying temperature is 85 - 120 °C, and the time is 12 - 6 h.

9. The preparation method according to claim 1, characterized in that, The calcining temperature is 850 - 1100 °C, and the heat preservation time is 8 - 10 h. The high aspect ratio tantalum oxide prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The bulk density of the tantalum oxide is 1.4 to 1.5 g / cm 3 .