Method for preparing potassium fluorotantalate from tantalum liquor

Abstract

This invention relates to a method for preparing potassium fluorotantalate from tantalum solution, comprising the following steps: heating and conversion of the solution, transferring the potassium fluorotantalate crystallization solution, cooling and crystallizing the potassium fluorotantalate, discharging the potassium fluorotantalate crystallization mother liquor, washing the potassium fluorotantalate crystals, discharging the potassium fluorotantalate crystals, and drying the potassium fluorotantalate crystals. The beneficial effects are: the method of this invention is suitable for preparing potassium fluorotantalate from tantalum solution with a tantalum oxide concentration of 50 g / L to 80 g / L; high-concentration tantalum solutions do not require dilution with deionized water, saving conversion reaction materials; before adding the potassium fluorotantalate crystallization solution to the crystallization washing tank, hot water is circulated through the media jacket to preheat the crystallization washing tank, preventing excessively rapid cooling when the potassium fluorotantalate crystallization solution is added to the crystallization washing tank, thus preventing the formation of a large number of crystal nuclei or the generation of fine crystals, while allowing sufficient time for crystal growth.

Description

Technical Field

[0001] This invention relates to the field of potassium fluorotantalate preparation, and more particularly to a method for preparing potassium fluorotantalate from tantalum solution. Background Technology

[0002] Potassium fluorotantalate is mainly used to prepare metallic tantalum and other tantalum compounds. A typical production process for potassium fluorotantalate involves decomposing tantalum-niobium ore with a mixture of hydrofluoric acid and sulfuric acid. The resulting tantalum solution is extracted, acid-washed, and subjected to anti-niobium and anti-tantalum processes in a hydrofluoric acid-sulfuric acid-2-octanol or methyl isobutyl ketone system. This solution is then heated to 85°C in a heating tank, and hydrofluoric acid and potassium chloride are added and stirred until homogeneous. The resulting crystallization solution is then transferred to a crystallization container and allowed to cool naturally for 4-6 hours, followed by forced cooling for 12-16 hours to complete the entire potassium fluorotantalate crystallization process. The mother liquor is then extracted, and the potassium fluorotantalate crystals are transferred to a washing and filtration tank for washing, filtration, drying, and packaging.

[0003] After extraction, separation, and purification, the tantalum oxide content of the molten tantalum solution generally ranges from 30 to 100 g / L, depending on the specific mineral. Currently, in the potassium fluorotantalate production process, the crystallization concentration of the potassium fluorotantalate solution after heating and synthesis is typically controlled at 25-45 g / L. Too low a concentration results in low yield and high production costs; too high a concentration leads to the formation of a large amount of ultrafine powder at the bottom of the crystallization container, which is lost during washing, affecting the yield. Furthermore, the potassium fluorotantalate crystals on the inner wall of the container and at the bottom of the sedimentation layer consist of multiple layers of irregular, coarse particles that carry or coat a large amount of impurities, affecting product quality. Therefore, tantalum solutions with a concentration exceeding 50 g / L generally require the addition of deionized water as a diluent for heating synthesis. This added deionized water necessitates the addition of hydrofluoric acid to increase acidity, which increases material costs and further lowers the yield. Additionally, lower concentration crystallization results in higher hydrofluoric acid consumption per unit of output compared to higher concentration crystallization.

[0004] Meanwhile, different manufacturers have different choices when selecting crystallization containers. For example, companies in the south tend to use small crystallization containers, which are beneficial for cooling and increasing yield, and also for producing finer particles with uniform particle size, resulting in better product quality. However, the operation is too cumbersome and prone to product contamination. Companies in the north use large crystallization tanks with jackets and agitators to control the stirring speed during the cooling and crystallization process. This is beneficial for uniform temperature cooling and also for obtaining finer particles with uniform particle size. However, these crystallization containers are limited to lower crystallization concentrations, which limits their ability to improve yield.

[0005] Therefore, it is necessary to make appropriate improvements to the production methods and crystallization equipment based on the existing conventional potassium fluorotantalate production process in order to solve the current problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for preparing potassium fluorotantalate from tantalum solution.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0008] A method for preparing potassium fluorotantalate from tantalum solution includes the following steps:

[0009] Step 1: Heating and converting the tantalum solution. Tantalum solution with a concentration of 50 g / L to 80 g / L is pumped into a potassium fluorotantalate crystallization heating tank. The stirring motor on the potassium fluorotantalate crystallization heating tank is started to stir the tantalum solution in the tank at a stirring frequency of 30 Hz. Steam is supplied to the potassium fluorotantalate crystallization heating tank to internally heat the tantalum solution. When the temperature of the tantalum solution in the potassium fluorotantalate crystallization heating tank rises to 95℃ to 100℃, hydrofluoric acid is added for acid adjustment. The temperature is then heated again to 95℃ to 100℃. Solid potassium chloride is added to the potassium fluorotantalate crystallization heating tank, and stirring is continued for 5 minutes to react and form a potassium fluorotantalate crystal solution.

[0010] Step 2: Transfer the potassium fluorotantalate crystallization solution. Add hot water to the medium jacket of the crystallization washing tank to preheat the crystallization washing tank for 5 minutes. Place multiple crystallization panels in the crystallization washing tank, open the discharge port at the bottom of the potassium fluorotantalate crystallization heating tank, and discharge the potassium fluorotantalate crystallization solution into the crystallization washing tank to stand.

[0011] Step 3: Cooling and crystallizing potassium fluorotantalate. When the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to 60°C, cooling water is introduced into the medium jacket of the crystallization washing tank to force-cool the potassium fluorotantalate crystallization solution in the crystallization washing tank until the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to room temperature.

[0012] Step 4: Discharge of potassium fluorotantalate crystallization mother liquor. Open the upper mother liquor discharge port of the crystallization washing tank and discharge the upper layer of crystallization mother liquor in the crystallization washing tank into the mother liquor pool. When there is no crystallization mother liquor being discharged from the upper mother liquor discharge port, slowly open the lower mother liquor discharge port of the crystallization washing tank until the crystallization mother liquor in the crystallization washing tank is completely discharged, and then close the lower mother liquor discharge port of the crystallization washing tank.

[0013] Step 5: Washing potassium fluorotantalate crystals. Use deionized water to wash the potassium fluorotantalate crystals on the inner wall and crystallization panel of the crystallization washing tank into the crystallization washing tank. Continue to add deionized water and use a pusher plate to slowly push the potassium fluorotantalate crystals at the bottom of the crystallization washing tank. After stopping the pushing, let it stand for 5 minutes. Open the lower mother liquor discharge port of the crystallization washing tank to discharge the washing water in the crystallization washing tank into the mother liquor pool.

[0014] Step 6: Discharge and dry potassium fluorotantalate crystals. Open the potassium fluorotantalate outlet of the crystallization washing tank, and use deionized water to discharge the potassium fluorotantalate crystals in the crystallization washing tank into the vacuum filter. Start the vacuum filter for filtration, discharge the filtrate into the mother liquor tank, and transfer the filtered potassium fluorotantalate crystals to the drying box for drying.

[0015] In step 1, the concentration of tantalum oxide in the tantalum solution is 78 g / L.

[0016] In step 1, the hydrofluoric acid is AR grade hydrofluoric acid and the potassium chloride is CP grade potassium chloride.

[0017] In step 2, the hot water added to the medium jacket of the crystallization washing tank has a temperature of 80-85℃.

[0018] In step 5, before pushing the potassium fluorotantalate crystals, the crystallization panel in the crystallization washing tank is removed or moved to the other end of the discharge port.

[0019] In step 5, before opening the lower mother liquor discharge port of the crystallization washing tank, the potassium fluorotantalate crystals in front of the lower mother liquor discharge port of the crystallization washing tank are pushed away.

[0020] The potassium fluorotantalate crystallization heating tank includes a cylindrical first tank body with a conical bottom. A first tank cover is installed on the top opening of the first tank body, and a geared motor is installed on the top of the first tank cover. A stirring paddle extending into the first tank body is connected to the motor shaft of the geared motor. The first tank cover is provided with a potassium chloride feed port, a heating pipe, a tantalum liquid feed port, a hydrofluoric acid feed port, and a deionized water feed port. A steam delivery pipe is connected to the heating pipe, and a discharge port is provided at the bottom of the first tank body.

[0021] The crystallization washing tank includes a rectangular box-shaped second tank body, a rectangular second tank cover, and multiple T-shaped crystallization panels. A rectangular box-shaped outer jacket is fixed to the outside of the second tank body. A square tube-shaped inner jacket arranged along the long axis of the second tank body is fixed to the second tank body. The inner jacket and the outer jacket are connected to form a media jacket. One side of the outer jacket is provided with a media inlet and a media outlet communicating with the outer jacket, and the media inlet is located below the media outlet. One side of the second tank body is provided with a potassium fluorocarbonate crystallization solution inlet communicating with the second tank body, and the potassium fluorocarbonate crystallization solution inlet is higher than the top of the outer jacket. The other side of the second tank body is provided with an upper mother liquor discharge port, a lower mother liquor discharge port, and a potassium fluorotantalate discharge port. The upper mother liquor discharge port is located above the lower mother liquor discharge port, and the lower mother liquor discharge port and the potassium fluorotantalate discharge port are at the same horizontal height. The lugs on both sides of the top of the crystallization panels rest on the inner jacket and the second tank body, respectively.

[0022] The height difference between the bottom end of the inner jacket and the bottom end of the inner side of the second tank is 20 cm, and the height difference between the upper mother liquor discharge port and the bottom end of the inner side of the second tank is 15 cm.

[0023] The top of the inner sleeve is fixedly connected to an intermediate support plate perpendicular to the top of the inner sleeve, and the top of the intermediate support plate is flush with the top of the second groove.

[0024] The beneficial effects of this invention are:

[0025] 1. The method of the present invention is suitable for preparing potassium fluorotantalate from tantalum solution with a tantalum oxide concentration of 50 g / L to 80 g / L. High-concentration tantalum solution does not require dilution with deionized water, thus saving conversion reaction materials;

[0026] 2. Increase the heating temperature of the potassium fluorotantalate crystallization solution in the potassium fluorotantalate crystallization heating tank to between 95℃ and 100℃ to ensure that the potassium fluorotantalate crystallization solution has a sufficiently high temperature during the transfer from the potassium fluorotantalate crystallization heating tank to the crystallization washing tank, and prevent rapid crystallization caused by excessively rapid temperature drop.

[0027] 3. Before adding the potassium fluorotantalate crystallization solution to the crystallization washing tank, preheat the crystallization washing tank by passing hot water through the media jacket to prevent the cooling rate from being too fast when the potassium fluorotantalate crystallization solution is added to the crystallization washing tank, thus preventing the formation of a large number of crystal nuclei or the generation of fine crystals, while allowing sufficient time for crystal growth.

[0028] 4. Setting multiple movable crystallization panels in the crystallization washing tank increases the crystallization wall area of ​​potassium fluorotantalate crystals, which is beneficial for generating uniform particle size and also prevents most of the crystals from falling off naturally, thus preventing the formation of a large number of crystals stacking and peritectic formation.

[0029] 5. The cooling crystallization equipment and crystal washing equipment are combined into one, which facilitates washing and makes operation simple and convenient;

[0030] 6. The crystallization washing tank is equipped with an upper discharge outlet for mother liquor, which prioritizes the discharge of organic matter suspended in the crystallization mother liquor, preventing organic matter from re-contaminating the potassium fluorotantalate crystals and improving product purity. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0032] Figure 1 This is a flowchart of the method for preparing potassium fluorotantalate from tantalum solution in this invention;

[0033] Figure 2 This is a schematic diagram of the potassium fluorotantalate crystallization heating tank in this invention;

[0034] Figure 3 This is a schematic diagram of the crystallization washing tank in this invention;

[0035] Figure 4 yes Figure 3 Schematic diagram of the structure in the AA direction;

[0036] Figure 5 yes Figure 3 Schematic diagram of the structure in the middle BB direction;

[0037] Figure 6 yes Figure 3 Schematic diagram of the CC-axis structure;

[0038] The following are the labels in the diagram: Potassium fluorotantalate crystallization heating tank 1, first tank body 11, first tank cover 12, geared motor 13, stirring paddle 14, potassium chloride feed port 15, heating pipe 16, tantalum liquid feed port 17, hydrofluoric acid feed port 18, deionized water feed port 19, discharge port 110, crystallization washing tank 2, second tank body 21, potassium fluorotantalate crystallization solution inlet 21a, upper mother liquor discharge port 21b, lower mother liquor discharge port 21c, potassium fluorotantalate discharge port 21d, second tank cover 22, crystallization panel 23, medium jacket 24, outer jacket 24a, inner jacket 24b, medium inlet 24c, medium outlet 24d, support block 25, intermediate support plate 26. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] like Figures 1 to 6 As shown, a method for preparing potassium fluorotantalate from tantalum solution includes the following steps:

[0041] Step 1: Heating and converting the tantalum solution. Tantalum solution with a concentration of 50 g / L to 80 g / L is pumped into a potassium fluorotantalate crystallization heating tank. The stirring motor on the potassium fluorotantalate crystallization heating tank is started to stir the tantalum solution in the tank at a stirring frequency of 30 Hz. Steam is supplied to the potassium fluorotantalate crystallization heating tank to internally heat the tantalum solution. When the temperature of the tantalum solution in the potassium fluorotantalate crystallization heating tank rises to 95℃ to 100℃, hydrofluoric acid is added for acid adjustment. The temperature is then heated again to 95℃ to 100℃. Solid potassium chloride is added to the potassium fluorotantalate crystallization heating tank, and stirring is continued for 5 minutes to react and form a potassium fluorotantalate crystal solution.

[0042] Step 2: Transfer the potassium fluorotantalate crystallization solution. Add hot water to the medium jacket of the crystallization washing tank to preheat the crystallization washing tank for 5 minutes. Place multiple crystallization panels in the crystallization washing tank, open the discharge port at the bottom of the potassium fluorotantalate crystallization heating tank, and discharge the potassium fluorotantalate crystallization solution into the crystallization washing tank to stand.

[0043] Step 3: Cooling and crystallizing potassium fluorotantalate. When the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to 60°C, cooling water is introduced into the medium jacket of the crystallization washing tank to force-cool the potassium fluorotantalate crystallization solution in the crystallization washing tank until the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to room temperature.

[0044] Step 4: Discharge of potassium fluorotantalate crystallization mother liquor. Open the upper mother liquor discharge port of the crystallization washing tank and discharge the upper layer of crystallization mother liquor in the crystallization washing tank into the mother liquor pool. When there is no crystallization mother liquor being discharged from the upper mother liquor discharge port, slowly open the lower mother liquor discharge port of the crystallization washing tank until the crystallization mother liquor in the crystallization washing tank is completely discharged, and then close the lower mother liquor discharge port of the crystallization washing tank.

[0045] Step 5: Washing potassium fluorotantalate crystals. Use deionized water to wash the potassium fluorotantalate crystals on the inner wall and crystallization panel of the crystallization washing tank into the crystallization washing tank. Continue to add deionized water and use a pusher plate to slowly push the potassium fluorotantalate crystals at the bottom of the crystallization washing tank. After stopping the pushing, let it stand for 5 minutes. Open the lower mother liquor discharge port of the crystallization washing tank to discharge the washing water in the crystallization washing tank into the mother liquor pool.

[0046] Step 6: Discharge and dry potassium fluorotantalate crystals. Open the potassium fluorotantalate outlet of the crystallization washing tank, and use deionized water to discharge the potassium fluorotantalate crystals in the crystallization washing tank into the vacuum filter. Start the vacuum filter for filtration, discharge the filtrate into the mother liquor tank, and transfer the filtered potassium fluorotantalate crystals to the drying box for drying.

[0047] like Figure 2 As shown, the potassium fluorotantalate crystallization heating tank 1 includes a cylindrical first tank body 11 with a conical bottom. A first tank cover 12 is installed on the top opening of the first tank body 11. A geared motor 13 is installed on the top of the first tank cover 12. A stirring paddle 14 extending into the first tank body 11 is connected to the motor shaft of the geared motor 13. The first tank cover 12 is provided with a potassium chloride feed port 15, a heating pipe 16, a tantalum liquid feed port 17, a hydrofluoric acid feed port 18, and a deionized water feed port 19. A steam delivery pipe is connected to the heating pipe 16. A discharge port 110 is provided at the bottom of the first tank body 11.

[0048] like Figures 3 to 6As shown, the crystallization washing tank 2 includes a rectangular box-shaped second tank body 21, a rectangular second tank cover 22, and multiple T-shaped crystallization panels 23. A rectangular box-shaped outer jacket 24a is fixed to the outside of the second tank body 21. A square tube-shaped inner jacket 24b arranged along the long axis of the second tank body 21 is fixed to the inside of the second tank body 21. The inner jacket 24b and the outer jacket 24a are connected and combined to form a media jacket 24. A media inlet 24c and a media outlet 24d are provided on one side of the outer jacket 24a, and the media inlet 24c is located below the media outlet 24d. A potassium fluorotantalate crystallization solution inlet 21a is provided on one side of the second tank body, which is connected to the second tank body. The potassium fluorotantalate crystallization solution inlet 21a is higher than the top of the outer jacket 24. An upper mother liquor discharge port 21b, a lower mother liquor discharge port 21c, and a potassium fluorotantalate discharge port 21d are provided on the other side of the second tank body 21. The upper mother liquor discharge port 21b is located above the lower mother liquor discharge port 21c. The lower mother liquor discharge port 21c and the potassium fluorotantalate discharge port 21d are at the same horizontal height. The ear blocks on both sides of the top of the crystallization panel 23 are respectively placed on the inner jacket 24b and the second tank body 21.

[0049] The height difference between the bottom end of the inner jacket 24b and the bottom end of the inner side of the second tank 21 is 20 cm, ensuring that the liquid in the second tank 21 on both sides of the inner jacket 24b can flow normally; the height difference between the upper mother liquor discharge port 21b and the bottom end of the inner side of the second tank 21 is 15 cm. The upper mother liquor discharge port 21b is used to drain organic matter floating on the liquid surface or impurities in the crystallizing mother liquor, reducing the carbon content; multiple support blocks 25 are installed between the bottom end of the second tank 21 and the outer jacket 24a to prevent the bottom of the second tank 21 from deforming and sinking.

[0050] The top of the inner jacket 24b is fixed with an intermediate support plate 26 perpendicular to the top of the inner jacket 24b. The top of the intermediate support plate 26 is flush with the top of the second tank 21. The intermediate support plate 26 supports the middle of the second tank cover 22 to prevent the middle of the second tank cover 22 from sagging, and also limits the crystallization panel 23.

[0051] Example 1:

[0052] A method for preparing potassium fluorotantalate from tantalum solution includes the following steps:

[0053] Step 1: Heating and converting the tantalum solution. 1000 liters of tantalum oxide solution with a concentration of 78 g / L is pumped into a potassium fluorotantalate crystallization heating tank. The stirring motor on the potassium fluorotantalate crystallization heating tank is started to stir the tantalum solution at a stirring frequency of 30 Hz. Steam is supplied to the potassium fluorotantalate crystallization heating tank for internal heating of the tantalum solution. When the temperature of the tantalum solution in the potassium fluorotantalate crystallization heating tank reaches 96℃, AR-grade hydrofluoric acid is added for acid adjustment. The temperature is then raised again to 96℃. Solid CP-grade potassium chloride is added to the potassium fluorotantalate crystallization heating tank, and stirring is continued for 5 minutes to react and form a potassium fluorotantalate crystallization solution. After stopping stirring, the total volume of the solution in the potassium fluorotantalate crystallization heating tank is 1150 liters, meaning the concentration of the potassium fluorotantalate crystallization solution after heating and conversion is 67.826 g / L.

[0054] Step 2: Transfer of potassium fluorotantalate crystallization solution. Add hot water at a temperature of 80-85℃ to the medium jacket of the crystallization washing tank to preheat the crystallization washing tank for 5 minutes. Place 18 crystallization panels in the crystallization washing tank and 9 crystallization panels on each side of the inner jacket. Open the discharge port at the bottom of the potassium fluorotantalate crystallization heating tank and discharge the potassium fluorotantalate crystallization solution into the crystallization washing tank to stand.

[0055] Step 3: Cooling and crystallizing potassium fluorotantalate. When the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to 60°C, cooling water is introduced into the medium jacket of the crystallization washing tank to force-cool the potassium fluorotantalate crystallization solution in the crystallization washing tank until the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to room temperature.

[0056] Step 4: Discharge of potassium fluorotantalate crystallization mother liquor. Open the upper mother liquor discharge port of the crystallization washing tank and discharge the upper layer of crystallization mother liquor in the crystallization washing tank into the mother liquor pool. When there is no crystallization mother liquor being discharged from the upper mother liquor discharge port, slowly open the lower mother liquor discharge port of the crystallization washing tank until the crystallization mother liquor in the crystallization washing tank is completely discharged, and then close the lower mother liquor discharge port of the crystallization washing tank.

[0057] Step 5: Washing potassium fluorotantalate crystals. Use deionized water to wash the potassium fluorotantalate crystals on the inner wall and crystallization panel of the crystallization washing tank into the crystallization washing tank. Remove the crystallization panel from the crystallization washing tank. Continue to add deionized water to the crystallization washing tank until the potassium fluorotantalate crystals are completely submerged. Use a pusher plate to slowly push the potassium fluorotantalate crystals at the bottom of the crystallization washing tank. After stopping the pushing, let it stand for 5 minutes. Push the potassium fluorotantalate crystals in front of the lower mother liquor discharge port of the crystallization washing tank away. Open the lower mother liquor discharge port of the crystallization washing tank to discharge the washing water clear liquid in the crystallization washing tank into the mother liquor pool.

[0058] Step 6: Discharge and dry potassium fluorotantalate crystals. Open the potassium fluorotantalate outlet of the crystallization washing tank, and use deionized water to discharge the potassium fluorotantalate crystals in the crystallization washing tank into the vacuum filter. Start the vacuum filter for filtration, discharge the filtrate into the mother liquor tank, and transfer the filtered potassium fluorotantalate crystals to the drying box for drying.

[0059] The formula for calculating the volume of hydrofluoric acid added in this embodiment is as follows:

[0060] The volume of hydrofluoric acid is calculated as follows: (volume of tantalum liquid + volume of water liquefied from steam before adding hydrofluoric acid + volume of hydrofluoric acid) × crystallization acidity ÷ 20 - volume of tantalum liquid × tantalum liquid acidity ÷ 20. In this formula, the volume unit is L.

[0061] The formula for calculating the addition of potassium chloride in this embodiment is as follows:

[0062] Potassium chloride (kg) = (volume of tantalum solution + volume of vaporized water before adding potassium chloride + volume of hydrofluoric acid) × tantalum oxide concentration in tantalum solution (g / L) × 0.88 ÷ 1000; In this formula, the volume unit is L;

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing potassium fluorotantalate from tantalum solution, characterized in that, Includes the following steps: Step 1: Heating and converting the tantalum solution. A tantalum solution with a concentration of 50 g / L to 80 g / L is pumped into a potassium fluorotantalate crystallization heating tank. The stirring motor on the potassium fluorotantalate crystallization heating tank is started and stirred at a stirring frequency of 30 Hz. Steam is supplied to the potassium fluorotantalate crystallization heating tank to internally heat the tantalum solution. When the temperature of the tantalum solution in the potassium fluorotantalate crystallization heating tank rises to 95℃ to 100℃, hydrofluoric acid is added for acid adjustment. The temperature is then heated again to 95℃ to 100℃. Solid potassium chloride is added to the potassium fluorotantalate crystallization heating tank, and stirring is continued for 5 minutes to react and form a potassium fluorotantalate crystal solution. Step 2: Transfer the potassium fluorotantalate crystallization solution. Add hot water to the medium jacket of the crystallization washing tank to preheat the crystallization washing tank for 5 minutes. Place multiple crystallization panels in the crystallization washing tank, open the discharge port at the bottom of the potassium fluorotantalate crystallization heating tank, and discharge the potassium fluorotantalate crystallization solution into the crystallization washing tank to stand. Step 3: Cooling and crystallizing potassium fluorotantalate. When the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to 60°C, cooling water is introduced into the medium jacket of the crystallization washing tank to force-cool the potassium fluorotantalate crystallization solution in the crystallization washing tank until the temperature of the potassium fluorotantalate crystallization solution in the crystallization washing tank drops to room temperature. Step 4: Discharge of potassium fluorotantalate crystallization mother liquor. Open the upper mother liquor discharge port of the crystallization washing tank and discharge the upper layer of crystallization mother liquor in the crystallization washing tank into the mother liquor pool. When there is no crystallization mother liquor being discharged from the upper mother liquor discharge port, slowly open the lower mother liquor discharge port of the crystallization washing tank until the crystallization mother liquor in the crystallization washing tank is completely discharged, and then close the lower mother liquor discharge port of the crystallization washing tank. Step 5: Washing potassium fluorotantalate crystals. Use deionized water to wash the potassium fluorotantalate crystals on the inner wall and crystallization panel of the crystallization washing tank into the crystallization washing tank. Continue to add deionized water and use a pusher plate to slowly push the potassium fluorotantalate crystals at the bottom of the crystallization washing tank. After stopping the pushing, let it stand for 5 minutes. Open the lower mother liquor discharge port of the crystallization washing tank to discharge the washing water in the crystallization washing tank into the mother liquor pool. Step 6: Discharge and dry potassium fluorotantalate crystals. Open the potassium fluorotantalate outlet of the crystallization washing tank, and use deionized water to discharge the potassium fluorotantalate crystals in the crystallization washing tank into the vacuum filter. Start the vacuum filter for filtration, discharge the filtrate into the mother liquor tank, and transfer the filtered potassium fluorotantalate crystals to the drying box for drying. The crystallization washing tank includes a rectangular box-shaped second tank body, a rectangular second tank cover, and multiple T-shaped crystallization panels. A rectangular box-shaped outer jacket is fixed to the outside of the second tank body. A square tube-shaped inner jacket arranged along the long axis of the second tank body is fixed to the inside of the second tank body. The inner jacket and the outer jacket are connected and combined to form a medium jacket. The lugs on both sides of the top of the crystallization panels are respectively placed on the inner jacket and the second tank body.

2. The method according to claim 1, characterized in that: The concentration of tantalum oxide in the tantalum solution in step 1 is 78 g / L.

3. The method according to claim 1, characterized in that: The hydrofluoric acid in step 1 is AR grade hydrofluoric acid, and the potassium chloride is CP grade potassium chloride.

4. The method according to claim 1, characterized in that: In step 2, the hot water added to the medium jacket of the crystallization washing tank is at a temperature of 80-85℃.

5. The method according to claim 1, characterized in that: In step 5, before pushing the potassium fluorotantalate crystals, the crystallization panel in the crystallization washing tank is removed or moved to the end of the crystallization washing tank away from the lower mother liquor discharge port.

6. The method according to claim 1, characterized in that: Before opening the lower mother liquor discharge port of the crystallization washing tank in step 5, push away the potassium fluorotantalate crystals in front of the lower mother liquor discharge port of the crystallization washing tank.

7. The method according to claim 1, characterized in that: The potassium fluorotantalate crystallization heating tank includes a cylindrical first tank body with a conical bottom. A first tank cover is installed on the top opening of the first tank body, and a geared motor is installed on the top of the first tank cover. A stirring paddle extending into the first tank body is connected to the motor shaft of the geared motor. The first tank cover is provided with a potassium chloride feed port, a heating pipe, a tantalum liquid feed port, a hydrofluoric acid feed port, and a deionized water feed port. A steam delivery pipe is connected to the heating pipe. A discharge port is provided at the bottom of the first tank body.

8. The method according to claim 1, characterized in that: One side of the outer jacket is provided with a medium inlet and a medium outlet communicating with the outer jacket, and the medium inlet is located below the medium outlet. One side of the second tank is provided with a potassium fluorocarbonate crystallization solution inlet communicating with the second tank, and the potassium fluorocarbonate crystallization solution inlet is higher than the top of the outer jacket. The other side of the second tank is provided with an upper mother liquor discharge port, a lower mother liquor discharge port, and a potassium fluorotantalate discharge port. The upper mother liquor discharge port is located above the lower mother liquor discharge port, and the lower mother liquor discharge port and the potassium fluorotantalate discharge port are at the same horizontal height.

9. The method according to claim 8, characterized in that: The height difference between the bottom end of the inner jacket and the bottom end of the inner side of the second tank is 20 cm, and the height difference between the upper mother liquor discharge port and the bottom end of the inner side of the second tank is 15 cm.

10. The method according to claim 8, characterized in that: The top of the inner sleeve is fixedly connected to an intermediate support plate perpendicular to the top of the inner sleeve, and the top of the intermediate support plate is flush with the top of the second groove.

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