A method for controlling crystallization of potassium fluorotantalate based on flow field design
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CNMC NINGXIA ORIENT GRP
- Filing Date
- 2026-03-30
- Publication Date
- 2026-08-07
AI Technical Summary
该现象的本质是流场设计缺陷导致晶体与溶液的接触传质环境失衡，沉积的晶体无法参与正常的溶质传质与晶体生长过程，不仅易造成细晶大量生成，导致产品细粉率显著增加，还会因晶体生长环境的差异造成晶粒大小不均，使得产品粒度均匀性大幅下降，最终制得的氟钽酸钾产品难以满足高端制造领域的质量要求
本发明提供了一种基于流场设计的氟钽酸钾结晶控制方法，通过构建轴向推流-径向分散-罐底导流的一体化协同流场，并匹配设计三层适配式搅拌结构，结合结晶不同阶段实现流场参数的动态调控，有效解决了现有氟钽酸钾结晶工艺中流场分布失衡、轴向径向协同性差、晶体易沉降堆积的技术问题，能使结晶器内流场混合死区占比≤5%，实现小晶粒稳定悬浮生长、大晶粒定向沉降的差异化调控，既避免了二次成核的发生，又解决了大小晶粒竞争生长资源的问题，大幅降低了产品细粉率，显著提升了氟钽酸钾产品的粒度均匀性，且产品纯度可保持≥99.999%。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of potassium fluorotantalate production technology, and specifically to a method for controlling the crystallization of potassium fluorotantalate based on flow field design. Background Technology
[0002] Potassium fluorotantalate is a core intermediate in the preparation of high-purity tantalum powder and tantalum materials. Tantalum products made from potassium fluorotantalate through processes such as molten salt electrolysis possess excellent conductivity, high-temperature resistance, and corrosion resistance, making them widely used in high-end manufacturing fields such as electronics, semiconductor sputtering targets, and high-temperature components for aerospace. Potassium fluorotantalate can also be used as an additive and catalyst in optical glass. With the rapid development of the electronics and high-end manufacturing industries, the market demand for potassium fluorotantalate is increasing year by year, placing stringent requirements on its product quality. High purity and uniform particle size distribution have become core quality indicators for potassium fluorotantalate products, directly determining the processing performance and application effects of subsequent tantalum products.
[0003] The industrial production process of potassium fluorotantalate mainly includes decomposition, extraction, synthesis, crystallization, and drying. Among these, the crystallization process is the core key step that determines the particle size uniformity and fine powder rate of the product. The rationality of the flow field design within the crystallizer directly affects the overall environment for crystal growth, and thus determines the final quality of the potassium fluorotantalate crystal product. As the core environmental carrier for crystal growth, the flow field's uniformity, fluidity, and axial-radial synergistic effect are directly related to the suspension state of the crystal in the solution and the mass transfer and diffusion efficiency of the solute, which is the foundation for ensuring uniform crystal growth.
[0004] Currently, potassium fluorotantalate crystallization processes generally employ cooling crystallization, with cooling supplied through the crystallizer jacket or external heat exchanger. The uniform transfer of cooling and efficient diffusion of solutes in the solution both depend on a stable flow field. The stirring device, as the core component for flow field control, directly determines the overall morphology of the flow field through its structural design. In existing technologies, potassium fluorotantalate crystallizers all use traditional straight-blade impellers. These impellers are typical radial flow impeller structures, capable of only driving the solution in a horizontal radial circular motion during operation. Their axial mixing and propulsion capabilities are extremely weak, resulting in a severely unbalanced flow field within the crystallizer, characterized by strong radial flow and weak axial flow. This leads to poor overall flow field uniformity, with numerous mixing dead zones and short-circuit flows within the crystallizer, making it impossible to form a uniform crystal growth environment throughout the entire crystallizer.
[0005] As the potassium fluorotantalate cooling and crystallization process progresses, potassium fluorotantalate crystals continuously precipitate and accumulate in the solution. However, the unbalanced flow field cannot provide sufficient axial lifting force and global dispersion capability for the crystals. The crystals struggle to achieve uniform suspension in a radially flow-dominated flow field, and most crystals quickly settle to the bottom of the crystallization tank due to insufficient axial power, forming an accumulation. The essence of this phenomenon is that a flawed flow field design leads to an imbalance in the mass transfer environment between the crystals and the solution. The deposited crystals cannot participate in the normal solute mass transfer and crystal growth process, which not only easily results in the formation of a large number of fine crystals, leading to a significant increase in the fine powder ratio of the product, but also causes uneven grain size due to differences in the crystal growth environment, resulting in a significant decrease in product particle size uniformity. Ultimately, the obtained potassium fluorotantalate product fails to meet the quality requirements of high-end manufacturing fields. Summary of the Invention
[0006] To address the problems existing in the prior art, the present invention provides a method for controlling the crystallization of potassium fluorotantalate based on flow field design.
[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A method for controlling the crystallization of potassium fluorotantalate based on flow field design includes the following steps: Step 1, Design of the synergistic flow field: Construct an integrated synergistic flow field of axial thrust, radial dispersion, and bottom guide flow. The radial dispersion flow field can achieve uniform horizontal diffusion of the solution, the axial thrust flow field can provide a gradient axial lifting force, and the bottom guide flow field is adapted to the arc-shaped structure at the bottom of the potassium fluorotantalate crystallizer. Step 2, Design of flow field adaptable stirring structure: Based on the flow field morphology requirements in Step 1, design the corresponding stirring impeller. The stirring impeller includes a stirring shaft and three layers of stirring blades. The maximum outer diameter of the three layers of stirring blades is the same, and the diameter of the three layers of stirring blades is 1 / 3 to 1 / 2 of the diameter of the potassium fluorotantalate crystallizer. Step 3, Control of dynamic parameters of flow field: During the crystal nucleation stage, a low-intensity flow field with a stirring paddle speed of 5-30 r / min is adopted, and the low-intensity flow field lasts for 6-10 h; During the crystal growth stage, the stirring paddle speed is gradually increased to a medium-high intensity flow field of 30-100 r / min within 2-4 h, and the medium-high intensity flow field is maintained until the potassium fluorotantalate crystallization is completed.
[0008] Furthermore, the three layers of stirring blades are, from top to bottom, a first layer of stirring blades, a second layer of stirring blades, and a third layer of stirring blades; the first layer of stirring blades is a four-bladed straight blade structure, with the blade plane perpendicular to the stirring shaft; the second layer of stirring blades is a four-bladed propulsion structure, consisting of four oblique blades spirally distributed along the circumference of the stirring shaft, with the angle between the oblique blades and the horizontal direction being 20-30°; the third layer of stirring blades is a single-bladed arc-shaped flow guiding structure, with the blade as a whole being crescent-shaped, and the arc shape of the lower surface of the blade matching the arc-shaped bottom surface of the potassium fluorotantalate crystallizer.
[0009] Furthermore, the proportion of the mixing dead zone in the flow field within the potassium fluorotantalate crystallizer is ≤5%.
[0010] Furthermore, the stirring shaft of the stirring paddle and the three-layer stirring blades are both made of corrosion-resistant materials, which are composite materials of a stainless steel inner core and a polytetrafluoroethylene coating.
[0011] Furthermore, the stirring paddle speed during the crystal growth stage is increased in a stepwise manner, with the speed increased every 0.5-1 hour, and each increase being 10-20 r / min.
[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for controlling potassium fluorotantalate crystallization based on flow field design. By constructing an integrated synergistic flow field of axial push flow, radial dispersion, and bottom guide flow, and matching it with a three-layer adaptive stirring structure, the flow field parameters are dynamically controlled in combination with different crystallization stages. This effectively solves the technical problems of unbalanced flow field distribution, poor axial and radial synergy, and easy crystal sedimentation and accumulation in existing potassium fluorotantalate crystallization processes. It can ensure that the proportion of the mixing dead zone in the crystallizer is ≤5%, and achieve differentiated control of stable suspension growth of small crystals and directional sedimentation of large crystals. This avoids the occurrence of secondary nucleation and solves the problem of competition for growth resources between large and small crystals, significantly reduces the fine powder rate of the product, significantly improves the particle size uniformity of potassium fluorotantalate products, and maintains a product purity of ≥99.999%. Attached Figure Description
[0013] The embodiments of the present invention will be further described below with reference to the accompanying drawings, wherein: Figure 1 A schematic diagram of an embodiment of the stirring paddle is shown; The attached diagram is labeled as follows: 1-first layer of stirring blades, 2-second layer of stirring blades, 3-third layer of stirring blades, 4-stirring shaft. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0015] A method for controlling the crystallization of potassium fluorotantalate based on flow field design includes the following steps: Step 1: Design of the synergistic flow field: Construct an integrated synergistic flow field consisting of axial thrust, radial dispersion, and bottom guide flow. The radial dispersion flow field enables uniform horizontal diffusion of the solution, ensuring a balanced distribution of solute concentration and cooling capacity across the entire surface. The axial thrust flow field provides a gradient of axial lifting force, providing dynamic support for the suspension of small crystals and meeting the fluid circulation requirements at different crystallization stages. The bottom guide flow field is adapted to the arc-shaped structure at the bottom of the potassium fluorotantalate crystallizer, disturbing the fluid at the bottom to prevent crystal sedimentation and accumulation, while guiding large crystals to settle and separate along the flow field. Step 2, Design of flow field adaptable stirring structure: Based on the flow field morphology requirements in Step 1, design the corresponding stirring impeller. The stirring impeller includes stirring shaft 4 and three layers of stirring blades. The maximum outer diameter of the three layers of stirring blades is the same, and the diameter of the three layers of stirring blades is 1 / 3 to 1 / 2 of the diameter of the potassium fluorotantalate crystallizer. Step 3, Control of dynamic parameters of flow field: During the crystal nucleation stage, a low-intensity flow field with a stirring speed of 5-30 r / min is used, and the low-intensity flow field is maintained for 6-10 h; During the crystal growth stage, the stirring speed is gradually increased to a medium-high intensity flow field of 30-100 r / min within 2-4 h, and the medium-high intensity flow field is maintained until the potassium fluorotantalate crystallization is completed.
[0016] In one embodiment of the invention, reference is made to the appendix. Figure 1 The three layers of stirring blades are arranged from top to bottom as follows: first layer stirring blade 1, second layer stirring blade 2, and third layer stirring blade 3. The first layer stirring blade 1 is a four-bladed straight blade structure with the blade plane perpendicular to the stirring shaft 4. The second layer stirring blade 2 is a four-bladed propulsion structure, consisting of four oblique blades spirally distributed around the stirring shaft 4, with the angle between the oblique blades and the horizontal direction being 20-30°. The third layer stirring blade 3 is a single-bladed arc-shaped flow guiding structure with the blade being crescent-shaped, and the arc shape of the lower surface of the blade matching the arc-shaped bottom surface of the potassium fluorotantalate crystallizer.
[0017] In one embodiment of the present invention, the proportion of the mixing dead zone in the flow field of the potassium fluorotantalate crystallizer is ≤5%.
[0018] In one embodiment of the present invention, the stirring shaft 4 and the three-layer stirring blades of the stirring paddle are both made of corrosion-resistant material, which is a composite material of stainless steel inner core and polytetrafluoroethylene coating.
[0019] In one embodiment of the present invention, the stirring paddle speed during the crystal growth stage is increased in a stepwise manner, with the speed increased once every 0.5-1h, and each increase being 10-20r / min.
[0020] Example 1 This embodiment is adapted to a potassium fluorotantalate crystallizer with an inner diameter of 20cm and an effective volume of 2L, and adopts the potassium fluorotantalate crystallization control method of the present invention. The specific steps are as follows: Step 1: Morphological design of the cooperative flow field An integrated synergistic flow field is constructed, consisting of axial thrust flow, radial dispersion flow, and bottom guide flow. The radial dispersion flow field is used to achieve uniform diffusion of the potassium fluorotantalate crystallization solution in the horizontal direction, ensuring a balanced distribution of solute concentration and cooling capacity across the entire range, and avoiding local overcooling or oversaturation that could lead to the formation of fine crystals. The axial thrust flow field provides a gradient axial lifting force, providing continuous dynamic support for the suspension of small potassium fluorotantalate crystals. The bottom guide flow field is perfectly adapted to the arc-shaped bottom structure of the crystallizer, disturbing the bottom fluid to prevent crystal sedimentation and accumulation, while guiding large crystals that have reached the target particle size to settle directionally along the flow field.
[0021] Step 2: Design of the flow field adaptation stirring structure Based on the synergistic flow field morphology requirements of step 1, a matching impeller is designed. This impeller includes a stirring shaft and three layers of impeller blades. The maximum outer diameter of the three layers of impeller blades is the same, set to 1 / 3 of the crystallizer diameter (approximately 6.7 cm). The three layers of impeller blades, from top to bottom, are the first, second, and third layers: the first layer is a four-bladed straight impeller structure, with the blade plane perpendicular to the stirring shaft, its main function being to form a radially dispersed flow field; the second layer is a four-bladed propeller structure, consisting of four blades spirally distributed circumferentially along the stirring shaft. The system consists of inclined blades, with the angle between the blades and the horizontal direction set at 25°. Its main function is to form a gradient axial flow field. The third layer is a single-blade arc-shaped guide structure. The blade is crescent-shaped, and the arc-shaped lower surface of the blade is completely in contact with the arc-shaped bottom surface of the crystallizer. Its main function is to form a bottom guide flow field. The stirring shaft and the three-layer stirring blades are all made of composite materials with a stainless steel inner core and a polytetrafluoroethylene coating. They have good corrosion resistance, are suitable for the working conditions of the potassium fluorotantalate crystallization system, and ensure the long-term stability of the flow field morphology.
[0022] Step 3: Adjustment of dynamic parameters of the flow field Crystal nucleus generation stage: Start the stirring system and use a low-intensity flow field with a stirring paddle speed of 5 r / min. Maintain this low-intensity flow field for 8 hours. Use a constant speed operation mode throughout the process to avoid secondary nucleation induced by speed fluctuations and ensure uniform crystal nucleus generation.
[0023] Crystal growth stage: The stirring paddle speed is adjusted in a stepwise manner, gradually increasing to a medium-high intensity flow field of 45 r / min within 2 hours. Specifically, the speed is increased by 10 r / min every 0.5 hours (5 r / min → 15 r / min → 25 r / min → 35 r / min → 45 r / min). The medium-high intensity flow field of 45 r / min is maintained until potassium fluorotantalate crystallization is completed, ensuring that small crystals are stably suspended in the solution to participate in mass transfer and grow uniformly, while creating flow field conditions for the directional sedimentation of large crystals.
[0024] Implementation effect testing After crystallization in this embodiment, the proportion of the mixing dead zone in the crystallizer was found to be 4.6%, meeting the requirement of ≤5%. The small crystals of potassium fluorotantalate grew stably in suspension throughout the process, while the large crystals settled directionally along the flow field at the bottom of the tank, without any crystal settling or accumulation. The fine powder rate (the proportion of particles with a diameter ≤150μm) of the product was found to be 3.3%, which is 67% lower than the existing technology. The product purity was ≥99.999%, and the uniformity of particle size distribution was significantly improved, meeting the quality requirements of potassium fluorotantalate intermediates for the production of high-end tantalum products.
[0025] Example 2 This embodiment is adapted to a potassium fluorotantalate crystallizer with an inner diameter of 50cm and an effective volume of 20L, and adopts the potassium fluorotantalate crystallization control method of the present invention. The specific steps are as follows: Step 1: Morphological design of the cooperative flow field An integrated synergistic flow field of axial thrusting, radial dispersion, and tank bottom guiding is constructed with the same structure as in Example 1. The functions of the radial dispersion flow field, axial thrusting flow field, and tank bottom guiding flow field are the same as in Example 1. The tank bottom guiding flow field is adapted to the arc-shaped bottom structure of the crystallizer in this example.
[0026] Step 2: Design of the flow field adaptation stirring structure The design includes a stirring paddle consisting of a stirring shaft and three layers of stirring blades. The three layers of stirring blades have the same maximum outer diameter, which is set to 1 / 2 (25cm) of the crystallizer diameter. The structure and distribution of the three layers of stirring blades are as follows: the first layer is a four-bladed straight blade structure with the blade plane perpendicular to the stirring shaft; the second layer is a four-bladed propulsion structure with the angle between the oblique blades and the horizontal direction set at 20°; the third layer is a single-bladed arc-shaped guide structure with the arc shape of the lower surface of the blade matching the arc-shaped bottom surface of the crystallizer in this embodiment. The stirring shaft and the three layers of stirring blades are all made of a composite material with a stainless steel inner core and a polytetrafluoroethylene coating.
[0027] Step 3: Adjustment of dynamic parameters of the flow field Crystal nucleus generation stage: A low-intensity flow field with a stirring paddle speed of 30 r / min is used and maintained for 6 hours. The constant speed operation is used to avoid secondary nucleation.
[0028] Crystal growth stage: The rotation speed is adjusted in a stepwise manner, gradually increasing to a medium-high intensity flow field of 90 r / min within 3 hours. Specifically, the rotation speed is increased by 20 r / min every 1 hour (30 r / min → 50 r / min → 70 r / min → 90 r / min); the medium-high intensity flow field of 90 r / min is maintained until crystallization is completed.
[0029] Implementation effect testing After crystallization in this embodiment, the proportion of the dead zone in the flow field of the crystallizer is 3.8%, ≤5%; there is no sedimentation or accumulation of potassium fluorotantalate crystals, small crystals are uniformly suspended and large crystals are directionally settled; the fine powder rate of the product is 4.2%, which is 58% lower than that of the prior art, the purity is ≥99.999%, the particle size distribution is uniform, and it is suitable for the needs of industrial-scale batch production of potassium fluorotantalate.
[0030] Example 3 This embodiment is adapted to a potassium fluorotantalate crystallizer with an inner diameter of 30cm and an effective volume of 5L, and adopts the potassium fluorotantalate crystallization control method of the present invention. The specific steps are as follows: Step 1: Morphological design of the cooperative flow field An integrated synergistic flow field is constructed, consisting of axial propulsion, radial dispersion, and bottom guidance. The bottom guidance flow field is adapted to the arc-shaped bottom structure of the crystallizer in this embodiment, and the functions of each flow field are consistent with those in the aforementioned embodiments.
[0031] Step 2: Design of the flow field adaptation stirring structure The design includes a matching stirring paddle. The structure of the stirring shaft and three-layer stirring blades is consistent with the aforementioned embodiment. The maximum outer diameter of the three-layer stirring blades is the same, and the diameter is set to 2 / 5 (12cm) of the crystallizer diameter. The angle between the oblique blades of the second-layer propulsion stirring blade and the horizontal direction is set to 30°. The arc-shaped guide blades of the third layer are adapted to the arc-shaped bottom surface of the crystallizer. Both the stirring shaft and the blades are made of composite materials with a stainless steel inner core and a polytetrafluoroethylene coating.
[0032] Step 3: Adjustment of dynamic parameters of the flow field Crystal nucleation stage: A low-intensity flow field with a stirring paddle speed of 15 r / min was used and maintained for 10 h with constant speed operation.
[0033] Crystal growth stage: The rotation speed is adjusted in a stepwise manner, gradually increasing to a medium-high intensity flow field of 70 r / min within 4 hours. Specifically, the rotation speed is increased by 15 r / min every 1 hour (15 r / min → 30 r / min → 45 r / min → 60 r / min → 75 r / min); the medium-high intensity flow field of 75 r / min is maintained until crystallization is completed.
[0034] Implementation effect testing After crystallization in this embodiment, the proportion of the mixing dead zone in the crystallizer is 4.2%, ≤5%; the potassium fluorotantalate small crystals exhibit good suspension growth and directional sedimentation of large crystals, with no crystal accumulation; the fine powder rate of the product is 3.8%, which is 62% lower than that of the prior art, the purity is ≥99.999%, and the particle size uniformity meets the requirements of high-end applications.
[0035] Comparative Example 1 This comparative example uses the same potassium fluorotantalate crystallizer with an inner diameter of 20 cm and an effective volume of 2 L as in Example 1. It adopts the existing potassium fluorotantalate crystallization control method, specifically: a single flat-blade paddle stirring device (which can only form radial flow) is used, the diameter of the stirring blade is 1 / 3 of the diameter of the crystallizer, the stirring blade material is ordinary stainless steel, the flow field intensity is fixed at a constant speed of 30 r / min, there is no segmented control throughout the crystallization process, and other crystallization process conditions are completely consistent with those in Example 1.
[0036] Comparative effect test After crystallization, the proportion of the mixing dead zone in the flow field of the crystallizer was 18.7%, which is far higher than the requirement of ≤5% in this invention. The flow field distribution in the crystallizer was unbalanced, with a large number of mixing dead zones. Both small and large potassium fluorotantalate crystals settled to the bottom of the tank and accumulated, making it impossible to achieve the differentiated requirements of small crystal suspension growth and large crystal directional sedimentation. The fine powder rate of the product was 3 times that of Example 1, the particle size distribution was disordered, and the quality stability was poor, which could not meet the quality requirements of high-end tantalum product production.
[0037] This invention provides a method for controlling potassium fluorotantalate crystallization based on flow field design. By constructing an integrated synergistic flow field of axial push flow, radial dispersion, and bottom guide flow, and matching it with a three-layer adaptive stirring structure, the flow field parameters are dynamically controlled in combination with different crystallization stages. This effectively solves the technical problems of unbalanced flow field distribution, poor axial and radial synergy, and easy crystal sedimentation and accumulation in existing potassium fluorotantalate crystallization processes. It can ensure that the proportion of the mixing dead zone in the crystallizer is ≤5%, and achieve differentiated control of stable suspension growth of small crystals and directional sedimentation of large crystals. This avoids the occurrence of secondary nucleation and solves the problem of competition for growth resources between large and small crystals, significantly reduces the fine powder rate of the product, significantly improves the particle size uniformity of potassium fluorotantalate products, and maintains a product purity of ≥99.999%.
[0038] The foregoing descriptions have outlined some exemplary embodiments of the present invention. It is understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of the present invention. Features in these embodiments can be rearranged in suitable ways, and the resulting solutions remain within the scope of protection claimed by the present invention. All other embodiments obtained by those skilled in the art based on the foregoing embodiments without inventive effort, i.e., all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by the present invention.
Claims
1. A method for controlling the crystallization of potassium fluorotantalate based on flow field design, characterized in that, Includes the following steps: Step 1, Design of the synergistic flow field: Construct an integrated synergistic flow field of axial thrust, radial dispersion, and bottom guide flow. The radial dispersion flow field can achieve uniform horizontal diffusion of the solution, the axial thrust flow field can provide a gradient axial lifting force, and the bottom guide flow field is adapted to the arc-shaped structure at the bottom of the potassium fluorotantalate crystallizer. Step 2, Design of flow field adaptable stirring structure: Based on the flow field morphology requirements in Step 1, design the corresponding stirring impeller. The stirring impeller includes a stirring shaft and three layers of stirring blades. The maximum outer diameter of the three layers of stirring blades is the same, and the diameter of the three layers of stirring blades is 1 / 3 to 1 / 2 of the diameter of the potassium fluorotantalate crystallizer. Step 3, Control of dynamic parameters of flow field: During the crystal nucleation stage, a low-intensity flow field with a stirring paddle speed of 5-30 r / min is used, and the low-intensity flow field lasts for 6-10 h; During the crystal growth stage, the stirring speed is gradually increased to a medium-high intensity flow field of 30-100 r / min within 2-4 hours, and the medium-high intensity flow field is maintained until the potassium fluorotantalate crystallization is completed.
2. The method for controlling potassium fluorotantalate crystallization based on flow field design according to claim 1, characterized in that, The three layers of stirring blades are, from top to bottom, the first layer, the second layer, and the third layer. The first layer of stirring blades is a four-bladed straight blade structure, with the blade plane perpendicular to the stirring shaft. The second layer of stirring blades is a four-bladed propulsion structure, consisting of four oblique blades spirally distributed along the circumference of the stirring shaft, with the angle between the oblique blades and the horizontal direction being 20-30°. The third layer of stirring blades is a single-bladed arc-shaped flow guide structure, with the blade as a whole being crescent-shaped, and the arc shape of the lower surface of the blade matching the arc-shaped bottom surface of the potassium fluorotantalate crystallizer.
3. The method for controlling potassium fluorotantalate crystallization based on flow field design according to claim 1, characterized in that, The proportion of the mixing dead zone in the flow field of the potassium fluorotantalate crystallizer is ≤5%.
4. The method for controlling potassium fluorotantalate crystallization based on flow field design according to claim 1, characterized in that, The stirring shaft and the three-layer stirring blades of the stirring paddle are both made of corrosion-resistant material, which is a composite material of stainless steel inner core and polytetrafluoroethylene coating.
5. The method for controlling potassium fluorotantalate crystallization based on flow field design according to claim 1, characterized in that, The stirring paddle speed during the crystal growth stage is increased in a stepwise manner, with the speed increased every 0.5-1 hour, and each increase being 10-20 r / min.