Device and method for multi-stage crystallization of ammonium metavanadate

Abstract

The invention discloses an ammonium metavanadate multi-stage crystallization device and method, and particularly relates to the technical field of industrial crystallization equipment, the ammonium metavanadate multi-stage crystallization device comprises a large-particle-size crystal settlement area, a main-particle-size crystal settlement area, a small-particle-size crystal settlement area and a circulating discharge area, the large-particle-size crystal settling area, the main-particle-size crystal settling area, the small-particle-size crystal settling area and the circulating discharging area are sequentially connected from bottom to top. The free sedimentation rate of crystals with different particle sizes and the optimal barrel diameter for realizing crystal suspension are determined through a method of combining theoretical calculation and analogue simulation, the equipment is reasonably partitioned, the crystals with different particle sizes are uniformly suspended in different regions, the quality of the product crystals is improved, and the production cost is reduced. And the number of small-particle-size crystals entering the circulating system can be greatly reduced, and pipeline blockage and equipment failure caused after the ammonium metavanadate crystals enter the circulating system are prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial crystallization equipment, and in particular to a device and method for multi-stage crystallization of ammonium metavanadate. Background Art

[0002] Continuous industrial crystallization processes play a crucial role in chemical and hydrometallurgical production, particularly in the emerging new energy industry, where demand for lithium, sodium, and vanadium salts is extremely high, both in terms of volume and quality. Crystallizers are key equipment in the production of lithium, sodium, and vanadium salts, and their crystallization performance directly impacts the quality of the final product.

[0003] The crystallization process for ammonium metavanadate often uses an Oslo cooling crystallizer with an external heat exchanger. This crystallizer produces large particle size and is easy to operate, but during use, some fine crystals can easily enter the heat exchanger with the solution and circulate, leading to blockage. Summary of the Invention

[0004] The object of the present invention is to provide a device and method for multi-stage crystallization of ammonium metavanadate to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a device for multi-stage crystallization of ammonium metavanadate, comprising: The large particle size crystal sedimentation zone, the main particle size crystal sedimentation zone, the small particle size crystal sedimentation zone and the circulation discharge zone are connected in sequence from bottom to top.

[0006] Furthermore, the large-particle size crystal sedimentation zone includes a first conical shell and a spherical head, the spherical head is fixed at the bottom of the first conical shell, and adopts a combined structure of the first conical shell and the spherical head. The first conical shell can guide the flow of materials, so that the large-particle size crystals can settle more smoothly under the action of gravity. A circulating feed pipe is provided in the first conical shell, and the circulating feed pipe is an L-shaped elbow. The end of the horizontal pipe section of the circulating feed pipe passes through the side wall of the first conical shell and extends to the outside of the first conical shell. The lower end of the vertical pipe section of the circulating feed pipe extends to the spherical head. A drain pipe is provided at the bottom of the spherical head, which can effectively remove impurities and sediments that may be generated during the sedimentation process to ensure the cleanliness of the sedimentation zone. A large-particle size crystal slurry discharge pipe is provided at the lower part of the side wall of the first conical shell.

[0007] Furthermore, the central axis of the vertical pipe section of the circulating feed pipe is located on the same straight line as the central axis of the first conical shell, and the lower end of the vertical pipe section of the circulating feed pipe is 500-700 mm away from the bottom of the spherical head, which can ensure that the material has sufficient residence time in the sedimentation area for sedimentation, while avoiding the accumulation of material at the bottom, further improving the sedimentation efficiency of large-particle crystals.

[0008] Furthermore, the main particle size crystal sedimentation area includes a first cylinder, the lower side wall of the first cylinder is provided with a main particle size crystal slurry discharge pipe, the bottom of the first cylinder is fixedly connected to the top of the first cone shell, the cylinder structure is easy to process and manufacture, and the cylinder structure can provide a stable sedimentation environment for the material, so that the main particle size crystals can settle smoothly therein.

[0009] Furthermore, the small-particle crystal sedimentation area includes a second cone shell, a second cylinder and a third cone shell. The third cone shell and the second cone shell are respectively fixed at the upper and lower ends of the second cylinder. The bottom end of the second cone shell is connected to the top end of the first cylinder. A small-particle crystal slurry discharge pipe is provided at the bottom of the side wall of the second cylinder. The second cone shell can guide the material flow and preliminarily separate the small-particle crystals. The second cylinder provides a stable sedimentation environment. The third cone shell helps to smoothly transport the settled small-particle crystal slurry to the circulation discharge area, thereby realizing effective graded sedimentation of small-particle crystals.

[0010] Furthermore, the circulating discharge area includes a third cylinder and a top cover, the top cover is located at the top of the third cylinder, the side wall of the third cylinder is provided with a circulating discharge pipe, and the bottom of the third cylinder is fixedly connected to the top of the third cone shell, so as to facilitate the recycling of materials after sedimentation treatment, improve the utilization rate of materials, and reduce production costs.

[0011] Furthermore, the top cover and the third cylinder are connected by welding.

[0012] The present invention also provides a method for multi-stage crystallization of ammonium metavanadate, comprising the following steps: Step 1: Calculate the free settling rate of ammonium metavanadate crystals of different particle sizes based on the material properties; Step 2: Calculate the concentration of crystals of different particle sizes according to the normal distribution. The crystals with the largest concentration are defined as the main particle size crystals, and the crystals with a particle size smaller than the main particle size crystals are defined as small particle size crystals. Step 3: Calculate the diameter of the first cylinder in the settling zone of the main particle size crystals based on the material circulation volume and the free settling rate of the main particle size crystals; Step 4: Calculate the diameter of the second cylinder in the small-size crystal settling area based on the material circulation volume and the free settling rate of the small-size crystals; Step 5: Calculate the volume of the crystallization device according to the feed rate of the crystallization system and the crystallization time, and then determine the appropriate heights of the large particle size crystal settling area, the main particle size crystal settling area, the small particle size crystal settling area and the circulating discharge area; Step 6: Perform three-dimensional modeling and fluid simulation on the preliminarily determined device model, and determine the optimal size of each area based on the crystallization effect obtained by the simulation.

[0013] In the above technical solution, the technical effects and advantages provided by the present invention are: 1. The apparatus for multi-stage crystallization of ammonium metavanadate of the present invention determines the free settling rate of crystals of different particle sizes and the optimal cylinder diameter for achieving crystal suspension by combining theoretical calculation and simulation, rationally partitions the equipment, achieves uniform suspension of crystals of different particle sizes in different areas, and improves the quality of the product crystals; 2. The multi-stage crystallization device of ammonium metavanadate of the present invention can greatly reduce the number of small-size crystals entering the circulation system, and prevent pipe blockage and equipment failure caused by ammonium metavanadate crystals entering the circulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0015] Figure 1 Schematic diagram of an ammonium metavanadate crystallization device in a preferred embodiment of the present invention.

[0016] Description of reference numerals: 10. Large-size crystal sedimentation area; 11. First cone shell; 12. Ball head; 13. Circulating feed pipe; 14. Drain pipe; 15. Large-size crystal slurry discharge pipe; 20. Main particle size crystal sedimentation area; 21. First cylinder; 22. Main particle size slurry discharge pipe; 30. Small-size crystal sedimentation zone; 31. Second cone shell; 32. Second cylinder; 33. Third cone shell; 34. Small-size crystal slurry discharge pipe; 40. Circulation discharge area; 41. Third cylinder; 42. Top cover; 43. Circulation discharge pipe. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 The device for multi-stage crystallization of ammonium metavanadate shown includes: The large particle size crystal sedimentation zone 10, the main particle size crystal sedimentation zone 20, the small particle size crystal sedimentation zone 30 and the circulation discharge zone 40 are connected in sequence from bottom to top.

[0019] The large-size crystal sedimentation zone 10 includes a first cone shell 11 and a spherical head 12. The spherical head 12 is fixed to the bottom of the first cone shell 11. The combined structure of the first cone shell 11 and the spherical head 12 is adopted. The first cone shell 11 can guide the flow of materials so that the large-size crystals can settle more smoothly under the action of gravity. A circulating feed pipe 13 is provided in the first cone shell 11. The circulating feed pipe 13 is an L-shaped elbow. The end of the horizontal pipe section of the circulating feed pipe 13 passes through the side wall of the first cone shell 11 and extends to the outside of the first cone shell 11. The lower end of the vertical pipe section of the circulating feed pipe 13 extends to the spherical head 12. The spherical head 1 2 is provided with a drain pipe 14 at the bottom, which can effectively remove impurities and sediments that may be generated during the sedimentation process to ensure the cleanliness of the sedimentation area. A large-particle size slurry discharge pipe 15 is provided at the lower part of the side wall of the first cone shell 11. The central axis of the vertical pipe section of the circulating feed pipe 13 is on the same straight line as the central axis of the first cone shell 11. The lower end of the vertical pipe section of the circulating feed pipe 13 is 500-700mm away from the bottom of the ball head 12, which can ensure that the material has sufficient residence time in the sedimentation area for sedimentation, while avoiding the accumulation of material at the bottom, further improving the sedimentation efficiency of large-particle size crystals.

[0020] The main particle size crystal sedimentation zone 20 includes a first cylinder 21, and the lower side wall of the first cylinder 21 is provided with a main particle size crystal slurry discharge pipe 22. The bottom of the first cylinder 21 is fixedly connected to the top of the first cone shell 11. The cylinder structure is easy to process and manufacture. The cylinder structure can provide a stable sedimentation environment for the material, so that the main particle size crystals can settle smoothly therein.

[0021] The small-particle crystal sedimentation area 30 includes a second cone shell 31, a second cylinder 32 and a third cone shell 33. The third cone shell 33 and the second cone shell 31 are respectively fixed at the upper and lower ends of the second cylinder 32. The bottom end of the second cone shell 31 is connected to the top of the first cylinder 21. A small-particle crystal slurry discharge pipe 34 is provided at the bottom of the side wall of the second cylinder 32. The second cone shell 31 can guide the material flow and preliminarily separate the small-particle crystals. The second cylinder 32 provides a stable sedimentation environment. The third cone shell 33 helps to smoothly transport the settled small-particle crystal slurry to the circulation discharge area 40, thereby realizing effective graded sedimentation of small-particle crystals.

[0022] The circulating discharge area 40 includes a third cylinder 41 and a top cover 42. The top cover 42 is located at the top of the third cylinder 41. The side wall of the third cylinder 41 is provided with a circulating discharge pipe 43. The bottom of the third cylinder 41 is fixedly connected to the top of the third cone shell 33, which is convenient for recycling the material after sedimentation treatment, improving the utilization rate of the material and reducing the production cost. The top cover 42 and the third cylinder 41 are connected by welding.

[0023] The device processing process of ammonium metavanadate multi-stage crystallization of the present embodiment is as follows: The ammonium metavanadate solution is added from the circulating feed pipe 13 to the ball head 12 at the bottom of the large-diameter crystal settling area 10. Under the action of the circulating pump, the circulating material has a large dynamic pressure head, which forms a huge impact on the slurry inside the device. This impact force can fully stir the large-diameter ammonium metavanadate crystals that have settled in the ball head 12 to prevent agglomeration. The mixed slurry rises in the first cone shell 11. The lower part of the first cone shell 11 has a small diameter and the slurry rises quickly. The upper part of the first cone shell 11 has a large diameter and the slurry rises slowly. The ammonium metavanadate crystals with larger particle sizes are suspended in the first cone shell 11 due to their fast free sedimentation speed, while the ammonium metavanadate crystals with smaller particle sizes continue to rise and grow. When the crystals grow to a point where their free settling velocity is greater than the rising velocity of the slurry in the settling zone 20 of the main particle size crystals, the crystals of this particle size are suspended in the first cylinder 21; Smaller ammonium metavanadate crystals continue to rise to the small-size crystal settling zone 30. Due to the expansion of the diameter of this zone, the rising speed of the slurry is further reduced, allowing the smaller crystals to be suspended in this zone, thereby controlling the number and diameter of the crystals flowing out of the circulating discharge pipe 43 of the circulating discharge zone 40 and into the circulation system. Finally, only a very small amount of crystals with extremely small particle size flow out from the circulating discharge pipe 43 along with the slurry and enter the next cycle to continue growing.

[0024] The ammonium metavanadate crystals in the large-particle crystal sedimentation zone 10 in the device are the most ideal product. The ammonium metavanadate crystals in the main-particle crystal sedimentation zone 20 and the small-particle crystal sedimentation zone 30 gradually grow during multiple cycles until they can be settled in the large-particle crystal sedimentation zone 10.

[0025] In order to meet the demand for crystal products of different particle sizes in the actual production process and to deal with some special situations, a large particle size slurry discharge pipe 15, a main particle size slurry discharge pipe 22, a small particle size slurry discharge pipe 34 and a sewage pipe 14 are set up in different areas.

[0026] In order to realize the apparatus for multi-stage crystallization of ammonium metavanadate of this embodiment, the present invention also provides a method for multi-stage crystallization of ammonium metavanadate, comprising the following steps: Step 1: Calculate the free settling rate of ammonium metavanadate crystals of different particle sizes based on the material properties; Step 2: Calculate the concentration of crystals of different particle sizes according to the normal distribution. The crystals with the largest concentration are defined as the main particle size crystals, and the crystals with a particle size smaller than the main particle size crystals are defined as small particle size crystals. Step 3: Calculate the diameter of the first cylinder 21 in the settling area of ​​the main particle size crystals based on the material circulation volume and the free settling rate of the main particle size crystals; Step 4: Calculate the diameter of the second cylinder 32 in the small-size crystal settling area based on the material circulation rate and the free settling rate of the small-size crystals; Step 5: Calculate the volume of the crystallization device according to the feed rate of the crystallization system and the crystallization time, and then determine the appropriate heights of the large-size crystal settling zone 10, the main-size crystal settling zone 20, the small-size crystal settling zone 30 and the circulating discharge zone 40; Step 6: Perform three-dimensional modeling and fluid simulation on the preliminarily determined device model, and determine the optimal size of each area based on the crystallization effect obtained by the simulation.

[0027] The advantages of the apparatus and method for multi-stage crystallization of ammonium metavanadate of this embodiment are as follows: The apparatus for multi-stage crystallization of ammonium metavanadate of the present invention determines the free settling rate of crystals of different particle sizes and the optimal cylinder diameter for achieving crystal suspension by combining theoretical calculation and simulation, rationally partitions the equipment, achieves uniform suspension of crystals of different particle sizes in different areas, and improves the quality of the product crystals. The ammonium metavanadate multi-stage crystallization device of the present invention can greatly reduce the number of small-size crystals entering the circulation system, and prevent pipeline blockage and equipment failure caused by the ammonium metavanadate crystals entering the circulation system.

[0028] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A device for multi-stage crystallization of ammonium metavanadate, characterized in that: include: A large-size crystal sedimentation zone (10), a main-size crystal sedimentation zone (20), a small-size crystal sedimentation zone (30) and a circulating discharge zone (40) are sequentially connected from bottom to top.

2. The device for multi-stage crystallization of ammonium metavanadate according to claim 1, wherein: The large-particle-size crystal sedimentation zone (10) includes a first cone shell (11) and a spherical head (12), wherein the spherical head (12) is fixed to the bottom of the first cone shell (11), and a circulating feed pipe (13) is provided in the first cone shell (11). The circulating feed pipe (13) is an L-shaped elbow, and the end of the horizontal pipe section of the circulating feed pipe (13) passes through the side wall of the first cone shell (11) and extends to the outside of the first cone shell (11). The lower end of the vertical pipe section of the circulating feed pipe (13) extends to the spherical head (12), and a sewage pipe (14) is provided at the bottom of the spherical head (12). A large-particle-size crystal slurry discharge pipe (15) is provided at the lower part of the side wall of the first cone shell (11).

3. The device for multi-stage crystallization of ammonium metavanadate according to claim 2, wherein: The central axis of the vertical pipe section of the circulating feed pipe (13) and the central axis of the first cone shell (11) are located on the same straight line, and the lower end of the vertical pipe section of the circulating feed pipe (13) is 500-700 mm away from the bottom of the ball head (12).

4. The device for multi-stage crystallization of ammonium metavanadate according to claim 3, wherein: The main particle size crystal sedimentation zone (20) comprises a first cylinder (21), a main particle size slurry discharge pipe (22) is provided on the lower side wall of the first cylinder (21), and the bottom of the first cylinder (21) is fixedly connected to the top of the first cone shell (11).

5. The device for multi-stage crystallization of ammonium metavanadate according to claim 4, wherein: The small-particle-size crystal sedimentation zone (30) includes a second cone shell (31), a second cylinder (32) and a third cone shell (33). The third cone shell (33) and the second cone shell (31) are respectively fixed at the upper and lower ends of the second cylinder (32). The bottom end of the second cone shell (31) is connected to the top end of the first cylinder (21). A small-particle-size crystal slurry discharge pipe (34) is provided at the bottom of the side wall of the second cylinder (32).

6. The device for multi-stage crystallization of ammonium metavanadate according to claim 5, wherein: The circulating discharge area (40) includes a third cylinder (41) and a top cover (42), wherein the top cover (42) is located on the top of the third cylinder (41), a circulating discharge pipe (43) is provided on the side wall of the third cylinder (41), and the bottom of the third cylinder (41) is fixedly connected to the top of the third cone shell (33).

7. The device for multi-stage crystallization of ammonium metavanadate according to claim 6, wherein: The top cover (42) and the third cylinder (41) are connected by welding.

8. A method for multi-stage crystallization of ammonium metavanadate, applied to the apparatus for multi-stage crystallization of ammonium metavanadate according to claim 7, characterized in that: The following steps are involved: Step 1: Calculate the free settling rate of ammonium metavanadate crystals of different particle sizes based on the material properties; Step 2: Calculate the concentration of crystals of different particle sizes according to the normal distribution. The crystals with the largest concentration are defined as the main particle size crystals, and the crystals with a particle size smaller than the main particle size crystals are defined as small particle size crystals. Step 3: Calculate the diameter of the first cylinder (21) in the settling area of ​​the main particle size crystals based on the material circulation volume and the free settling rate of the main particle size crystals; Step 4: Calculate the diameter of the second cylinder (32) in the small-size crystal settling area based on the material circulation volume and the free settling rate of the small-size crystals; Step 5: Calculate the volume of the crystallization device based on the feed rate of the crystallization system and the crystallization time, and then determine the appropriate heights of the large-size crystal settling zone (10), the main-size crystal settling zone (20), the small-size crystal settling zone (30) and the circulating discharge zone (40); Step 6: Perform three-dimensional modeling and fluid simulation on the preliminarily determined device model, and determine the optimal size of each area based on the crystallization effect obtained by the simulation.

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