Crystal purification apparatus and purification method

Abstract

This invention discloses a crystal purification apparatus and method, relating to the field of crystal purification technology. The apparatus includes a crystallization vessel, a centrifuge cylinder, a driving device, and a heating unit. The crystallization vessel has a first cavity, a feed inlet, and a waste liquid outlet. The centrifuge cylinder is disposed within the first cavity, having a top opening and multiple drainage holes on its sidewalls. The output component of the driving device extends into the first cavity and is fixedly connected to the centrifuge cylinder, driving the centrifuge cylinder to rotate around a first axis. Suspended crystal slurry falls into the centrifuge cylinder from the feed inlet and through the top opening. The heating unit heats the gas within the first cavity, causing the crystals in the centrifuge cylinder to "sweat." By integrating centrifugation and sweating, there is no need to transfer the crystals, avoiding contamination and labor costs associated with crystal transfer. Furthermore, after sweating, the centrifuge cylinder can be used to further separate the sweating liquid from the crystals, improving product purity and work efficiency.

Description

Technical Field

[0001] This invention relates to the field of crystal purification technology, and in particular to a crystal purification apparatus and purification method. Background Technology

[0002] Because electronic-grade phosphoric acid requires extremely low levels of metal impurity ions, and the separation and purification of phosphoric acid is quite difficult, coupled with production and operating costs, pre-purified industrial-grade or food-grade phosphoric acid is typically used as raw material to prepare electronic-grade phosphoric acid. Currently known purification methods include ion exchange, electrodialysis, extraction, and crystallization. Compared to other methods, crystallization does not require the introduction of additional solvents or dilution of phosphoric acid, and its operating conditions are mild. It also boasts advantages such as low energy consumption, simple equipment, and minimal pollution, making it a key research method for the preparation of electronic-grade phosphoric acid.

[0003] Melt crystallization is a crucial method for preparing electronic-grade phosphoric acid. Phosphoric acid crystallizes below its melting temperature, leaving impurity ions in the mother liquor. The crystals are then separated from the mother liquor to achieve purification. Therefore, effectively separating the crystals from the mother liquor is key. Common methods include sweating, washing, and filtration to separate the mother liquor. However, during sweating or washing, the mother liquor naturally drains, leaving a small amount remaining on the crystal surface or in the gaps, which reduces product purity. Furthermore, the crystals may dissolve back into the mother liquor, decreasing yield. If centrifugation or filtration is used to separate the mother liquor before sweating, the crystals need to be transferred multiple times, which can introduce contamination and increases labor costs. Summary of the Invention

[0004] The purpose of this invention is to provide a crystal purification apparatus and method to solve the problems existing in the prior art, reduce pollution risks and labor costs, and improve product purity.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a crystal purification apparatus, comprising a crystallization vessel, a centrifuge cylinder, a driving device, and a heating unit. The crystallization vessel has a first cavity and a feed inlet and a waste liquid outlet communicating with the first cavity. The centrifuge cylinder is disposed within the first cavity, has a top opening, and has multiple drain holes communicating with the first cavity on its side wall. The output component of the driving device extends into the first cavity and is fixedly connected to the centrifuge cylinder, and the output component of the driving device is used to drive the centrifuge cylinder to rotate around a first axis. Suspended crystal slurry falls into the centrifuge cylinder from the feed inlet through the top opening. The heating unit is used to heat the gas in the first cavity to cause the crystals in the centrifuge cylinder to sweat.

[0007] Preferably, the first axis coincides with the axis of the centrifuge tube, and in the direction of the first axis, the first end of the drain hole near the first axis is higher than the second end of the drain hole away from the first axis.

[0008] Preferably, it further includes a liquid collection tank, which is fixedly disposed on the inner side wall of the first cavity. In the direction of the first axis, the top of the liquid collection tank is lower than the second end of the drain hole at the lowest point on the side wall of the centrifuge cylinder. The liquid collection tank has an upper opening, and the crystallization vessel body is provided with a liquid outlet communicating with the interior of the liquid collection tank.

[0009] Preferably, the system further includes a plurality of sprayers, which are fixedly disposed within the first cavity; in the first axial direction, at least a portion of the sprayers are above the top opening of the centrifuge cylinder, and the sprayers are used to spray cleaning fluid.

[0010] Preferably, the driving device includes a motor and a rotating shaft. The output shaft of the motor is fixedly connected to one end of the rotating shaft. The end of the rotating shaft away from the motor extends into the first cavity, passes through the centrifuge tube along the axial direction of the centrifuge tube, and is rotatably connected to the crystallizing vessel body around the first axis. The first axis coincides with the axis of the rotating shaft. The centrifuge tube is fixedly connected to the rotating shaft.

[0011] Preferably, it also includes a protective baffle, which is disposed outside the rotating shaft below the centrifuge cylinder. The protective baffle can prevent the rotating shaft located inside the protective baffle from contacting the liquid in the first cavity.

[0012] Preferably, the protective baffle includes an upper annular baffle and a lower annular baffle; along the first axial direction, the lower end of the lower annular baffle is fixedly connected to the inner bottom of the first cavity, and the upper end of the lower annular baffle has a through hole for the rotating shaft to pass through; along the first axial direction, the upper annular baffle is fixedly connected to the outer bottom of the centrifuge tube and extends downward, and the rotating shaft passes through the interior of the upper annular baffle; along the first axial direction, the upper end of the lower annular baffle is higher than the lower end of the upper annular baffle; the circumferential edge of the upper end of the lower annular baffle is located inside the circumferential edge of the lower end of the upper annular baffle.

[0013] Preferably, the crystallization vessel is further provided with a gas replacement channel communicating with the first cavity, through which the gas replacement channel is used to replace the gas in the first cavity.

[0014] Preferably, the heating unit is a gas heater, and the heating end of the gas heater is located inside the first cavity and is used to heat the gas inside the first cavity.

[0015] The present invention also provides a purification method based on the crystal purification apparatus described in any one of the above claims, comprising the following steps:

[0016] S1, the suspended crystallization slurry is injected into the centrifuge tube from the feed port, the drive device is turned on to make the centrifuge tube rotate centrifugally, and the mother liquor is thrown out by centrifugal force and discharged from the waste liquid outlet;

[0017] S2, turn on the heating unit to heat the crystals in the centrifuge tube to sweat. After sweating is completed, turn on the driving device to drive the centrifuge tube to centrifuge and get sweated liquid.

[0018] S3, collect the remaining crystals in the centrifuge tube.

[0019] Preferably, after the sweating liquid is expelled in S2, molten crystals with a temperature higher than that of the remaining crystals in the centrifuge tube are introduced. The heat of the molten crystals is used to melt the remaining crystals in the centrifuge tube. After all the remaining crystals in the centrifuge tube have melted, the drive device is turned on to make the centrifuge tube rotate centrifugally and the molten crystals are expelled by centrifugal force.

[0020] The present invention achieves the following technical effects compared to the prior art:

[0021] The crystal purification device provided by this invention integrates centrifugation and sweating by placing both the centrifuge cylinder for centrifugation and the heating unit for sweating in the crystallization vessel. After centrifugation, there is no need to transfer the crystals; sweating can be performed directly. Therefore, it can avoid the pollution and labor costs caused by crystal transfer. Furthermore, after sweating, the centrifugation action of the centrifuge cylinder can be used to separate the sweating liquid from the crystals, thereby improving product purity and work efficiency.

[0022] Furthermore, the drain hole adopts a structure with a higher inner side and a lower outer side, which can prevent liquid outside the centrifuge from entering the centrifuge through the drain hole after the liquid is spun out of the centrifuge, thereby ensuring the purity of the crystals inside the centrifuge.

[0023] Furthermore, the collection tank facilitates the collection and recycling of sweat. Since the purity of sweat is higher than that of the raw materials, it can be recycled, thus reducing costs.

[0024] Furthermore, the sprayer can rinse the first cavity, preventing the high-impurity mother liquor residue from the centrifuge from affecting the purity of the sweating liquid and the final crystal product.

[0025] Furthermore, the drive device consists of a motor and a rotating shaft. Its structure is simple, and the end of the rotating shaft away from the motor is rotatably connected to the crystallizing vessel, which can drive the centrifuge cylinder to rotate stably and ensure the centrifugation effect.

[0026] Furthermore, the protective baffle can prevent the liquid in the first cavity from coming into contact with the rotating shaft, thereby preventing corrosion of the rotating shaft and extending its service life.

[0027] Furthermore, the protective baffle is composed of an upper annular baffle and a lower annular baffle. The lower annular baffle can provide protection for the rotating shaft below the centrifuge tube when it rotates, while the upper annular baffle is set between the centrifuge tube and the lower annular baffle. When it rotates with the centrifuge tube, its protective area can prevent the mother liquor from contacting the rotating shaft between the centrifuge tube and the lower annular baffle, thus ensuring the safe use of the rotating shaft.

[0028] Furthermore, the gas replacement channel facilitates the replacement of the gas in the first cavity with an inert gas that does not affect the centrifugation and sweating process of crystal purification, thereby avoiding interference from substances in the gas that react with the crystal and ensuring the purity of the crystal.

[0029] Furthermore, a gas heater is used to directly heat the gas in the first cavity, using the internal gas to assist in heating the crystals inside the centrifuge, thereby achieving their sweating and subsequent auxiliary collection.

[0030] The present invention also provides a purification method based on the above crystal purification device. By centrifuging and filtering the crystals to be purified in the same container and then sweating them, the crystals will not be contaminated during the centrifugation and sweating process. The sweating liquid can be recycled using a centrifuge and the sweating liquid can be separated from the crystals in a timely manner, thereby improving the purity of the crystal products and improving work efficiency.

[0031] Furthermore, by utilizing the heat of the molten crystal itself to melt the remaining crystals inside the centrifuge tube, it is easier to collect the crystal products and less likely to be mixed with other substances. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of an overall structure of the crystal purification apparatus provided by the present invention;

[0034] Figure 2 This is a schematic diagram of another overall structure of the crystal purification apparatus provided by the present invention.

[0035] In the diagram: 100 - Crystal purification device;

[0036] 10-Crystallization vessel body; 11-Feed inlet; 12-Waste liquid outlet; 13-Support leg; 14-First cavity; 15-Gas replacement channel;

[0037] 20 - Centrifuge tube; 21 - Drain hole;

[0038] 30 - Drive unit; 31 - Motor; 32 - Shaft;

[0039] 40 - Heating unit;

[0040] 50 - Collection tank; 51 - Liquid outlet;

[0041] 60 - Protective baffle; 61 - Upper annular baffle; 62 - Lower annular baffle;

[0042] 70-Sprayer. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The purpose of this invention is to provide a crystal purification apparatus and method to solve the problems existing in the prior art, reduce pollution risks and labor costs, and improve product purity.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1

[0047] This embodiment provides a crystal purification apparatus 100, mainly for, but not limited to, the purification of electronic-grade phosphate crystals, such as... Figure 1 and Figure 2As shown, the system includes a crystallization vessel 10, a centrifuge cylinder 20, a drive device 30, and a heating unit 40. The crystallization vessel 10 has a first cavity 14 and a feed inlet 11 and a waste liquid outlet 12 communicating with the first cavity 14. The centrifuge cylinder 20 is disposed in the first cavity 14, and the centrifuge cylinder 20 has a top opening and multiple drain holes 21 communicating with the first cavity 14 are provided on the side wall of the centrifuge cylinder 20. The output component of the drive device 30 extends into the first cavity 14 and is fixedly connected to the centrifuge cylinder 20. The output component of the drive device 30 is used to drive the centrifuge cylinder 20 to rotate around a first axis. The suspended crystal slurry falls into the centrifuge cylinder 20 from the feed inlet 11 through the top opening. The heating unit 40 is used to heat the gas in the first cavity 14 to make the crystals in the centrifuge cylinder 20 sweat. By placing both the centrifuge cylinder 20 for centrifugation and the heating unit 40 for heating and sweating in the crystallization vessel 10, centrifugation and sweating are integrated together. After centrifugation is completed, there is no need to transfer the crystals; sweating can be carried out directly. Therefore, the pollution and labor costs caused by crystal transfer can be avoided. After sweating, the centrifugation action of the centrifuge cylinder 20 can be used to separate the sweating liquid from the crystals, thereby improving product purity and work efficiency.

[0048] Specifically, after sweating, the remaining crystals in the centrifuge tube 20 can be indirectly heated and melted into a liquid state by the heating unit 40 using the gas in the first cavity 14 as a medium. Then, the crystals are thrown out into the collection tank 50 by the centrifugal force of the centrifuge tube 20 and collected through the liquid outlet 51. Alternatively, a molten liquid of the crystal product at a certain temperature can be added to the centrifuge tube 20. The heat of the molten liquid of the crystal product can be used to melt the solid crystal product in the centrifuge tube 20, and the crystals are thrown out into the collection tank 50 by the centrifugal force of the centrifuge tube 20 and collected through the liquid outlet 51. For example, when preparing phosphoric acid products, high-purity phosphoric acid liquid at 50°C can be added. The high-purity phosphoric acid liquid mentioned here can be the product produced by this crystal purification device 100. At the same time, the heating unit 40 is turned on for auxiliary heating. After the remaining solid crystals in the centrifuge tube 20 are completely melted, the crystals are thrown out into the collection tank 50 by the centrifugal force of the centrifuge tube 20 and collected through the liquid outlet 51.

[0049] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 As shown, the first axis coincides with the axis of the centrifuge cylinder 20. Specifically, the axis of the centrifuge cylinder 20 is parallel to the vertical direction. In the direction of the first axis, the first end of the drain hole 21 closer to the first axis is higher than the second end of the drain hole 21 farther from the first axis. The drain hole 21 adopts a structure that is higher on the inside and lower on the outside, which can prevent liquid outside the centrifuge cylinder 20 from easily entering the centrifuge cylinder 20 through the drain hole 21 after the liquid is spun out by centrifugation, thereby ensuring the purity of the crystals inside the centrifuge cylinder 20.

[0050] Specifically, the inclination angle of the drain hole 21 is 10° to 50°, preferably 30°, so that the liquid in the centrifuge tube 20 is concentrated downward when it is thrown out into the first cavity 14.

[0051] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2 As shown, the crystallization and purification device also includes a collection tank 50, which is fixedly installed on the inner wall of the first cavity 14. In the direction of the first axis, the top of the collection tank 50 is lower than the second end of the lowest drain hole 21 on the side wall of the centrifuge cylinder 20. The collection tank 50 has an opening at the top, and the crystallization vessel 10 is provided with a liquid outlet 51 communicating with the interior of the collection tank 50. The collection tank 50 facilitates the collection and recycling of the sweat. Since the purity of the sweat is higher than that of the raw materials, it can be recycled, thus reducing costs.

[0052] Specifically, the liquid collection tank 50 can be a continuous annular tank or it can be composed of multiple segmented arc-shaped tanks. When it is composed of multiple segmented arc-shaped tanks, the overall structure is circumferentially continuous in the horizontal projection.

[0053] Specifically, some of the liquid ejected from the centrifuge tube 20 will flow down the inner wall of the first cavity 14 into the collection tank 50. After the collection tank 50 is full, the liquid will overflow to the bottom of the first cavity 14. The liquid in the collection tank 50 will be discharged through the liquid outlet 51, and the liquid in the first cavity 14 will be discharged through the waste liquid outlet 12.

[0054] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2 As shown, the crystallization purification apparatus also includes multiple sprayers 70, which are fixedly disposed within the first cavity 14. Along the first axial direction, at least a portion of the sprayers 70 extend above the top opening of the centrifuge cylinder 20. The sprayers 70 are used to spray the cleaning solution. The arrangement of the sprayers 70 enables the first cavity 14 to be rinsed, preventing the high-impurity mother liquor ejected from the centrifuge cylinder 20 from affecting the purity of the rinsing solution and the final crystal product.

[0055] Specifically, the sprayers 70 can be evenly distributed along the first axis on the inner wall of the first cavity 14. Alternatively, they can be located at the top inner part of the first cavity 14, i.e., on the inner wall of the top cover of the crystallization vessel 10. The arrangement and method of the sprayers 70 can also be any other existing arrangement selected based on the actual situation and desired effect.

[0056] Specifically, the first axis coincides with the axis of the crystallization vessel 10.

[0057] Specifically, in addition to setting multiple sprayers 70, a single spray device can also be set, with multiple spray nozzles on the circumferential sidewall of the first cavity 14.

[0058] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2 As shown, the drive device 30 includes a motor 31 and a rotating shaft 32. The output shaft of the motor 31 is fixedly connected to one end of the rotating shaft 32. The end of the rotating shaft 32 away from the motor 31 extends into the first cavity 14, passes through the centrifuge cylinder 20 along its axial direction, and is rotatably connected to the crystallization vessel 10 around a first axis. The first axis coincides with the axis of the rotating shaft 32. The centrifuge cylinder 20 is fixedly connected to the rotating shaft 32. The drive device 30, composed of a motor 31 and a rotating shaft 32, has a simple structure. The end of the rotating shaft 32 away from the motor 31 is rotatably connected to the crystallization vessel 10, which can drive the centrifuge cylinder 20 to rotate stably, ensuring the centrifugation effect.

[0059] Specifically, the end of the rotating shaft 32 that passes through the centrifuge cylinder 20 can be directly rotatably connected to the crystallizing vessel 10 via a bearing, or it can be rotatably connected to the crystallizing vessel via a rotating shaft fixing component.

[0060] Specifically, the rotating shaft 32 is the output component of the drive device 30.

[0061] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2 As shown, it also includes a protective baffle 60. In the first axial direction, the protective baffle 60 is disposed outside the rotating shaft 32 below the centrifuge cylinder 20. The protective baffle 60 can prevent the rotating shaft 32 located inside the protective baffle 60 from contacting the liquid in the first cavity 14. The protective baffle 60 can prevent the liquid in the first cavity 14 from contacting the rotating shaft 32, thereby preventing corrosion of the rotating shaft 32 and extending the service life of the rotating shaft 32.

[0062] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2As shown, the protective baffle 60 includes an upper annular baffle 61 and a lower annular baffle 62. Along the first axis, the lower end of the lower annular baffle 62 is fixedly connected to the inner bottom of the first cavity 14, and the upper end of the lower annular baffle 62 has a through hole through which the rotating shaft 32 passes. Along the first axis, the upper annular baffle 61 is fixedly connected to the outer bottom of the centrifuge cylinder 20 and extends downward, and the rotating shaft 32 passes through the interior of the upper annular baffle 61. Along the first axis, the upper end of the lower annular baffle 62 is higher than the lower end of the upper annular baffle 61. The circumferential edge of the upper end of the lower annular baffle 62 is located inside the circumferential edge of the lower end of the upper annular baffle 61. The protective baffle 60 is composed of an upper annular baffle 61 and a lower annular baffle 62. The lower annular baffle 62 can provide protection for the rotating shaft 32 below the centrifuge cylinder 20 when it rotates. The upper annular baffle 61 is located between the centrifuge cylinder 20 and the lower annular baffle 62. When it rotates with the centrifuge cylinder 20, its protective area can prevent the mother liquor from contacting the rotating shaft 32 between the centrifuge cylinder 20 and the lower annular baffle 62, thus ensuring the safe use of the rotating shaft 32.

[0063] Specifically, to ensure good discharge effect, the liquid outlet 51 and the waste liquid outlet 12 can both be set at the lowest point of their respective positions.

[0064] Specifically, such as Figure 1 As shown, at least one support foot 13 is also fixedly provided on the bottom of the crystallization vessel 10. The support foot 13 enables the crystallization vessel 10 to be placed more stably and firmly on the ground.

[0065] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 2 As shown, the crystallization vessel 10 is also provided with a gas replacement channel 15 communicating with the first cavity 14. The gas replacement channel 15 is used to replace the gas in the first cavity 14. The gas replacement channel 15 facilitates the replacement of the gas in the first cavity 14 with an inert gas that does not affect the centrifugation and sweating processes of crystal purification, thereby avoiding interference from substances in the gas that react with the crystals and ensuring the purity of the crystals.

[0066] Specifically, the original gas in the first cavity 14 is replaced by introducing a clean gas at 30°C to 40°C, such as an inert gas, into the gas replacement channel 15. Here, replacement means using clean gas to replace as much of the original gas in the first cavity 14 as possible.

[0067] Specifically, when replacing the gas in the first cavity 14, a certain temperature of clean gas can be introduced after the replacement is completed. This allows the clean gas to carry away some of the residual liquid on the inner wall of the first cavity 14 when it is discharged, thereby improving the crystal purification effect.

[0068] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 As shown, the heating unit 40 is a gas heater. The heating end of the gas heater is located inside the first cavity 14 and is used to heat the gas inside the first cavity 14. The gas heater directly heats the first cavity 14, and the internal gas is used to assist in heating the crystals inside the centrifuge tube 20, thereby achieving their sweating and subsequent auxiliary collection.

[0069] Specifically, the gas heater can be an electrically heated heating rod, which heats the gas in the first cavity 14, and then the heated gas heats the crystals in the centrifuge tube 20; alternatively, it can be achieved by directly introducing an inert gas at a certain temperature through the gas replacement channel 15; or it can be achieved by setting a jacket on the crystallization vessel 10, such as... Figure 2 As shown, the jacket is circulated with a medium at a certain temperature, which can be a fluid or a gas; or a heating device, such as an electric heating wire, can be installed on the outer or inner wall of the crystallizing vessel 10. In order to ensure the separation between the heating component and the liquid in the first cavity 14, a protective cover or other components can be sealed on the outside of the heating component.

[0070] Example 2

[0071] This embodiment provides a purification method based on the crystal purification apparatus 100 of Embodiment 1, including the following steps:

[0072] S1, the suspended crystallization slurry is injected into the centrifuge cylinder 20 through the feed inlet 11, the drive device 30 is turned on to make the centrifuge cylinder 20 rotate centrifugally, and the mother liquor is thrown out by centrifugal force and discharged from the waste liquid outlet 12.

[0073] Specifically, in S1, when it is necessary to discharge the mother liquor ejected from the centrifuge tube 20, both the liquid outlet 51 and the waste liquid outlet 12 are opened to allow the mother liquor to be discharged.

[0074] Specifically, since the mother liquor will be thrown from the drain hole 21 of the centrifuge cylinder 20 onto the inner wall of the first cavity 14, after the mother liquor is discharged, it can be cleaned by spraying washing liquid through the sprayer 70 to ensure that there is no mother liquor residue in the first cavity 14. The cleaning liquid after cleaning by the sprayer 70 is completely discharged through the liquid outlet 51 and the waste liquid outlet 12.

[0075] S2, turn on the heating unit 40 to heat the crystals in the centrifuge cylinder 20 to sweat. After sweating is completed, turn on the drive device 30 to drive the centrifuge cylinder 20 to centrifuge and throw out the sweat liquid.

[0076] Specifically, in S2, the sweating liquid is ejected from the centrifuge tube 20 into the collection tank 50, and the operator collects the sweating liquid in the collection tank 50 by opening the liquid outlet 51.

[0077] S3, collect the remaining crystals in centrifuge tube 20.

[0078] By centrifuging and filtering the crystals to be purified in the same container, the crystals are not contaminated during the centrifugation and sweating process. The sweating liquid can be recycled using the centrifuge cylinder 20 and the sweating liquid can be separated from the crystals in a timely manner, thereby improving the purity of the crystal product and increasing work efficiency.

[0079] Specifically, after the sweating liquid in S2 is expelled, molten crystals at a temperature higher than the remaining crystals in centrifuge cylinder 20 are introduced. The heat of the molten crystals melts the remaining crystals in centrifuge cylinder 20. Once all the remaining crystals in centrifuge cylinder 20 have melted, the drive device is activated to make centrifuge cylinder 20 rotate centrifugally, and the molten crystals are expelled by centrifugal force. Utilizing the heat of the molten crystals themselves to melt the remaining crystals in centrifuge cylinder 20 makes the collection of crystalline products more convenient and less prone to contamination by other substances.

[0080] The preparation of electronic-grade phosphoric acid is used as an example to illustrate the specific steps:

[0081] ① Separate the mother liquor: Add the suspended crystal slurry into the centrifuge cylinder 20, turn on the motor 31 to rotate at a certain speed for a certain time, and discharge the mother liquor by centrifugal force. Close the waste liquid outlet 12 and the liquid outlet 51, turn on the sprayer 70 to rinse the residual mother liquor on the wall of the crystallization vessel 10, and discharge the mother liquor from the waste liquid outlet 12 and the liquid outlet 51;

[0082] ② Heating and sweating: The heating unit 40 is turned on to heat and sweat the crystals in the centrifuge cylinder 20. After a period of time, the sweating is stopped, and the motor 31 is turned on to centrifuge and remove the sweat. The sweat is collected in the collection tank 50, and the outlet 51 is opened to collect the sweat. The purity of the sweat is higher than that of the raw material, and it can be recycled through the collection tank 50 to reduce costs.

[0083] ③ Crystal Collection: High-purity phosphoric acid liquid at 50℃ is introduced and mixed with the crystals in centrifuge cylinder 20. The heat of the phosphoric acid liquid melts the crystals, while heating unit 40 is turned on for auxiliary heating. After the crystals have melted, motor 31 is turned on to centrifuge and the product is collected by opening outlet 51.

[0084] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for purifying crystals, characterized in that: It includes a crystal purification device, which includes a crystallization vessel, a centrifuge cylinder, a drive device, and a heating unit; The crystallization vessel has a first cavity and a feed inlet and a waste liquid outlet communicating with the first cavity; The centrifuge tube is disposed in the first cavity, the centrifuge tube has a top opening and a plurality of drain holes communicating with the first cavity are provided on the side wall of the centrifuge tube; The output component of the drive device extends into the first cavity and is fixedly connected to the centrifuge tube, and the output component of the drive device is used to drive the centrifuge tube to rotate around the first axis. The suspended crystal slurry falls into the centrifuge tube from the feed inlet through the top opening, and the heating unit is used to heat the gas in the first cavity to make the crystals in the centrifuge tube sweat. The first axis coincides with the axis of the centrifuge tube. In the direction of the first axis, the first end of the drain hole near the first axis is higher than the second end of the drain hole away from the first axis. It also includes a liquid collection tank, which is fixedly installed on the inner side wall of the first cavity. In the direction of the first axis, the top of the liquid collection tank is lower than the second end of the drain hole at the lowest point on the side wall of the centrifuge cylinder. The liquid collection tank has an opening at the top, and the crystallization vessel body is provided with a liquid outlet that communicates with the inside of the liquid collection tank. The purification method includes the following steps: S1, the suspended crystallization slurry is injected into the centrifuge tube from the feed port, the drive device is turned on to make the centrifuge tube rotate centrifugally, and the mother liquor is thrown out by centrifugal force and discharged from the waste liquid outlet; S2, turn on the heating unit to heat the crystals in the centrifuge tube to sweat. After sweating is completed, turn on the driving device to drive the centrifuge tube to centrifuge and get sweated liquid. S3, collect the remaining crystals in the centrifuge tube. After the sweating liquid is spun out in S2, introduce molten crystals with a temperature higher than that of the remaining crystals in the centrifuge tube. Use the heat of the molten crystals to melt the remaining crystals in the centrifuge tube. After all the remaining crystals in the centrifuge tube have melted, turn on the drive device to make the centrifuge tube rotate centrifugally and throw out the molten crystals by centrifugal force.

2. The crystal purification method according to claim 1, characterized in that: The crystal purification device further includes a plurality of sprayers, which are fixedly disposed in the first cavity; in the first axial direction, at least a portion of the sprayers are higher than the top opening of the centrifuge tube, and the sprayers are used to spray cleaning liquid.

3. The crystal purification method according to claim 1, characterized in that: The driving device includes a motor and a rotating shaft. The output shaft of the motor is fixedly connected to one end of the rotating shaft. The end of the rotating shaft away from the motor extends into the first cavity, passes through the centrifuge tube along the axial direction of the centrifuge tube, and is rotatably connected to the crystallizing vessel body around the first axis. The first axis coincides with the axis of the rotating shaft. The centrifuge tube is fixedly connected to the rotating shaft.

4. The crystal purification method according to claim 3, characterized in that: The crystal purification device also includes a protective baffle, which is disposed outside the rotating shaft below the centrifuge cylinder. The protective baffle can prevent the rotating shaft located inside the protective baffle from contacting the liquid in the first cavity.

5. The crystal purification method according to claim 4, characterized in that: The protective baffle includes an upper annular baffle and a lower annular baffle; along the first axis, the lower end of the lower annular baffle is fixedly connected to the inner bottom of the first cavity, and the upper end of the lower annular baffle has a through hole for the rotating shaft to pass through; along the first axis, the upper annular baffle is fixedly connected to the outer bottom of the centrifuge tube and extends downward, and the rotating shaft passes through the interior of the upper annular baffle; along the first axis, the upper end of the lower annular baffle is higher than the lower end of the upper annular baffle; the circumferential edge of the upper end of the lower annular baffle is located inside the circumferential edge of the lower end of the upper annular baffle.

6. The crystal purification method according to claim 1, characterized in that: The crystallization vessel is also provided with a gas replacement channel that communicates with the first cavity, and the gas replacement channel is used to replace the gas in the first cavity.

7. The crystal purification method according to claim 1, characterized in that: The heating unit is a gas heater, and the heating end of the gas heater is located inside the first cavity and is used to heat the gas inside the first cavity.

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