System for preparing large-particle cobalt chloride hexahydrate through ultralow-temperature evaporative crystallization

Abstract

The invention discloses a system for preparing large-particle cobalt chloride hexahydrate through ultralow-temperature evaporative crystallization, which comprises a stock solution tank, a forced circulation pump, a forced heat exchanger, an ultralow-temperature crystallizer and a vacuum unit, the stock solution tank is connected with the forced circulation pump through a preheating unit, the forced circulation pump is located between the forced heat exchanger and the ultralow-temperature crystallizer, and the vacuum unit is connected with the forced heat exchanger. The forced circulation pump is used for circularly conveying a cobalt chloride solution to enter the forced heat exchanger to be heated and then enter the ultralow-temperature crystallizer to be subjected to flash evaporation, the ultralow-temperature crystallizer is connected with a centrifugal machine, and a gas treatment unit is arranged between the ultralow-temperature crystallizer and the forced heat exchanger; the gas treatment unit is used for treating secondary steam generated by flash evaporation and then supplying the treated secondary steam to the forced heat exchanger, and the vacuum unit is connected with the forced heat exchanger and used for maintaining a low-temperature environment for the ultralow-temperature crystallizer; no matched cooling crystallization equipment is needed, crystallization is directly completed through an ultralow-temperature evaporation and crystallization integrated process, the technological process is shortened, and the equipment investment and the occupied area are reduced.

Description

Technical Field

[0001] This invention relates to the field of cobalt chloride hexahydrate production technology, specifically to a system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation and crystallization. Background Technology

[0002] Cobalt chloride hexahydrate is an important cobalt salt with unique physicochemical properties. It can be used in electroplating, as a colorant for glass and ceramics, and as a paint drying agent.

[0003] In the industrial production of cobalt chloride hexahydrate, the preparation process using cobalt chloride solution as raw material typically employs multi-effect evaporation or micro-negative pressure MVR (mechanical vapor recompression) evaporation technology. This requires subsequent support from an Oslo continuous cooling crystallization unit or a batch reactor cooling crystallization device. The crystallization of cobalt chloride hexahydrate is achieved through a combination of evaporation concentration and cooling, but this necessitates a separate cooling crystallization unit, resulting in a long process flow, increased equipment investment and floor space. Furthermore, the crystal growth rate is difficult to control during cooling crystallization, easily leading to uneven particle size distribution (high proportion of fine crystals). Temperature fluctuations during the cooling stage can also cause co-crystallization of impurity ions, affecting product purity. Therefore, this invention proposes an ultra-low temperature evaporation crystallization system for preparing large-particle cobalt chloride hexahydrate that can solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation and crystallization, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization, comprising a raw liquid tank, a forced circulation pump, a forced heat exchanger, an ultra-low temperature crystallizer, and a vacuum unit, wherein the raw liquid tank is connected to the forced circulation pump via a preheating unit; The forced circulation pump is located between the forced heat exchanger and the cryogenic crystallizer. The forced circulation pump is used to circulate and transport the cobalt chloride solution into the forced heat exchanger for heating and then into the cryogenic crystallizer for flash evaporation. The cryogenic crystallizer is connected to a centrifuge. A gas processing unit is provided between the ultra-low temperature crystallizer and the forced heat exchanger. The gas processing unit is used to process the secondary steam generated by flash evaporation and then supply it to the forced heat exchanger. The vacuum unit is connected to the forced heat exchanger, and the vacuum unit is used to maintain a low-temperature environment for the cryogenic crystallizer.

[0006] Preferably, the preheating unit includes a preheater and a feed pump, wherein the feed pump is used to deliver the cobalt chloride solution into the preheater for preheating.

[0007] Preferably, the forced heat exchanger is connected to a condensate tank, and the condensate tank is connected to the preheater via a condensate pump.

[0008] Preferably, the centrifuge is connected to a mother liquor tank, and the mother liquor tank is connected to the forced circulation pump via a mother liquor pump.

[0009] Preferably, the gas processing unit includes a gas scrubbing tower and a cryogenic compressor.

[0010] Preferably, the vacuum unit includes a vacuum unit, a chiller unit, and a condenser.

[0011] A method for preparing large-particle cobalt chloride hexahydrate is also provided, which can be used in any of the above technical solutions, and specifically includes the following steps: S1. The feed pump delivers cobalt chloride solution into the preheater for preheating; S2. The preheated cobalt chloride solution is circulated by a forced circulation pump into a forced heat exchanger for heating, and then enters an ultra-low temperature crystallizer for flash evaporation. During the flash evaporation process, the vacuum unit maintains a low-temperature environment for the ultra-low temperature crystallizer, and the gas processing unit processes the secondary steam generated during flash evaporation and supplies it to the forced heat exchanger. S3. When the generated crystals reach the predetermined concentration, the crystals enter a centrifuge. The centrifuge centrifuges the crystals generated by flash evaporation to obtain large-particle cobalt chloride hexahydrate crystals.

[0012] Compared with the prior art, the beneficial effects of the present invention are: No additional cooling crystallization equipment is required; crystallization can be completed directly through an integrated ultra-low temperature evaporation and crystallization process, shortening the process flow and reducing equipment investment and floor space. The crystallization process is carried out in a stable ultra-low temperature environment, the crystal growth rate is controllable, large particles and narrow particle size distribution are achieved, and impurity ions are not easy to co-crystallize, which significantly reduces the impurity content of the product. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the vacuum unit structure of the present invention; Figure 3 This is a schematic diagram of the gas treatment single structure of the present invention; Figure 4 This is a schematic diagram of the preheating unit structure of the present invention; In the diagram: 10. Raw material tank; 20. Forced circulation pump; 30. Forced heat exchanger; 40. Cryogenic crystallizer; 50. Vacuum unit; 51. Vacuum unit; 52. Chiller unit; 53. Condenser; 60. Preheating unit; 61. Preheater; 62. Feed pump; 63. Condensate tank; 64. Condensate pump; 70. Gas handling unit; 71. Gas scrubbing tower; 72. Cryogenic compressor; 80. Centrifuge; 81. Mother liquor tank; 82. Mother liquor pump; 83. Packaging machine. Detailed Implementation

[0014] 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.

[0015] Please see Figure 1-4 Example 1

[0016] A system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization is provided: The raw material tank 10 is connected to the forced circulation pump 20 via the preheating unit 60. The preheating unit 60 includes a preheater 61 and a feed pump 62. The feed pump 62 is used to transport the cobalt chloride solution into the preheater 61 for preheating.

[0017] A forced circulation pump 20 is located between a forced heat exchanger 30 and a cryogenic crystallizer 40. The forced circulation pump 20 circulates cobalt chloride solution into the forced heat exchanger 30 for heating before it enters the cryogenic crystallizer 40 for flash evaporation. The cryogenic crystallizer 40 is connected to a centrifuge 80. A transfer valve and a concentration detector are installed on the connecting pipe between the centrifuge 80 and the cryogenic crystallizer 40. During the circulating heating and crystallization process of the cobalt chloride solution, when the generated crystals reach a predetermined concentration, the crystals can enter the centrifuge 80 through a height difference. The centrifuge 80 is used to centrifuge the crystals generated during flash evaporation. The centrifuge 80 is connected to a mother liquor tank 81, which is connected to the forced circulation pump 20 via a mother liquor pump 82. By recovering the mother liquor generated during centrifugation and re-integrating the recovered mother liquor into the system, cobalt chloride hexahydrate crystals with a uniform particle size distribution and a D50 are obtained. The thickness can be controlled to 0.5mm, and the moisture content is ≤0.5% and the total impurity content (such as iron, nickel, copper, etc.) is ≤50ppm. The centrifuge 80 is connected to a packaging machine 83 for packaging the obtained cobalt chloride hexahydrate crystals.

[0018] A gas processing unit 70 is provided between the cryogenic crystallizer 40 and the forced heat exchanger 30. The gas processing unit 70 is used to process the secondary steam generated by flash evaporation and then supply it to the forced heat exchanger 30. The gas processing unit 70 includes a gas scrubbing tower 71 and a cryogenic compressor 72. The secondary steam enters the gas scrubbing tower 71 for scrubbing and then enters the cryogenic compressor 72 for pressurization and heating before being pumped into the forced heat exchanger 30. By utilizing the heat recovery design of the cryogenic compressor 72 and the forced circulation heat exchanger, combined with the low-energy evaporation characteristics under cryogenic environment, energy saving is effectively achieved.

[0019] Vacuum unit 50 is connected to forced heat exchanger 30. Vacuum unit 50 is used to maintain a low temperature environment for ultra-low temperature crystallizer 40. Vacuum unit 50 includes vacuum unit 51, chiller unit 52 and condenser 53. Vacuum unit 51 draws suction from forced heat exchanger 30, and chiller unit 52 supplies low temperature working fluid to vacuum unit 51. The temperature and pressure of forced heat exchanger 30 on the hot side decrease, thereby causing the temperature and pressure of ultra-low temperature crystallizer 40 on the cold side to decrease, thereby maintaining ultra-low temperature crystallizer 40 in a low temperature environment below 40°C for evaporation and crystallization. No additional cooling crystallization equipment is required; crystallization can be completed directly through an integrated ultra-low temperature evaporation and crystallization process, shortening the process flow and reducing equipment investment and floor space. The crystallization process is carried out in a stable ultra-low temperature environment, the crystal growth rate is controllable, large particles and narrow particle size distribution are achieved (reducing fine crystals), and impurity ions are not easy to co-crystallize, which significantly reduces the impurity content of the product.

[0020] The forced heat exchanger 30 is connected to a condensate tank 63, which is connected to the preheater 61 via a condensate pump 64. The condensate produced after the secondary steam heats the cobalt chloride solution enters the condensate tank 63, which then uses the condensate pump 64 to deliver the condensate to the condensate preheater 61 to preheat the cobalt chloride solution.

[0021] The entire system is controlled by a combination of negative pressure and temperature, which reduces product quality fluctuations caused by operating condition fluctuations and makes it suitable for continuous large-scale production. Example 2

[0022] A method for preparing large-particle cobalt chloride hexahydrate specifically includes the following steps: S1, Feed pump 62 delivers cobalt chloride solution into preheater 61 for preheating; S2. The preheated cobalt chloride solution is circulated by the forced circulation pump 20 into the forced heat exchanger 30 for heating, and then enters the ultra-low temperature crystallizer 40 for flash evaporation. During the flash evaporation process, the vacuum unit 50 maintains a low temperature environment for the ultra-low temperature crystallizer 40, and the gas processing unit 70 processes the secondary steam generated by flash evaporation and supplies it to the forced heat exchanger 30. S3. When the generated crystals reach the predetermined concentration, the crystals enter the centrifuge 80. The centrifuge 80 centrifuges the crystals generated by flash evaporation to obtain large-particle cobalt chloride hexahydrate crystals.

[0023] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization, characterized in that, It includes a raw liquid tank (10), a forced circulation pump (20), a forced heat exchanger (30), an ultra-low temperature crystallizer (40), and a vacuum unit (50). The raw liquid tank (10) is connected to the forced circulation pump (20) through a preheating unit (60). The forced circulation pump (20) is located between the forced heat exchanger (30) and the cryogenic crystallizer (40). The forced circulation pump (20) is used to circulate and transport the cobalt chloride solution into the forced heat exchanger (30) for heating and then into the cryogenic crystallizer (40) for flash evaporation. The cryogenic crystallizer (40) is connected to a centrifuge (80). A gas processing unit (70) is provided between the ultra-low temperature crystallizer (40) and the forced heat exchanger (30). The gas processing unit (70) is used to process the secondary steam generated by flash evaporation and then supply it to the forced heat exchanger (30). The vacuum unit (50) is connected to the forced heat exchanger (30) and is used to maintain a low-temperature environment for the cryogenic crystallizer (40).

2. The system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization according to claim 1, characterized in that, The preheating unit (60) includes a preheater (61) and a feed pump (62), the feed pump (62) being used to deliver cobalt chloride solution into the preheater (61) for preheating.

3. The system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization according to claim 2, characterized in that, The forced heat exchanger (30) is connected to a condensate tank (63), which is connected to the preheater (61) via a condensate pump (64).

4. The system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization according to claim 3, characterized in that, The centrifuge (80) is connected to a mother liquor tank (81), which is connected to the forced circulation pump (20) via a mother liquor pump (82).

5. The system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization according to claim 1, characterized in that, The gas processing unit (70) includes a gas scrubbing tower (71) and a cryogenic compressor (72).

6. The system for preparing large-particle cobalt chloride hexahydrate by ultra-low temperature evaporation crystallization according to claim 1, characterized in that, The vacuum unit (50) includes a vacuum unit (51), a chiller unit (52), and a condenser (53).

7. A method for preparing large-particle cobalt chloride hexahydrate, used in the ultra-low temperature evaporation crystallization system for preparing large-particle cobalt chloride hexahydrate as described in any one of claims 1-6, specifically comprising the following steps: S1, the feed pump (62) delivers the cobalt chloride solution into the preheater (61) for preheating; S2. The preheated cobalt chloride solution is circulated by a forced circulation pump (20) into a forced heat exchanger (30) for heating, and then enters an ultra-low temperature crystallizer (40) for flash evaporation. During the flash evaporation process, the vacuum unit (50) maintains a low-temperature environment for the ultra-low temperature crystallizer (40), and the gas processing unit (70) processes the secondary steam generated by flash evaporation and supplies it to the forced heat exchanger (30). S3. When the generated crystals reach the predetermined concentration, the crystals enter the centrifuge (80). The centrifuge (80) centrifuges the crystals generated by flash evaporation to obtain large-particle cobalt chloride hexahydrate crystals.

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