Cobaltous sulfate evaporative crystallization equipment and process

[0026] Example 1

[0027] This embodiment provides a cobalt sulfate evaporation crystallization device, which is a device that uses MVR technology to directly prepare cobalt sulfate heptahydrate crystals from cobalt sulfate solution. The device is such as figure 1 As shown, it includes a raw liquid preheating system, an evaporation concentration system, a cooling crystallization system, and a filtration separation system connected in sequence, and also includes a control signal connection with the raw liquid preheating system, evaporation concentration system, cooling crystallization system, and filtration separation system. The control mechanism is a PLC, and the control mechanism is used to control the automatic processing process of the raw liquid preheating system, the evaporation concentration system, the cooling crystallization system, and the filtration separation system. All input and output signals can be controlled by a computer with PLC control software. carry out.

[0028] Specifically, the raw liquid preheating system includes a raw liquid storage tank 1, a distilled water preheater 2 and a fresh steam preheater 3 which are sequentially connected by pipelines, and the raw liquid storage tank 1 and the distilled water preheater 2 A raw liquid pump 4 is provided in the raw liquid storage tank 1, and the raw liquid storage tank 1 is filled with cobalt sulfate solution. The raw liquid pump 4 sequentially pumps the cobalt sulfate solution in the raw liquid storage tank 1 into the distilled water preheater 2 and the fresh steam preheater 3 , Exchange heat with the distilled water in the distilled water preheater 2 and the fresh steam in the fresh steam preheater 3. Wherein, the fresh steam preheater 3 is connected to the evaporation concentration system, and the distilled water preheater 2 is also connected to a distilled water storage tank 6 through a distilled water pump 5. The fresh steam preheater 3 is also connected to a non-condensable gas condenser 20 through a pipeline, and the non-condensable gas condenser 20 is connected to a vacuum pump 21.

[0029] The evaporative concentration system includes a gas-liquid separator 7 and a forced circulation heat exchanger 8 connected through a pipeline. The gas-liquid separator 7 and the fresh steam preheater 3 are connected through a pipeline and are preheated by fresh steam. The cobalt sulfate preheated by the fresh steam in the reactor enters the gas-liquid separator 7 for flash evaporation and concentration. The gas-liquid separator 7 is also connected to a secondary separator 9 through a pipeline, and the secondary separator 9 passes through A steam compressor 10 is connected to the pipeline, and the steam compressor 10 is connected to the forced circulation heat exchanger 8 at the same time. Further, the steam compressor 10 is also connected to a liquid accumulation tank 11, and the liquid accumulation tank 11 is connected with Effusion pump 19. A forced circulation pump 12 is also connected to the bottom of the forced circulation heat exchanger 8. The forced circulation pump 12 is connected to the gas-liquid separator 7 through a pipeline for pumping the concentrated liquid produced in the gas-liquid separator 7 into the forced The circulating heat exchanger 8 circulates and concentrates.

[0030] The cooling and crystallization system includes a first enamel cooling kettle 13 and a second enamel cooling kettle 14 connected by pipelines. The gas-liquid separator 7 is connected to the first enamel cooling kettle 13 and the second enamel cooling kettle 13 through a discharge pump 15 The enamel cooling kettle 14 is connected, and the first enamel cooling kettle 13 and the second enamel cooling kettle 14 cool the saturated cobalt sulfate solution to obtain cobalt sulfate heptahydrate crystals and its low-temperature saturated mother liquor.

[0031] The filtration and separation system includes a piston pushing centrifuge 16. The first enamel cooling kettle 13 and the second enamel cooling kettle 14 are connected to the piston pushing centrifuge 16, and the piston pushing centrifuge 16 passes through a pipeline. A mother liquor tank 17 for storing the filtrate filtered by the piston push centrifuge 16 is connected. The piston pushing centrifuge 16 has a piston pusher. After the mother liquor containing crystallization in the first enamel cooling kettle 13 and the second enamel cooling kettle 14 enters the piston pushing centrifuge 16, it will move along the piston pushing centrifuge 16. The inner wall of the conical feeding hopper flows to the filter screen of the rotating drum, and the filtrate is continuously discharged through the filter screen through the filtrate outlet, and the filter residue accumulated on the inner surface of the filter screen is pushed out along the inner wall of the rotating drum by the reciprocating piston pusher. The filtrate is stored in the mother liquor tank 17, and is connected to the raw liquor storage tank 1 through the mother liquor pump 18, so that the mother liquor is mixed with the raw liquor, after preheating, it is evaporated and concentrated again and cooled and crystallized.

[0032] Example 2

[0033] This embodiment provides a process for evaporative crystallization using the cobalt sulfate evaporative crystallization equipment described in Embodiment 1, which includes the following steps:

[0034] S1. Preheating the stock solution. The cobalt sulfate solution is heated to the evaporation temperature through the stock solution preheating system, and the cobalt sulfate stock solution stored in the stock solution storage tank 1 is sequentially injected into the distilled water preheater 2 and the fresh steam preheater 3 by the stock solution pump 4 , Sequentially heat exchange with the distilled water and fresh steam in each preheater to reach the evaporation temperature of the cobalt sulfate solution 93°C. The distilled water is the secondary steam condensed water obtained by evaporation of the distilled water in the distilled water storage tank 6. The fresh steam is saturated steam with a pressure of 0.1MpaG and a temperature of 120°C.

[0035] S2. Evaporation and concentration. The preheated cobalt sulfate solution enters the evaporation concentration system. After the temperature is raised and pressured, it is flashed and concentrated to obtain a cobalt sulfate solution with a concentration close to saturation and secondary steam. Specifically, the preheated cobalt sulfate solution enters the gas In the liquid separator 7, and under the action of the forced circulation pump 12, it enters the forced circulation heat exchanger 8 to raise the temperature and pressure, and then enters the gas-liquid separator 7 for flash evaporation and concentration. The concentrated liquid after gas-liquid separation is forced Under the action of the circulation pump 12 and gravity, it enters the forced circulation heat exchanger 8 again, and then enters the gas-liquid separator 7 again for concentration and flash evaporation after the temperature rises. The above process is cyclically carried out. The gas-liquid separator 7 provides a slight load of 70.1KPa. Pressure. After crystallization and separation, the secondary steam with a temperature of 85°C and a pressure of 57.8KPa will enter the secondary separator 9 after defoaming at the top of the gas-liquid separator, and the secondary steam will enter the steam after further gas-liquid separation. Compressor 10 obtains high-temperature and high-pressure steam with a temperature of 105°C and a pressure of 120.8KPa after compression. The high-temperature and high-pressure steam is reused in the forced circulation heat exchanger 8 to heat the material. In the process of heating the material, the high-temperature and high-pressure steam is condensed into water. The distilled water storage tank 6 is sent to the distilled water preheater 2 by the distilled water pump 5 to exchange heat with the raw material liquid, and is discharged out of the system after being cooled to 35°C. The steam compressor 10 is connected with a large secondary steam pipeline, and the condensed liquid remaining in the large pipeline flows to the liquid accumulation tank 11 during the startup process, and is sent to the distilled water storage tank 6 by the liquid accumulation pump 19, and is sent out of the system by the distilled water pump 5.

[0036] S3. Cooling and crystallization. The nearly saturated cobalt sulfate solution after evaporation and concentration is cooled by a cooling crystallization system. The temperature is reduced, and the cobalt sulfate heptahydrate crystals are saturated and precipitated. The cobalt sulfate solution in the gas-liquid separator 7 is concentrated by continuous evaporation and concentration. The saturated solution is sent to the first enamel cooling kettle 13 and the second enamel cooling kettle 14 by the discharge pump 15 after observing the density through the mass flowmeter. The two enamel cooling kettles are operated alternately, and the first enamel cooling kettle 13 and the second enamel cooling kettle are operated alternately. Cooling water with a temperature of about 25°C is passed into the jacket of the enamel cooling kettle 14, and the cobalt sulfate solution is gradually cooled to about 40°C. At this time, the solubility of cobalt sulfate decreases and cobalt sulfate heptahydrate crystals are precipitated to obtain cobalt sulfate heptahydrate. Crystal and its low temperature saturated mother liquor.

[0037] S4. Filtration and separation. The cooled and crystallized cobalt sulfate heptahydrate crystals are passed through the filtration separation system. The cooled solution containing cobalt sulfate heptahydrate crystals is centrifuged through the filtration separation system to obtain filtrate and cobalt sulfate heptahydrate crystals, and the filtrate is returned to The evaporative concentration system evaporates and concentrates again. The cobalt sulfate heptahydrate crystal grains produced by cooling and crystallization continuously grow in the first enamel cooling kettle 13 and the second enamel cooling kettle 14, and then the solution containing cobalt sulfate heptahydrate crystals and its low-temperature saturated mother liquor passes through the tube The path enters the piston pushing centrifuge 16, and flows along the inner wall of the cone feeding hopper of the piston pushing centrifuge 16 to the filter screen of the rotating drum. The filtrate is continuously discharged through the filter screen through the filtrate outlet, and the filter residue accumulated on the inner surface of the filter screen is pushed out along the inner wall of the drum by the reciprocating piston pusher, thereby separating the cobalt sulfate heptahydrate crystals and the low-temperature saturated mother liquor. The cobalt sulfate heptahydrate crystals are packaged and sent out of the system. The low-temperature saturated mother liquor flows out of the filtrate outlet of the piston pushing centrifuge 16, and flows into the connected mother liquid tank 17 through the pipeline, and then is transported to the connected raw liquid storage tank 1 through the mother liquid pump 18. After the mother liquor and the original liquor are mixed, the preheating is carried out again for evaporation and concentration and cooling and crystallization.

[0038] Experimental example

[0039] The processing capacity and operating energy consumption of the acid cobalt evaporation crystallization equipment described in Example 1 were tested, and the results are shown in Table 1:

[0040] Table 1

[0041] Serial number

[0042] The above test results show that the evaporation crystallization device described in Example 1 has the advantages of low energy consumption, high output, simple process, small number of equipment, and low construction investment.