A continuous production device for carbonate nanometerization purification

Abstract

This invention belongs to the field of carbonate production technology and discloses a continuous production device for the nano-purification of carbonates. The device includes a carbonate slurry storage tank, a stirred filter reactor, a hydrocyclone, and a decomposition reactor. The carbonate slurry storage tank is connected to the inlet of the stirred filter reactor, which also has a carbon dioxide inlet. The bottom of the stirred filter reactor has an outlet connected to the decomposition reactor via a bicarbonate pipeline. The outlet of the decomposition reactor is connected to the hydrocyclone via an outlet pipeline, and the outlet of the decomposition reactor is connected to the inlet via a carbon dioxide circulation pipeline. The bottom outlet of the hydrocyclone discharges nano-carbonate slurry, and the upper outlet of the hydrocyclone is connected to the stirred filter reactor. This invention achieves continuous output of reaction products, ensuring continuous production, saving space, reducing equipment, and lowering energy consumption.

Description

Technical Field

[0001] This invention belongs to the field of carbonate production technology, specifically relating to a continuous production device for the nano-purification of carbonates. Background Technology

[0002] Nano-calcium carbonate is a novel ultrafine solid material developed in the 1980s, generally referring to calcium carbonate products with a particle size in the range of 1–100 nm. This type of calcium carbonate exhibits surface effects, small size effects, and macroscopic quantum tunneling effects. It also shows superior performance in terms of magnetism, catalysis, photothermal resistance, and melting point, making it one of the research hotspots in carbonate materials in recent years.

[0003] In existing technologies, carbonation is the core process for the production of nano-carbonates. Taking nano-calcium carbonate as an example, since calcium carbonate itself is a widely used material in the industrial field and is relatively easy to obtain, the key to the preparation of nano-calcium carbonate lies in how to purify conventional calcium carbonate materials to nanoscale. The carbonation method mainly involves calcining limestone to obtain calcium oxide and carbon dioxide. The calcium oxide is then digested with water, and the resulting calcium hydroxide emulsion is further carbonized by passing carbon dioxide gas through it. During the carbonation process, appropriate crystal control agents are added to control the crystal form. At the end of carbonation, the desired calcium carbonate slurry is obtained, which is then dehydrated, dried, and surface-treated to obtain the calcium carbonate product.

[0004] This carbonation method requires high-temperature calcination of carbonates, resulting in high energy consumption. Furthermore, the key to producing nano-calcium carbonate in this method is the reaction between calcium hydroxide emulsion and carbon dioxide gas. Due to the involvement of gas-liquid two-phase mass transfer and reaction issues, the traditional bubbling carbonation method suffers from a small gas-liquid contact area, leading to a low reaction rate, slow nucleation, large and widely distributed product particle size, long carbonation time, and low production efficiency. While the supergravity carbonation method can solve the problems of the traditional bubbling method, it suffers from drawbacks such as high equipment requirements, large investment, and low carbon dioxide utilization efficiency. Moreover, existing equipment systems in these methods struggle to continuously input raw materials and continuously produce and output products, making continuous production impossible and resulting in insufficient production continuity and stability. Summary of the Invention

[0005] The purpose of this invention is to provide a continuous production device for the nano-purification of carbonates, so as to solve the technical problems of long reaction time, high energy consumption, high equipment cost and inability to achieve continuous production in the prior art.

[0006] A continuous production apparatus for the nano-purification of carbonates includes a carbonate slurry storage tank, a stirred filter reactor, a hydrocyclone, and a decomposition reactor. The carbonate slurry storage tank is used to generate and store a slurry formed by mixing crude carbonate with water. The stirred filter reactor is used to promote the reaction of the carbonate slurry with carbon dioxide to generate bicarbonate. The decomposition reactor is used to heat and decompose the bicarbonate solution. The carbonate slurry storage tank is connected to the inlet of the stirred filter reactor via a pipeline equipped with a feed pump. The stirred filter reactor is also equipped with a carbon dioxide inlet. The bottom of the stirred filter reactor has an outlet, which is connected to the inlet of the decomposition reactor via a bicarbonate pipeline. The outlet of the decomposition reactor is connected to the inlet of the hydrocyclone via an outlet pipeline. The outlet of the decomposition reactor is connected to the inlet via a carbon dioxide circulation pipeline. The bottom outlet of the hydrocyclone discharges nano-carbonate slurry, and the upper outlet of the hydrocyclone is connected to the circulating liquid inlet at the top of the stirred filter reactor via a liquid circulation pipe.

[0007] Preferably, the stirred filter reactor is provided with a filter cloth and a stirring device. The filter cloth is horizontally arranged to divide the inner cavity of the stirred filter reactor into a reaction zone at the top and a filtration zone at the bottom. The feed inlet, the air inlet, the circulating liquid inlet and the stirring component of the stirring device are all located in the reaction zone, and the output port is located in the filtration zone.

[0008] Preferably, the air inlet is connected to a carbon dioxide gas source via a carbon dioxide input pipe. The carbon dioxide gas source can adjust the gas flow rate and pressure. The reaction zone is equipped with a first pressure sensor, and the carbon dioxide circulation pipeline is equipped with a first flow meter. The carbon dioxide gas source adjusts the gas flow rate and pressure according to the pressure measured by the first pressure sensor and the circulating gas flow rate of the carbon dioxide controlled by the first flow meter.

[0009] Preferably, the reaction zone is further provided with a first temperature sensor and a pH sensor. The stirred filter reactor is covered with a jacket. The filtration zone and the reaction zone are in partial contact with the jacket. The inner cavity of the jacket is provided with an inlet and an outlet. The inlet and the outlet are both connected to the interface of the temperature control device via a temperature control circulation pipe. The temperature control circulation pipe is used to transport circulating cooling water.

[0010] Preferably, the decomposition reactor is equipped with a heating device and a second temperature sensor, and the continuous production device further includes a heat exchanger, through which the liquid outlet pipeline and the bicarbonate pipeline exchange heat; the liquid inlet of the decomposition reactor is connected to an inlet pump, which is used to control the pressure and flow rate of the bicarbonate input to the decomposer, and the decomposition reactor is equipped with a second pressure sensor.

[0011] Preferably, the continuous production apparatus for carbonate nano-purification controls the reaction temperature, carbon dioxide pressure, and pH value of the stirred filter reactor within the range where bicarbonate is continuously generated through the heat exchange medium in the jacket, the inlet pump, and the first flow meter.

[0012] Preferably, the opening of the carbonate slurry storage tank is also provided with a solid feeder for inputting crude carbonate and a second flow meter for controlling the water volume. The crude carbonate is quantitatively supplied through the solid feeder, and the water supply pipe is controlled by the second flow meter to control the delivery flow rate.

[0013] This invention offers the following advantages: The use of a stirred-filter reactor saves on the number of devices and space required, and enables the recycling of carbon dioxide. The recovered carbon dioxide is used for pressurized reaction, and the stirring action ensures continuous reaction and filtration. This invention allows for the continuous production of bicarbonate while a constant supply of slurry is provided, ensuring a stable amount of raw materials used in the production process and a continuous and stable output of reaction products. Furthermore, the invention utilizes the liquid products obtained from thermal decomposition to preheat the bicarbonate solution, achieving heat recovery. Therefore, this invention saves space, reduces equipment requirements, and lowers energy consumption. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a continuous production device for the nano-purification of carbonates according to the present invention.

[0015] The labels in the attached diagram include: 1. Carbonate slurry storage tank; 11. Solid feeder; 12. Second flow meter; 2. Stirred filter reactor; 21. Stirring component; 22. First pressure sensor; 23. Filter cloth; 24. Jacket; 25. pH sensor; 26. First temperature sensor; 3. Hydrocyclone; 4. Heat exchanger; 5. Decomposition reactor; 51. Second temperature sensor; 52. Second pressure sensor; 6. Feed pump; 7. Inlet pump; 8. Carbon dioxide circulation pipeline; 9. First flow meter. Detailed Implementation

[0016] The following detailed description of the embodiments, with reference to the accompanying drawings, will further illustrate the specific implementation of the present invention, in order to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solution of the present invention.

[0017] like Figure 1As shown, this invention provides a continuous production apparatus for the nano-purification of carbonates, comprising a carbonate slurry storage tank 1, a stirred filter reactor 2, a hydrocyclone 3, and a decomposition reactor 5. The carbonate slurry storage tank 1 is used to generate and store a slurry formed by mixing crude carbonate with water. The stirred filter reactor 2 is used to promote the reaction of the carbonate slurry with carbon dioxide to generate bicarbonate. The decomposition reactor 5 is used to heat and decompose the bicarbonate solution. The carbonate slurry storage tank 1 is connected to the inlet of the stirred filter reactor 2 via a pipeline equipped with a feed pump 6. The stirred filter reactor 2 is also equipped with an inlet for inputting carbon dioxide. The bottom of the stirred filter reactor 2 has an outlet, which is connected to the inlet of the decomposition reactor 5 via a bicarbonate pipeline. The outlet of the decomposition reactor 5 is connected to the inlet of the hydrocyclone 3 via an outlet pipeline. The outlet of the decomposition reactor 5 is connected to the inlet via a carbon dioxide circulation pipeline 8. The bottom outlet of the hydrocyclone 3 discharges nano-carbonate slurry, and the upper outlet of the hydrocyclone 3 is connected to the circulating liquid inlet at the top of the stirred filter reactor 2 via a liquid circulation pipeline. The gaseous carbon dioxide generated by the decomposition reactor 5 is transported to the stirred filter reactor 2 through pipelines, realizing the recycling of carbon dioxide.

[0018] The stirred filter reactor 2 is equipped with a filter cloth 23 and a stirring device. The filter cloth 23 is horizontally arranged to divide the inner cavity of the stirred filter reactor 2 into a reaction zone at the top and a filtration zone at the bottom. The feed inlet, the air inlet, the circulating liquid inlet and the stirring component 21 of the stirring device are all located in the reaction zone, and the output port is located in the filtration zone.

[0019] The air inlet is connected to a carbon dioxide gas source through a carbon dioxide input pipe. The carbon dioxide gas source can adjust the gas flow rate and pressure. The reaction zone is equipped with a first pressure sensor 22. The carbon dioxide circulation pipeline 8 is equipped with a first flow meter 9. The carbon dioxide gas source adjusts the gas flow rate and pressure according to the pressure measured by the first pressure sensor 22 and the circulating gas flow rate of the carbon dioxide controlled by the first flow meter 9.

[0020] The reaction zone is also equipped with a first temperature sensor 26 and a pH sensor. The stirred filter reactor 2 is covered by a jacket 24. The filtration zone and the reaction zone partially contact the jacket 24. The inner cavity of the jacket 24 is provided with an inlet and an outlet. Both the inlet and outlet are connected to the interface of the temperature control device via a temperature-regulating circulation pipe, which is used to transport circulating cooling water. The use of the jacket 24 and the liquid heat exchange medium enables temperature control of the liquid in the reaction zone and the filtration zone, and has the advantages of large heat exchange area and stable and uniform heat exchange.

[0021] The stirred filter reactor 2 has a separable tank structure, comprising an upper tank above the filter cloth 23 and a lower tank below the filter cloth 23. The filter cloth 23 is fixed to the top opening of the lower tank. The lower tank and the upper tank are connected by a lifting device, and a sealing structure is provided between the top opening sidewall of the lower tank and the bottom opening sidewall of the upper tank, allowing the upper and lower tanks to be sealed shut after assembly. This structure facilitates the removal of filter cake from the filter cloth 23 after the reaction and allows for rapid reassembly and subsequent reaction.

[0022] The decomposition reactor 5 is equipped with a heating device and a second temperature sensor 51. The continuous production device also includes a heat exchanger 4, through which the liquid outlet pipeline and the bicarbonate pipeline exchange heat. The decomposition reactor 5 is a batch reactor or a tubular reactor. The heating device is a steam heater or an electric heater to increase the reactor temperature and achieve relatively precise control of the reaction temperature.

[0023] The second temperature sensor 51 is used to monitor the reaction temperature in the decomposition reactor 5. Thermodynamically, the higher the reaction temperature, the more thoroughly calcium bicarbonate decomposes, and the less likely a reverse reaction will occur. If forward and reverse reactions occur continuously, the nano-calcium carbonate will continuously dissolve and precipitate, leading to the growth of calcium carbonate crystals. Therefore, maintaining a higher temperature can prevent the growth of calcium carbonate crystals. In addition, kinetically, the higher the temperature, the faster the reaction rate, the more nuclei formed, and the smaller the particle size. Therefore, the size of nano-calcium carbonate can be controlled by temperature.

[0024] The inlet of the decomposition reactor 5 is connected to an inlet pump 7, which controls the pressure and flow rate of bicarbonate input to the decomposer. A second pressure sensor 52 is installed in the decomposition reactor 5 to monitor the pressure caused by carbon dioxide produced during the decomposition reaction. The pressure in the decomposition reactor 5 is controlled by the inlet pump 7 and the flow meters of the carbon dioxide circulation pipeline 8.

[0025] The opening of the carbonate slurry storage tank 1 is also equipped with a solid feeder 11 for inputting crude carbonate and a second flow meter 12 for controlling the water volume. The crude carbonate is quantitatively supplied through the solid feeder, and the water supply pipe controls the delivery flow rate through the second flow meter 12.

[0026] The continuous production process is as follows: Crude carbonate and water are fed at a certain feed rate through the solid feeder 11 and the second flow meter 12, respectively, and then mixed in the carbonate slurry storage tank 1 to form a slurry of the required concentration. The slurry is then pumped by the feed pump 6 to the stirred filter reactor 2 at a certain rate for reaction. Carbon dioxide is introduced into the upper end of the stirred filter reactor 2 for pressurization, and circulating cooling water is circulated through the jacket 24 outside the stirred filter reactor 2 to control the reaction temperature. At a certain temperature, the reaction occurs in the stirred filter reactor 2: MCO3 + H2O + CO2 == M(HCO3)2, where MCO3 is a carbonate. After the reaction, water-soluble bicarbonate M(HCO3)2 is generated. M represents metal elements such as Ca, Mg, Ba, and Sr, whose bicarbonates are soluble in water but whose carbonates are insoluble in water. Impurities such as SiO2, Al2O3, and Fe2O3 cannot react with CO2 and remain in solid form. Impurities and unreacted carbonates are insoluble in water and cannot pass through the filter cloth 23. The bicarbonate solution continuously passes through the filter cloth 23 into the filtration zone, so that the reaction in the reaction zone continues to proceed in the forward direction and achieves the separation of bicarbonate from impurities and carbonates.

[0027] The reaction temperature in the stirred filter reactor 2 is controlled by the heat exchange medium in the jacket 24, the carbon dioxide pressure is controlled by the inlet pump 7 and the first flow meter 9, and the pH value of the reaction is affected by the above three factors. By controlling the reaction temperature, carbon dioxide pressure and pH value within the range where bicarbonate is continuously generated through the heat exchange medium, the inlet pump 7 and the first flow meter 9, the reaction that generates bicarbonate can occur continuously while the slurry is continuously supplied, and the raw materials can also be continuously input.

[0028] In the stirred filter reactor 2, carbon dioxide not only participates in the reaction as a raw material but also provides the driving force for filtering the bicarbonate solution, ensuring that the solution can quickly pass through the filter cake and filter cloth 23 without external power supply. The filter cake, stirred by the stirring component 21, detaches from the filter cloth 23 and mixes into the slurry in the reaction zone, thus preventing clogging of the filter cloth 23 for a relatively long period, allowing the device to operate continuously for extended periods. The bicarbonate solution entering the filtration zone is then fed into the decomposition reactor 5, where it is preheated by the heat exchanger 4. In the decomposition reactor 5, heating is used to decompose the bicarbonate, producing nano-carbonate, water, and carbon dioxide. The corresponding reaction formula is: M(HCO3)2==MCO3+H2O+CO2. This reaction allows for temperature control of the nano-calcium carbonate size. Simultaneously, the production of gaseous carbon dioxide causes a pressure increase, and the decomposition reactor 5 subsequently outputs liquid and gaseous carbon dioxide. The liquid includes nano-carbonate and a solution containing a small amount of residual bicarbonate.

[0029] The aforementioned liquid is heated to a high temperature in decomposition reactor 5 and then used to preheat the bicarbonate solution. Afterward, the liquid is fed into hydrocyclone 3 for separation. The less dense water, carbon dioxide, and water-soluble solutes are discharged from the top of hydrocyclone 3 and fed into stirred filter reactor 2 for reuse. The denser nano-carbonate slurry is discharged from the bottom of hydrocyclone 3. The nano-carbonate slurry is dried to obtain the corresponding nano-carbonates. The feed rate of the slurry material delivered by feed pump 6 should be comparable to the output rate of the nano-carbonate slurry, thereby ensuring a stable amount of raw materials used in the production process and a continuous and stable output of reaction products. Simultaneously, the concentration of crude carbonate in the raw material slurry should match the concentration of carbonate in the nano-carbonate slurry output by hydrocyclone 3 to ensure stable system operation.

[0030] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A continuous production apparatus for the nano-purification of carbonates, characterized in that: The system includes a carbonate slurry storage tank (1), a stirred filter reactor (2), a hydrocyclone (3), and a decomposition reactor (5). The carbonate slurry storage tank (1) is used to generate and store a slurry formed by mixing crude carbonate with water. The stirred filter reactor (2) is used to promote the reaction of the carbonate slurry with carbon dioxide to generate bicarbonate. The decomposition reactor (5) is used to heat and decompose the bicarbonate solution. The carbonate slurry storage tank (1) is connected to the inlet of the stirred filter reactor (2) through a pipeline equipped with a feed pump (6). The stirred filter reactor (2) is also equipped with an input... The carbon dioxide inlet is provided, and the bottom of the stirred filter reactor (2) is provided with an outlet. The outlet is connected to the liquid inlet of the decomposition reactor (5) through a bicarbonate pipeline. The liquid outlet of the decomposition reactor (5) is connected to the inlet of the hydrocyclone (3) through a liquid outlet pipeline. The gas outlet of the decomposition reactor (5) is connected to the gas inlet through a carbon dioxide circulation pipeline (8). The bottom outlet of the hydrocyclone (3) discharges nano-carbonate slurry. The upper outlet of the hydrocyclone (3) is connected to the circulation liquid inlet at the top of the stirred filter reactor (2) through a liquid circulation pipeline. The stirred filter reactor (2) is equipped with a filter cloth (23) and a stirring device. The filter cloth (23) is horizontally arranged to divide the inner cavity of the stirred filter reactor (2) into a reaction zone at the top and a filtration zone at the bottom. The feed inlet, the air inlet, the circulating liquid inlet and the stirring component (21) of the stirring device are all located in the reaction zone, and the output port is located in the filtration zone.

2. The continuous production apparatus for carbonate nano-purification according to claim 1, characterized in that: The air inlet is connected to a carbon dioxide gas source through a carbon dioxide input pipe. The carbon dioxide gas source can adjust the gas flow rate and pressure. The reaction zone is equipped with a first pressure sensor (22). The carbon dioxide circulation pipeline (8) is equipped with a first flow meter (9). The carbon dioxide gas source adjusts the gas flow rate and gas pressure according to the pressure measured by the first pressure sensor (22) and the circulating gas flow rate of the carbon dioxide controlled by the first flow meter (9).

3. The continuous production apparatus for carbonate nano-purification according to claim 2, characterized in that: The reaction zone is also equipped with a first temperature sensor (26) and a pH sensor. The stirred filter reactor (2) is covered with a jacket (24). The filtration zone and the reaction zone are in partial contact with the jacket (24). The inner cavity of the jacket (24) is provided with an inlet and an outlet. The inlet and the outlet are both connected to the interface of the temperature control device through a temperature control circulation pipe. The temperature control circulation pipe is used to transport circulating cooling water.

4. The continuous production apparatus for carbonate nano-purification according to claim 3, characterized in that: The decomposition reactor (5) is equipped with a heating device and a second temperature sensor (51). The continuous production device also includes a heat exchanger (4). The liquid outlet pipeline and the bicarbonate pipeline exchange heat through the heat exchanger (4). The liquid inlet of the decomposition reactor (5) is connected to an inlet pump (7). The inlet pump (7) is used to control the pressure and flow rate of bicarbonate input to the decomposition reactor (5). The decomposition reactor (5) is equipped with a second pressure sensor (52).

5. The continuous production apparatus for carbonate nano-purification according to claim 4, characterized in that: The reaction temperature, carbon dioxide pressure, and pH value of the stirred filter reactor (2) are controlled within the range where bicarbonate is continuously generated by the heat exchange medium in the jacket (24), the inlet pump (7), and the first flow meter (9).

6. The continuous production apparatus for carbonate nano-purification according to claim 1, characterized in that: The opening of the carbonate slurry storage tank (1) is also provided with a solid feeder (11) for inputting crude carbonate and a second flow meter (12) for controlling the water volume. The crude carbonate is quantitatively fed through the solid feeder (11), and the water supply pipe controls the conveying flow through the second flow meter (12).

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