Multistage drying method and drying device for superfine nano calcium

Abstract

The application discloses a kind of superfine nano calcium multistage drying method and drying device thereof, its method includes S1, superfine nano calcium is transported to drying device by conveying belt and is carried out primary drying, wherein the mixed gas of fuel gas and air in combustion chamber is burned after passing through burner, and is heated into drying chamber, convection is formed in drying chamber, and it is guaranteed that drying temperature distribution is uniform in drying chamber;S2, with the conveying of multilayer conveying belt, calcium carbonate falls from the end of last layer conveying belt into vertical drying box, and nano calcium is automatically turned over and shaken in vertical drying box, and secondary drying is carried out;S3, after heating in vertical drying box, nano calcium falls from the outlet of vertical drying box onto the next layer conveying belt and is carried out tertiary drying;S4, repeat steps S2-S3 until the moisture content of nano calcium reaches the requirement, and the bottom conveying belt transports nano calcium out of drying device.The application has the characteristics of saving drying time and improving drying capacity.

Description

Technical Field

[0001] This invention relates to a processing technology for ultrafine nano-calcium, and in particular to a multi-stage drying method and drying apparatus for ultrafine nano-calcium. Background Technology

[0002] Nano-calcium is short for nano-sized calcium carbonate. The common preparation method for nano-calcium carbonate is the carbonation method, with the following steps: Raw material preparation: High-quality limestone is selected as the raw material and pre-treated through crushing, sieving, and other processes to ensure that the particle size and purity of the raw material meet production requirements. Calcination and decomposition: The limestone raw material is fed into a calcination furnace for high-temperature calcination, decomposing it into calcium oxide (quicklime). This step requires strict control of the calcination temperature and time to ensure the purity and activity of the calcium oxide. Digestion and pulping: The calcined calcium oxide is added to water for a digestion reaction to generate a calcium hydroxide (hydrated lime) emulsion. During the digestion process, the amount of water added and the reaction temperature need to be controlled to obtain a stable calcium hydroxide emulsion. Carbonation reaction: Carbon dioxide gas is passed through the calcium hydroxide emulsion to carry out a carbonation reaction, generating calcium carbonate particles. During the carbonation process, by controlling parameters such as reaction temperature, gas flow rate, and stirring speed, and by adding appropriate amounts of crystal form control agents and dispersants, nano-calcium carbonate particles with uniform particle size and good dispersibility can be prepared. Subsequent processing: After filtration, washing, drying and other subsequent processing steps, impurities and moisture are removed to obtain nano calcium carbonate products.

[0003] The drying process for nano-calcium primarily aims to remove moisture to improve its stability and application performance. Existing nano-calcium drying methods typically employ a single-stage drying process, which requires high energy consumption and necessitates maintaining a certain pressure within the drying chamber. Insufficient pressure negatively impacts drying efficiency, leading to product quality issues, low yield, and increased overall costs. Furthermore, current single-stage drying devices are mostly static drying methods, resulting in localized heating of the nano-calcium. This localized agglomeration of nano-calcium can hinder drying, leading to low efficiency and prolonged drying time. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage drying method and apparatus for ultrafine nano-calcium. This invention features reduced drying time and improved drying capacity.

[0005] The technical solution of this invention: a multi-stage drying method for ultrafine nano-calcium, comprising the following steps:

[0006] S1. The ultrafine nano-calcium is conveyed to the drying device via a conveyor belt for primary drying. The gas mixture of combustion gas and air in the combustion chamber is burned by the burner and heated before entering the drying chamber, where convection is formed to ensure uniform temperature distribution.

[0007] S2. As the multi-layer conveyor belts transport the calcium carbonate, it falls from the end of the upper conveyor belt into the vertical drying box. The nano-calcium automatically flips and shakes in the vertical drying box for secondary drying.

[0008] S3. After being heated in the vertical drying oven, the nano-calcium falls from the outlet of the vertical drying oven onto the conveyor belt of the next layer for three-stage drying.

[0009] S4. Repeat steps S2-S3 until the moisture content of the nano-calcium reaches the required level. The bottom conveyor belt will then transport the nano-calcium out of the drying device.

[0010] In the aforementioned multi-stage drying method for ultrafine nano-calcium, in step S2, when the nano-calcium is subjected to secondary drying in a vertical drying oven, the nano-calcium falls into the drying trough. The vertical drying oven itself rotates, and at the same time, the drying trough swings back and forth, turning and filtering the nano-calcium layer by layer. While the drying trough swings, a strong magnet moves closer to the nano-calcium along with the swing direction of the drying trough, adsorbing and removing ferromagnetic impurities from the nano-calcium.

[0011] In the aforementioned multi-stage drying method for ultrafine nano-calcium, the air pressure difference between the inside and outside of the drying chamber inlet is monitored in real time during the drying process. If the air pressure inside the drying chamber inlet is greater than the air pressure outside the drying chamber inlet, the wind speed of the exhaust fan in the drying chamber is increased to adjust the pressure inside the drying chamber, so that the pressure inside the drying chamber is in a negative pressure state.

[0012] In the aforementioned multi-stage drying method for ultrafine nano-calcium, the waste heat and moisture discharged from the drying chamber are exchanged with the fresh air from the outside through a heat exchange device. The cooled waste heat gas is then discharged for purification treatment, and the hot air formed after the fresh air heat exchange is input into the combustion chamber for combustion and utilization.

[0013] A multi-stage drying device for ultrafine nano-calcium includes a drying chamber and a combustion chamber. The combustion chamber is equipped with a burner, a gas pipe, and an air pipe. The outlet of the combustion chamber is connected to the drying chamber. The bottom and top of the drying chamber are equipped with heat equalizing fans that are staggered vertically. The drying chamber is equipped with several layers of conveyor belts. A vertical drying box is installed between the end of the upper conveyor belt and the beginning of the lower conveyor belt. The inlet of the vertical drying box corresponds to the end of the upper conveyor belt, and the outlet of the vertical drying box corresponds to the beginning of the lower conveyor belt. A fixed frame is provided on the inner wall of the drying chamber. The vertical drying box is rotatably connected to the fixed frame by a rotating mechanism. The vertical drying box is equipped with several layers of drying troughs with a grid-like bottom.

[0014] In the aforementioned multi-stage drying device for ultrafine nano-calcium, the vertical drying box includes an outer box, an inner box inside the outer box, an airflow channel between the inner box and the outer box, ventilation holes communicating with the airflow channel on both the outer box and the inner box, and an electric heating tube on the outer wall of the inner box.

[0015] In the aforementioned multi-stage drying device for ultrafine nano-calcium, the rotating mechanism includes a gear ring installed on the periphery of the outer casing, a gear meshing on the gear ring, a drive shaft on the gear, a worm gear coaxially distributed on the drive shaft, a worm meshing on the worm gear, and one end of the worm gear connected to a drive motor.

[0016] In the aforementioned multi-stage drying device for ultrafine nano-calcium, the drying tank is rotatably connected to the inner box via a rotating shaft. A torsion spring is sleeved on the rotating shaft, with one end of the torsion spring connected to the drying tank and the other end connected to the inner box. A swing shaft driven by a swing motor is provided on one side or symmetrical sides below the drying tank. An eccentric wheel is provided on the swing shaft. The eccentric wheel collides with the drying tank under the rotation of the swing shaft, causing the drying tank to swing back and forth.

[0017] In the aforementioned multi-stage drying device for ultrafine nano-calcium, a transverse screw is rotatably connected to the inner box above the drying tank. One end of the transverse screw is connected to a rotating motor, and a movable frame is threaded onto the transverse screw. The movable frame moves laterally as the transverse screw rotates. A drum driven by the movable motor is mounted on the movable frame, and a ring-shaped strong magnet is mounted on the outside of the drum.

[0018] In the aforementioned multi-stage drying device for ultrafine nano-calcium, the drying chamber is equipped with an exhaust pipe, and the exhaust pipe is equipped with a dehumidifying fan. A first pressure sensor is installed inside the inlet of the drying chamber, and a second pressure sensor is installed outside the inlet of the drying chamber. The detection heads of the first and second pressure sensors are on the same horizontal plane. Both the first and second pressure sensors are connected to the dehumidifying fan via a controller.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention involves burning the mixture of fuel gas and air in the combustion chamber, heating it up, and then introducing it into the drying chamber. Through a heat equalization fan with staggered vertical flow, the hot airflow in the drying chamber forms vertical convection, ensuring full contact with the nano-calcium carbonate, thus improving the drying effect on the nano-calcium. This allows the moisture on the surface of the material to evaporate rapidly and ensures uniform temperature distribution within the drying chamber.

[0021] The ultrafine nano-calcium is conveyed through multiple conveyor belts in the drying device. During the conveying process, it first undergoes primary drying, forming a pre-drying process. Then, the nano-calcium falls from the end of the upper conveyor belt into a vertical drying chamber, where it falls onto the layered drying troughs. The vertical drying chamber is driven by a rotating mechanism, which rotates the internal drying troughs, dispersing the nano-calcium for secondary deep drying, improving the drying effect and uniformity. After being heated in the vertical drying chamber, the nano-calcium falls from the outlet of the vertical drying chamber onto the next conveyor belt for tertiary drying. The above steps are repeated until the required moisture content is achieved, improving drying efficiency and uniformity, and saving drying time.

[0022] Therefore, the present invention has the characteristics of improving drying capacity and saving drying time. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the internal structure of a vertical drying oven.

[0025] Figure 3 This is a schematic diagram of the rotating mechanism.

[0026] Figure 4 This is a schematic diagram of the drying tank.

[0027] Figure 5 This is a schematic diagram of a strong magnet.

[0028] Figure 6 yes Figure 1 Enlarged view of the local structure at point A in the middle.

[0029] Figure 7 This is a schematic diagram of the heat exchange device.

[0030] The labels in the attached diagram are as follows: 1. Drying chamber; 11. Conveyor belt; 12. Heat equalizing fan; 2. Combustion chamber; 21. Gas pipe; 22. Air pipe; 3. Vertical drying oven; 31. Fixing frame; 32. Drying trough; 33. Outer casing; 34. Inner casing; 35. Airflow channel; 36. Vent; 37. Electric heating element; 4. Rotating mechanism; 41. Gear ring; 42. Gear; 43. Drive shaft; 44. Worm gear; 45. Worm; 51. Rotating shaft; 52. Torsion spring; 53. Oscillating motor; 54. Oscillating shaft; 55. 61. Eccentric wheel; 62. Transverse screw; 63. Rotating motor; 64. Movable frame; 65. Roller; 7. Strong magnet; 8. Exhaust duct; 71. Dehumidifying fan; 72. First air pressure sensor; 73. Second air pressure sensor; 8. Heat exchange device; 81. Housing; 82. First heat exchange space; 83. Second heat exchange space; 84. First heat exchange tube; 85. Fresh air inlet; 851. Sealing cover; 852. Sleeve brush; 86. Exhaust gas inlet; 87. Hot air outlet; 88. Exhaust gas outlet; 89. Second heat exchange tube. Detailed Implementation

[0031] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0032] Example:

[0033] A multi-stage drying method for ultrafine nano-calcium includes the following steps:

[0034] S1. The ultrafine nano-calcium is conveyed to the drying device via conveyor belt 11 for primary drying. The gas mixture of combustion gas and air in combustion chamber 2 is heated by the burner and enters drying chamber 1, forming convection in drying chamber 1 to ensure uniform drying temperature distribution in drying chamber 1.

[0035] S2. As the multi-layer conveyor belt 11 is conveyed, the nano-calcium is transported from the beginning of the conveyor belt 11 to the end of the conveyor belt 11. The nano-calcium falls from the end of the upper layer of the conveyor belt 11 into the vertical drying box 3. The nano-calcium is automatically turned and shaken in the vertical drying box 3 for secondary drying, so that the nano-calcium is heated more evenly and more fully.

[0036] S3. After being heated in the vertical drying oven 3, the nano-calcium falls from the outlet of the vertical drying oven 3 onto the conveyor belt 11 of the next layer for three-stage drying.

[0037] S4. Repeat steps S2-S3 until the moisture content of the nano-calcium reaches the required level. The bottom conveyor belt 11 will then transport the nano-calcium out of the drying device.

[0038] When nano-calcium undergoes secondary drying in the vertical drying oven 3, the nano-calcium falls into the drying trough 32. The vertical drying oven 3 rotates, and the drying trough 32 swings back and forth, turning and filtering the nano-calcium layer by layer. This ensures that the nano-calcium in the vertical drying oven 3 is heated evenly and fully, guaranteeing that the nano-calcium particles discharged from the bottom outlet of the vertical drying oven 3 meet the requirements. At the same time as the drying trough 32 swings, the strong magnet 65 moves closer to the nano-calcium along with the swing direction of the drying trough 32, adsorbing and removing ferromagnetic impurities from the nano-calcium, thereby improving the quality of the nano-calcium.

[0039] During the drying process, the air pressure difference between the inside and outside of the inlet of drying chamber 1 is monitored in real time. If the air pressure inside the inlet of drying chamber 1 is greater than the air pressure outside the inlet of drying chamber 1, the wind speed of the exhaust fan 71 on the top of drying chamber 1 is increased to adjust the pressure inside drying chamber 1 so that the pressure inside drying chamber 1 is in a negative pressure state, slightly less than the air pressure outside the inlet of drying chamber 1, thereby preventing the hot and humid gas and polluted exhaust gas inside drying chamber 1 from being discharged from the inlet of drying chamber 1 and polluting the working environment.

[0040] The waste heat and moisture discharged from the drying chamber 1 are exchanged with the fresh air from the outside through the heat exchange device 8. The cooled waste heat gas is discharged for purification treatment, and the hot air formed after the fresh air is exchanged is input into the combustion chamber 2 for combustion and utilization, saving natural gas and other fuels and reducing material costs.

[0041] like Figures 1-7 As shown, a multi-stage drying device for ultrafine nano-calcium includes a drying chamber 1 and a combustion chamber 2. The combustion chamber 2 is equipped with a burner, a gas pipe 21, and an air pipe 22. The outlet of the combustion chamber 2 is connected to the drying chamber 1. The bottom and top of the drying chamber 1 are equipped with heat equalizing fans 12 that are staggered vertically. The drying chamber 1 is equipped with several layers of conveyor belts 11. A vertical drying box 3 is provided between the end of the upper layer of conveyor belt 11 and the beginning of the lower layer of conveyor belt 11. The inlet of the vertical drying box 3 corresponds to the end of the upper layer of conveyor belt 11, and the outlet of the vertical drying box 3 corresponds to the beginning of the lower layer of conveyor belt 11. A fixed frame 31 is provided on the inner wall of the drying chamber 1. The vertical drying box 3 is rotatably connected to the fixed frame 31 by a rotating mechanism 4. The vertical drying box 3 is equipped with several layers of drying troughs 32 with a grid-like bottom.

[0042] The gas mixture of combustion gas and air in combustion chamber 2 is heated by the burner and enters drying chamber 1. The hot air in drying chamber 1 is made to form vertical convection by the heat equalizing fan 12 with vertical crossflow, so that it can fully contact the nano-calcium carbonate, improve the drying effect of nano-calcium, make the moisture on the surface of the material evaporate rapidly, and ensure that the drying temperature distribution in drying chamber 1 is uniform.

[0043] The ultrafine nano-calcium is conveyed through multiple conveyor belts 11 in the drying device. During the conveying process, it first undergoes primary drying to form a pre-drying process. Then, the nano-calcium falls from the end of the upper conveyor belt 11 into the vertical drying chamber 3, where it falls onto the layered drying troughs 32. The vertical drying chamber 3 is driven by the rotating mechanism 4 to rotate, which in turn drives the internal drying troughs 32 to rotate, dispersing the nano-calcium and performing secondary deep drying, thereby improving the drying effect and uniformity of the nano-calcium. After being heated in the vertical drying chamber 3, the nano-calcium falls from the outlet of the vertical drying chamber 3 onto the next layer of conveyor belt 11 for tertiary drying. The above steps are repeated until the required moisture content is achieved, improving drying efficiency and uniformity, and saving drying time.

[0044] The vertical drying oven 3 includes an outer casing 33, within which an inner casing 34 is located. An airflow channel 35 is formed between the inner casing 34 and the outer casing 33. Both the outer casing 33 and the inner casing 34 are provided with vents 36 that communicate with the airflow channel 35. An electric heating element 37 is also provided on the outer wall of the inner casing 34. The vertical drying oven 3 allows hot airflow from the drying chamber 1 to flow into the inner casing 34 through the airflow channel 35 via the vents 36. The hot airflow undergoes further temperature control within the airflow channel 35 via the electric heating element 37, facilitating the secondary drying of the nano-calcium within the vertical drying oven 3.

[0045] The rotating mechanism 4 includes a gear ring 41 mounted on the periphery of the outer casing 33. A gear 42 meshes with the gear ring 41, and a drive shaft 43 is mounted on the gear 42. A worm gear 44, coaxially distributed with the gear 42, is mounted on the drive shaft 43. A worm 45 meshes with the worm gear 44, and one end of the worm 45 is connected to a drive motor and rotates. The drive motor drives the worm 45 to rotate, which in turn drives the worm gear 44 to rotate. The worm gear 44, through the drive shaft 43, drives the gear 42 to rotate, thereby causing the gear ring 41 and the outer casing 33 to rotate. This allows the nano-calcium inside the vertical drying oven 3 to undergo rotational drying, resulting in more thorough and uniform drying.

[0046] The drying tank 32 is rotatably connected to the inner chamber 34 via a rotating shaft 51. A torsion spring 52 is fitted on the rotating shaft 51, with one end of the torsion spring 52 connected to the drying tank 32 and the other end connected to the inner chamber 34. A swing shaft 54, driven by a swing motor 53, is located on one or both sides below the drying tank 32. An eccentric wheel 55 is mounted on the swing shaft 54. The eccentric wheel 55, driven by the rotation of the swing shaft 54, collides with the drying tank 32, causing it to swing back and forth. The swing motor 53 drives the swing shaft 54 ​​to rotate, which in turn drives the eccentric wheel 55 to rotate. During rotation, the eccentric wheel 55 impacts the drying tank 32, causing it to rotate and automatically reset under the influence of the torsion spring 52. Therefore, the combination of the eccentric wheel 55 and the torsion spring 52 causes the drying tank 32 to swing back and forth, causing the internal nano-calcium to tumble, reducing agglomeration, adjusting the heating surface of the nano-calcium, and improving heating efficiency.

[0047] Above the drying tank 32 is a transverse screw 61 rotatably connected to the inner chamber 34. One end of the transverse screw 61 is connected to a rotary motor 62. A movable frame 63 is threaded onto the transverse screw 61. The movable frame 63 moves laterally as the transverse screw 61 rotates. A roller 64, driven by the movable motor, is mounted on the movable frame 63. An annular strong magnet 65 is mounted on the outside of the roller 64. The rotary motor 62 drives the transverse screw 61 to rotate, and the movable frame 63 moves back and forth along the transverse screw 61 under the action of the forward and reverse rotation of the transverse screw 61, matching the oscillation of the drying tank 32. This causes the roller 64 to approach the nano-calcium, and the strong magnet 65 is used to adsorb and remove ferromagnetic impurities.

[0048] The drying chamber 1 is equipped with an exhaust duct 7, and a dehumidifying fan 71 is mounted on the exhaust duct 7. A first pressure sensor 72 is located inside the inlet of the drying chamber 1, and a second pressure sensor 73 is located outside the inlet of the drying chamber 1. The detection heads of the first pressure sensor 72 and the second pressure sensor 73 are on the same horizontal plane. Both the first pressure sensor 72 and the second pressure sensor 73 are connected to the dehumidifying fan 71 via a controller. The first pressure sensor 72 and the second pressure sensor 73 are used to detect the air pressure inside and outside the inlet of the drying chamber 1, respectively. By detecting the pressure difference between the inside and outside of the inlet, if the air pressure inside the inlet of the drying chamber 1 is not less than the air pressure outside the inlet, the dehumidifying fan 71 is activated to adjust the pressure inside the drying chamber 1, so that a slightly negative pressure is formed inside the drying chamber 1, preventing the gas inside the drying chamber 1 from escaping from the inlet and improving the cleanliness and dryness of the external environment of the drying chamber 1.

[0049] The exhaust duct 7 is connected to a heat exchange device 8, and the hot air outlet 87 of the heat exchange device 8 is connected to the combustion chamber 2. After the fresh air is heated by the heat exchange device 8, the discharged hot air is connected to the combustion chamber 2 through the hot air outlet 87, thus supplying heated air to the combustion chamber 2, thereby saving dye and reducing costs.

[0050] The heat exchange device 8 includes a housing 81. The internal space of the housing 81 is divided into a first heat exchange space 82 and a second heat exchange space 83 by a partition plate. The first heat exchange space 82 is provided with a plurality of first heat exchange tubes 84. The wall of the first heat exchange space 82 is provided with a fresh air inlet 85 and an exhaust gas inlet 86. The fresh air inlet 85 is provided with a sealing cover 851 connected to the first heat exchange tubes 84 and a sleeve brush 852 wrapped around the outside of the first heat exchange tubes 84. One end of the first heat exchange tube 84 is connected to the fresh air inlet 85, and the other end of the first heat exchange tube 84 is connected to the second heat exchange space 83. The wall of the second heat exchange space 83 is provided with a hot air outlet 87 and an exhaust gas outlet 88. The second heat exchange space 83 is provided with a second heat exchange tube 89, which is staggered with the first heat exchange tubes 84. One end of the second heat exchange tube 89 is connected to the first heat exchange space 82, and the other end of the second heat exchange tube 89 is connected to the exhaust gas outlet 88.

[0051] In the heat exchange device 8, the waste heat and moisture first enter the first heat exchange space 82, and the outside fresh air enters the first heat exchange tube 84 to carry out primary heat exchange with the waste heat and moisture. Particulate pollutants in the waste gas easily adhere to the outside of the first heat exchange tube 84 and are cleaned. Then, the heat-exchanged fresh air enters the second heat exchange space 83, and the waste gas enters the second heat exchange tube 89 to carry out secondary heat exchange, which improves heat exchange efficiency and reduces dust accumulation in the second heat exchange tube 89.

[0052] The outer wall of the first heat exchange tube 84 is rough, making it easier for pollutants in the waste heat gas to adhere to it. Conversely, the inner wall of the second heat exchange tube 89 is smooth, making it less likely for pollutants to adhere to it. The first heat exchange tube 84 is connected to the sealing cap 851 for easy removal and cleaning. During removal, the first heat exchange tube 84 moves within the sleeve brush 852, allowing the brush to clean its outer wall and improving cleaning convenience.

[0053] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A multi-stage drying device for ultrafine nano-calcium, characterized in that: The equipment includes a drying chamber (1) and a combustion chamber (2). The combustion chamber (2) is equipped with a burner, a gas pipe (21) and an air pipe (22). The outlet of the combustion chamber (2) is connected to the drying chamber (1). The bottom and top of the drying chamber (1) are equipped with heat equalization fans (12) that are staggered vertically. The drying chamber (1) is equipped with several layers of conveyor belts (11). A vertical drying box (3) is provided between the end of the upper layer of conveyor belt (11) and the beginning of the lower layer of conveyor belt (11). The inlet of the vertical drying box (3) corresponds to the end of the upper layer of conveyor belt (11), and the outlet of the vertical drying box (3) corresponds to the beginning of the lower layer of conveyor belt (11). A fixed frame (31) is provided on the inner wall of the drying chamber (1). The vertical drying box (3) is rotatably connected to the fixed frame (31) by a rotating mechanism (4). The vertical drying box (3) is equipped with several layers of drying troughs (32) with a grid-like bottom. The vertical drying oven (3) includes an outer box (33), an inner box (34) is provided inside the outer box (33), an airflow channel (35) is formed between the inner box (34) and the outer box (33), and ventilation holes (36) communicating with the airflow channel (35) are provided on both the outer box (33) and the inner box (34). An electric heating tube (37) is also provided on the outer wall of the inner box (34). The rotating mechanism (4) includes a gear ring (41) installed around the outer casing (33), a gear (42) meshing on the gear ring (41), a drive shaft (43) on the gear (42), a worm gear (44) coaxially distributed on the drive shaft (43), a worm (45) meshing on the worm gear (44), and one end of the worm (45) connected to a drive motor; the drying tank (32) is rotatably connected to the inner casing (34) via a rotating shaft (51). (51) A torsion spring (52) is fitted on the top. One end of the torsion spring (52) is connected to the drying trough (32), and the other end of the torsion spring (52) is connected to the inner box (34). A swing shaft (54) driven by a swing motor (53) is provided on one side or symmetrical sides below the drying trough (32). An eccentric wheel (55) is provided on the swing shaft (54). The eccentric wheel (55) collides with the drying trough (32) under the rotation of the swing shaft (54), causing the drying trough (32) to swing back and forth. Above the drying tank (32) is a transverse screw (61) rotatably connected to the inner box (34). One end of the transverse screw (61) is connected to a rotating motor (62). A movable frame (63) is threaded onto the transverse screw (61). The movable frame (63) moves laterally as the transverse screw (61) rotates. A roller (64) driven by the movable motor is provided on the movable frame (63). A ring-shaped strong magnet (65) is provided on the outside of the roller (64).

2. The multi-stage drying device for ultrafine nano-calcium according to claim 1, characterized in that: The drying chamber (1) is equipped with an exhaust pipe (7), and an exhaust fan (71) is installed on the exhaust pipe (7). A first pressure sensor (72) is installed inside the inlet of the drying chamber (1), and a second pressure sensor (73) is installed outside the inlet of the drying chamber (1). The detection heads of the first pressure sensor (72) and the second pressure sensor (73) are on the same horizontal plane. The first pressure sensor (72) and the second pressure sensor (73) are both connected to the exhaust fan (71) via a controller.

3. A multi-stage drying method for ultrafine nano-calcium, employing the multi-stage drying device for ultrafine nano-calcium as described in any one of claims 1-2, characterized in that: Includes the following steps: S1. The ultrafine nano-calcium is conveyed to the drying device via conveyor belt (11) for primary drying. The gas mixture in the combustion chamber (2) is heated by the burner and enters the drying chamber (1) to form convection in the drying chamber (1) to ensure uniform drying temperature distribution in the drying chamber (1). S2. As the multi-layer conveyor belt (11) is conveyed, calcium carbonate falls from the end of the upper layer of the conveyor belt (11) into the vertical drying box (3). The nano-calcium automatically flips and shakes in the vertical drying box (3) for secondary drying. S3. After being heated in the vertical drying oven (3), the nano-calcium falls from the outlet of the vertical drying oven (3) onto the conveyor belt (11) of the next layer for three-stage drying. S4. Repeat steps S2-S3 until the moisture content of the nano-calcium reaches the required level. The bottom conveyor belt (11) will then transport the nano-calcium out of the drying device.

4. The multi-stage drying method for ultrafine nano-calcium according to claim 3, characterized in that: In step S2, when the nano-calcium is subjected to secondary drying in the vertical drying oven (3), the nano-calcium falls into the drying tank (32), the vertical drying oven (3) rotates itself, and the drying tank (32) swings back and forth, turning and filtering the nano-calcium layer by layer; and while the drying tank (32) swings, the strong magnet (65) moves closer to the nano-calcium with the swing direction of the drying tank (32), adsorbing and removing ferromagnetic impurities in the nano-calcium.

5. The multi-stage drying method for ultrafine nano-calcium according to claim 3, characterized in that: During the drying process, the air pressure difference between the inside and outside of the inlet of the drying chamber (1) is detected in real time. If the air pressure inside the inlet of the drying chamber (1) is greater than the air pressure outside the inlet of the drying chamber (1), the wind speed of the exhaust fan (71) on the drying chamber (1) is increased, and the pressure inside the drying chamber (1) is adjusted so that the pressure inside the drying chamber (1) is in a negative pressure state.

6. The multi-stage drying method for ultrafine nano-calcium according to claim 3, characterized in that: The waste heat and moisture discharged from the drying chamber (1) are exchanged with the fresh air from the outside through the heat exchange device (8). The cooled waste heat gas is discharged for purification treatment, and the hot air formed after the fresh air is exchanged is input into the combustion chamber (2) for combustion and utilization.

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