Old asphalt mixture aggregate separation and recovery device and method

Abstract

The invention relates to the technical field of asphalt aggregate separation and recovery equipment, and discloses an old asphalt mixture aggregate separation and recovery device and method.The device comprises a first-stage separation mechanism, the first-stage separation mechanism comprises a fixed cylinder and separation cylinders, the fixed cylinder is fixedly installed on a base, the separation cylinders are coaxially arranged in the fixed cylinder at intervals, and the second-stage separation mechanism comprises a second-stage separation mechanism; and the secondary separation mechanism comprises a reaction kettle. The primary separation mechanism and the secondary separation mechanism are arranged to sequentially carry out primary separation treatment and secondary separation treatment on the old asphalt mixture, asphalt can be separated from aggregate through the centrifugal effect of rotation of a separation barrel of the primary separation mechanism, and the old asphalt mixture can be fully heated; asphalt remaining on the aggregate subjected to primary separation treatment can be dissolved and collected through supercritical carbon dioxide, effective separation of the asphalt and the aggregate can be achieved, the separated aggregate is few in asphalt residue and high in quality, and the recovery rate of the asphalt and the aggregate is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of asphalt aggregate separation and recovery equipment. Specifically, it relates to an old asphalt mixture aggregate separation and recovery device and method. Background Art

[0002] Asphalt mixture is the general term for the mixture formed by mixing mineral materials and asphalt binder, mainly composed of asphalt, coarse aggregate, fine aggregate, and mineral powder. In order to promote the recycling of old asphalt pavement aggregates to reduce the loss of mineral resources, when the asphalt pavement is damaged, reaches the service life, or undergoes secondary road construction, it is necessary to mill or dig up the old asphalt mixture for aggregate separation, and the separated recycled aggregate is reused for the maintenance or paving construction of municipal roads.

[0003] The separation of asphalt and aggregate requires heating the old asphalt mixture to soften the asphalt, so as to separate the asphalt from the aggregate. For example, an asphalt pavement aggregate separation and regeneration device and method disclosed in Chinese Patent No. CN111236006B includes a feed inlet, a crushing and separation mechanism, an aggregate cleaning tank, and an aggregate tank. The crushing and separation mechanism includes an inner and outer cylinder. By setting a microwave heating device in the outer cylinder and a multi-stage screening disk and stirring and crushing blades in the inner cylinder, the rotation of the inner cylinder driven by a motor is used to complete the crushing and aggregate separation of the old asphalt mixture; and an asphalt aggregate regeneration device and method based on microwave technology disclosed in Chinese Patent No. CN111364319B includes a box body and a filter screen. A rotating shaft and a multi-stage aggregate screen are arranged in the filter screen, so as to screen and separate the aggregate from the old asphalt mixture by the cooperation of the action of a microwave oven and driving the box body to vibrate left and right.

[0004] For the existing asphalt aggregate separation devices such as the above patents, the screening and aggregate separation of the old asphalt mixture are realized by driving the filter cylinder body equipped with multi-stage screening components to rotate. However, this will cause the situation that the aggregate enters the next-stage screening component or leaves the filter cylinder body before the asphalt is completely peeled off. The heating time of the old asphalt mixture in the filter cylinder is limited, so that the old asphalt mixture is not fully heated, and there are problems such as incomplete separation of aggregate and asphalt, much asphalt residue, and poor aggregate quality in the aggregate separation operation. Summary of the Invention

[0005] To solve or partially solve the problems existing in the related technologies, the present application provides an old asphalt mixture aggregate separation and recovery device and method, which can effectively separate asphalt and aggregate, with less asphalt residue in the separated aggregate, high aggregate quality, and high recovery rates of asphalt and aggregate.

[0006] In the first aspect of the present application, an old asphalt mixture aggregate separation and recovery device is provided, including:

[0007] The primary separation mechanism, the primary separation mechanism includes a fixed cylinder and a separation cylinder. The fixed cylinder is fixedly installed on the base. The separation cylinder is coaxially and spacedly arranged inside the fixed cylinder. The side wall of the separation cylinder extends downward beyond the bottom wall to form an installation cavity. An actuating mechanism for driving the separation cylinder to rotate relative to the fixed cylinder is arranged in the installation cavity. A microwave heating device is arranged at the top inside the fixed cylinder corresponding to the separation cylinder. Filter holes are formed on the side wall of the separation cylinder. A collection trough is inclined downwardly installed between the outer wall of the bottom of the separation cylinder and the inner wall of the fixed cylinder. The lower side of the collection trough is connected with a guide trough extending outside the fixed cylinder, and the collection trough just does not contact the outer wall of the separation cylinder. A discharge pipe is fixedly installed on the bottom wall of the separation cylinder, and a discharge valve is installed on the discharge pipe;

[0008] The secondary separation mechanism, the secondary separation mechanism is used to dissolve the residual asphalt adhering to the aggregate after being treated by the primary separation mechanism through supercritical carbon dioxide. The secondary separation mechanism includes a reaction kettle. A feed pipe corresponding to and not contacting the discharge pipe is communicated with the feed port of the reaction kettle. Each time the actuating mechanism stops, the discharge pipe is located at the position corresponding to the feed pipe. A feed valve is installed on the feed pipe.

[0009] In an alternative embodiment, the fixed cylinder includes a cylinder body and a cover plate detachably and fixedly installed on the top of the cylinder body. A feed hopper is fixedly installed on the cover plate. The lower end of the feed hopper extends into the separation cylinder and does not contact the separation cylinder;

[0010] A stirrer is arranged inside the separation cylinder. The stirrer is drivenly connected with a stirring motor. The stirring motor is fixedly installed on the top of the cover plate. The microwave heating device is arranged at the bottom of the cover plate.

[0011] In an alternative embodiment, the actuating mechanism includes a separation motor and a driving gear drivingly connected with the separation motor. A gear ring coaxial with the separation cylinder is fixedly arranged on the outer bottom wall of the separation cylinder. The driving gear is coaxially arranged inside the gear ring. Three driven gears meshing with both the driving gear and the gear ring are arranged in an array on the outer circumference of the driving gear. An opening is formed at the bottom of the cylinder body. A support plate is detachably and fixedly installed at the opening. The separation motor is installed on the support plate.

[0012] In an alternative embodiment, rolling rings are fixedly arranged on the outer side walls at both ends of the separation cylinder. A plurality of rollers are installed in an array on the inner wall of the cylinder body corresponding to the rolling rings in the circumferential direction;

[0013] The bottom wall of the cylinder body is recessed downward corresponding to the extended part of the side wall of the separation cylinder to form a chute. The bottom end of the side wall of the separation cylinder is arranged in the chute, and a low-friction gasket is arranged between the bottom of the chute and the bottom end of the side wall of the separation cylinder.

[0014] In an alternative solution, an intake system and an exhaust system for supplying and discharging carbon dioxide are connected to the reaction kettle. At least one layer of metal filter screen is installed inside the reaction kettle at an interval from the bottom wall of the reaction kettle. An asphalt discharge pipe and an aggregate discharge pipe are installed on the bottom wall of the reaction kettle, and the upper end of the aggregate discharge pipe extends upward to a position slightly higher than the bottom of the metal filter screen. An asphalt discharge valve is installed on the asphalt discharge pipe, and an aggregate discharge valve is installed on the aggregate discharge pipe.

[0015] In an alternative solution, the intake system includes a gas storage tank, a liquid storage tank, a pressure pump, and a booster pump. The gas storage tank and the liquid storage tank are respectively connected to the reaction kettle through the booster pump and the pressure pump. An intake valve is connected between the booster pump and the reaction kettle, and a liquid inlet valve is connected between the pressure pump and the reaction kettle;

[0016] The exhaust system includes an exhaust pipe, a gas-liquid separator, and a compressor. The exhaust pipe is connected to the reaction kettle, and an exhaust valve is connected to the exhaust pipe. The gas-liquid separator is connected to the exhaust pipe at a position between the exhaust valve and the reaction kettle. A pressure relief valve is connected between the intake port of the gas-liquid separator and the exhaust pipe. The outlet of the gas-liquid separator is connected to the intake port of the compressor, and the compressor is connected to the liquid storage tank.

[0017] In an alternative solution, it further includes an aggregate conveying mechanism and a screening mechanism. The aggregate conveying mechanism is arranged between the lower part of the aggregate discharge pipe of the reaction kettle and the screening mechanism, and the aggregate conveying mechanism is used to convey the separated aggregates into the screening mechanism;

[0018] The screening mechanism includes a chassis, a material guiding groove, and a first-stage vibrating screen, a second-stage vibrating screen, and a third-stage vibrating screen with gradually increasing mesh diameters. The first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen are successively installed in the chassis in a head-to-tail corresponding and inclined downward manner. The discharging end of the aggregate conveying mechanism extends into the chassis above the first-stage vibrating screen, and a material guiding groove is inclined downward and installed below the first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen respectively. The discharging ends of each material guiding groove pass through the side wall of the chassis and extend outside the chassis.

[0019] In an alternative solution, a drying fan is respectively installed on the side wall of the chassis at the position between the first-stage vibrating screen, the second-stage vibrating screen, the third-stage vibrating screen and their corresponding material guiding grooves, and the air outlet of each drying fan is horizontally oriented towards the direction where the aggregates roll on each vibrating screen.

[0020] The second aspect of the present application provides an old asphalt mixture aggregate separation and recovery method. Using the aforementioned old asphalt mixture aggregate separation and recovery device, the old asphalt mixture aggregate separation and recovery method at least includes the following steps:

[0021] S1: Preparation: After crushing the recycled old asphalt mixture obtained by milling or digging, put it into the fixed cylinder through the feed hopper;

[0022] S2: Stirring and heating: Start the stirring motor to drive the stirrer to stir the old asphalt mixture in the separation cylinder, and start the microwave heating device to perform microwave heating on the old asphalt mixture in the separation cylinder during the stirring process until the asphalt melts into a fluid state;

[0023] S3: Preliminary separation of asphalt: Continuously stir and heat, start the driving mechanism to drive the separation cylinder to rotate at a high speed, and during the stirring and heating process, the melted asphalt is thrown out of the separation cylinder through the filter holes by the centrifugal force of the rotation of the separation cylinder. The thrown asphalt droplets drip along the inner wall of the fixed cylinder into the collection tank, are collected through the collection tank, and then discharged from the fixed cylinder through the guide groove;

[0024] S4: Transfer the old asphalt mixture: Transfer the old asphalt mixture after the preliminary separation of asphalt in step S3 into the reaction kettle through the discharge pipe and the feed pipe;

[0025] S5: Secondary separation of asphalt: Blow pure carbon dioxide into the reaction kettle through the gas storage tank to discharge the air in the reaction kettle, then inject liquid carbon dioxide into the reaction kettle through the liquid storage tank and the compressor. Subsequently, raise the temperature and pressure of the reaction kettle to make the carbon dioxide in the reaction kettle in a supercritical state. Start the stirring mechanism on the reaction kettle to stir the old asphalt mixture, and dissolve the asphalt remaining attached to the aggregate after being treated in step S3 through supercritical carbon dioxide under the state of heat preservation and pressure maintenance;

[0026] S6: Carbon dioxide recovery and asphalt precipitation: Adjust the stirring mechanism on the reaction kettle to stir at a low speed. Under the state of heat preservation, reduce the pressure of the reaction kettle to gradually change the carbon dioxide from the supercritical state to the gaseous state, so that the asphalt dissolved in the supercritical carbon dioxide precipitates to form droplets. During the pressure reduction process, the asphalt droplets pass through the metal filter screen and gather at the bottom of the reaction kettle. The tiny asphalt droplets that are not precipitated in time are discharged to the gas-liquid separator together with the supercritical carbon dioxide or carbon dioxide gas through the exhaust pipe. The asphalt dissolved in the carbon dioxide is separated and collected through the gas-liquid separator, and the carbon dioxide gas purified by the gas-liquid separator is compressed into liquid carbon dioxide by the compressor and then discharged into the liquid storage tank for storage;

[0027] S7: Aggregate screening and drying: Under the state of heat preservation, discharge the asphalt in the reaction kettle, and then reduce the temperature and pressure of the reaction kettle to normal temperature and pressure. Start the aggregate conveying mechanism, and gradually discharge the aggregate to the feeding end of the aggregate conveying mechanism. The aggregate is conveyed to the feeding end of the first-stage vibrating screen of the screening mechanism through the aggregate conveying mechanism. At the same time, start the drying fan. The aggregate passes through the first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen in turn and is screened into three particle size grades during the drying process and discharged from the machine box through the corresponding guide grooves.

[0028] In an alternative solution, in step S2, the heating time of the microwave heating device for the old asphalt mixture is 10 - 20 min;

[0029] In step S5, at least just enough liquid carbon dioxide is injected into the reaction kettle to completely submerge the old asphalt mixture. During the process of dissolving the asphalt, the temperature in the reaction kettle is 110 - 130 °C, the pressure is 15 - 25 MPa, and the stirring and dissolving time is 5 - 15 min;

[0030] In step S6, the rotation speed of the stirring mechanism on the reaction kettle is reduced to 5 - 15 rpm, the temperature in the reaction kettle is maintained at 80 - 100 °C, the pressure in the reaction kettle is gradually reduced to 4 - 6 MPa, and the pressure reduction rate is 1 - 3 MPa / min. If the asphalt viscosity is high, heating coils are set in the gas-liquid separator, and the internal temperature of the gas-liquid separator is maintained at 50 - 70 °C.

[0031] Advantages of this application:

[0032] In this application, by setting a primary separation mechanism and a secondary separation mechanism to perform primary separation treatment and secondary separation treatment on the old asphalt mixture in sequence, the asphalt can be separated from the aggregate by the centrifugal force generated by the rotation of the separation cylinder of the primary separation mechanism, and the old asphalt mixture in the separation cylinder can be heated by the microwave heating device until the asphalt is thrown out, so that the old asphalt mixture can be fully heated. The secondary separation mechanism can dissolve and collect the asphalt remaining on the aggregate after the primary separation treatment by supercritical carbon dioxide, so that the remaining asphalt can be further separated from the aggregate, thereby realizing the effective separation of asphalt and aggregate. The separated aggregate has less asphalt residue and high aggregate quality, with high recovery rates of asphalt and aggregate, effectively reducing the loss of mineral resources, being energy-saving and environmentally friendly, and having high economic benefits.

[0033] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this application. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0035] Figure 1 is the overall structural schematic diagram in an embodiment of this application;

[0036] Figure 2 is the installation schematic diagram of the driving mechanism of the primary separation mechanism in an embodiment of this application;

[0037] Figure 3 is the structural and connection schematic diagram of the secondary separation mechanism in an embodiment of this application;

[0038] Figure 4It is a schematic structural and installation diagram of an aggregate conveying mechanism and a screening mechanism in an embodiment of the present application;

[0039] Figure 5 It is a process flow diagram of an old asphalt mixture aggregate separation and recovery method in an embodiment of the present application.

[0040] Reference numerals in the figure: 1 - primary separation mechanism, 11 - fixed cylinder, 111 - cylinder body, 1111 - opening, 1112 - chute, 112 - cover plate, 113 - hopper, 114 - support plate, 115 - roller, 116 - low-friction gasket, 12 - separation cylinder, 121 - installation cavity, 122 - filter hole, 123 - rolling ring, 13 - base, 14 - driving mechanism, 141 - separation motor, 142 - driving gear, 143 - gear ring, 144 - driven gear, 15 - microwave heating device, 16 - collection tank, 161 - guide groove, 17 - discharge pipe, 18 - discharge valve, 19 - stirrer, 110 - stirring motor;

[0041] 2 - secondary separation mechanism, 21 - reaction kettle, 22 - intake system, 221 - gas storage tank, 222 - liquid storage tank, 223 - booster pump, 224 - pressure pump, 225 - intake valve, 226 - liquid inlet valve, 23 - exhaust system, 231 - exhaust pipe, 232 - gas-liquid separator, 233 - compressor, 234 - exhaust valve, 235 - pressure relief valve, 24 - metal filter screen, 25 - asphalt discharge pipe, 26 - aggregate discharge pipe, 27 - asphalt discharge valve, 28 - aggregate discharge valve;

[0042] 3 - feed pipe, 31 - feed valve; 4 - aggregate conveying mechanism; 5 - screening mechanism, 51 - chassis, 52 - guide chute, 53 - primary vibrating screen, 54 - secondary vibrating screen, 55 - tertiary vibrating screen, 56 - drying fan. Detailed implementation manners

[0043] The following combines the accompanying drawings and embodiments to further describe in detail the specific implementation manners of the present application. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application. Similarly, the following embodiments are only some embodiments of the present application rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0045] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection, or communication with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0047] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0048] In the asphalt aggregate separation and recovery device in the prior art, since the heating time of the old asphalt mixture by microwave is limited, the old asphalt mixture is not heated sufficiently, resulting in problems such as incomplete separation of aggregate and asphalt, a large amount of asphalt residue, and poor aggregate quality.

[0049] In view of the above problems, the present application makes improvements and innovations and proposes the following embodiments.

[0050] In one embodiment, please refer to Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 , in the first aspect of the present application, an old asphalt mixture aggregate separation and recovery device is provided, including a primary separation mechanism 1. The primary separation mechanism 1 includes a fixed cylinder 11 and a separation cylinder 12. The fixed cylinder 11 is fixedly installed on a base 13. The separation cylinder 12 is coaxially and spacedly arranged inside the fixed cylinder 11. The side wall of the separation cylinder 12 extends downward beyond the bottom wall to form an installation cavity 121. A driving mechanism 14 for driving the separation cylinder 12 to rotate relative to the fixed cylinder 11 is arranged in the installation cavity 121. A microwave heating device 15 is arranged at the top inside the fixed cylinder 11 corresponding to the separation cylinder 12. Filter holes 122 are formed on the side wall of the separation cylinder 12. Specifically, the aperture of the filter holes 122 is smaller than the particle size of the smallest particle size aggregate. A collection trough 16 is inclined downwardly installed between the outer wall of the bottom of the separation cylinder 12 and the inner wall of the fixed cylinder 11. The lower side of the collection trough 16 is connected with a guide trough 161 extending outside the fixed cylinder 11, and the collection trough 16 just does not contact the outer wall of the separation cylinder 12. A discharge pipe 17 is fixedly installed on the bottom wall of the separation cylinder 12, and a discharge valve 18 is installed on the discharge pipe 17.

[0051] In this way, the old asphalt mixture to be processed is broken and put into the separation cylinder 12. The old asphalt mixture can be fully heated by the microwave heating device 15, so that the asphalt in the old asphalt mixture melts sufficiently in the separation cylinder 12. The driving mechanism 14 can drive the separation cylinder 12 to rotate at a high speed relative to the fixed cylinder 11, so that the melted asphalt is thrown out of the separation cylinder 12 from the filtering holes 122 under the centrifugal action of the rotation of the separation cylinder 12. The thrown asphalt droplets are blocked by the fixed cylinder 11 and drip along the inner wall of the fixed cylinder 11 into the collection tank 16. Then, after being collected by the collection tank 16, it can be discharged from the fixed cylinder 11 through the guide groove 161. After the asphalt is thrown out, the discharge valve 18 is opened to discharge the old asphalt mixture in the separation cylinder 12 through the discharge pipe 17, thus completing a preliminary separation of the aggregate and asphalt of the old asphalt mixture. Through the centrifugal action of the rotation of the separation cylinder 12, the asphalt is separated from the aggregate, and the old asphalt mixture in the separation cylinder 12 can be heated by the microwave heating device 15 until the asphalt is thrown out, so that the old asphalt mixture can be fully heated, thereby effectively separating the asphalt from the aggregate, with high separation efficiency, good separation effect, less asphalt residue in the separated aggregate, high aggregate quality, high recovery rates of asphalt and aggregate, effectively reducing the loss of mineral resources, energy-saving and environmental protection, and high economic benefits.

[0052] Among them, the driving mechanism 14 includes a separation motor 141 and a driving gear 142 drivingly connected to the separation motor 141. A gear ring 143 coaxial with the separation cylinder 12 is fixedly arranged on the outer bottom wall of the separation cylinder 12. The driving gear 142 is coaxially arranged inside the gear ring 143. Three driven gears 144 meshing with both the driving gear 142 and the gear ring 143 are arranged in an array on the outer circumference of the driving gear 142. In this way, by driving the driving gear 142 to rotate through the separation motor 141, the driving gear 142 drives the three driven gears 144 to rotate, and the three driven gears 144 drive the gear ring 143 to rotate, thereby realizing driving the separation cylinder 12 to rotate at a high speed relative to the fixed cylinder 11. The fixed cylinder 11 includes a cylinder body 111 and a cover plate 112 detachably and fixedly installed on the top of the cylinder body 111. An opening 1111 is formed at the bottom of the cylinder body 111 of the fixed cylinder 11. A support plate 114 is detachably and fixedly installed at the opening 1111. The separation motor 141 is installed on the support plate 114, so that the installation and subsequent maintenance of the driving mechanism 14 can be facilitated through the opening 1111 formed at the bottom of the cylinder body 111.

[0053] The old asphalt mixture aggregate separation and recovery device further includes a secondary separation mechanism 2. The secondary separation mechanism 2 is used to dissolve the asphalt remaining and adhering to the aggregate after being processed by the primary separation mechanism 1 through supercritical carbon dioxide. Among them, the secondary separation mechanism 2 includes a reaction kettle 21. A feed pipe 3 corresponding to and not in contact with the discharge pipe 17 is connected to the feed inlet of the reaction kettle 21, so as to avoid the interference of the discharge pipe 17 on the rotation of the separation cylinder 12. Specifically, the diameter of the feed pipe 3 is larger than that of the discharge pipe 17, so that the old asphalt mixture in the separation cylinder 12 can smoothly enter the feed pipe 3 after being discharged from the discharge pipe 17, avoiding material spillage. Each time the driving mechanism 14 stops, the discharge pipe 17 is located at a position corresponding to the feed pipe 3. A feed valve 31 is installed on the feed pipe 3. The separation motor 141 in the driving mechanism 14 uses a servo motor, so as to control that each time the separation cylinder 12 stops rotating, the discharge pipe 17 is located at a position corresponding to the feed pipe 3 through the separation motor 141, so as to achieve the "point-to-point" precise stop rotation between the discharge pipe 17 and the feed pipe 3, ensuring that the discharge valve 18 and the feed valve 31 can be accurately opened to discharge and transfer the old asphalt mixture after the initial separation is completed.

[0054] In this way, by arranging the secondary separation mechanism 2 downstream of the primary separation mechanism 1, after the old asphalt mixture is initially separated by the primary separation mechanism 1, the secondary separation mechanism 2 can dissolve and collect the asphalt remaining and adhering to the aggregate through supercritical carbon dioxide. The dissolution and separation efficiency is high and the separation effect is good, so that the remaining asphalt can be further separated from the aggregate, and further reduce the asphalt residue on the aggregate and improve the aggregate quality.

[0055] In some embodiments, the fixed cylinder 11 includes a cylinder body 111 and a cover plate 112 detachably and fixedly installed on the top of the cylinder body 111, so as to facilitate hoisting the separation cylinder 12 from the upper end opening of the cylinder body 111 after removing the cover plate 112, thus facilitating the installation and maintenance of the separation cylinder 12; a feed hopper 113 is fixedly installed on the cover plate 112, and the lower end of the feed hopper 113 extends into the separation cylinder 12 and does not contact the separation cylinder 12, so as to facilitate feeding the old asphalt mixture to be processed into the separation cylinder 12 through the feed hopper 113, and at the same time avoid the interference of the feed hopper 113 on the rotation of the separation cylinder 12; a stirrer 19 is arranged in the separation cylinder 12, the stirrer 19 is drivenly connected to a stirring motor 110, and the stirring motor 110 is fixedly installed on the top of the cover plate 112. The microwave heating device 15 is arranged at the bottom of the cover plate 112, so as to effectively improve the heating uniformity and sufficiency of the old asphalt mixture in the separation cylinder 12 while heating the old asphalt mixture by the microwave heating device 15, so as to improve the separation effect of the asphalt and the aggregate.

[0056] In some embodiments, rolling rings 123 are fixedly arranged on the outer side walls at both ends of the separation cylinder 12. A plurality of roller cylinders 115 are arrayed and installed on the inner wall of the cylinder body 111 of the fixed cylinder 11 corresponding to the rolling rings 123 in the circumferential direction. In this way, through the cooperation of the rolling rings 123 and the roller cylinders 115, the separation cylinder 12 can be radially positioned, and the separation cylinder 12 can be effectively prevented from toppling during rotation.

[0057] In some embodiments, a chute 1112 is recessed downward on the bottom wall of the cylinder body 111 of the fixed cylinder 11 corresponding to the extended part of the side wall of the separation cylinder 12. The bottom end of the side wall of the separation cylinder 12 is arranged in the chute 1112, and a low-friction gasket 116 is arranged between the bottom of the chute 1112 and the bottom end of the side wall of the separation cylinder 12. In this way, by arranging the low-friction gasket 116, while the bottom wall of the cylinder body 111 of the fixed cylinder 11 forms a supporting effect on the separation cylinder 12, the frictional resistance between the bottom end of the side wall of the separation cylinder 12 and the bottom surface of the chute 1112 can be effectively reduced, thereby ensuring the efficiency of the driving mechanism 14 to drive the separation cylinder 12 to rotate; specifically, the low-friction gasket 116 can be made of materials with good load-bearing capacity and low surface friction, such as ultra-high molecular weight polyethylene plates and nylon plates.

[0058] In some embodiments, an intake system 22 and an exhaust system 23 for supplying and discharging carbon dioxide are connected to the reaction kettle 21. Among them, the intake system includes a gas storage tank 221, a liquid storage tank 222, a pressure pump 224, and a supercharger pump 223. The gas storage tank 221 and the liquid storage tank 222 are respectively connected to the reaction kettle 21 through the supercharger pump 223 and the pressure pump 224. An intake valve 225 is connected between the supercharger pump 223 and the reaction kettle 21, and a liquid inlet valve 226 is connected between the pressure pump 224 and the reaction kettle 21. The gas storage tank 221 is used to store carbon dioxide gas, and the liquid storage tank 222 is used to store liquid carbon dioxide.

[0059] The exhaust system 23 includes an exhaust pipe 231, a gas-liquid separator 232, and a compressor 233. The exhaust pipe 231 is connected to the reaction kettle 21, and an exhaust valve 234 is connected to the exhaust pipe 231. The gas-liquid separator 232 is connected to the exhaust pipe 231 at a position between the exhaust valve 234 and the reaction kettle 21. A pressure relief valve 235 is connected between the intake port of the gas-liquid separator 232 and the exhaust pipe 231. The outlet of the gas-liquid separator 232 is connected to the intake port of the compressor 233, and the compressor 233 is connected to the liquid storage tank 222; the gas-liquid separator 232 is used to separate and collect the asphalt dissolved in the carbon dioxide discharged from the reaction kettle 21, and the compressor 233 is used to compress the discharged carbon dioxide gas into liquid carbon dioxide and then discharge it into the liquid storage tank 222 for storage.

[0060] Inside the reactor 21, at least one layer of metal filter screen 24 is installed at an interval from the bottom wall of the reactor 21. The metal filter screen 24 is used to store the aggregate generated by the preliminary separation treatment of the primary separation mechanism 1 inside the reactor 21, and separate the aggregate from the asphalt during the subsequent treatment process. In this embodiment, three layers of metal filter screens 24 are installed to improve the structural strength of the metal filter screen 24 and avoid the compression deformation of the metal filter screen 24. An asphalt discharge pipe 25 and an aggregate discharge pipe 26 are installed on the bottom wall of the reactor 21, and the upper end of the aggregate discharge pipe 26 extends upward to a position slightly higher than the bottom of the metal filter screen 24. An asphalt discharge valve 27 is installed on the asphalt discharge pipe 25, and an aggregate discharge valve 28 is installed on the aggregate discharge pipe 26.

[0061] A small amount of asphalt remains attached to the aggregate formed by the preliminary separation treatment of the old asphalt mixture through the primary separation mechanism 1. Therefore, in the secondary separation mechanism 2, after the preliminarily separated old asphalt mixture enters the reactor 21, pure carbon dioxide is blown into the reactor 21 through the gas storage tank 221 to discharge the air in the reactor 21, and then liquid carbon dioxide is injected into the reactor 21 through the liquid storage tank 222 and the compressor 233. Subsequently, the reactor 21 is heated and pressurized to make the carbon dioxide in the reactor 21 in a supercritical state. The stirring mechanism on the reactor 21 is started to stir the old asphalt mixture, so that under the state of heat preservation and pressure maintenance, the asphalt remaining attached to the aggregate generated by the preliminary separation treatment is fully dissolved by the supercritical carbon dioxide, and the surface of the asphalt aggregate is separated. Subsequently, the pressure relief valve 235 is used to control the reactor 21 to depressurize, so that the carbon dioxide gradually changes from the supercritical state to the gaseous state, and the asphalt dissolved in the supercritical carbon dioxide precipitates to form liquid droplets. During the depressurization process, the precipitated asphalt liquid droplets, under the action of the supercritical carbon dioxide that has not yet changed into the gaseous state, pass through the aggregate and the metal filter screen 24 and gather at the bottom of the reactor 21. The tiny asphalt liquid droplets that are not precipitated in time are discharged to the gas-liquid separator 232 through the exhaust pipe 231 along with the supercritical carbon dioxide or carbon dioxide gas. The asphalt dissolved in the carbon dioxide is separated and collected through the gas-liquid separator 232. The carbon dioxide gas purified by the gas-liquid separator 232 is compressed into liquid carbon dioxide by the compressor 233 and then discharged into the liquid storage tank 222 for storage. Subsequently, the asphalt discharge valve 27 and the aggregate discharge valve 28 are opened in sequence, and the asphalt at the bottom of the reactor 21 is discharged through the asphalt discharge pipe 25, and the aggregate on the metal filter screen 24 in the reactor 21 is gradually discharged through the aggregate discharge pipe 26, so as to realize the secondary separation treatment of the old asphalt mixture aggregate.

[0062] Thus, by setting up the secondary separation mechanism 2, the asphalt remaining and adhering to the aggregates of the old asphalt mixture after the preliminary separation by the primary separation mechanism 1 can be dissolved and collected by supercritical carbon dioxide, so that the remaining asphalt can be further separated from the aggregates, and further reduce the asphalt residue on the aggregates and improve the quality of the aggregates.

[0063] In some embodiments, the old asphalt mixture aggregate separation and recovery device further includes an aggregate conveying mechanism 4 and a screening mechanism 5. The aggregate conveying mechanism 4 is arranged between the aggregate discharge pipe 26 of the reaction kettle 21 and the screening mechanism 5 below. The aggregate conveying mechanism 4 is used to convey the separated aggregates into the screening mechanism 5. Specifically, the aggregate conveying mechanism 4 can adopt a belt elevator. Among them, the screening mechanism 5 includes a chassis 51, a material guiding groove 52, and a primary vibrating screen 53, a secondary vibrating screen 54, and a tertiary vibrating screen 55 with gradually increasing mesh diameters. The primary vibrating screen 53, the secondary vibrating screen 54, and the tertiary vibrating screen 55 are sequentially installed obliquely downward at the head and tail corresponding to each other inside the chassis 51. The discharge end of the aggregate conveying mechanism 4 extends into the chassis 51 and is located above the primary vibrating screen 53. And a material guiding groove 52 is installed obliquely downward below the primary vibrating screen 53, the secondary vibrating screen 54, and the tertiary vibrating screen 55 respectively. The discharge ends of the respective material guiding grooves 52 pass through the side wall of the chassis 51 and extend outside the chassis 51.

[0064] Thus, after the old asphalt mixture is preliminarily separated by the primary separation mechanism 1 and secondarily separated by the secondary separation mechanism 2, the asphalt and the aggregates are effectively separated. By setting up the aggregate conveying mechanism 4 and the screening mechanism 5, the aggregates discharged from the reaction kettle 21 can be conveyed into the screening mechanism 5 by the aggregate conveying mechanism 4, and then the aggregates are screened into three particle size grades by the primary vibrating screen 53, the secondary vibrating screen 54, and the tertiary vibrating screen 55 in the screening mechanism 5, and are respectively discharged from the chassis 51 through the corresponding material guiding grooves 52 for collection and standby.

[0065] In this embodiment, a drying fan 56 is respectively installed at the position on the side wall of the chassis 51 between the primary vibrating screen 53, the secondary vibrating screen 54, the tertiary vibrating screen 55 and their corresponding material guiding grooves 52. The air outlets of the respective drying fans 56 are horizontally directed towards the direction where the aggregates roll on each vibrating screen. Thus, by setting up the drying fans 56 to blow dry air during the aggregate screening process, the moisture formed on the surface of the aggregates during the aggregate separation process can be effectively removed, so as to effectively dry the aggregates, which is convenient for the subsequent storage and use of the aggregates.

[0066] Thus, by successively processing the old asphalt mixture to be treated through the primary separation mechanism 1, the secondary separation mechanism 2, and the screening mechanism 5, the primary separation treatment, secondary separation treatment, and screening and drying treatment of the old asphalt mixture can be completed in sequence, so as to realize the separation and recovery of asphalt and aggregates in the old asphalt mixture. Thus, the recovered asphalt and aggregates can be reused in the maintenance or paving construction of municipal roads, effectively reducing the loss of mineral resources, saving energy and protecting the environment, and having high economic benefits.

[0067] Corresponding to the foregoing embodiment of the old asphalt mixture aggregate separation and recovery device, the present application also provides an old asphalt mixture aggregate separation and recovery method and a corresponding embodiment. Using the foregoing old asphalt mixture aggregate separation and recovery device, the old asphalt mixture aggregate separation and recovery method includes the following steps:

[0068] S1: Preparation of materials: The old asphalt mixture recovered by milling or excavation is crushed and put into the fixed cylinder 11 through the feed hopper 113.

[0069] S2: Stirring and heating: Keep the discharge valve 18 closed, start the stirring motor 110 to drive the stirrer 19 to stir the old asphalt mixture in the separation cylinder 12, and start the microwave heating device 15 to perform microwave heating on the old asphalt mixture in the separation cylinder 12 for 15 minutes during the stirring process until the asphalt melts into a fluid state.

[0070] S3: Primary separation of asphalt: Continuously stir and heat, start the drive mechanism 14 to drive the separation cylinder 12 to rotate at a high speed, and during the stirring and heating process, the melted asphalt is thrown out of the separation cylinder 12 through the filter holes 122 by the centrifugal force of the rotation of the separation cylinder 12. The thrown asphalt droplets drip along the inner wall of the fixed cylinder 11 into the collection tank 16, and are collected by the collection tank 16 and discharged from the fixed cylinder 11 through the guide groove 161.

[0071] S4: Transfer of the old asphalt mixture: The microwave heating device 15 keeps heating, the stirring motor 110 drives the stirrer 19 to continuously stir, control the drive mechanism 14 to stop running, so that the separation cylinder 12 stops rotating, and the discharge pipe 17 is located at a position directly above the feed pipe 3. Open the discharge valve 18 on the discharge pipe 17 and the feed valve 31 on the feed pipe 3, and introduce the old asphalt mixture after the primary separation of asphalt in step S3 into the reaction kettle 21 through the discharge pipe 17 and the feed pipe 3. After the transfer of the old asphalt mixture is completed, control the microwave heating device 15 and the stirring motor 110 to stop running, and close the discharge valve 18 and the feed valve 31.

[0072] S5: Secondary separation of asphalt: Open the intake valve 225 and the exhaust valve 234 and start the booster pump 223. Close the liquid inlet valve 226 and the pressure relief valve 235. Blow pure carbon dioxide into the reactor 21 through the gas storage tank 221 and the booster pump 223 to discharge the air in the reactor 21. Then close the exhaust valve 234, turn off the booster pump 223, keep the pressure relief valve 235 closed, open the liquid inlet valve 226 and start the pressure pump 224. Inject liquid carbon dioxide into the reactor 21 through the liquid storage tank 222 and the pressure pump 224 until the liquid carbon dioxide injected into the reactor 21 completely submerges the old asphalt mixture, then close the liquid inlet valve 226 and the pressure pump 224. Then start the booster pump 223 to pump carbon dioxide gas into the reactor 21 to increase the pressure of the reactor 21, and pass high-temperature and high-pressure steam into the jacket of the reactor 21 to raise the temperature inside the reactor 21 until the temperature inside the reactor 21 is 120 °C and the pressure is 20 MPa, so that the carbon dioxide in the reactor 21 is in a supercritical state. Start the stirring mechanism on the reactor 21 to stir the old asphalt mixture, and dissolve the asphalt remaining attached to the aggregate after being treated in step S3 through supercritical carbon dioxide under the condition of heat preservation and pressure maintenance. The stirring and dissolving time is 10 min;

[0073] S6: Carbon dioxide recovery and asphalt precipitation: Adjust the stirring mechanism on the reactor 21 to stir at a low speed of 10 rpm. When the temperature inside the reactor 21 is maintained at 90 °C, open the pressure relief valve 235 to reduce the pressure inside the reactor 21 to 5 MPa at a pressure reduction rate of 2 MPa / min, so that the carbon dioxide gradually changes from the supercritical state to the gaseous state, thereby causing the asphalt dissolved in the supercritical carbon dioxide to precipitate and form droplets. During the pressure reduction process, the precipitated asphalt droplets, under the action of the supercritical carbon dioxide that has not yet turned into a gaseous state, pass through the aggregate and the metal filter net 24 and gather at the bottom of the reactor 21. The tiny asphalt droplets that are not precipitated in time are discharged to the gas-liquid separator 232 through the exhaust pipe 231 along with the supercritical carbon dioxide or carbon dioxide gas. Then, the asphalt dissolved in the carbon dioxide is separated and collected through the gas-liquid separator 232. The carbon dioxide gas purified by the gas-liquid separator 232 is compressed into liquid carbon dioxide by the compressor 233 and then discharged into the liquid storage tank 222 for storage and standby; among them, if the asphalt viscosity is high, a heating coil can be set in the gas-liquid separator 232 and the internal temperature of the gas-liquid separator 232 is maintained at 60 °C to promote the fluidity of the asphalt in the gas-liquid separator 232, so that the asphalt is easy to aggregate and deposit at the bottom of the gas-liquid separator 232, which can effectively prevent blockage and facilitate asphalt collection;

[0074] S7: Aggregate screening and drying: Stop the stirring mechanism on the reactor 21. To prevent the asphalt collected at the bottom of the reactor 21 from solidifying due to too low temperature, maintain the temperature in the reactor 21 at 90 °C, open the asphalt discharge valve 27 on the asphalt discharge pipe 25, and discharge the asphalt in the reactor 21 through the asphalt discharge pipe 25. Subsequently, cool down and depressurize the reactor 21 to normal temperature and pressure. All the carbon dioxide in the reactor 21 is converted into gas state, and the air pressure inside and outside the reactor 21 is balanced. Start the aggregate conveying mechanism 4, open the aggregate discharge valve 28 on the aggregate discharge pipe 26, and gradually discharge the aggregates in the reactor 21 to the feeding end of the aggregate conveying mechanism 4 through the aggregate discharge pipe 26. Convey the aggregates to the feeding end of the primary vibrating screen 53 of the screening mechanism 5 through the aggregate conveying mechanism 4. At the same time, start the drying fan. The aggregates separated from the asphalt are successively screened into three particle size grades during the drying process through the primary vibrating screen 53, the secondary vibrating screen 54, and the tertiary vibrating screen 55 and discharged from the chassis 51 through the corresponding guide grooves 52 respectively; After two separation treatments in steps S3 and S5, the asphalt residue in the aggregates is less than 1%, and the quality of the aggregates in the asphalt mixture is high.

[0075] Finally, it should also be noted that although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations of the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention, and all of them should be included in the protection scope of this application.

Claims

1. An old asphalt mixture aggregate separation and recovery device, characterized in that, Including: A primary separation mechanism, the primary separation mechanism includes a fixed cylinder and a separation cylinder. The fixed cylinder is fixedly installed on the base. The separation cylinder is coaxially and spacedly arranged inside the fixed cylinder. The side wall of the separation cylinder extends downward beyond the bottom wall to form an installation cavity. A driving mechanism for driving the separation cylinder to rotate relative to the fixed cylinder is arranged in the installation cavity. A microwave heating device is arranged at the top inside the fixed cylinder corresponding to the separation cylinder. Filter holes are formed on the side wall of the separation cylinder. A collection trough is obliquely downwardly installed between the outer wall of the bottom of the separation cylinder and the inner wall of the fixed cylinder. The lower side of the collection trough is connected with a guide trough extending outside the fixed cylinder, and the collection trough just does not contact the outer wall of the separation cylinder. A discharge pipe is fixedly installed on the bottom wall of the separation cylinder, and a discharge valve is installed on the discharge pipe. A secondary separation mechanism, the secondary separation mechanism is used to dissolve the residual asphalt attached to the aggregate after being processed by the primary separation mechanism through supercritical carbon dioxide. The secondary separation mechanism includes a reaction kettle. A feed pipe corresponding to and not contacting the discharge pipe is communicated with the feed inlet of the reaction kettle. Each time the driving mechanism stops, the discharge pipe is located at a position corresponding to the feed pipe. A feed valve is installed on the feed pipe.

2. The old asphalt mixture aggregate separation and recovery device according to claim 1, wherein: The fixed cylinder includes a cylinder body and a cover plate detachably and fixedly installed on the top of the cylinder body. A feed hopper is fixedly installed on the cover plate. The lower end of the feed hopper extends into the separation cylinder and does not contact the separation cylinder. A stirrer is arranged inside the separation cylinder. The stirrer is drivenly connected with a stirring motor. The stirring motor is fixedly installed on the top of the cover plate. The microwave heating device is arranged at the bottom of the cover plate.

3. The old asphalt mixture aggregate separation and recovery device according to claim 2, characterized in that: The driving mechanism includes a separation motor and a driving gear drivenly connected with the separation motor. A gear ring coaxial with the separation cylinder is fixedly arranged on the outer bottom wall of the separation cylinder. The driving gear is coaxially arranged inside the gear ring. Three driven gears that are simultaneously meshed with the driving gear and the gear ring are arranged in an array on the outer periphery of the driving gear. An opening is formed at the bottom of the cylinder body. A support plate is detachably and fixedly installed at the opening. The separation motor is installed on the support plate.

4. An old asphalt mixture aggregate separation and recovery device according to claim 2, characterized in that: Rolling rings are fixedly arranged on the outer side walls at both ends of the separation cylinder. A plurality of roller cylinders are installed in an array on the inner wall of the cylinder body corresponding to the rolling rings. The bottom wall of the cylinder body is concavely constructed with a chute corresponding to the extended part of the side wall of the separation cylinder. The bottom end of the side wall of the separation cylinder is arranged in the chute, and a low-friction gasket is arranged between the bottom of the chute and the bottom end of the side wall of the separation cylinder.

5. An old asphalt mixture aggregate separation and recovery device according to claim 1, characterized in that: An air inlet system and an exhaust system for supplying and discharging carbon dioxide are communicated with the reaction kettle. At least one layer of metal filter screen spaced from the bottom wall of the reaction kettle is installed inside the reaction kettle. An asphalt discharge pipe and an aggregate discharge pipe are installed on the bottom wall of the reaction kettle. The upper end of the aggregate discharge pipe extends upward to a position slightly higher than the bottom of the metal filter screen. An asphalt discharge valve is installed on the asphalt discharge pipe. An aggregate discharge valve is installed on the aggregate discharge pipe.

6. The old asphalt mixture aggregate separation and recovery device according to claim 5, characterized in that: The intake system includes an air storage tank, a liquid storage tank, a booster pump, and a pressure pump. The air storage tank and the liquid storage tank are respectively connected to the reaction kettle through the booster pump and the pressure pump. An intake valve is connected between the booster pump and the reaction kettle, and a liquid inlet valve is connected between the pressure pump and the reaction kettle; The exhaust system includes an exhaust pipe, a gas-liquid separator, and a compressor. The exhaust pipe is connected to the reaction kettle, and an exhaust valve is connected to the exhaust pipe. The gas-liquid separator is connected to the exhaust pipe at a position between the exhaust valve and the reaction kettle. A pressure relief valve is connected between the air inlet of the gas-liquid separator and the exhaust pipe. The air outlet of the gas-liquid separator is connected to the air inlet of the compressor, and the compressor is connected to the liquid storage tank.

7. An old asphalt mixture aggregate separation and recovery device according to claim 1, characterized in that: It further includes an aggregate conveying mechanism and a screening mechanism. The aggregate conveying mechanism is arranged between the aggregate discharge pipe of the reaction kettle and the screening mechanism below, and the aggregate conveying mechanism is used to convey the separated aggregate into the screening mechanism; The screening mechanism includes a chassis, a material guiding groove, and a first-stage vibrating screen, a second-stage vibrating screen, and a third-stage vibrating screen with gradually increasing mesh diameters. The first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen are successively installed in the chassis in a head-to-tail corresponding and inclined downward manner. The discharging end of the aggregate conveying mechanism extends into the chassis above the first-stage vibrating screen, and a material guiding groove is respectively installed inclined downward below the first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen. The discharging ends of the material guiding grooves pass through the side wall of the chassis and extend outside the chassis.

8. An old asphalt mixture aggregate separation and recovery device according to claim 7, characterized in that: A drying fan is respectively installed on the side wall of the chassis at a position between the first-stage vibrating screen, the second-stage vibrating screen, and the third-stage vibrating screen and their corresponding material guiding grooves. The air outlet of each drying fan is horizontally oriented towards the direction where the aggregate rolls on each vibrating screen.

9. A method for separating and recycling aggregates of old asphalt mixture, characterized in that: Using the old asphalt mixture aggregate separation and recovery device according to any one of the above claims 1-8, the old asphalt mixture aggregate separation and recovery method at least includes the following steps: S1: Preparation of materials: The old asphalt mixture recovered by milling or excavation is crushed and put into the fixed cylinder through the feed hopper; S2: Stirring and heating: Start the stirring motor to drive the stirrer to stir the old asphalt mixture in the separation cylinder, and start the microwave heating device to perform microwave heating on the old asphalt mixture in the separation cylinder during the stirring process until the asphalt melts into a fluid state; S3: Preliminary separation of asphalt: Continuously stir and heat, start the driving mechanism to drive the separation cylinder to rotate at a high speed, and during the stirring and heating process, the melted asphalt is thrown out of the separation cylinder from the filter holes by the centrifugal force of the rotation of the separation cylinder. The thrown asphalt droplets drip along the inner wall of the fixed cylinder into the collection tank, are collected by the collection tank, and are discharged from the fixed cylinder through the guide groove; S4: Transfer of the old asphalt mixture: The old asphalt mixture after the preliminary separation of asphalt in step S3 is introduced into the reaction kettle through the discharge pipe and the feed pipe; S5: Secondary separation of asphalt: Pure carbon dioxide is blown into the reaction kettle through the gas storage tank to discharge the air in the reaction kettle. Then, liquid carbon dioxide is injected into the reaction kettle through the liquid storage tank and the compressor. Subsequently, the reaction kettle is heated and pressurized so that the carbon dioxide in the reaction kettle is in a supercritical state. The stirring mechanism on the reaction kettle is started to stir the old asphalt mixture. Under the conditions of heat preservation and pressure maintenance, the asphalt remaining attached to the aggregate after being treated in step S3 is dissolved by supercritical carbon dioxide. S6: Carbon dioxide recovery and asphalt precipitation: The stirring mechanism on the reaction kettle is adjusted to stir at a low speed. Under the condition of heat preservation, the pressure in the reaction kettle is reduced, and the carbon dioxide gradually changes from the supercritical state to the gaseous state, causing the asphalt dissolved in the supercritical carbon dioxide to precipitate and form droplets. During the pressure reduction process, the asphalt droplets pass through the metal filter screen and gather at the bottom of the reaction kettle. The tiny asphalt droplets that are not precipitated in time are discharged to the gas-liquid separator along with the supercritical carbon dioxide or carbon dioxide gas through the exhaust pipe. The asphalt dissolved in the carbon dioxide is separated and collected through the gas-liquid separator. The carbon dioxide gas purified by the gas-liquid separator is compressed into liquid carbon dioxide by the compressor and then discharged into the liquid storage tank for storage. S7: Aggregate screening and drying: Under the condition of heat preservation, the asphalt in the reaction kettle is discharged. Subsequently, the reaction kettle is cooled and depressurized to normal temperature and pressure. The aggregate conveying mechanism is started, and the aggregate is gradually discharged to the feeding end of the aggregate conveying mechanism. The aggregate is conveyed to the feeding end of the primary vibrating screen of the screening mechanism through the aggregate conveying mechanism. At the same time, the drying fan is started. The aggregate passes through the primary vibrating screen, the secondary vibrating screen, and the tertiary vibrating screen in sequence and is screened into three particle size grades during the drying process and discharged from the machine box through the corresponding guide grooves respectively.

10. A method for separating and recycling aggregates of old asphalt mixture according to claim 9, characterized in that: In step S2, the heating time of the microwave heating device for the old asphalt mixture is 10 - 20 min. In step S5, the injected liquid carbon dioxide into the reaction kettle is at least just enough to completely submerge the old asphalt mixture. During the process of dissolving asphalt, the temperature in the reaction kettle is 110 - 130 °C, the pressure is 15 - 25 MPa, and the stirring and dissolving time is 5 - 15 min. In step S6, the rotation speed of the stirring mechanism on the reaction kettle is reduced to 5 - 15 rpm, the temperature in the reaction kettle is maintained at 80 - 100 °C, the pressure in the reaction kettle is gradually reduced to 4 - 6 MPa, and the pressure reduction rate is 1 - 3 MPa / min. If the asphalt viscosity is high, a heating coil is set in the gas-liquid separator, and the internal temperature of the gas-liquid separator is maintained at 50 - 70 °C.

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