Asphalt recovery method

Abstract

The invention discloses an asphalt recovery method which comprises the following steps: recovering a waste asphalt pavement material and carrying out preliminary crushing to obtain asphalt particles; dividing the asphalt particles into first asphalt particles and second asphalt particles according to the particle size; mechanically separating the first asphalt particles to obtain a first aggregate and third asphalt particles; the second asphalt particles and the third asphalt particles are placed in a recovery device, the recovery device comprises an inner layer and an outer layer which can rotate relatively, the inner layer is provided with a through hole or a channel, and a collection area used for bearing asphalt is formed between the inner layer and the outer layer; adding a first solvent in stages, heating and centrifuging according to a preset procedure, softening asphalt in the second asphalt particles and the third asphalt particles, seeping the asphalt into a collecting area through the through holes or the channels to obtain an asphalt crude product, and intercepting a second aggregate in an inner layer; and adding a second solvent into the crude asphalt product, uniformly mixing and sieving to obtain pure asphalt. By implementing the method, the asphalt recovery operation threshold is low, the asphalt recovery efficiency and quality are remarkably improved, and the asphalt recovery rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt recovery, and particularly to an asphalt recovery method. Background Art

[0002] The highway mileage in China has exceeded 5 million kilometers. Rapidly recovering asphalt from old asphalt mixtures can provide a reference for analyzing the causes of asphalt pavement diseases, and provide a basis for mixture proportion design, asphalt pavement maintenance and regeneration. It can be seen that the efficient and high-quality recovery of asphalt plays a crucial role in highway construction. At present, the recovery of aged asphalt generally uses the Abson method or the rotary evaporation instrument method. The asphalt recovered by the Abson method has a lot of solvent residues, and the rotary evaporation instrument method is prone to cause secondary aging of the recovered asphalt. Moreover, both the Abson method and the rotary evaporation instrument method require special distillation equipment, with high costs and operation thresholds, and it is difficult to implement especially in on-site inspections or laboratories with limited conditions. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an asphalt recovery method with a low operation threshold for asphalt recovery, and significantly improved asphalt recovery efficiency and quality.

[0004] To solve the above problems, the present invention discloses an asphalt recovery method, including the following steps:

[0005] (1) Recover waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles; classify the asphalt particles into first asphalt particles and second asphalt particles according to particle size;

[0006] (2) Mechanically separate the first asphalt particles to obtain first aggregates and third asphalt particles;

[0007] (3) Place the second asphalt particles and the third asphalt particles in a recovery device, the recovery device includes an inner layer and an outer layer that can rotate relative to each other, the inner layer is provided with through holes or channels, and a collection area for carrying asphalt is formed between the inner layer and the outer layer;

[0008] Add the first solvent in stages and perform heating and centrifugation according to a preset program. The asphalt in the second asphalt particles and the third asphalt particles softens and seeps out through the through holes or channels into the collection area to obtain a crude asphalt product, and the second aggregates are intercepted in the inner layer;

[0009] (4) Add a second solvent to the crude asphalt product, mix evenly and screen to obtain pure asphalt.

[0010] As an improvement of the above technical solution, the particle size of the first asphalt particles is larger than that of the second asphalt particles and larger than that of the third asphalt particles;

[0011] The particle size of the first asphalt particle is 2.5 mm to 10 mm; the particle size of the second asphalt particle is < 2.5 mm; the particle size of the third asphalt particle is < 2.5 mm.

[0012] As an improvement to the above technical solution, the preset program includes:

[0013] Heat to 120°C to 140°C, add the first amount of the first solvent and stir at a constant speed at the first rotation speed;

[0014] At 120°C to 140°C, add the second amount of the first solvent and stir at a constant speed at the second rotation speed;

[0015] Heat to 140°C to 160°C, centrifuge at the third rotation speed to obtain a crude asphalt product;

[0016] As an improvement to the above technical solution, add the first amount of the first solvent and stir at a constant speed at the first rotation speed for the first time, the first rotation speed is 50 r / min to 80 r / min, and the first time is 4 min to 8 min;

[0017] The total mass of the second asphalt particle and the third asphalt particle and the total amount of the first solvent is in a mass ratio of 1:(0.2 to 0.4);

[0018] The first amount accounts for 1 / 3 to 1 / 2 of the total amount of the first solvent.

[0019] As an improvement to the above technical solution, add the second amount of the first solvent and stir at a constant speed at the second rotation speed for the second time, the second rotation speed is 90 r / min to 120 r / min, and the second time is 25 min to 35 min.

[0020] As an improvement to the above technical solution, centrifuge at the third rotation speed for the third time, the third rotation speed is 2800 r / min to 3200 r / min, and the third time is 8 min to 15 min.

[0021] As an improvement to the above technical solution, the mass ratio of the crude asphalt product and the total amount of the second solvent is 1:(3 to 5);

[0022] After the crude asphalt product and the second solvent are mixed evenly, let it stand for 60 min to 90 min.

[0023] As an improvement to the above technical solution, the mechanical separation of the first aggregate and the third asphalt particle is realized by friction separation;

[0024] Before preliminary crushing, the waste asphalt pavement material is pretreated, and the pretreatment includes the following steps:

[0025] Perform high-pressure water spray cleaning on the waste asphalt pavement materials, drain them until the water content is 5% - 8%, and set aside;

[0026] Heat the drained waste asphalt pavement materials, with the heating temperature being 95°C - 105°C and the heating time being 10 min - 15 min.

[0027] As an improvement to the above technical solution, the aperture of the through hole is 0.04 mm - 0.08 mm;

[0028] The channel is a long strip hole, and the length direction of the channel is consistent with the axial direction. The length of the channel is 0.06 mm - 0.12 mm, and the width is 0.04 mm - 0.08 mm;

[0029] The through holes or channels are evenly spaced along the side wall of the inner layer in the circumferential direction; on the same horizontal plane, the included angle between two adjacent through holes or channels in the circumferential direction is 45° - 90°;

[0030] Along the axial direction of the inner layer, the bottom through hole or channel has a preset distance from the bottom of the inner layer, and the ratio of the preset distance to the height of the inner layer is 1:(5 - 10);

[0031] Along the axial direction of the inner layer, the top through hole or channel has a preset distance from the bottom of the inner layer, and the ratio of the preset distance to the height of the inner layer is 1:(2 - 4).

[0032] As an improvement to the above technical solution, the first solvent is acetone; the second solvent is petroleum ether.

[0033] Implementing the present invention has the following beneficial effects:

[0034] 1. The asphalt recovery method provided by the present invention performs different treatments on asphalt particles of different particle sizes, which can not only improve the recovery rate of asphalt, but also recover the first aggregate with better performance and reuse it in construction.

[0035] 2. The asphalt recovery method provided by the present invention adopts the method of adding materials in batches to mix the asphalt particles and the first solvent, ensuring the uniformity of stirring of the first solvent and the asphalt particles. Combined with stepwise heating, the temperature is raised above the asphalt softening point and below the asphalt decomposition temperature, the heating time is shortened, the generation of high-temperature aging phenomenon is avoided, and the asphalt and fine aggregate are quickly stratified by centrifugal separation. The entire recovery process can be completed within 1 h.

[0036] 3. The asphalt recovery method provided by the present invention is simple to operate, does not require professional distillation equipment and strict temperature and heating rate control, and is applicable to on-site detection or laboratories with limited conditions. Brief Description of the Drawings

[0037] Figure 1 It is a schematic flow chart of the asphalt recovery method provided by the embodiment of the present invention;

[0038] Figure 2 It is a schematic structural diagram of the asphalt recovery device provided by the embodiment of the present invention;

[0039] Figure 3 It is a schematic structural diagram of the recovery container provided by the embodiment of the present invention;

[0040] Figure 4 It is a side sectional view of the recovery container provided by an embodiment of the present invention;

[0041] Figure 5 It is a side sectional view of the recovery container provided by another embodiment of the present invention;

[0042] Figure 6 It is a top sectional view of the recovery container provided by an embodiment of the present invention. Detailed implementation manner

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below.

[0044] As Figure 1 shown, the present invention provides an asphalt recovery method, including the following steps;

[0045] S1. Recover waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles; classify the asphalt particles into first asphalt particles and second asphalt particles according to the particle size.

[0046] In one implementation manner, recover waste asphalt pavement materials for crushing, and the particle size of the crushed asphalt particles ≤ 10 mm.

[0047] In a preferred implementation manner, before preliminary crushing, perform pretreatment on the waste asphalt pavement materials, and the pretreatment includes the following steps:

[0048] (1) Perform high-pressure water mist spraying and cleaning on the waste asphalt pavement materials, drain until the water content is 5% - 8%, and set aside; high-pressure water mist spraying can remove the dust and clay on the surface of the waste asphalt pavement materials. Preferably, the high-pressure water mist spraying and cleaning is carried out for 10 min - 30 min.

[0049] (2) Heat the drained waste asphalt pavement materials. The heating temperature is 95°C to 105°C, and the heating time is 15 minutes to 20 minutes. Whether the waste asphalt pavement materials are recovered by mechanical excavation or cold milling, the crushing process may cause the aggregate to be refined, resulting in changes in the properties of the aggregate, which is not conducive to the recycling of the aggregate. Therefore, in the present invention, a heating treatment is carried out before crushing. After heating at an appropriate temperature and time and then crushing, the phenomenon of aggregate refinement is reduced, and the recycling rate of the aggregate is increased.

[0050] In one embodiment, after crushing, metal impurities in the asphalt particles are adsorbed and removed.

[0051] Specifically, the particle size of the first asphalt particles is larger than that of the second asphalt particles. The particle size of the first asphalt particles is 2.5 mm to 10 mm; the particle size of the second asphalt particles < 2.5 mm. A complex interaction is formed between the asphalt and the aggregate. Part of the asphalt combines with the aggregate to form structural asphalt, and part of the asphalt is free between the aggregates to form free asphalt. The specific surface area of the large-particle-size first asphalt particles is relatively small, and both the structural asphalt and the free asphalt are relatively less. Subsequently, separation is achieved through friction and collision. The specific surface area of the small-particle-size second asphalt particles is relatively large, and the structural asphalt in them is relatively more and the free asphalt is relatively less. Therefore, subsequent stripping of the asphalt from the aggregate is achieved through a method combining stage heating and melting, batchwise solvent dissolution, and rotary centrifugation.

[0052] S2. Mechanically separate the first asphalt particles to obtain first aggregates and third asphalt particles.

[0053] In one embodiment, friction separation is used to achieve the mechanical separation of the first aggregates and the third asphalt particles. Optionally, a abrasion tester is used for friction separation. The particle size of the third asphalt particles < 2.5 mm.

[0054] The performance indicators of the first aggregates obtained by mechanical separation are somewhat reduced compared with those of brand-new aggregates, but still meet the requirements. The separated first aggregates are used in subsequent construction, improving the recycling rate of the aggregates.

[0055] S3. As Figures 2 to 6 shown, place the second asphalt particles and the third asphalt particles in the recycling device 1. The recycling device 1 includes a recycling container 2. The recycling container 2 includes an inner layer 21 and an outer layer 22 that can rotate relative to each other. The inner layer 21 is provided with through holes 23a or channels 23b. A collection area 24 for carrying the asphalt is formed between the inner layer 21 and the outer layer 22;

[0056] The first solvent is added in stages and heated and centrifuged according to a preset procedure. The asphalt in the second asphalt particles and the third asphalt particles is softened and seeps out into the collection area 24 through the through holes 23a or the channels 23b to obtain a crude asphalt product. The second aggregate is retained in the inner layer 21.

[0057] The double-layered asphalt recovery device is conducive to the efficient recovery of asphalt. By combining heating and rotating centrifugation, asphalt is separated from asphalt particles. The asphalt enters the collection area through the through holes or channels in the inner layer, and aggregates with larger particle size and density remain in the inner layer. The asphalt in the collection area is taken out and subsequent operations can be carried out.

[0058] Specifically, the aperture of the through hole 23a is 0.04 mm to 0.08 mm, and is exemplarily 0.045 mm, 0.05 mm, 0.055 mm, 0.06 mm or 0.07 mm, but is not limited thereto. The channel 23b is a long hole, and the length direction of the channel is consistent with the axial direction. The length of the channel 23b is 0.06 mm to 0.12 mm, and the width is 0.04 mm to 0.08 mm. If the size of the through hole 23a or the channel 23b is too small, it is not conducive to the throwing out of the asphalt, and may even cause the through hole 23a or the channel 23b to be blocked; if the size of the through hole 23a or the channel 23b is too large, the separated aggregate may be thrown out with the asphalt, and the asphalt separation effect is poor.

[0059] In a preferred embodiment, the through holes 23a or channels 23b are evenly spaced along the side wall of the inner layer in the circumferential direction; on the same horizontal plane, the angle α between two adjacent through holes 23a or channels 23b in the circumferential direction is 45° to 90°. The evenly spaced through holes 23a or channels 23b can ensure that the separated asphalt is fully thrown out to the collection area 24.

[0060] In order to facilitate the throwing out of asphalt and avoid aggregate clogging the through hole 23a or the channel 23b, along the axial direction of the inner layer, the bottom through hole 23a or the channel 23b has a preset distance from the bottom of the inner layer 21, and the ratio of the preset distance to the height of the inner layer 21 is 1:(5~10), exemplarily 1:5.5, 1:6, 1:7, 1:8 or 1:9, but not limited to this.

[0061] Along the axial direction of the inner layer, there is a preset distance between the top through hole 23a or channel 23b and the top of the inner layer 21, and the ratio of the preset distance to the height of the inner layer is 1:(2-4), for example, 1:2.2, 1:2.5, 1:3, 1:3.2 or 1:3.8, but not limited thereto. In the asphalt recovery device provided by the present invention, through the setting of the size and position of the through hole 23a or channel 23b, efficient throwing out of asphalt is realized. The asphalt is thrown out to the side wall of the outer layer 22, and it is not necessary to set through holes with small apertures and dense distribution on the side wall of the entire inner layer. Only a few through holes can achieve efficient throwing out of asphalt, reducing the preparation complexity of the recovery device.

[0062] In one embodiment, the preset program includes:

[0063] S31. Heat to 120°C - 140°C, add the first dosage of the first solvent and stir at a constant speed at the first rotation speed. The asphalt is initially melted, and the first solvent is added during the heating process to dissolve the asphalt.

[0064] Specifically, stir at a constant speed at the first rotation speed for the first time. The first rotation speed is 50 r / min - 80 r / min, for example, 55 r / min, 60 r / min, 65 r / min, 70 r / min or 75 r / min, but not limited thereto. The first time is 4 min - 8 min, for example, 4.5 min, 5 min, 5.5 min, 6 min or 7 min, but not limited thereto.

[0065] In one embodiment, the mass ratio of the total mass of the second asphalt particles and the third asphalt particles to the total dosage of the first solvent is 1:(0.2 - 0.4), for example, 1:0.22, 1:0.25, 1:0.28, 1:0.3, 1:0.35 or 1:0.38, but not limited thereto. If the dosage of the first solvent is too low, it is difficult to achieve the dissolution and separation of the asphalt; if the dosage of the first solvent is too high, the subsequent purification difficulty will increase.

[0066] In a preferred embodiment, the first dosage accounts for 1 / 3 - 1 / 2 of the total dosage of the first solvent, for example, 11 / 30, 2 / 5, 5 / 12, 13 / 30 or 7 / 15, but not limited thereto.

[0067] Optionally, the first solvent is acetone. Compared with trichloroethylene used in the prior art, acetone has low toxicity and safety, and high dissolution efficiency for asphalt.

[0068] S32. At 120°C - 140°C, add the second dosage of the first solvent and stir at a constant speed at the second rotation speed. Through further heating, the melting of the asphalt particles is realized, and the first solvent is added during the heating process to dissolve the asphalt.

[0069] Specifically, stir at a second rotation speed for a second time at a constant temperature. The second rotation speed is 90 r / min to 120 r / min, and exemplary values are 95 r / min, 100 r / min, 105 r / min, 110 r / min, or 115 r / min, but are not limited thereto. The second time is 25 min to 35 min, and exemplary values are 26 min, 28 min, 30 min, 32 min, or 34 min, but are not limited thereto.

[0070] Heat from room temperature to 120°C to 140°C, and add 1 / 3 to 1 / 2 of the first solvent. The first solvent further accelerates the mixing with the asphalt particles as the temperature rises. Subsequently, keep the temperature constant at 120°C to 140°C, and add the remaining first solvent. The first solvent is added in batches by means of staged heating. After each thorough stirring and mixing, the next addition is carried out to ensure the uniformity of each stirring and achieve the full dissolution of the asphalt in the first solvent.

[0071] S33: Heat to 140°C to 160°C and centrifuge at a third rotation speed to obtain a crude asphalt product.

[0072] Specifically, centrifuge at a third rotation speed for a third time. The third rotation speed is 2800 r / min to 3200 r / min, and exemplary values are 2850 r / min, 2900 r / min, 3000 r / min, 3100 r / min, or 3150 r / min, but are not limited thereto. The third time is 8 min to 15 min, and exemplary values are 9 min, 10 min, 11 min, 12 min, or 14 min, but are not limited thereto. Controlling the centrifugation time within 8 min to 15 min can not only ensure the separation of the asphalt from the aggregate but also prevent the secondary aging of the asphalt caused by long-term high temperature.

[0073] The first rotation speed is less than the second rotation speed and less than the third rotation speed. Through the change of the rotation speed, the heating program, and the addition of the first solvent in batches, the efficient separation of the crude asphalt product from the aggregate is achieved, and the entire heating and centrifugation process can be completed within 1 h.

[0074] S4: Add a second solvent to the crude asphalt product, mix evenly, and screen to obtain pure asphalt.

[0075] Specifically, add a second solvent to the crude asphalt product. After stirring evenly, filter through a 0.075 mm sieve to remove the residual fine aggregate. Place the filtrate after removing the fine aggregate in a fume hood to naturally volatilize the solvent to obtain pure asphalt.

[0076] Specifically, the mass ratio of the amount of the second solvent to the asphalt crude product is 1:(3 - 5), and exemplary ratios are 1:3.4, 1:3.6, 1:3.8, 1:4, or 1:4.5, but not limited thereto.

[0077] Optionally, the second solvent is petroleum ether. The boiling range of petroleum ether is 30°C - 60°C. It has a low boiling point and can dissolve the light components and most of the insoluble heavy components in the asphalt crude product. In addition, petroleum ether has low toxicity and a moderate price and will not cause harm to the human body.

[0078] The following further illustrates the present invention with specific examples:

[0079] Example 1

[0080] This example provides an asphalt recovery method, including the following steps;

[0081] S1. Recycle waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles. The asphalt particles are divided into first asphalt particles and second asphalt particles according to particle size. The particle size of the first asphalt particles is 5 mm - 10 mm, and the particle size of the second asphalt particles < 5 mm.

[0082] S2. Mechanically separate the first asphalt particles by further crushing to obtain first aggregates and third asphalt particles.

[0083] The particle size of the third asphalt particles < 5 mm.

[0084] S3. Place 500 g of the second asphalt particles and the third asphalt particles in a recovery device, add acetone in stages and heat and centrifuge according to a preset program. The asphalt in the second asphalt particles and the third asphalt particles in the inner layer of the recovery device softens and seeps out through the through holes into the collection area between the inner layer and the outer layer to obtain an asphalt crude product. Specifically, the preset program includes:

[0085] S31. Heat to 110°C, add 30 mL of acetone and stir at a constant temperature of 60 r / min for 20 min.

[0086] S32. At 110°C, add 60 mL of acetone and stir at a constant temperature of 100 r / min for 5 min.

[0087] S33. Heat to 130°C and keep the temperature constant for 30 min, centrifuge at 3000 r / min for 10 min to obtain an asphalt crude product.

[0088] S4. Add petroleum ether to the asphalt crude product. The mass ratio of the amount of petroleum ether to the asphalt crude product is 1:6. Mix evenly and pass through a 0.075 mm sieve to obtain pure asphalt.

[0089] Example 2

[0090] This embodiment provides an asphalt recycling method, including the following steps;

[0091] S1. Recycle waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles. The asphalt particles are divided into first asphalt particles and second asphalt particles according to the particle size. The particle size of the first asphalt particles is 2.5 mm to 10 mm, and the particle size of the second asphalt particles is < 2.5 mm.

[0092] S2. Mechanically separate the first asphalt particles through friction separation to obtain first aggregates and third asphalt particles.

[0093] The particle size of the third asphalt particles is < 2.5 mm.

[0094] S3. Place 500 g of the second asphalt particles and the third asphalt particles in a recycling device, add acetone in stages and perform heating and centrifugation according to a preset program. The asphalt in the second asphalt particles and the third asphalt particles in the inner layer of the recycling device softens and oozes out through through-holes into the collection area between the inner layer and the outer layer to obtain a crude asphalt product. Specifically, the preset program includes:

[0095] S31. Heat to 140 °C, add 100 mL of acetone and stir at a constant temperature of 60 r / min for 21 min.

[0096] S32. At 140 °C, add 100 mL of acetone and stir at a constant temperature of 100 r / min for 5 min.

[0097] S33. Heat to 150 °C and keep it at a constant temperature for 34 min, and centrifuge at 3000 r / min for 10 min to obtain a crude asphalt product.

[0098] S4. Add petroleum ether to the crude asphalt product. The dosage of petroleum ether is in a mass ratio of 1:4 to the mass of the crude asphalt product. Mix evenly and sieve through a 0.075 mm sieve to obtain pure asphalt.

[0099] Example 3

[0100] This embodiment provides an asphalt recycling method, including the following steps;

[0101] S1. Recycle waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles. The asphalt particles are divided into first asphalt particles and second asphalt particles according to the particle size. The particle size of the first asphalt particles is 2.5 mm to 10 mm, and the particle size of the second asphalt particles is < 2.5 mm.

[0102] S2. Mechanically separate the first asphalt particles through friction separation to obtain first aggregates and third asphalt particles.

[0103] The particle size of the third asphalt particle < 2.5 mm.

[0104] S3. Place 500 g of the second asphalt particles and the third asphalt particles into a recovery device, add acetone in stages and heat and centrifuge according to a preset program. The asphalt in the second asphalt particles and the third asphalt particles in the inner layer of the recovery device softens and oozes out through the through holes into the collection area between the inner layer and the outer layer to obtain a crude asphalt product. Specifically, the preset program includes:

[0105] S31. Heat to 130 °C, add 100 mL of acetone and stir at a constant temperature of 60 r / min for 21 min.

[0106] S32. At 130 °C, add 100 mL of acetone and stir at a constant temperature of 100 r / min for 5 min.

[0107] S33. Heat to 150 °C and keep the temperature constant for 34 min, centrifuge at 3000 r / min for 10 min to obtain a crude asphalt product.

[0108] S4. Add petroleum ether to the crude asphalt product. The dosage of petroleum ether is in a mass ratio of 1:3 to the mass of the crude asphalt product. Mix evenly and sieve through a 0.075 mm sieve to obtain pure asphalt.

[0109] Comparative Example 1

[0110] This comparative example provides an asphalt recovery method, including the following steps:

[0111] S1. Recycle waste asphalt pavement materials and perform preliminary crushing to obtain asphalt particles; the particle size of the asphalt particles ≤ 10 mm.

[0112] S2. Add trichloroethylene to the crushed asphalt particles. The mass ratio of trichloroethylene to the asphalt particles is 1:0.4. At the same time, heat using an oil bath. The oil bath temperature is 120 °C and the oil bath time is 40 min. Then distill to separate the asphalt and the first aggregate.

[0113] S3. The asphalt solution containing fine aggregates is centrifuged by a centrifuge at a centrifugal speed of 3000 r / min for 10 min. After the centrifuged asphalt solution is further filtered through a filtering device, it is evaporated to further remove the solvent to obtain pure asphalt.

[0114] Calculate the asphalt recovery rates of Examples 1 to 3 and Comparative Example 1 respectively, and measure the properties of the asphalt recovered in Examples 1 to 3 and Comparative Example 1 according to JTGE20 2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The results are shown in the following table.

[0115]

[0116]

[0117] The asphalt recovery rate obtained by the asphalt recovery method provided by the present invention is high, and the recovery will not cause secondary aging of the asphalt.

[0118] The above is the preferred embodiment of the invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for asphalt recovery, characterized in that, It includes the following steps: (1) Recycling waste asphalt pavement materials and performing preliminary crushing to obtain asphalt particles; classifying the asphalt particles into first asphalt particles and second asphalt particles according to the particle size; (2) Mechanically separating the first asphalt particles to obtain first aggregates and third asphalt particles; (3) Placing the second asphalt particles and the third asphalt particles in a recycling device, the recycling device including an inner layer and an outer layer that can rotate relative to each other, the inner layer being provided with through holes or channels, and a collection area for carrying asphalt being formed between the inner layer and the outer layer; Adding a first solvent in stages and heating and centrifuging according to a preset program, the asphalt in the second asphalt particles and the third asphalt particles softens and seeps out through the through holes or channels into the collection area to obtain a crude asphalt product, and the second aggregates are intercepted in the inner layer; (4) Adding a second solvent to the crude asphalt product, mixing evenly and sieving to obtain pure asphalt.

2. The asphalt recovery method according to claim 1, characterized in that, The particle size of the first asphalt particles is larger than that of the second asphalt particles and larger than that of the third asphalt particles; The particle size of the first asphalt particles is 2.5 mm to 10 mm; the particle size of the second asphalt particles < 2.5 mm; the particle size of the third asphalt particles < 2.5 mm.

3. The asphalt recovery method according to claim 1, wherein The preset program includes: Heating to 120°C to 140°C, adding a first dosage of the first solvent and stirring at a first rotation speed at a constant temperature; At 120°C to 140°C, adding a second dosage of the first solvent and stirring at a second rotation speed at a constant temperature; Heating to 140°C to 160°C and centrifuging at a third rotation speed to obtain a crude asphalt product.

4. The asphalt recovery method according to claim 3, characterized in that, Adding a first dosage of the first solvent and stirring at a first rotation speed at a constant temperature for a first time, the first rotation speed being 50 r / min to 80 r / min, and the first time being 4 min to 8 min; The mass ratio of the total mass of the second asphalt particles and the third asphalt particles to the total dosage of the first solvent is 1:(0.2 to 0.4); The first dosage accounts for 1 / 3 to 1 / 2 of the total dosage of the first solvent.

5. The asphalt recovery method according to claim 3, characterized in that, Adding a second dosage of the first solvent and stirring at a second rotation speed at a constant temperature for a second time, the second rotation speed being 90 r / min to 120 r / min, and the second time being 25 min to 35 min.

6. The asphalt recovery method according to claim 3, wherein, Centrifuging at a third rotation speed for a third time, the third rotation speed being 2800 r / min to 3200 r / min, and the third time being 8 min to 15 min.

7. The asphalt recovery method according to claim 1, characterized in that, The mass ratio of the crude asphalt product to the total dosage of the second solvent is 1:(3 to 5); After the crude asphalt product and the second solvent are mixed evenly, they are left standing for 60 min to 90 min.

8. The asphalt recovery method according to claim 1, characterized in that, The mechanical separation of the first aggregates and the third asphalt particles is achieved by friction separation; Before preliminary crushing, the waste asphalt pavement materials are pretreated, and the pretreatment includes the following steps: Performing high-pressure water mist spraying and cleaning on the waste asphalt pavement materials, draining to a water content of 5% to 8%, and setting aside; Heating the drained waste asphalt pavement materials, the heating temperature being 95°C to 105°C, and the heating time being 15 min to 20 min.

9. The asphalt recovery method according to claim 1, characterized in that, The aperture of the through hole is 0.04 mm to 0.08 mm; The channel is a long strip hole, and the length direction of the channel is consistent with the axial direction. The length of the channel is 0.06 mm to 0.12 mm, and the width is 0.04 mm to 0.08 mm; The through holes or channels are evenly spaced along the side wall of the inner layer in the circumferential direction; on the same horizontal plane, the included angle between two adjacent through holes or channels in the circumferential direction is 45° to 90°; Along the axial direction of the inner layer, the bottom through hole or channel has a preset distance from the bottom of the inner layer, and the ratio of the preset distance to the height of the inner layer is 1:(5 to 10); Along the axial direction of the inner layer, the top through hole or channel has a preset distance from the bottom of the inner layer, and the ratio of the preset distance to the height of the inner layer is 1:(2 to 4).

10. The asphalt recovery method according to claim 1, characterized in that, The first solvent is acetone; the second solvent is petroleum ether.

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