Production method of low-grade road asphalt

Abstract

The invention discloses a production method of low-grade road asphalt. The method comprises the following steps: (1) pretreating a polymer modifier to obtain a polymer precursor; (2) mixing ethylene tar with the polymer precursor, heating and stirring to obtain a premix; (3) carrying out shearing circulation on the premix in the step (2); and (4) performing countercurrent contact on the material obtained in the step (3) and an extraction solvent for supercritical extraction, wherein the obtained raffinate heavy component is used as low-grade asphalt. According to the method, high value-added utilization of ethylene tar can be realized, and the produced low-grade road asphalt has the advantages of high ductility at 10 DEG C before a film and good storage stability.

Description

Technical Field

[0001] The invention relates to a method for preparing low-grade road asphalt from ethylene tar, and belongs to the field of high value-added utilization of low-value resources. Background Art

[0002] Data from the transportation industry show that high temperatures and heavy loads have caused increasing damage to asphalt pavements year by year, and the requirements for asphalt application performance on highways have tended to be harder to improve the final performance of asphalt pavements. In order to adapt to market development trends, improve the service functions of asphalt pavements, and improve their high-temperature stability, low-grade asphalt has become the first choice for road construction in some areas. Compared with the currently commonly used No. 70 asphalt, No. 50 asphalt has high viscosity, high softening point, low penetration, better high-temperature stability and water stability. Asphalt pavements in Guangdong, Hainan and other provinces in China have begun to use low-grade No. 50 asphalt.

[0003] The research and application of low-grade asphalt in roads is still in its infancy. Among them, 50#A grade asphalt is difficult to produce. The commonly used vacuum deep drawing process has the problem of unqualified 10°C elongation before film; the blending process of hard asphalt and soft asphalt can slightly improve the 10°C elongation before film, but the surplus is not large and there is a problem of uneven product properties; by adding polymers, polymer-modified low-grade asphalt is prepared, which can improve the 10°C elongation before film, but there is a problem of low storage stability, and the upper and lower softening point difference after the separation test is large. For example, CN103554926B discloses a low-grade high-grade road asphalt and its preparation method, which uses vacuum residue oil, deoiled asphalt and solvent refined extracted oil to prepare low-grade high-grade road asphalt that meets 50#A grade, but its 10°C elongation before film is not large.

[0004] Ethylene tar is a byproduct produced during the high-temperature condensation of raw materials in the production of ethylene. It accounts for about 15% of ethylene production. China has abundant ethylene tar resources. Ethylene tar is mainly composed of C and H elements, with a high aromatic content. It is composed of a variety of single-ring, double-ring, and multi-ring cyclic structure compounds, from C9 fraction to C90 fraction. Its distillation range spans nearly 600°C and its components are relatively complex. Due to the lack of awareness of the use of low-quality resources in the past, ethylene tar was only used as fuel oil for combustion, resulting in a huge waste of resources. Summary of the invention

[0005] In order to overcome the problems of low-grade road asphalt in the prior art having low elongation at 10°C before film formation and insufficient storage stability using polymer modification, the present invention provides a method for producing low-grade road asphalt. The method can not only realize high value-added utilization of ethylene tar, but also the low-grade road asphalt produced has the advantages of high elongation at 10°C before film formation and good storage stability.

[0006] The present invention provides a method for producing low-grade road asphalt, comprising the following steps:

[0007] (1) pretreatment with a polymer modifier to obtain a polymer precursor;

[0008] (2) mixing ethylene tar with a polymer precursor, heating and stirring to obtain a premix;

[0009] (3) subjecting the premix of step (2) to shear cycling;

[0010] (4) The material obtained in step (3) is contacted with an extraction solvent in countercurrent to perform supercritical extraction, and the heavy component of the residue obtained is used as low-grade asphalt.

[0011] In the method of the present invention, the polymer modifier in step (1) is one or more of a thermoplastic elastomer and a rubber polymer. The thermoplastic elastomer is one or more of SBS, SEBS, and SIS. The rubber polymer is styrene-butadiene rubber.

[0012] In the method of the present invention, the pretreatment method of the polymer modifier in step (1) is hydrogen peroxide treatment, wherein the mass content of H2O2 in the hydrogen peroxide used is 15% to 30%.

[0013] In the method of the present invention, the pretreatment conditions described in step (1) include: the mass ratio of polymer modifier to hydrogen peroxide is 1:1-3, the treatment temperature is 100-150°C, and the treatment time is 60-120min.

[0014] In the method of the present invention, the properties of the ethylene tar in step (2) include: a density of 1.0 to 1.2 g / cm at 25°C; 3 The residual carbon value is 10wt% to 20wt%, and the mass content of aromatic hydrocarbons is more than 70%.

[0015] In the method of the present invention, the mass ratio of the ethylene tar to the polymer precursor in step (2) is 100:1-10, preferably 100:2-8.

[0016] In the method of the present invention, the conditions for heating and stirring in step (2) are: temperature of 110 to 130° C., and stirring time of 60 to 120 min.

[0017] In the method of the present invention, in step (3), the shearing temperature is 130-180° C., the number of cycles is 2-6 times, and the shearing time each time is 10-30 minutes. The shearing is preferably carried out in a colloid mill.

[0018] In the method of the present invention, in step (4), the extraction solvent is a C3-C5 alkane, such as at least one of propane, butane and pentane. The volume ratio of the extraction solvent to the material obtained in step (3) is 3-6:1.

[0019] In the method of the present invention, in step (4), the extraction temperature is 80-180° C. and the pressure is 4-6 MPa.

[0020] In the method of the present invention, in step (4), the light component of the extract obtained is separated to obtain light tar and solvent. The solvent can be recycled. The separation temperature is 200-250°C and the pressure is 5-10MPa.

[0021] In the method of the present invention, the properties of the low-grade road asphalt are as follows: needle penetration at 25°C is 40-60 0.1mm, softening point is 70-100°C, elongation at 10°C before film is ≥40cm, and softening point difference in segregation test is ≤0.5°C.

[0022] The present invention adopts a method combining polymer pretreatment with supercritical extraction to achieve efficient crosslinking of ethylene tar and polymer modifier and improve crosslinking stability. The two stages work synergistically to produce the following

[0023] Beneficial effects:

[0024] 1. In the method of the present invention, the polymer modifier is pretreated with hydrogen peroxide to activate the unsaturated double bonds in the polymer modifier, reducing the difficulty of cross-linking between ethylene tar and the polymer modifier. After high-temperature shearing and supercritical extraction, the inactive components in the system can be removed. The remaining ethylene tar active components in the system greatly promote the swelling development of the polymer modifier. The polymer quickly forms a network structure in the ethylene tar, which can not only significantly improve the ductility index of low-grade asphalt, but also make the asphalt structure stable and the quality uniform, thereby improving storage stability.

[0025] 2. The present invention uses ethylene tar as raw material, which has a wide source and low price, and can achieve high added value utilization of low-value resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process of the present invention;

[0027] Explanation of the reference numerals: 1-pretreatment tank, 2-premixing tank, 3-colloid mill, 4-extraction tower, 5-separator, 6-solvent tank, 7-polymer modifier, 8-ethylene tar, 9-polymer precursor, 10-premix, 11-sheared material, 12-raffinate, 13-extract, 14-light tar, 15-solvent. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with embodiments, but is not limited to the following embodiments.

[0029] Combine the following Figure 1 The method of the present invention is described in detail. The present invention provides a method for producing low-grade road asphalt, comprising: a polymer modifier 7 is pretreated with hydrogen peroxide to obtain a polymer precursor 9, ethylene tar 8 and the polymer precursor 9 enter a premixing tank 2 for mixing, heating and stirring to obtain a premix 10; the premix 10 enters a colloid mill 3 for shearing circulation to obtain a sheared material 11, the sheared material 11 is countercurrently contacted with an extraction solvent 15 in an extraction tower for supercritical extraction, the obtained raffinate heavy component 12 is used as low-grade asphalt, the extract 13 enters a separator, light tar 14 is obtained at the bottom, and a solvent 15 is obtained at the top, the solvent 15 enters a solvent tank, and the solvent can be recycled.

[0030] The relevant parameter testing method of the present invention:

[0031] The penetration and penetration index PI were measured according to the Ministry of Transportation Standard T0604, the softening point (ring and ball method) was measured according to the Ministry of Transportation Standard T0606, the ductility was measured according to the Ministry of Transportation Standard T0605, the dynamic viscosity at 60°C was measured according to the Ministry of Transportation Standard T0620, the polymer modified asphalt segregation test was carried out according to the Ministry of Transportation Standard T0661, and the thin film heating test (TFOT) was carried out according to the Ministry of Transportation Standard T0609.

[0032] Example 1

[0033] In this example, Figure 1 The process is as follows, the polymer modifier is SBS, the extraction solvent is butane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 20wt%) are mixed in a mass ratio of 1:3 and treated at 120℃ for 80min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:6, heated to 130℃ and stirred for 80min to obtain a premix; the premix is ​​sheared and cycled at 160℃ for 4 times, and the shearing time for each time is 20min. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction. The extraction conditions are as follows: the extraction temperature is 145℃, the pressure is 5MPa, the volume ratio of the extraction solvent to the sheared material is 4:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt. The properties are shown in Table 2. The light component of the obtained raffinate is separated, and the separation conditions are: temperature 220℃, pressure 6MPa, to obtain light tar and solvent. The solvent can be recycled.

[0034] Example 2

[0035] In this example, Figure 1The process is as follows, the polymer modifier is SBS, the extraction solvent is propane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 25wt%) are mixed in a mass ratio of 1:3 and treated at 130℃ for 90min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:5, heated to 120℃ and stirred for 60min to obtain a premix; the premix is ​​sheared and cycled at 180℃ for 4 times, and each shearing time is 30min. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction. The extraction conditions are as follows: the extraction temperature is 100℃, the pressure is 5MPa, the volume ratio of the extraction solvent to the sheared material is 5:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt. The properties are shown in Table 2. The light component of the obtained raffinate is separated, and the separation conditions are: temperature 200℃, pressure 9MPa, to obtain light tar and solvent. The solvent can be recycled.

[0036] Example 3

[0037] In this example, Figure 1 The process is as follows, the polymer modifier is SIS, the extraction solvent is butane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 30wt%) are mixed in a mass ratio of 1:2 and treated at 140℃ for 80min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:4, heated to 130℃ and stirred for 100min to obtain a premix; the premix is ​​sheared and cycled at 160℃ for 3 times, and each shearing time is 20min. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction. The extraction conditions are as follows: the extraction temperature is 150℃, the pressure is 5MPa, the volume ratio of the extraction solvent to the sheared material is 4:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt. The properties are shown in Table 2. The light component of the obtained raffinate is separated under the separation conditions: temperature 220℃, pressure 7MPa, and light tar and solvent are obtained. The solvent can be recycled.

[0038] Example 4

[0039] In this example, Figure 1The process is as follows, the polymer modifier is styrene-butadiene rubber, the extraction solvent is propane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 15wt%) are mixed in a mass ratio of 1:2 and treated at 140℃ for 70min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:3, heated to 110℃ and stirred for 80min to obtain a premix; the premix is ​​sheared and cycled at 180℃ for 3 times, and each shearing time is 30min. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction. The extraction conditions are as follows: the extraction temperature is 95℃, the pressure is 4MPa, the volume ratio of the extraction solvent to the sheared material is 3:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt. The properties are shown in Table 2. The light component of the obtained raffinate is separated, and the separation conditions are: temperature 200℃, pressure 8MPa, to obtain light tar and solvent. The solvent can be recycled.

[0040] Example 5

[0041] In this example, Figure 1 The process is as follows, the polymer modifier is styrene-butadiene rubber, the extraction solvent is pentane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 20wt%) are mixed in a mass ratio of 1:1, and treated at 130℃ for 120min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:8, heated to 130℃ and stirred for 110min to obtain a premix; the premix is ​​sheared and cycled at 170℃, the number of cycles is 5, and the shearing time for each time is 20min. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction, and the extraction conditions are as follows: the extraction temperature is 170℃, the pressure is 5MPa, the volume ratio of the extraction solvent to the sheared material is 4:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt, and the properties are shown in Table 2. The light component of the obtained raffinate is separated, and the separation conditions are: temperature 250℃, pressure 5MPa, to obtain light tar and solvent. The solvent can be recycled.

[0042] Example 6

[0043] In this example, Figure 1The process is as follows, the polymer modifier is SEBS, the extraction solvent is pentane, and the properties of ethylene tar are shown in Table 1. The polymer modifier and hydrogen peroxide (H2O2 content 30wt%) are mixed in a mass ratio of 1:1, and treated at 100℃ for 100min to obtain a polymer precursor. Ethylene tar and polymer precursor are mixed in a mass ratio of 100:2, heated to 120℃ and stirred for 80min to obtain a premix; the premix is ​​sheared and cycled at 160℃, the number of cycles is 4, and the shearing time is 20min each time. The sheared material is countercurrently contacted with the extraction solvent for supercritical extraction, and the extraction conditions are as follows: the extraction temperature is 175℃, the pressure is 4MPa, the volume ratio of the extraction solvent to the sheared material is 3:1, and the heavy component of the extract obtained after extraction is used as low-grade asphalt, and the properties are shown in Table 2. The light component of the obtained raffinate is separated, and the separation conditions are: temperature 240℃, pressure 6MPa, to obtain light tar and solvent. The solvent can be recycled.

[0044] Comparative Example 1

[0045] Compared with Example 1, the difference is that the polymer modifier is SBS without pretreatment and is directly mixed with ethylene tar. The results are shown in Table 2.

[0046] Comparative Example 2

[0047] Compared with Example 1, the difference is that the sheared material is not subjected to supercritical extraction, but low-grade asphalt is obtained by deep drawing. The results are shown in Table 2.

[0048] Table 1 Properties of ethylene tar

[0049] Analyze Project data Density at 25℃, g / cm 1.103 Kinematic viscosity at 60℃, cst 194.3 Carbon residue,% 16.31 Aromatic content, % 78.23 Ash content, % 0.034 Elemental composition, % C 92.56 H 7.30 S 0.05 N 0.03 O 0.06

[0050] Table 2 Test results of the products obtained in each embodiment

[0051]

[0052] Table 3 Product test results of the products obtained in each comparative example

[0053]

[0054]

[0055] The embodiments of the present invention are only detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention can be implemented without relying on the steps described in the above embodiments. In summary, any improvements made to the present invention by those skilled in the art, as long as they do not deviate from the content of the technical solutions of the present invention, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for producing low-grade road asphalt, comprising the following steps: (1) pretreatment with a polymer modifier to obtain a polymer precursor; (2) mixing ethylene tar with a polymer precursor, heating and stirring to obtain a premix; (3) subjecting the premix of step (2) to shear cycling; (4) The material obtained in step (3) is contacted with an extraction solvent in countercurrent to perform supercritical extraction, and the heavy component of the residue obtained is used as low-grade asphalt.

2. The preparation method according to claim 1, characterized in that: The polymer modifier described in step (1) is one or more of a thermoplastic elastomer and a rubber-like polymer; preferably, the thermoplastic elastomer is one or more of SBS, SEBS, and SIS; and the rubber-like polymer is styrene-butadiene rubber.

3. The preparation method according to claim 1, characterized in that: The pretreatment method of the polymer modifier in step (1) is hydrogen peroxide treatment, wherein the mass content of H2O2 in the hydrogen peroxide used is preferably 15% to 30%.

4. The preparation method according to claim 3, characterized in that: The pretreatment conditions described in step (1) include: a mass ratio of polymer modifier to hydrogen peroxide of 1:1-3, a treatment temperature of 100-150°C, and a treatment time of 60-120 minutes.

5. The preparation method according to claim 1, characterized in that: The properties of the ethylene tar in step (2) include: a density of 1.0 to 1.2 g / cm at 25°C; 3 The residual carbon value is 10wt% to 20wt%, and the mass content of aromatic hydrocarbons is more than 70%.

6. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of the ethylene tar to the polymer precursor is 100:1-10, preferably 100:2-8.

7. The preparation method according to claim 1, characterized in that: The heating and stirring conditions in step (2) are: temperature of 110-130° C., and stirring time of 60-120 min.

8. The preparation method according to claim 1, characterized in that: In step (3), the shearing temperature is 130-180° C., the number of cycles is 2-6 times, and the shearing time each time is 10-30 minutes.

9. The preparation method according to claim 1, characterized in that: In step (4), the extraction solvent is C3-C5 alkane, and / or the volume ratio of the extraction solvent to the material obtained in step (3) is 3-6:

1.

10. The preparation method according to claim 1 or 9, characterized in that: In step (4), the extraction temperature is 80-180° C. and the pressure is 4-6 MPa.

11. The preparation method according to claim 1, characterized in that: In step (4), the light components of the obtained extract are separated to obtain light tar and solvent. Preferably, the solvent is recycled. More preferably, the separation temperature is 200-250° C. and the pressure is 5-10 MPa.

12. The preparation method according to claim 1, characterized in that: The properties of the low-grade road asphalt are as follows: needle penetration at 25°C is 40-60 0.1mm, softening point is 70-100°C, elongation at 10°C before film is ≥40cm, and softening point difference in segregation test is ≤0.5°C.

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