Method for purifying asphalt

Abstract

The invention discloses a method for purifying asphalt. The method comprises the following steps: S1, mixing aliphatic hydrocarbon and aromatic hydrocarbon to prepare a mixed solvent; and S2, uniformly mixing the coal-based asphalt and the mixed solvent at 90-150 DEG C, then pumping the mixture into a settling tank, and after standing and settling, obtaining purified asphalt in which the quinoline insolubles are less than or equal to 0.01 wt% and the beta resin is more than or equal to 2.6 wt%. According to the method, the quinoline insoluble (QI) in the asphalt is removed by adopting the mixed solvent, the beta resin in the purified asphalt is rich, and the yield of the purified asphalt is up to 85wt% or above; the QI-rich heavy phase hardly contains a solvent and beta resin, is loose like quicksand, and is convenient for subsequent transportation.

Description

Technical Field

[0001] The invention belongs to the technical field of asphalt deep processing and relates to a method for purifying asphalt. Background Art

[0002] During the deep processing of asphalt, quinoline insolubles will be adsorbed on the surface of the mesophase spherulites, hindering the further melting and growth of the small spheres, increasing the viscosity of the system, and causing the final product to develop in the direction of chaotic optical structure and orientation order. They can be divided into primary and secondary quinoline insolubles, that is, primary and secondary quinoline insolubles. Secondary quinoline insolubles are polymers with large molecular weights produced in subsequent high-temperature (>340℃) reactions. Therefore, what is removed in actual production is the primary quinoline insolubles, which are divided into organic and inorganic, with a particle size of more than 0.5um.

[0003] Asphalt deep processing products such as needle coke, spinning pitch and isostatic graphite binder pitch have strict requirements on the content of quinoline insolubles in the raw materials, usually requiring less than 0.1wt% or even no quinoline insolubles; the methods for removing quinoline insolubles include flash modification, solvent method, sedimentation method and centrifugation method, etc. At present, the more economical one is the solvent centrifugation method, such as Chinese patent publication number CN101787298A "a method for purifying coal tar pitch", CN102676196A "a coal tar pitch for preparing needle coke and its preparation method and solvent used for preparing the coal tar pitch", CN103642511A "a method for preparing high-quality needle coke raw material", etc., although quinoline insolubles can be purified to less than 0.03%, the above method contains more β resin in its heavy phase, which greatly reduces the yield of refined asphalt, and the heavy phase has high viscosity, and the later storage and transportation are cumbersome. Summary of the invention

[0004] In view of the above-mentioned defects existing in the prior art, the object of the present invention is to provide a method for purifying asphalt, which adopts a mixed solvent to remove quinoline insolubles (QI) in asphalt, so that the purified asphalt is rich in β-resin, and the yield of purified asphalt is as high as more than 85wt%; the heavy phase rich in QI contains almost no solvent and β-resin, and is loose like quicksand, which is convenient for subsequent transportation.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for purifying asphalt, comprising the following steps:

[0007] S1, mixing aliphatic hydrocarbons and aromatic hydrocarbons to prepare a mixed solvent;

[0008] S2, mixing the coal-based asphalt and the mixed solvent at 90-150° C. uniformly, and then pumping into a sedimentation tank. After standing and settling, a purified asphalt with quinoline insoluble matter ≤ 0.01 wt% and β resin ≥ 2.6 wt% is obtained.

[0009] Preferably, in step S1:

[0010] The aliphatic hydrocarbon is selected from one or a mixture of several of the light oil, kerosene, naphtha and cyclohexane of the oil system; and / or

[0011] The aromatic hydrocarbon is selected from one or a mixture of several of naphthalene oil, heavy oil, light oil and wash oil of coal series.

[0012] Preferably, in step S1, the aromatics index BMCI of the mixed solvent is 30-60, and the boiling point or 95wt% distillation temperature of the mixed solvent is ≤300°C.

[0013] Preferably, in step S2, the mass ratio of the coal-based asphalt to the mixed solvent is 1:0.3 to 1:1.1.

[0014] Preferably, the mass ratio of the coal-based asphalt to the mixed solvent is 1:0.4 to 1:0.5.

[0015] Preferably, in step S2, the coal-based asphalt and the mixed solvent are mixed by mechanical stirring or a pipeline mixer.

[0016] Preferably, when mechanical stirring is used for mixing, the stirring time is 0.1 to 5 hours.

[0017] Preferably, when the coal-based asphalt is mixed with the mixed solvent, a cooler is added for reflux or pressurized nitrogen sealing.

[0018] Preferably, in step S2, the static sedimentation time is 0.1 to 3 hours.

[0019] Preferably, the purified asphalt yield is ≥85%.

[0020] The method for purifying asphalt provided by the present invention has the following beneficial effects:

[0021] Although the traditional method can remove QI to a very low level below 0.02%, its light phase yield is low, the effective component β resin content in the light phase is low, and most of it enters the heavy phase, making it difficult to handle the slag phase due to stickiness in the later stage, and the slag phase contains a small amount of solvent. However, by controlling the solvent aromatic index value and the solvent boiling point, the β resin is basically retained in the purified asphalt without being polluted, the purified asphalt contains almost no QI, and the purified asphalt yield is as high as more than 85%; and the heavy phase rich in QI contains almost no solvent and β resin, and it is loose like quicksand, which is easy to transport. DETAILED DESCRIPTION

[0022] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.

[0023] A method for purifying asphalt of the present invention comprises the following steps:

[0024] S1, mixing aliphatic hydrocarbons and aromatic hydrocarbons to prepare a mixed solvent; the specific process is as follows:

[0025] Aliphatic hydrocarbons: one or a mixture of several oils selected from the group consisting of light oil, kerosene, crude gasoline and cyclohexane;

[0026] Aromatic hydrocarbons: a mixture of one or more oils selected from naphthalene oil, heavy oil, light oil and wash oil (such as C-methyl naphthalene oil, D-methyl naphthalene oil) of coal series;

[0027] The aliphatic hydrocarbons and aromatic hydrocarbons selected above are mixed to obtain a mixed solvent, and the mixed solvent meets the following requirements:

[0028] a. The aromatic index BMCI of the mixed solvent is 30-60; (BMCI = 48640 / K + 473.7S - 456.8, where K is the average boiling point, S is the density of the mixed solvent at 60F, in g / cm 3 );

[0029] b. Boiling point or 95wt% distillation temperature ≤ 300℃.

[0030] When aliphatic hydrocarbons and aromatic hydrocarbons are mixed, they are first randomly proportioned, and the aromatic index BMCI of the final mixed solvent is 30-60.

[0031] S2, the coal-based asphalt and the mixed solvent are mixed evenly at 90-150°C, and then poured into a sedimentation tank. After standing and settling, a purified asphalt with quinoline insoluble matter ≤ 0.01wt% and β resin ≥ 2.6wt% is obtained.

[0032] Specifically, the coal-based asphalt and the mixed solvent are mixed in a mass ratio of 1:0.3 to 1:1.1. In a further preferred embodiment, the mass ratio of the coal-based asphalt to the mixed solvent is 1:0.4 to 1:0.5. The coal-based asphalt and the mixed solvent are mixed evenly at 90 to 150°C by mechanical stirring or pipeline mixer, and then poured into a sedimentation tank and allowed to settle for 0.1 to 3 hours; when mechanical stirring is used for mixing, the stirring time is 0.1 to 5 hours; to avoid loss of the mixed solvent, a cooler reflux or pressurized nitrogen sealing can be added during mixing.

[0033] After static sedimentation, a purified asphalt with quinoline insoluble matter ≤ 0.01wt% and β resin (intermediate phase precursor) ≥ 2.6wt% is obtained, and the yield of the purified asphalt is ≥ 85%. After static sedimentation, most of the quinoline insoluble matter enters the heavy phase, and the solvent content and β resin content in the heavy phase are low.

[0034] The method for purifying asphalt of the present invention is further described below with reference to specific examples.

[0035] Example 1

[0036] A method for purifying asphalt in this embodiment, the specific process is as follows:

[0037] Cyclohexane and naphthalene oil are combined to obtain a mixed solvent with a BMCI of 35 and a boiling point of 189°C;

[0038] 140℃ coal tar soft asphalt (QI: 5.6%wt) and room temperature mixed solvent in a mass ratio of 1:0.3wt% are mixed in a pipeline mixer and then enter into a sedimentation tank. After being sealed with slightly positive pressure nitrogen and allowed to stand and settle for 1h at 100℃, the light phase is separated from the heavy phase to obtain the light phase (i.e. purified asphalt) and the heavy phase. The QI, β resin content, purified asphalt yield in the purified asphalt, and β resin content and solvent content in the heavy phase are analyzed, as shown in Table 1.

[0039] Table 1

[0040]

[0041] Example 2

[0042] A method for purifying asphalt in this embodiment, the specific process is as follows:

[0043] Cyclohexane, kerosene and naphthalene oil were mixed to obtain a mixed solvent with a BMCI of 40 and a boiling point of 209°C;

[0044] 90℃ coal tar (QI: 3.3%wt) and room temperature mixed solvent were mixed in a mass ratio of 1:1.1 through a pipeline mixer and then entered into a sedimentation tank. After being sealed with nitrogen under a slightly positive pressure and allowed to stand and settle for 0.5h at 80℃, the light phase was separated from the heavy phase to obtain the light phase (i.e., purified asphalt) and the heavy phase. The QI, β resin content, purified asphalt yield in the purified asphalt, and the β resin content and solvent content in the heavy phase were analyzed, as shown in Table 2.

[0045] Table 2

[0046]

[0047] Example 3

[0048] A method for purifying asphalt in this embodiment, the specific process is as follows:

[0049] The crude gasoline, kerosene and washing oil are mixed to obtain a mixed solvent with a BMCI of 45 and a boiling point of 237°C;

[0050] The 160°C coal tar bottom asphalt (QI: 7.6%wt) and the room temperature mixed solvent were mixed in a mass ratio of 1:0.4wt%, mechanically stirred for 2h, and then pumped into a sedimentation tank. After being sealed with nitrogen under a slightly positive pressure and allowed to stand for 3h at 120°C, the light phase was separated from the heavy phase to obtain the light phase (i.e., purified asphalt) and the heavy phase. The QI, β resin content, purified asphalt yield in the purified asphalt, and the β resin content and solvent content in the heavy phase were analyzed, as shown in Table 3.

[0051] Table 3

[0052]

[0053] Example 4

[0054] A method for purifying asphalt in this embodiment, the specific process is as follows:

[0055] The kerosene, wash oil and heavy oil are mixed to obtain a mixed solvent with a BMCI of 50, and the boiling point of the mixed solvent is 289°C;

[0056] 90℃ coal tar (QI: 5.6%wt) and room temperature mixed solvent in a mass ratio of 1:0.45wt% were mixed in a pipeline mixer and then entered into a sedimentation tank. After being sealed with nitrogen under slightly positive pressure and allowed to stand and settle for 1h at 80℃, the light phase was separated from the heavy phase to obtain the light phase (i.e. purified asphalt) and the heavy phase. The QI, β resin content, purified asphalt yield in the purified asphalt, and β resin content and solvent content in the heavy phase were analyzed, as shown in Table 4.

[0057] Table 4

[0058]

[0059] Example 5

[0060] A method for purifying asphalt in this embodiment, the specific process is as follows:

[0061] Cyclohexane, crude gasoline, wash oil and light oil are mixed to obtain a mixed solvent with a BMCI of 60 and a boiling point of 295°C;

[0062] The 160°C coal tar bottom asphalt (QI: 7.6%wt) and the mixed solvent were mixed in a mass ratio of 1:0.5wt%, mechanically stirred for 3h, and then put into a sedimentation tank. After being sealed with nitrogen under a slightly positive pressure and allowed to stand for 2.5h at 120°C, the light phase was separated from the heavy phase to obtain the light phase (i.e., purified asphalt) and the heavy phase. The QI, β resin content, purified asphalt yield in the purified asphalt, and the β resin content and solvent content in the heavy phase were analyzed, as shown in Table 5.

[0063] Table 5

[0064]

[0065] In summary, although the traditional method can remove QI from asphalt to a very low level, such as 0.01%, the yield of the light phase (purified asphalt) is relatively low, and the content of the effective component β resin in the light phase is relatively low, generally below 2.1%, and most of it enters the heavy phase, making the heavy phase difficult to handle due to the stickiness of the slag phase in the later stage. In the embodiment of the present invention, by controlling the aromatic index of the solvent and the boiling point of the solvent or the distillation temperature of 95wt%, most of the β resin remains in the light phase, and the QI content in the light phase is ≤0.01wt%, the β resin content in the light phase is 2.6-5.3wt%, and the yield of the light phase is ≥85%; while the β resin content in the heavy phase is ≤0.1% or even zero, and the solvent content is ≤0.06%.

[0066] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for purifying asphalt, characterized in that: The following steps are involved: S1, mixing aliphatic hydrocarbons and aromatic hydrocarbons to prepare a mixed solvent; S2, mixing the coal-based asphalt and the mixed solvent at 90-150° C. uniformly, and then pumping into a sedimentation tank. After standing and settling, a purified asphalt with quinoline insoluble matter ≤ 0.01 wt% and β resin ≥ 2.6 wt% is obtained.

2. The method for purifying asphalt according to claim 1, characterized in that: In step S1: The aliphatic hydrocarbon is selected from one or a mixture of several of the light oil, kerosene, naphtha and cyclohexane of the oil system; and / or The aromatic hydrocarbon is selected from one or a mixture of several of naphthalene oil, heavy oil, light oil and wash oil of coal series.

3. The method for purifying asphalt according to claim 1, characterized in that: In the step S1, the aromatics index BMCI of the mixed solvent is 30-60, and the boiling point or 95wt% distillation temperature of the mixed solvent is ≤300°C.

4. The method for purifying asphalt according to claim 1, characterized in that: In the step S2, the mass ratio of the coal-based asphalt to the mixed solvent is 1:0.3 to 1:1.

1.

5. The method for purifying asphalt according to claim 4, characterized in that: The mass ratio of the coal-based asphalt to the mixed solvent is 1:0.4 to 1:0.

5.

6. The method for purifying asphalt according to claim 1, characterized in that: In the step S2, the coal-based asphalt and the mixed solvent are mixed by mechanical stirring or a pipeline mixer.

7. The method for purifying asphalt according to claim 6, characterized in that: When mechanical stirring is used for mixing, the stirring time is 0.1 to 5 hours.

8. The method for purifying asphalt according to claim 6, characterized in that: When the coal-based asphalt is mixed with the mixed solvent, a cooler is added for reflux or pressurized nitrogen sealing.

9. The method for purifying asphalt according to claim 1, characterized in that: In the step S2, the static sedimentation time is 0.1 to 3 hours.

10. The method for purifying asphalt according to claim 1, characterized in that: The purified asphalt yield is ≥85%.

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