Method for preparing high-purity asphalt by deliming high-ash asphalt through mild chemical method

Abstract

The invention belongs to the technical field of asphalt deliming and purification, and discloses a method for preparing high-purity asphalt from high-ash asphalt through mild chemical deliming, and the specific technical scheme is as follows: adding the high-ash asphalt and a solvent into a mixing tank in proportion, heating, stirring and mixing, and then feeding into a filter; the high-ash asphalt solution is treated by the filter to be divided into a low-solid asphalt solution and a high-solid component; high-solid components are sent to a dryer and become solid fuel after solvent recovery by the dryer, the solid fuel is sent to a warehouse, and the recovered solvent returns to the mixing tank; feeding the low-solid asphalt solution into a deliming reactor, adding a deliming agent in proportion, heating to react to generate a high-purity asphalt solution, feeding the high-purity asphalt solution into the middle of a reduced pressure distillation tower, cooling a tower top gas phase by a condenser, and returning one part of the tower top gas phase as tower top reflux and the other part of the tower top gas phase as a circulating solvent to the mixing tank; one part of the tower bottom high-purity asphalt serves as tower bottom backflow, and the other part of the tower bottom high-purity asphalt is fed into a forming machine; the non-strong acid is used as the deliming agent, the reaction condition is mild, and the composition and the performance of the asphalt are not influenced.

Description

Technical Field

[0001] The present invention belongs to the technical field of asphalt deashing and purification, and specifically relates to a method for preparing high-purity asphalt by non-strong acid mild chemical deashing of high-ash asphalts such as coal tar asphalt, catalytic cracking oil slurry asphalt, and coal direct liquefaction oil residue. Background Art

[0002] The conversion and utilization of oil and coal produces a large amount of heavy oil, such as coal tar, catalytic cracking slurry, and direct liquefaction heavy oil. Most of these heavy oils contain large amounts of impurities such as catalyst powder, coal powder, and coke powder. Therefore, the asphalt remaining after extracting the light fraction cannot be used in carbon materials such as carbon fiber, needle coke, and other carbon materials, resulting in very low utilization and added value.

[0003] For example, during the direct coal liquefaction process, approximately 20% to 30% of the raw coal is converted into oil residue, of which asphalt components account for 40% to 60% of the oil residue content. Traditionally, this type of asphalt has only been used for road modification or fuel oil. The asphalt component in direct coal liquefaction oil residue is rich in polycyclic aromatic hydrocarbons and is an ideal precursor for the preparation of high-end carbon materials such as lithium battery negative electrode coating materials, asphalt-based carbon fibers, and needle coke. However, direct liquefaction oil residue contains coal powder, unconverted coal, and micron-sized inorganic catalyst particles, resulting in a high ash content, which limits its application in high-end carbon materials.

[0004] Publication number CN117531293A, "A System and Method for Deashing Direct Coal Liquefaction Residues," discloses a method for deashing direct coal liquefaction residues using a ceramic membrane filtration + circulating flushing method. First, the coal liquefaction residues are extracted with solvent oil to obtain an extract. This extract is then separated by sedimentation to obtain a top liquid. This extract is mixed with the circulating material in a circulating pump and passed through a ceramic membrane filter to obtain a purified liquid. The purification method employed in this patent has good filtration results, but the accumulation of high-viscosity asphaltenes and micron-sized particles easily clogs the ceramic membrane. Acid washing can only recover 60% to 80% of the flux, and chemically bound ash cannot be removed.

[0005] Publication number CN117987168A, "Deliming Method for Asphalt, Delimed Asphalt, and Applications Thereof," discloses a deliming method for asphalt that utilizes solvent extraction and acid washing. The asphalt is first dissolved with an extractant, and a filtrate is obtained after solid-liquid separation. An acid solution is then added to the filtrate for acid washing. After solid-liquid separation and drying, the resulting precipitate is the delimed asphalt product. This method places high demands on the corrosion resistance of the equipment, increasing equipment costs. Furthermore, the acidic environment may accelerate the decomposition of certain components in the asphalt (such as esters and carboxylic acid groups), affecting asphalt performance.

[0006] The publication number "CN116376593A" titled "A system and method for deashing and refining coal liquefaction residue by solvent extraction" discloses a method for deashing coal liquefaction residue by solvent extraction, which adopts a deashing method of solvent extraction + candle filtration. First, the coking wash oil or tetrahydrofuran extractant is mixed with the liquefied residue to prepare a slurry, which is passed through a candle filter. After forward blowing, filtering, and back-blowing with an inert gas, the filtrate and filter residue are discharged, and the filtrate is passed into a flash tower to separate the refined asphalt. The candle filter used in this patent is designed for low-viscosity liquids such as beer. The viscosity of the asphalt solution is high, resulting in low diffusion efficiency. An additional pre-coating filter aid layer is required to improve the separation efficiency, and the debugging time is long and the efficiency is low. Secondly, the candle filter has high requirements for the stability of the raw material. Fluctuations in the ash content of the raw material will greatly affect the stable operation of the filter. In addition, the filter cake formed after asphalt extraction and filtration has strong adhesion, and it is difficult to peel off the filter cake under conventional back-blowing.

[0007] These traditional deashing technologies primarily rely on filtration, acid washing, and solvent extraction, which have the following limitations: Filtration / solvent extraction can only remove particles larger than 50μm, reducing the ash content to a minimum of 0.2%-0.5%. It is unable to remove micron-sized particles such as catalysts, coal dust, and coke fines. Acid washing, while using strong acids to dissolve metal oxides, requires high corrosion resistance in the equipment. Furthermore, strong acids can catalyze reactions such as polycondensation in asphalt, altering its composition and directly affecting its performance. Summary of the Invention

[0008] In order to solve the technical problem of removing solid particles in high-ash asphalts such as coal tar asphalt, direct coal liquefaction oil residue, and catalytic cracking oil residue asphalt, especially the technical problem that micron-sized particles are difficult to completely remove through extraction and filtration methods, the present invention provides a method for preparing high-purity asphalt, especially a method for preparing high-purity asphalt comprising a mild chemical deashing process of high-ash asphalt using a non-strong acid as a deashing agent. The present invention can not only remove large particles of coal powder, etc., but also use a deashing chemical reaction, use a non-strong acid as a deashing agent, make micron-sized particles such as catalyst powder produce soluble salts, and separate from the asphalt phase as the solvent, and finally completely remove the micron-sized particles that are difficult to remove by filtration to prepare high-purity asphalt.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt, the specific steps of which are as follows: Step 1: High-ash asphalt and a mixed solvent are added into a mixing tank at a mass ratio of 1:1-1:2. The mixed solvent includes a circulating solvent, a recovered solvent, and a supplementary solvent. The mixture is stirred and mixed at a temperature range of 120°C-180°C for 0.5h-3h. The mixed high-ash asphalt solution is fed into a filter; Step 2: After being processed by a filter, the solid particles in the high-ash asphalt solution are filtered out, and the remaining solution becomes a low-solid asphalt solution; when the thickness of the high-solid component filter cake formed by filtration reaches a predetermined thickness, a mechanical scraper or the high-solid component filter cake is used to remove the high-solid component filter cake under its own gravity and convey it to a dryer. The solvent in the high-solid component filter cake is evaporated in the dryer to form steam that is sent to a cooler. After cooling, the steam forms a recovered solvent that is returned to the mixing tank. The solids after dehydration become solid fuel and are sent to the warehouse; Step 3: The low-solid asphalt solution is pumped into the deashing reactor through the filter. A deashing agent is added at a rate of 1%-5% (mass ratio) of the raw high-ash asphalt. The solution is reacted at 120-180°C for 1-3 hours to form a high-purity asphalt solution. Step 4: The high-purity asphalt solution generated by the reaction is pumped into the middle of a vacuum distillation tower with a vacuum degree of 80%-95%. The top gas phase at 100℃-160℃ is cooled by a condenser and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank as the circulating solvent. The high-purity asphalt at the bottom of the tower at 140℃-220℃ is divided into two parts. One part of the high-purity asphalt is used as reflux at the bottom of the tower, and the other part is sent to the molding machine. The molded products are sent to the warehouse.

[0010] In step 1, the high-ash asphalt is one or a mixture of any of coal tar asphalt, direct coal liquefaction oil residue, and catalytic cracking oil slurry asphalt.

[0011] Among them, the distillation range of catalytic cracking oil slurry asphalt is higher than 650℃.

[0012] In step 1, the mixed solvent is one or a mixture of any multiple of washing oil, anthracene oil, naphthalene oil, phenol oil, acetone, cyclohexane, n-heptane, and tetrahydrofuran.

[0013] In step 3, the deliming agent is one of formic acid, acetic acid, oxalic acid, phthalic acid, malic acid, citric acid, lactic acid, tartaric acid, and glycolic acid, or a mixture of any multiple thereof.

[0014] The filter is a plate and frame filter press, a vertical filter press, or a bag vacuum filter.

[0015] In step 2, the volatile matter content of the solid fuel is less than 1%; The ash content of high-purity asphalt is 0.02%-0.2%, and the quinoline insoluble matter content is less than 0.1%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses a mild chemical method to deash and purify high-ash asphalt, which can remove large-particle impurities and micron-level ash at the same time, and will not affect the quality of high-purity asphalt products due to the instability of the raw material asphalt ash; the present invention uses non-strong acid as a deashing agent, the reaction conditions are mild, and the requirements for equipment design, materials, etc. are low, and it will not trigger side reactions such as condensation and oxidation of asphalt, thereby affecting the composition and properties of the asphalt; in addition, the present invention has a wide range of applications and a simple process, and can be applied to the deashing and purification of various types of high-ash asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention.

[0018] In the figure, 1 is a solvent tank, 2 is a feeding belt, 3 is a mixing tank, 4 is a filter, 5 is a dryer, 6 is a cooler, 7 is a deashing reactor, 8 is a vacuum distillation tower, and 9 is a molding machine. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] like Figure 1 As shown, a method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt is provided, wherein the high-ash asphalt is fed into a mixing pipe by a feeding belt 2, and a mixed solvent is stored in a solvent tank 1; the high-ash asphalt is one or a mixture of any multiple of coal tar asphalt, direct coal liquefaction oil residue, and catalytic cracking oil slurry asphalt; and the mixed solvent is one or a mixture of any multiple of wash oil, anthracene oil, naphthalene oil, phenol oil, acetone, cyclohexane, n-heptane, and tetrahydrofuran. Example

[0021] Coal tar pitch and wash oil are added to mixing tank 3 at a weight ratio of 1:1.5 and stirred at 120°C for 0.5 hours. The mixed high-ash asphalt solution is processed through a plate-and-frame filter press to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake formed by filtration, when it reaches a thickness of 2 cm, is scraped off with a mechanical scraper and transferred to dryer 5. The solvent evaporates in dryer 5 to form steam, which is then fed into cooler 6. The solvent vapor is cooled to form recovered solvent and returned to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 3% formic acid is added and reacted at 120°C for 1 hour to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the 100°C top gas phase is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at the bottom of the tower at 140°C is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0022] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.02%, quinoline insoluble matter (QI) 0.04%, and solid fuel volatile matter 0.6%. Example

[0023] Coal liquefaction oil residue and anthracene oil are added to mixing tank 3 at a weight ratio of 1:1.2 and stirred at 150°C for 1.5 hours. The mixed high-ash asphalt solution is processed through a vertical filter press to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake, formed after filtration, falls off by gravity when it reaches a thickness of 2 cm and is transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 1% acetic acid is added and reacted at 150°C for 2 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 80%), and the 130°C top gas phase is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at the bottom of the tower at 180°C is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0024] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.02%, quinoline insoluble matter (QI) 0.03%, and solid fuel volatile matter 0.9%. Example

[0025] Catalytic cracking oil slurry asphalt with a distillation range above 650°C is mixed with tetrahydrofuran / acetone in a weight ratio of 1:1. The mixture of catalytic cracking oil slurry asphalt and tetrahydrofuran / acetone in a weight ratio of 1:1.8 is added to mixing tank 3 and stirred at 180°C for 3 hours. The high-ash asphalt liquid is filtered through a bag vacuum filter to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake formed by filtration, when it reaches a thickness of 2 cm, falls off by gravity and is transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped through filter 4 to deashing reactor 7, where 4% oxalic acid is added and the reaction is carried out at 180°C for 3 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 160°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 220°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0026] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.05%, quinoline insoluble matter (QI) 0.06%, and solid fuel volatile matter 0.8%. Example

[0027] Coal tar pitch and naphthalene oil are added to mixing tank 3 in a 1:1 weight ratio and stirred at 130°C for 1 hour. The mixed high-ash asphalt solution is processed through a plate-and-frame filter press to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake, formed after filtration and reaching a thickness of 2 cm, is scraped off with a mechanical scraper and transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are then sent to storage. The low-solids asphalt solution is pumped from filter 4 into deashing reactor 7, where 2% citric acid is added and reacted at 130°C for 1.5 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the 110°C top gas phase is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at the bottom of the tower at 160°C is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0028] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.03%, quinoline insoluble matter (QI) 0.06%, and solid fuel volatile matter 0.6%. Example

[0029] Coal liquefaction oil residue and cyclohexane are added to mixing tank 3 at a weight ratio of 1:1.5 and stirred at 140°C for 2 hours. The mixed high-ash asphalt solution is processed through a vertical filter press to remove solid particles from the high-ash asphalt solution, leaving the remaining liquid as a low-solids asphalt solution. The high-solids filter cake formed by filtration, when it reaches a thickness of 2 cm, falls off by gravity and is transferred to dryer 5. The solvent evaporates in dryer 5 to form steam, which is then fed into cooler 6. The solvent vapor is cooled to form recovered solvent, which returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 5% lactic acid is added and reacted at 140°C for 2.5 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the 120°C top gas phase is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at the bottom of the tower at 170°C is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0030] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.03%, quinoline insoluble matter (QI) 0.06%, and solid fuel volatile matter 0.6%. Example

[0031] Catalytic cracking oil slurry asphalt (fractions with a distillation range above 650°C) and n-heptane are added to mixing tank 3 at a ratio of 1:1.8 and stirred at 160°C for 2.5 hours. The mixed high-ash asphalt solution is filtered through a bag vacuum filter to remove solid particles from the high-ash asphalt solution, leaving the remaining liquid as a low-solids asphalt solution. The high-solids filter cake, formed after filtration and reaching a thickness of 2 cm, falls off by gravity and is transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 3.5% tartaric acid is added and reacted at 160°C for 1 hour to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 140°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 190°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0032] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.04%, quinoline insoluble matter (QI) 0.08%, and solid fuel volatile matter 0.7%. Example

[0033] Coal tar pitch and phenol oil are added to mixing tank 3 at a ratio of 1:1.3 and stirred at 170°C for 0.8 hours. The high-ash asphalt solution is then filtered through a plate-and-frame filter press to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The resulting high-solids filter cake, when it reaches a thickness of 2 cm, is scraped off with a mechanical scraper and transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed to cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are then sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 2.5% acetic acid and oxalic acid (1:1) are added and reacted at 170°C for 2 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 85%), and the top gas phase at 150°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 200°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0034] The high-purity asphalt prepared according to the operation of this embodiment has the following contents: ash content 0.03%, quinoline insoluble matter (QI) 0.08%, and solid fuel volatile matter 0.8%. Example

[0035] Coal liquefaction oil residue and wash oil / anthracene oil (2:1) are added to mixing tank 3 in a total ratio of 1:2 and stirred at 125°C for 1.2 hours. The mixed high-ash asphalt solution is processed through a vertical filter press to remove solid particles from the high-ash asphalt solution, leaving the remaining liquid as a low-solids asphalt solution. The high-solids filter cake formed by filtration, when it reaches a thickness of 2 cm, falls off by gravity and is transferred to dryer 5. The solvent evaporates in dryer 5 to form steam, which is then fed into cooler 6. The solvent vapor is cooled to form recovered solvent, which is returned to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 1.8% malic acid is added and reacted at 125°C for 1.8 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 105°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at the bottom of the tower at 150°C is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0036] The high-purity asphalt prepared according to the operation of this embodiment has an ash content of 0.08%, a quinoline insoluble matter (QI) of 0.09%, and a solid fuel volatile matter of 0.3%. Example

[0037] Catalytic cracking oil slurry asphalt (fractions with a distillation range above 650°C) and acetone are added to mixing tank 3 at a ratio of 1:1.2 and stirred at 155°C for 1.8 hours. The high-ash asphalt solution is filtered through a bag vacuum filter to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake, formed after filtration, falls off by gravity when it reaches a thickness of 2 cm and is transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed to cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 4.2% formic acid and lactic acid (3:1) are added and reacted at 155°C for 3 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 95%), and the top gas phase at 160°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 210°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0038] The high-purity asphalt prepared according to the operation of this embodiment has an ash content of 0.03%, a quinoline insoluble matter (QI) of 0.03%, and a solid fuel volatile matter of 0.8%. Example

[0039] Coal tar pitch and wash oil / tetrahydrofuran (3:1) are added to mixing tank 3 at a ratio of 1:1.6 and stirred at 135°C for 2.2 hours. The mixed high-ash asphalt solution is processed through a plate-and-frame filter press to remove solid particles from the high-ash asphalt solution, leaving a low-solids asphalt solution. The high-solids filter cake, formed after filtration and reaching a thickness of 2 cm, is scraped off with a mechanical scraper and transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are then sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 4.8% phthalic acid is added and reacted at 135°C for 1.2 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 115°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 165°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and sent to the warehouse after molding.

[0040] The high-purity asphalt prepared according to the operation of this embodiment has an ash content of 0.12%, a quinoline insoluble matter (QI) of 0.1%, and a solid fuel volatile matter of 0.5%. Example

[0041] Coal liquefaction oil residue and anthracene oil / cyclohexane (1:1) in a ratio of 1:1.4 are added to mixing tank 3 and stirred at 165°C for 0.7 hours. The mixed high-ash asphalt solution is processed through a vertical filter press to remove solid particles from the high-ash asphalt solution, leaving the remaining liquid as a low-solids asphalt solution. The high-solids filter cake formed by filtration, when it reaches a thickness of 2 cm, falls off by gravity and is transferred to dryer 5. The solvent evaporates in dryer 5 to form steam, which is then fed into cooler 6. The solvent vapor is cooled to form recovered solvent, which is returned to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 3.2% glycolic acid is added and reacted at 165°C for 2.3 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 125°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 175°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0042] The high-purity asphalt prepared according to the operation of this embodiment has an ash content of 0.05%, a quinoline insoluble matter (QI) of 0.08%, and a solid fuel volatile matter of 0.5%. Example

[0043] Catalytic cracking oil slurry asphalt (fractions with a distillation range above 650°C) and phenol oil / acetone (2:1) in a ratio of 1:1.7 are added to mixing tank 3 and stirred at 180°C for 3 hours. The high-ash asphalt solution is filtered through a bag vacuum filter to remove solid particles from the high-ash asphalt solution, leaving the remaining liquid as a low-solids asphalt solution. The high-solids filter cake, formed after filtration, falls off by gravity when it reaches a thickness of 2 cm and is transferred to dryer 5. The solvent evaporates in dryer 5, forming steam that is fed into cooler 6. The solvent vapor is cooled, forming recovered solvent that returns to mixing tank 3. The desolventized solids become solid fuel and are sent to storage. The low-solids asphalt solution is pumped from filter 4 to deashing reactor 7, where 2.7% citric acid and tartaric acid (1:1) are added and reacted at 180°C for 3 hours to form a high-purity asphalt solution. The high-purity asphalt solution generated by the reaction is sent to the middle part of the vacuum distillation tower 8 (vacuum degree 90%), and the top gas phase at 145°C is cooled by the condensing gas and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank 3 as the circulating solvent; a part of the high-purity asphalt at 220°C at the bottom of the tower is used as the bottom reflux, and the other part of the high-purity asphalt is sent to the molding machine 9, and then sent to the warehouse after molding.

[0044] The high-purity asphalt prepared according to the operation of this embodiment has an ash content of 0.02%, a quinoline insoluble matter (QI) of 0.05%, and a solid fuel volatile matter of 0.3%.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt, characterized in that: The specific steps are as follows: Step 1: Add high-ash asphalt and mixed solvent into a mixing tank at a mass ratio of 1:1-1:2, stir and mix at a temperature range of 120°C-180°C for 0.5h-3h, and send the mixed high-ash asphalt solution into a filter; Step 2: After being processed by a filter, the solid particles in the high-ash asphalt solution are filtered out, and the remaining solution becomes a low-solid asphalt solution; when the thickness of the high-solid component filter cake formed by filtration reaches a predetermined thickness, a mechanical scraper or the high-solid component filter cake is used to remove the high-solid component filter cake under its own gravity and convey it to a dryer. The solvent in the high-solid component filter cake is evaporated in the dryer to form steam that is sent to a cooler. After cooling, the steam forms a recovered solvent that is returned to the mixing tank. The solids after dehydration become solid fuel and are sent to the warehouse; Step 3: The low-solid asphalt solution is pumped into the deashing reactor through the filter, and a deashing agent is added at a ratio of 1%-5% of the mass of the raw high-ash asphalt. The mixture is reacted at 120℃-180℃ for 1h-3h to form a high-purity asphalt solution. Step 4: The high-purity asphalt solution generated by the reaction is pumped into the middle of a vacuum distillation tower with a vacuum degree of 80%-95%. The top gas phase at 100℃-160℃ is cooled by a condenser and flows into the top tank of the distillation tower. Part of the cooled liquid is used as the top reflux, and the other part of the cooled liquid is returned to the mixing tank as the circulating solvent. The high-purity asphalt at the bottom of the tower at 140℃-220℃ is divided into two parts. One part of the high-purity asphalt is used as reflux at the bottom of the tower, and the other part is sent to the molding machine. The molded products are sent to the warehouse.

2. The method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt according to claim 1, characterized in that: In step 1, the high-ash asphalt is one or a mixture of any of coal tar asphalt, direct coal liquefaction oil residue, and catalytic cracking oil slurry asphalt; The distillation range of the catalytic cracking slurry oil asphalt is higher than 650°C.

3. The method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt according to claim 2, characterized in that: In step 1, the mixed solvent is one or a mixture of any multiple of washing oil, anthracene oil, naphthalene oil, phenol oil, acetone, cyclohexane, n-heptane, and tetrahydrofuran.

4. The method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt according to claim 3, characterized in that: In step three, the deliming agent is one of formic acid, acetic acid, oxalic acid, phthalic acid, malic acid, citric acid, lactic acid, tartaric acid, and glycolic acid, or a mixture of any multiple thereof.

5. The method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt according to claim 4, characterized in that: The filter is a plate and frame filter press, or a vertical filter press, or a bag vacuum filter.

6. The method for preparing high-purity asphalt by mild chemical deashing of high-ash asphalt according to claim 5, characterized in that: In step 2, the volatile matter content of the solid fuel is less than 1%; The high-purity asphalt has an ash content of 0.02%-0.2%, and a quinoline insoluble matter content of less than 0.1%.

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