Modification of coal liquefied asphalt and process application method thereof

Abstract

Relating to the technical field of road building materials, the invention discloses a coal liquefaction modified asphalt, which comprises 70%-90% of coal liquefaction asphalt, 10%-15% of a modifier, 3%-8% of a collapsing agent, and 2%-4% of a stabilizer. The coal liquefaction modified asphalt product with excellent performance and regular shape is successfully prepared by performing systematic compound modification and granulation treatment on the coal liquefaction asphalt. The high and low temperature performance, the adhesiveness and the construction applicability are obviously improved, and the modified asphalt can be widely applied to road asphalt and waterproof materials; meanwhile, the product is converted into a regular particle form, so that the convenience of storage, transportation and use is greatly improved; according to the technology, high-added-value resource utilization of the coal liquefied asphalt is effectively achieved, remarkable energy-saving, consumption-reducing and environment-friendly benefits are embodied, the overall technology has the comprehensive advantages of being high in performance, high in added value, green and low in carbon, and a new feasible way is provided for efficient, clean and resource utilization of the coal chemical industry solid waste.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, and in particular to a method for modifying coal liquefaction asphalt and its technological application. Background Technology

[0002] Coal-to-oil projects primarily produce light fuels such as gasoline and diesel, but the byproduct, coal liquefaction asphalt, is a type of residual asphalt. Its current utilization value is low: Coal liquefaction asphalt products are not developed or utilized; currently, it is mainly used as a solid fuel like coal, with sales prices referencing those of raw coal. Due to its composition, coal liquefaction asphalt contains certain gums and other substances compared to coal, and it easily clogs fuel injector nozzles and forms gum on other components during combustion. Therefore, it is not competitive with raw coal as fuel and has low economic value. Current research results are unsatisfactory, and the utilization of coal liquefaction asphalt faces difficulties: Current research suggests two application routes: one is as a road asphalt blending material, used in small quantities; the other is as a matrix asphalt blending material for SBS modified asphalt, used in small quantities. However, neither of these application methods has been used on a large scale; only a few test roads have been constructed. The main reasons are that mixing coal liquefaction asphalt into road asphalt affects some key indicators, and the softening point of coal liquefaction asphalt is too high, making heating and liquid storage inconvenient during application.

[0003] When directly blending existing technologies (CN112094528A), the following results are observed: poor compatibility, storage stratification (segregation rate > 5%), low-temperature brittleness, and ductility < 15 cm at 5℃. The following is a comparison with literature.

[0004] Table 1: Literature Comparison Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a coal liquefaction-modified bitumen, which solves the problems mentioned in the background art, such as low utilization value, unsatisfactory research and development results, and the predicament of coal liquefaction bitumen utilization.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A coal liquefaction modified bitumen, comprising, by weight percentage of the total composition: 70%-90% coal liquefaction bitumen, 10%-15% modifier, 3%-8% disintegrating agent, and 2%-4% stabilizer.

[0007] According to the present invention, the stabilizer of the coal liquefaction modified bitumen contains 5–10% metal ions.

[0008] According to the present invention, a coal liquefaction modified bitumen is provided, wherein the coal liquefaction bitumen serves as a base binder, the softening point of the coal liquefaction bitumen is 150-160℃, the toluene-insoluble content in the coal liquefaction bitumen is not higher than 15%, the flash point of the modifier is above 230℃, the aliphatic hydrocarbon content in the modifier is not less than 60%, the softening point of the disintegrating agent is above 120℃, the aliphatic hydrocarbon content in the disintegrating agent is not less than 80%, the flash point of the stabilizer is not lower than 200℃, and the thermal decomposition temperature of the stabilizer is not lower than 300℃.

[0009] The present invention provides a process application method for modifying coal liquefaction pitch, comprising the above-mentioned modified coal liquefaction pitch, and further comprising the following preparation steps: S1. Raw material pretreatment: Large lumps of coal liquefaction pitch are initially crushed by a crusher to facilitate efficient melting in the future. Solid dispersants, stabilizers and some liquid modifiers are premixed in a premixing tank to form a slurry-like premix, which ensures high dispersion speed and high uniformity of these additives in the pitch matrix and prevents clumping caused by direct addition. S2. Melting and mixing: The crushed coal liquefaction pitch is put into a closed reactor equipped with a double-ribbon agitator and a jacketed heating system for initial stirring and heating in stages. First, the temperature is raised to 180±5℃ and held for 30 minutes to soften the coal liquefaction pitch. Then, the temperature is raised to 220±5℃ and accelerated stirring is carried out until the material is completely melted and there are no unmelted solid particles. S3. High-speed shear homogenization: After the asphalt is completely melted, the prepared modifier premix is ​​slowly and evenly added to the reactor through a metering pump, and the high-speed shear head in the reactor is started and sheared continuously for 40 minutes. S4. Chemical reaction development treatment: Stop high-speed shearing, switch back to spiral stirring, control the temperature of the reactor, and continue stirring to carry out swelling development for no less than 60 minutes. This process is a thermodynamic equilibrium process, which allows the initially dispersed modifier molecular chains to fully interact with the asphalt molecules to form a stable three-dimensional network structure, thereby improving the thermal storage stability and mechanical properties of the product. S5. Extrusion granulation: After development, the modified asphalt mixture is transported to the extrusion granulator through an insulated pipe. The extrusion granulator cuts the extruded strip material into uniform cylindrical granules by rotating blades. S6. Cooling and Packaging: The cut high-temperature granules immediately enter the double cyclone cooling system for cooling, so that the granules are cooled to below 60°C to prevent them from sticking together. After cooling, the granules are screened by a vibrating screen to remove debris and then enter the automatic packaging machine for packaging to obtain the final product.

[0010] According to the process application method for modifying coal liquefaction pitch provided by the present invention, in step S1, the particle size of the large coal liquefaction pitch after initial crushing does not exceed 50 mm, and the temperature of the premix tank is maintained at 80-90℃.

[0011] According to the process application method for modifying coal liquefaction pitch provided by the present invention, the initial stirring speed in step S2 is set to 20-30 rpm, and the speed for accelerating stirring is set to 40-50 rpm.

[0012] According to the process application method for modifying coal liquefaction pitch provided by the present invention, the temperature of the reactor in step S3 is maintained at 215-220℃, and the rotation speed of the high-speed shear head is set at 4000-5000 rpm.

[0013] According to the process application method for modifying coal liquefaction pitch provided by the present invention, the temperature of the reactor in step S4 is maintained at 218-222℃, and the speed of the ribbon stirrer is set at 60 rpm.

[0014] According to the process application method for modifying coal liquefaction pitch provided by the present invention, the temperature of the extrusion granulator in step S5 is maintained at 195-205℃.

[0015] Compared with existing technologies, the advantages of this invention are: 1: By optimizing the synergistic effect of modifiers, dispersants and stabilizers, the high and low temperature performance, adhesion and rheological properties of coal liquefaction pitch are significantly improved, making it easier to heat, melt, blend and apply.

[0016] 2: Through the extrusion granulation process, the original high softening point and difficult-to-process coal liquefaction pitch is transformed into uniform solid particles, which solves the problems of difficult liquid storage, easy segregation, and inconvenience in use.

[0017] 3: This technology not only realizes the high added value utilization of coal liquefaction pitch (each ton of product is more than 500 yuan more valuable than raw coal), but also achieves green and low-carbon production by reducing processing temperature (about 50°C), reducing energy consumption (20%) and VOCs emissions (60%).

[0018] In summary, this invention successfully prepared high-performance, regularly shaped modified coal liquefaction asphalt through systematic composite modification and granulation treatment. This significantly improves high and low temperature performance, adhesion, and workability, making it widely applicable in road asphalt and waterproofing materials. Simultaneously, the product's regular granular form greatly improves the convenience of storage, transportation, and use. This technology not only effectively realizes the high-value-added resource utilization of coal liquefaction asphalt but also demonstrates significant energy-saving, emission-reduction, and environmental benefits. The overall technology possesses comprehensive advantages of high performance, high added value, and green low-carbon characteristics, providing a practical new approach for the efficient, clean, and resource-based utilization of coal chemical solid waste. Attached Figure Description

[0019] Figure 1 This is a process flow diagram for preparing coal liquefaction modified bitumen proposed in this invention. Detailed Implementation

[0020] Reference Figure 1 A coal liquefaction modified bitumen, comprising, by weight percentage of the total composition: 70%-90% coal liquefaction bitumen, 10%-15% modifier, 3%-8% dispersant, and 2%-4% stabilizer; the metal ion content in the stabilizer is 5-10%; Coal liquefaction pitch is used as the base binder. The softening point of coal liquefaction pitch is 150-160℃, the content of toluene insoluble matter in coal liquefaction pitch is not higher than 15%, the flash point of the modifier is above 230℃, the content of aliphatic hydrocarbons in the modifier is not less than 60%, the softening point of the disintegrating agent is above 120℃, the content of aliphatic hydrocarbons in the disintegrating agent is not less than 80%, the flash point of the stabilizer is not less than 200℃, and the thermal decomposition temperature of the stabilizer is not less than 300℃. Specifically, coal liquefaction pitch, as a byproduct of the coal-to-oil process, has a complex composition, containing a large amount of aromatic hydrocarbons and resinous components. It has a high softening point, strong low-temperature brittleness, and poor compatibility with petroleum pitch. Direct use can easily lead to problems such as segregation and construction difficulties. Modifiers are characterized by high flash points and high aliphatic hydrocarbon content. Their molecular structure is rich in long-chain alkanes, which can swell and penetrate with the aromatic structures in pitch at high temperatures, thereby enhancing the flexibility and low-temperature crack resistance of the system. The polar groups in the modifier can form hydrogen bonds or van der Waals forces with the resinous components in pitch, thereby improving the compatibility and stability of the system. The dispersant has a high softening point and a high content of aliphatic hydrocarbons. During high-temperature melting, it can reduce the viscosity of the system, promote the uniform dispersion of each component, prevent agglomeration, and improve processing fluidity. During cooling and molding, the dispersant can promote particle shaping and separation, avoid adhesion, and ensure the regularity of particle morphology. The stabilizer has a high flash point and a high thermal decomposition temperature. The metal ions it contains can act as crosslinking points, forming ionic bonds or coordination bonds with the asphalt molecular chains to build a three-dimensional network structure, which significantly improves the thermal storage stability and mechanical strength of the product.

[0021] An embodiment of the present invention provides a process application method for modifying coal liquefaction pitch, comprising the following preparation steps: S1. Raw material pretreatment: Large lumps of coal liquefaction pitch are initially crushed by a crusher to facilitate efficient melting in the subsequent process. Solid dispersants, stabilizers, and some liquid modifiers are premixed in a premixing tank to form a slurry-like premix, which ensures high dispersion and uniformity of these additives in the pitch matrix and prevents clumping caused by direct addition. The particle size of the large lumps of coal liquefaction pitch after initial crushing does not exceed 50mm, and the temperature of the premixing tank is maintained at 80-90℃. S2. Melting and Mixing: The crushed coal liquefaction pitch is put into a closed reactor equipped with a double-ribbon agitator and a jacketed heating system for initial stirring and staged heating. First, the temperature is raised to 180±5℃ and held for 30 minutes to soften the coal liquefaction pitch. Then, the temperature is raised to 220±5℃ and accelerated stirring is carried out until the material is completely melted and there are no unmelted solid particles. The initial stirring speed is set at 20-30 rpm, and the accelerated stirring speed is set at 40-50 rpm. S3. High-speed shearing homogenization: After the asphalt is completely melted, the prepared modifier premix is ​​slowly and evenly added to the reactor through a metering pump, and the high-speed shear head in the reactor is started and sheared continuously for 40 minutes; the reactor temperature is maintained at 215-220℃, and the speed of the high-speed shear head is set at 4000-5000 rpm. S4. Chemical Reaction Development Treatment: Stop high-speed shearing, switch back to ribbon stirring, control the temperature of the reactor, and continue stirring for swelling development for no less than 60 minutes. This process is a thermodynamic equilibrium process, which allows the initially dispersed modifier molecular chains to fully interact with the asphalt molecules, forming a stable three-dimensional network structure, thereby improving the thermal storage stability and mechanical properties of the product. The reactor temperature is maintained at 218-222℃, and the ribbon stirring speed is set at 60 rpm. S5. Extrusion Granulation and Cooling Packaging: After development, the modified asphalt mixture is transported to the extrusion granulator through an insulated pipeline. The extrusion granulator cuts the extruded strip material into uniform cylindrical granules using rotating blades. The temperature of the extrusion granulator is maintained at 195-205℃. S6. Cooling and Packaging: The cut high-temperature granules immediately enter the double cyclone cooling system for cooling, so that the granules are cooled to below 60°C to prevent them from sticking together. After cooling, the granules are screened by a vibrating screen to remove debris and then enter the automatic packaging machine for packaging to obtain the final product.

[0022] Example 1 Raw material ratio (by mass percentage): 80% coal liquefaction pitch (softening point 155℃, toluene-insoluble matter 12%), 13% modifier (flash point 235℃, aliphatic hydrocarbon content 65%), 5% disintegrant (softening point 125℃, aliphatic hydrocarbon content 85%), 2% stabilizer (flash point 210℃, thermal decomposition temperature 320℃, metal ion content 8%); the metal ion content in the stabilizer is 7.5%; the preparation was carried out according to the above preparation steps, and the product performance was tested. Table 2 shows the performance test results of Example 1.

[0023] Table 2: Performance Testing

[0024] Example 2 Raw material ratio: 70% coal liquefaction pitch, 15% modifier, 8% disintegrating agent, 4% stabilizer; the metal ion content in the stabilizer is 7.5%; the process parameters are the same as in Example 1, and the performance test results show that the viscosity at 60℃ reaches 2600 Pa·s, the softening point is 122℃, and the segregation rate is ≤2%.

[0025] Example 3 Raw material ratio: 90% coal liquefaction pitch, 10% modifier, 3% disintegrating agent, 2% stabilizer; the metal ion content in the stabilizer is 7.5%; the process parameters are the same as in Example 1, and the performance test results show that the viscosity at 60℃ is 2200 Pa·s, the softening point is 115℃, and the segregation rate is ≤3%.

[0026] Example 4 The coal liquefaction modified asphalt of this invention was incorporated into road asphalt at a ratio of 20% to prepare composite modified asphalt. Test results showed that the dynamic stability of rutting was ≥8500 cycles / mm, the low-temperature bending strain was ≥3200με, and the adhesion was grade 5.

[0027] The coal liquefaction modified bitumen of this invention was used in the production of bitumen-based waterproof membranes, replacing part of the SBS modified bitumen. Test results showed that the heat resistance was improved to 130℃, the low-temperature flexibility reached -30℃ without cracking, and the production cost was reduced by approximately 18%. Tables 3 and 4 show the application test results of Example 4.

[0028] Table 3: Performance Comparison with Traditional Modified Asphalt

[0029] Table 4: Economic Analysis (Cost per Ton)

[0030] As can be seen from the above embodiments and application tests, the coal liquefaction modified bitumen and its preparation process provided by the present invention significantly improve the application performance and economic value of coal liquefaction bitumen, and have good prospects for industrial application.

[0031] In this invention, to achieve stable industrial production of coal liquefaction-modified asphalt, systematic and meticulous control of raw materials, processes, equipment, and product handling is essential. Ensuring the stability and compatibility of raw material quality and precisely controlling key process parameters such as temperature, shear strength, and reaction time at each stage is crucial to prevent insufficient modification or material degradation. Simultaneously, durable and wear-resistant specialized equipment and efficient, rapid cooling methods are necessary to guarantee the modification effect, particle morphology, and product stability. Finally, sealed packaging and proper storage ensure the high quality of the final product. By strictly adhering to the above precautions and flexibly adjusting applications, high-performance, high-value-added green asphalt products can be produced stably and efficiently.

[0032] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A coal liquefaction-modified bitumen, characterized in that, It comprises, by percentage of total mass of the composition: 70%-90% coal liquefaction pitch, 10%-15% modifier, 3%-8% disintegrating agent, and 2%-4% stabilizer.

2. The coal liquefaction-modified bitumen according to claim 1, characterized in that, The stabilizer contains 5–10% metal ions.

3. The coal liquefaction-modified bitumen according to claim 1, characterized in that, The coal liquefaction pitch is used as the base binder. The softening point of the coal liquefaction pitch is 150-160℃, the toluene insoluble content in the coal liquefaction pitch is not higher than 15%, the flash point of the modifier is above 230℃, the aliphatic hydrocarbon content in the modifier is not less than 60%, the softening point of the disintegrating agent is above 120℃, the aliphatic hydrocarbon content in the disintegrating agent is not less than 80%, the flash point of the stabilizer is not lower than 200℃, the thermal decomposition temperature of the stabilizer is not lower than 300℃, and the metal ion content in the stabilizer is 5-10%.

4. A process application method for modifying coal liquefaction pitch, characterized in that, The coal liquefaction modified bitumen according to any one of claims 1-3 further includes the following preparation steps: S1. Raw material pretreatment: Large lumps of coal liquefaction pitch are initially crushed by a crusher to facilitate efficient melting in the future. Solid dispersants, stabilizers and some liquid modifiers are premixed in a premixing tank to form a slurry-like premix, which ensures high dispersion speed and high uniformity of these additives in the pitch matrix and prevents clumping caused by direct addition. S2. Melting and mixing: The crushed coal liquefaction pitch is put into a closed reactor equipped with a double-ribbon agitator and a jacketed heating system for initial stirring and heating in stages. First, the temperature is raised to 180±5℃ and held for 30 minutes to soften the coal liquefaction pitch. Then, the temperature is raised to 220±5℃ and accelerated stirring is carried out until the material is completely melted and there are no unmelted solid particles. S3. High-speed shear homogenization: After the asphalt is completely melted, the prepared modifier premix is ​​slowly and evenly added to the reactor through a metering pump, and the high-speed shear head in the reactor is started and sheared continuously for 40 minutes. S4. Chemical reaction development treatment: Stop high-speed shearing, switch back to spiral stirring, control the temperature of the reactor, and continue stirring to carry out swelling development for no less than 60 minutes. This process is a thermodynamic equilibrium process, which allows the initially dispersed modifier molecular chains to fully interact with the asphalt molecules to form a stable three-dimensional network structure, thereby improving the thermal storage stability and mechanical properties of the product. S5. Extrusion granulation: After development, the modified asphalt mixture is transported to the extrusion granulator through an insulated pipe. The extrusion granulator cuts the extruded strip material into uniform cylindrical granules by rotating blades. S6. Cooling and Packaging: The cut high-temperature granules immediately enter the double cyclone cooling system for cooling, so that the granules are cooled to below 60°C to prevent them from sticking together. After cooling, the granules are screened by a vibrating screen to remove debris and then enter the automatic packaging machine for packaging to obtain the final product.

5. The process application method for modifying coal liquefaction pitch according to claim 4, characterized in that, In step S1, the particle size of the large coal liquefaction pitch after initial crushing does not exceed 50mm, and the temperature of the premix tank is maintained at 80-90℃.

6. The process application method for modifying coal liquefaction pitch according to claim 4, characterized in that, In step S2, the initial stirring speed is set to 20-30 rpm, and the speed for accelerating stirring is set to 40-50 rpm.

7. The process application method for modifying coal liquefaction pitch according to claim 4, characterized in that, In step S3, the temperature of the reactor is maintained at 215-220℃, and the rotation speed of the high-speed shear head is set at 4000-5000 rpm.

8. The process application method for modifying coal liquefaction pitch according to claim 4, characterized in that, In step S4, the temperature of the reactor is maintained at 218-222℃, and the speed of the ribbon stirrer is set at 60 rpm.

9. The process application method for modifying coal liquefaction pitch according to claim 4, characterized in that, The temperature of the extruder in step S5 is maintained at 195-205℃.

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