Preparation method of binder asphalt for oil-based prebaked anode

Abstract

The invention relates to a preparation method of binder asphalt for an oil-based prebaked anode, which comprises the following steps: adding an oil-based raw material with a set mass into a reaction kettle, closing an exhaust valve of the reaction kettle, and starting a heating program for heating under a non-stirring condition; adding a nucleating aid into the reaction kettle according to a set proportion, and starting stirring; the reaction kettle is heated and subjected to heat preservation according to the set heating rate, and after the reaction is finished, the temperature is naturally reduced to 320-400 DEG C, and pressure is slowly released to normal pressure; starting nitrogen purging until the temperature is 300-380 DEG C, and continuously cooling to room temperature to obtain the petroleum binder asphalt. The high-coking-value, low-viscosity and low-ash-content oil-based binder asphalt is prepared by taking the by-product in the oil refining industry as the raw material through thermal modification, so that the problems that the oil-based binder is low in coking value and easy to layer are solved, the application problem of micro coke powder is also solved, the adverse effects of cancerogens in a coal-based binder on the environment and human health are avoided, and the method is suitable for industrial production. And the application range of by-products in the oil refining industry is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation and application of binder asphalt for oil-based prebaked anodes, and specifically relates to a method for preparing binder asphalt for oil-based prebaked anodes. Background Art

[0002] Prebaked anodes are made of petroleum coke and asphalt coke as aggregates and coal tar as binder. They are used as anode materials in prebaked aluminum electrolytic cells and are an important component in aluminum electrolysis. The quality of their performance is directly related to key technical and economic indicators such as current efficiency, carbon consumption, and energy consumption in the aluminum electrolysis process, as well as whether the electrolytic cell can operate efficiently and stably. Therefore, the performance, proportion, molding process, and roasting process of the raw materials used in the preparation of prebaked anodes must be strictly controlled to ensure the reliable working performance of the prebaked anodes. Among them, the binder asphalt can bond the petroleum coke powder into shape and form a carbon bonding bridge in the carbonization stage to combine with the aggregate particles into a whole, so that the anode has a certain mechanical strength and geometric shape. In addition, the binder asphalt has a complex composition, which not only has an important influence on the viscosity and softening point of the binder, but also seriously restricts and affects the powder mixing, molding process, and the performance of the obtained prebaked anode. In summary, binder asphalt is a key raw material that affects the molding and performance of prebaked anodes.

[0003] At present, coal-based asphalt binder is the preferred binder for prebaked anodes. This is because coal-based asphalt is the residue after coal tar distillation. The main components of the residue are polycyclic aromatic hydrocarbons, and the content of aliphatic compounds, sulfur and ash is low. Coal-based asphalt melted into liquid at an appropriate temperature has good bonding properties. The content of high molecular weight aromatic hydrocarbons in coal-based asphalt is relatively high, so the coking value after carbonization is relatively high. The asphalt coke formed after the carbonization of coal-based asphalt binder not only consolidates the carbonaceous aggregates together, but also has high mechanical strength and electrical and thermal conductivity. However, coal-based asphalt binder is obtained by deep processing of coal tar to obtain medium-temperature asphalt, and then the medium-temperature asphalt is reformed by high-temperature heat. The whole process has high energy consumption, high cost and scarce coal tar sources, resulting in high prices for coal-based binder asphalt. In addition, coal-based asphalt contains toxic and harmful substances such as anthracene, phenol and benzopyrene, which seriously affect the ecological environment and human health. Therefore, it is urgent to develop low-cost, simple process and environmentally friendly binder asphalt. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an oil-based binder asphalt for prebaked anodes. By means of process methods and process parameter control, by-products of the oil refining industry (satisfying the conditions: saturated content ≯17%, asphaltene ≯20%, ash content ≯1000ppm, H / C molar ratio 0.65-1.05) are used as raw materials, and a nucleating agent homogenization reaction is performed to prepare an oil-based binder asphalt with uniform structure, high coking value and low viscosity, thereby achieving low-cost preparation of high-quality binder asphalt to solve the problems existing in the above-mentioned background technology.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions:

[0006] A method for preparing a binder asphalt for oil-based prebaked anodes, comprising the following specific steps:

[0007] S1. Add the set mass of oil-based raw materials into the reactor, close the exhaust valve of the reactor, and start the heating program to heat to 150-200°C without stirring;

[0008] S2, adding the nucleating agent into the reactor according to the set ratio, and starting stirring;

[0009] S3, heating the reactor to 350-450°C at a set heating rate and keeping it warm for 1-7h, the reaction pressure is 0.5-4MPa, and after the reaction is completed, the temperature is naturally lowered to 320-400°C and the pressure is slowly released to normal pressure;

[0010] S4. After the reactor is depressurized to normal pressure, nitrogen purging is started. When the temperature drops to 300-380°C, nitrogen purging is stopped. The temperature is continued to drop to room temperature to obtain petroleum-based binder asphalt.

[0011] Furthermore, the oil-based raw material is a by-product of the oil refining industry and meets the following conditions: saturated content ≯17%, asphaltenes ≯5%, ash content ≯1000ppm, and H / C molar ratio 0.90-1.05.

[0012] Furthermore, in step S1, the heating rate of the temperature raising program is 5°C / min.

[0013] Furthermore, the nucleation aid in step S2 is one or more of nanoscale carbon black, raw coke powder or organic sulfide.

[0014] Furthermore, the dosage of the nucleating agent is 0.1wt%-3wt%.

[0015] Furthermore, the stirring rate in step S2 is 200 r / min.

[0016] Furthermore, the set heating rate in step S3 is 2-5° C. / min.

[0017] Furthermore, the nitrogen flow rate of the nitrogen purge in step S4 is 3-9 L / min.

[0018] Furthermore, the softening point of the binder asphalt for the oil-based prebaked anode is 101-112°C, the coking value is >55%, the viscosity at 140°C is 6-18 Pa•s, and the viscosity at 160°C is 1.2-6 Pa•s.

[0019] The beneficial effects of the present invention are:

[0020] 1. In the present invention, a high-quality oil-based prebaked anode binder is prepared with abundant and low-cost oil-based raw materials, realizing low-cost preparation of binder asphalt. The binder contains less toxic and harmful substances such as anthracene, phenol and benzopyrene than coal-based materials, and is friendly to the environment and humans.

[0021] 2. In the present invention, a nucleating aid is introduced into the oil-based raw material, and an oil-based binder asphalt with uniform structure, high coking value and low viscosity is prepared through thermal modification, which solves the problem that the molecular weight distribution of the oil-based raw material is wide and the asphaltene with higher molecular weight has higher reaction activity, which leads to aggravated differences in the molecular weight distribution of the asphalt and thus stratification. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Polarized photos of the binder samples prepared before and after adding carbon black to by-products from the refining industry. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below through examples. The following examples are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, but cannot be construed as limiting the technical solution of the present invention.

[0024] Example 1

[0025] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0026] S1. Take a certain mass of by-product 1 from the oil refining industry (saturated content 12.5%, asphaltene 4%, ash content ≤1000ppm, H / C molar ratio 0.95) and add it into the reactor, close the exhaust valve, and start the heating program to heat up to 150-200℃ at 5℃ / min;

[0027] S2, add 0.2wt%-0.5wt% of nucleating aid carbon black according to the mass of by-product 1 of the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0028] S3, heating the reactor to the reaction temperature (400-440 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 hours. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 380-400 ℃ and the pressure is slowly released to normal pressure.

[0029] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 360-380°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0030] The binder asphalt prepared in this embodiment has a softening point of 101-105°C, a coking value of more than 55%, a viscosity of 8-12 Pa·s at 140°C, and a viscosity of 1.2-3 Pa·s at 160°C.

[0031] Example 2

[0032] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0033] S1. Take a certain mass of by-product 1 from the oil refining industry (saturated content 12.5%, asphaltene 4%, ash content ≤1000ppm, H / C molar ratio 0.95) and add it into the reactor, close the exhaust valve, and start the heating program to heat up to 150-200℃ at 5℃ / min;

[0034] S2, add 0.5wt%-1wt% of nucleating aid carbon black according to the mass of by-product 1 of the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0035] S3, heating the reactor to the reaction temperature (400-440 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 hours. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 380-400 ℃ and the pressure is slowly released to normal pressure.

[0036] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 340-360°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0037] The binder asphalt prepared in this embodiment has a softening point of 105-108°C, a coking value of more than 56%, a viscosity of 12-15 Pa·s at 140°C, and a viscosity of 3-5 Pa·s at 160°C.

[0038] Example 3

[0039] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0040] S1. Take a certain mass of by-product 1 from the oil refining industry (saturated content 12.5%, asphaltene 4%, ash content ≤1000ppm, H / C molar ratio 0.95) and add it into the reactor, close the exhaust valve, and start the heating program to heat up to 150-200℃ at 5℃ / min;

[0041] S2, add 0.5wt%-1wt% of nucleating aid carbon black according to the mass of by-product 1 of the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0042] S3, heating the reactor to the reaction temperature (400-440 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 hours. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 330-400 ℃ and the pressure is slowly released to normal pressure.

[0043] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 330-350°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0044] The binder asphalt prepared in this embodiment has a softening point of 108-112° C., a coking value greater than 57%, a viscosity of 15-18 Pa·s at 140° C., and a viscosity of 5-6 Pa·s at 160° C.

[0045] Example 4

[0046] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0047] S1. Take a certain mass of by-product 1 from the oil refining industry (saturated content 12.5%, asphaltene 4%, ash content ≤1000ppm, H / C molar ratio 0.95) and add it into the reactor, close the exhaust valve, and start the heating program to heat up to 150-200℃ at 5℃ / min;

[0048] S2, add 2wt%-3wt% of the nucleating aid coke powder according to the mass of the by-product 1 of the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0049] S3, heating the reactor to the reaction temperature (400-440 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 hours. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 330-400 ℃ and the pressure is slowly released to normal pressure.

[0050] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 360-380°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0051] The binder asphalt prepared in this embodiment has a softening point of 105-110°C, a coking value greater than 57%, a viscosity of 8-13 Pa·s at 140°C, and a viscosity of 1.2-4 Pa·s at 160°C.

[0052] Example 5

[0053] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0054] S1, take a certain mass of oil refining by-product 2 (saturated content 9.5%, asphaltene 6.8%, ash content ≤1000ppm, H / C molar ratio 0.87) and add it into the reactor, close the exhaust valve, start the heating program and heat it to 150-200℃ at 5℃ / min;

[0055] S2, add 1wt%-2wt% of nucleating aid carbon black according to the mass of by-product 2 of the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0056] S3, heating the reactor to the reaction temperature (370-400 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 h. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 330-400 ℃ and the pressure is slowly released to normal pressure.

[0057] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 360-380°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0058] The binder asphalt prepared in this embodiment has a softening point of 105-110°C, a coking value greater than 57%, a viscosity of 11-15 Pa·s at 140°C, and a viscosity of 4-6 Pa·s at 160°C.

[0059] Example 6

[0060] A method for preparing a binder asphalt for oil-based prebaked anodes, characterized by comprising the following steps:

[0061] S1. Take a certain mass of oil refining by-product 3 (saturated content 2.3%, asphaltene 18%, ash content ≤1000ppm, H / C molar ratio 0.7) and add it into the reactor, close the exhaust valve, and start the heating program to heat up to 150-200℃ at 5℃ / min;

[0062] S2, add 0.5wt%-1wt% of nucleating aid mercaptan according to the mass of by-product 3 in the oil refining industry into the reactor, start stirring, and the stirring rate is 200 r / min;

[0063] S3, heating the reactor to the reaction temperature (400-440 ℃) at a heating rate of 2-5 ℃ / min, and keeping the temperature for 1-7 hours. The reaction pressure is 0.5-4MPa. After the reaction is completed, the temperature is naturally lowered to 330-400 ℃ and the pressure is slowly released to normal pressure.

[0064] S4. After the reactor is depressurized to normal pressure, start nitrogen purging with a nitrogen flow rate of 3-9 L / min. Stop nitrogen purging when the temperature drops to 340-360°C, and continue to cool to room temperature to obtain petroleum-based binder asphalt.

[0065] The binder asphalt prepared in this embodiment has a softening point of 102-108°C, a coking value greater than 57%, a viscosity of 6-10 Pa·s at 140°C, and a viscosity of 1.2-3 Pa·s at 160°C.

[0066] Compared with the prior art, this specific implementation has the following positive effects:

[0067] (1) In the present invention, a high-quality oil-based prebaked anode binder is prepared from abundant and low-cost oil-based raw materials, thereby realizing the low-cost preparation of binder asphalt. The binder contains less toxic and harmful substances such as anthracene, phenol and benzopyrene than coal-based ones, and is friendly to the environment and humans. Table 1 is a comprehensive comparison of 15 data items of polycyclic aromatic hydrocarbons in coal-based and oil-based binder asphalts. It can be seen from the table that the total content of 15 polycyclic aromatic hydrocarbons in coal-based modified asphalt is 62244.3 ppm. In comparison, the total content of 15 polycyclic aromatic hydrocarbons in oil-based binder asphalt is only 2004.6 ppm, and the content of toxic and harmful substances is reduced by more than 30 times, indicating that oil-based binders are more environmentally friendly and safe.

[0068] Table 1 Comparison of the total content of 15 PAHs in coal-based and oil-based binder asphalt

[0069]

[0070] (2) In the present invention, a nucleating agent is introduced into the oil-based raw material, and an oil-based binder asphalt with uniform structure, high coking value and low viscosity is prepared by thermal polymerization, thereby solving the problem that the molecular weight distribution of the oil-based raw material is widely distributed and the asphaltene with higher molecular weight has higher reactivity, which leads to aggravated differences in the molecular weight distribution of the asphalt and thus stratification. Figure 1 These are polarized photos of binder samples made from byproducts of the refining industry before and after adding carbon black. Figure 1 As can be seen from (a, b), before the addition of nucleating agent, there is obvious stratification between the upper and lower layers of the binder asphalt, and there is obvious growth and coagulation of mesophase spheres in the lower part. In contrast, after the addition of nucleating agent carbon black, the mesophase spheres formed in the binder asphalt are smaller in size and evenly distributed in the binder asphalt, and there is no obvious stratification between the upper and lower layers ( Figure 1 (c, d)), indicating that the molecular weight distribution of the binder asphalt is more uniform.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a binder asphalt for oil-based prebaked anodes, characterized in that: The specific steps are: S1. Add the set mass of oil-based raw materials into the reactor, close the exhaust valve of the reactor, and start the heating program to heat to 150-200°C without stirring; S2, adding the nucleating agent into the reactor according to the set ratio, and starting stirring; S3, heating the reactor to 350-450°C at a set heating rate and keeping it warm for 1-7h, the reaction pressure is 0.5-4MPa, and after the reaction is completed, the temperature is naturally lowered to 320-400°C and the pressure is slowly released to normal pressure; S4. After the reactor is depressurized to normal pressure, nitrogen purging is started. When the temperature drops to 300-380°C, nitrogen purging is stopped. The temperature is continued to drop to room temperature to obtain petroleum-based binder asphalt.

2. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The oil-based raw material is a by-product of the oil refining industry and meets the following conditions: saturated content ≯17%, asphaltenes ≯20%, ash content ≯1000ppm, and H / C molar ratio 0.65-1.

05.

3. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: In step S1, the heating rate of the temperature raising program is 5°C / min.

4. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The nucleation aid in step S2 is one or more of nanoscale carbon black, raw coke powder or organic sulfide.

5. The method for preparing the binder pitch for oil-based prebaked anode according to claim 4, characterized in that: The dosage of the nucleating agent is 0.1wt%-3wt%.

6. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The stirring rate in step S2 is 200 r / min.

7. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The set heating rate in step S3 is 2-5°C / min.

8. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The nitrogen flow rate of nitrogen purging in step S4 is 3-9 L / min.

9. The method for preparing the binder pitch for oil-based prebaked anode according to claim 1, characterized in that: The softening point of the binder asphalt for oil-based prebaked anodes is 101-112°C, the coking value is >55%, the viscosity at 140°C is 6-18 Pa•s, and the viscosity at 160°C is 1.2-6 Pa•s.

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