Production method of asphalt
- Distillation method: It is to distill crude oil at atmospheric pressure to separate light fractions such as gasoline , kerosene , diesel oil , etc., and then separate vacuum fractions (residual pressure 10~100 mmHg) through vacuum distillation, and the remaining residues meet road asphalt specifications. Asphalt products can be directly produced at the same time, and the obtained asphalt is also called straight-run asphalt, which is the main method for producing road asphalt.
- Solvent precipitation method: non-polar low-molecular-weight alkane solvents have different solubility for each component in the vacuum residue, and the difference in solubility can be used to separate the components, so as to remove the unfavorable asphalt properties in the vacuum residue. components to produce a bitumen product that meets specifications, the solvent precipitation method.
- Oxidation method: The vacuum residue or deoiled asphalt is blown into the air, and the air is blown into the air within a certain temperature range to change its composition and performance. The resulting product is called oxidized asphalt. The vacuum residue is vaporized and evaporated under the action of high temperature and air blowing, and a series of reactions such as dehydrogenation, oxidation, polymerization and condensation occur at the same time. It is not just an oxidation reaction, but a very complex reaction process in which a variety of components interact. What we usually call oxidized asphalt is also called oxidized asphalt, also called air blowing method and air blowing asphalt.
- Blending method: The asphalt produced by blending method initially refers to the product obtained by readjusting the 4 components made of the same crude oil according to the ratio required by the quality requirements, that is, synthetic asphalt or reconstituted asphalt. With the development of process technology, the sources of mixed ingredients are constantly expanding. For example, the residues or components of the same crude oil or different crude oils, as well as various industrial waste oils, can be used as blending components in the production of asphalt, which can reduce the dependence on oil sources in the production of asphalt. Due to the increasing shortage of crude oil suitable for the production of bitumen, the flexibility and economy of its blending are more and more important and widely used.
- Emulsification method: The surface tension of asphalt and water is very different, and they are not miscible at room temperature or high temperature. When the asphalt undergoes mechanical action such as high-speed centrifugation, shearing, and impact, the particle size is 0.1~5 microns, and it is dispersed into the aqueous medium containing surfactant (emulsifier-stabilizer). The surface of the particles reduces the interfacial tension between water and asphalt, so that the asphalt particles can form a stable dispersion system in water, that is, an oil-in-water emulsion. The dispersion system is dark brown, the asphalt is the dispersed phase, and the water is the continuous phase, and the fluidity is good at room temperature. Emulsified bitumen is, in a sense, “thinning” the bitumen with water, thereby improving the fluidity of the bitumen.