In the process of coal tar processing, the residue after distillation to remove the liquid fraction is called coal pitch. Coal pitch is the main component of coal tar, accounting for about 50% to 60% of the total. It is generally believed that its main components are polycyclic, dense ring aromatic hydrocarbons and their derivatives. The current methods are mainly differentiated according to the softening temperature displayed.
Generally at room temperature, coal bitumen is black brittle lump and shiny; Smelly, flammable when molten, and toxic. Coal asphalt has low temperature stability, good adhesion to mineral aggregates, poor climate stability (large changes in cold and heat), and contains more harmful components to human body, especially carcinogenic polycyclic aromatic hydrocarbons such as benzopyrene, which is one of the main sources of such pollutants in the environment [1].