Atmospheric Residual is everything that cannot be vaporized under normal pressures . Atmospheric residual is fed into another distillation column, operating at lower pressures, which can separate out some of the lighter compounds. Lubricants and waxes reside in this fraction. Vacuum Residual is the bottom of the barrel . It includes asphalt and some coke .
Pitch is a thick, black, sticky material.
It is left behind when the lighter components of coal tar or petroleum are distilled off. Asphalt is a high boiling component of crude oil . Tars are byproducts formed when coke is made from coal or charcoal is made from wood. It is a thick, complex, oily black mixture of heavy organic compounds very similar to pitch or asphalt, though from a different source.