What is done with the asphalt flux?
The tower bottoms are blended with the de-asphalted bottoms producing an asphalt flux suitable for asphalt cement blending. The bottoms are actually the viscosity improvers and other solid additives that are contained in the used oil that come out in a solid form through the Interline process. This asphalt flux is not a binder by itself. It can be sold to asphalt plants with the benefits of it acting as a viscosity cut back agents, or as a modifier to improve penetration, elasticity, and aging of asphalt cement. It must be remembered, however, that the asphalt flux contains the contaminants removed from the waste oil stream, and therefore local regulatory specifications must be considered before adding it to finished asphalt mixes. Because the asphalt flux represents between 18-22% of the feed stream, its successful sale as a finished product is critical to the economics of the refinery. The asphalt flux cannot be viewed as a waste product from the plant with a disposal cost associated
