245Refining Processes for Used Oil Recycling to Base Oils or Fuels
over the whole column of 80°C (176°F), and the column is a conventional extraction
column with a screen at the bottom and a packing above this screen. Undesirable com-
ponents such as the polycyclic aromatic hydrocarbons (PAH) pass into the solvent phase
to be removed in the bottoms product. The rafnate or overow from the liquid-liquid
extraction column is taken to a solvent recovery step to obtain solvent to be recycled in
the process, the product oils being used to formulate new lubricating oils. The extract
or bottoms stream from the extraction column also passes through a solvent recovery
process with the remaining extract being used as a heating fuel oil or fuel oil d ...