Patent ID: 7226533

Claim:
A process to re-refine used petroleum oils, the process consisting of the following steps: a. separating water and asphalts from the used petroleum oils by extraction with an aliphatic solvent, said solvent extraction being carried out at temperatures below 45° C., wherein said step a. produces a water phase, an asphalt phase and an aliphatic solvent phase through liquid solvent extraction; b. eliminating the aliphatic solvent from the solvent extract containing extracted hydrocarbons; c. flash, continuous vaporisation at atmospheric pressure or near atmospheric pressure, of the solvent free extracted hydrocarbons to separate light fractions in the presence of small amounts of a basic compound or a reducing agent or a combination of both; and d. continuous distillation in a fractionating column of a bottom liquid obtained in c., after separating the light fractions, at vacuum and moderate temperutures; in the presence of a basic compound or a reducing agent or a combination of both, with recirculation from a bottom of the column to a feed of the column; separating, as lateral extractions, vacuum gas-oil or spindle oil and lubricant bases and fuel-oil or asphaltic component as the bottom of the column.