Patent ID: 6072065
Filing Date: 2000-06-06
Classification: C10M

Abstract:
A process for refining used oils containing various contaminants comprising the following sequence of steps consisting of:(a) fractionally distilling used oils and recovering a major fraction of the distillate, said distilling being first performed under atmospheric pressure at a temperature between about 130.degree. C. and 180.degree. C. and then under reduced pressure of about 650 to 12,000 Pa and at a temperature between about 240.degree. C. and 345.degree. C.,(b) contacting the major fraction of the distillate with an alkaline reactant selected from the group consisting of sodium hydroxide and potassium hydroxide in the presence of a solvent selected from water, monoalcohols, polyalcohols and a mixture thereof, the proportion of sodium hydroxide or potassium hydroxide used being in weight percent to the weight percent of the major fraction of the distillate equal to F.times.(TAN+SN), F being a multiplying factor between 2 and 50, TAN and SN being respectively the Total Acid Number and Saponification Number of the distillate, said contacting being carried out at a temperature between 80.degree. C. and 330.degree. C. for a time between 2 and 200 minutes,(c) washing the product of step (b) with 1 to 15% water, followed by settling to recover an oil phase, and(d) fractionally distilling said oil phase under vacuum of about 650 to 1,350 Pa and at a temperature between 210.degree. C. and 375.degree. C., in order to recover the refined oil fraction.