Abstract: A process for recovering a base oil of lubricating viscosity from used oil in which, following optional pretreatment, used oil is re-refined by distilling it in distillation apparatus having multiple theoretical plates. Impurities are then extracted from the lube range distillate fraction or fractions with a liquid extractant such as N-Methyl-2-Pyrrolidone (NMP) at a temperature below the temperature, if any, of complete miscibility of the extractant and the oil. The oil and extractant are then separated whereupon the extractant is re-used in the process and the oil is subject to further treatment, as necessary, for targeted uses.
Type:
Grant
Filed:
September 8, 1997
Date of Patent:
September 12, 2000
Assignee:
Probex Corporation
Inventors:
Alexander D. B. Daspit, Martin MacDonald, Thomas G. Murray