| 摘要 |
A method for processing a used oil which comprises about 70 percent by weight spindle and neutral oils, about 5 percent by weight lower and higher boiling point oils, about 10 percent by weight useful additives and oxidation products, about 10 percent by weight water, about 5 percent by weight difficultly volatile and nonvolatile hydrocarbons, and solid impurities, comprising: (a) dewatering the used oil; (b) contacting the dewatered used oil with a gas in a supercritical state, at a temperature above the critical temperature and at a pressure from its critical pressure up to about 350 bar to form (1) a gaseous extraction phase containing the spindle and neutral oils and the additives, the spindle and neutral oils and substantially all the additives being extracted into the gaseous extraction phase during the contact with the supercritical gas and (2) an extraction residue; (c) separating the gaseous extraction phase from the extraction residue; and (d) separating the extracted spindle and neutral oils and the extracted additives from the gaseous extraction phase obtained in step (c) by changing the thermodynamic state of the gaseous extraction phase.
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