US PATENT SUBCLASS 208 / 314
.~.~ Plural stages with different oil miscible solvents

Current as of: June, 1999
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208 /   HD   MINERAL OILS: PROCESSES AND PRODUCTS

308  DF  FRACTIONATION {5}
311  DF  .~ Liquid extraction with solvents {11}
314.~.~ Plural stages with different oil miscible solvents {2}
315  DF  .~.~.~> With recycle of product of later extraction to earlier extraction stage
316  DF  .~.~.~> Difference is mere change in proportions of solvents

DEFINITION

Classification: 208/314

(under subclass 311) Processes in which a mineral oil is subjected to a plurality of successive extractions, each involving the use of a different oil-miscible solvent, there being a separation of the extract phase from the oil between at least two of the extraction steps.

SEE OR SEARCH THIS CLASS, SUBCLASS:

321, for mineral oil extraction processes including solvent recovery or rehabilitation in which a second solvent miscible with the extraction solvent is employed to effect a separation of the extracted oil therefrom.

323+, for processes in which a mixture of solvent components is employed in a single extraction zone or where a solvent modifier is subsequently added to the extraction zone prior to any phase separation.