Recovery of deashed oil and naphthenic acids from residuum stocks

Claim 1

METHOD OF PRODUCING DE-ASHED OIL AND PURIFIED NAPHTHENIC ACIDS FROM A RESIDUUM CHARGE OIL CONTAINING ALKALI METAL NAPHTHENATES WHICH COMPRISES INTIMATELY ADMIXING THE CHARGE OIL WITH AN AQUEOUS PROPYL ALCOHOL CONTAINING 20-40% BY WEIGHT OF THE ALCOHOL IN SUFFICIENT AMOUNT TO DISSOLVE AT LEAST MOST OF THE NAPHTHENATES AND WITH AT LEAST AN EQUAL VOLUME AMOUNT OF A HYDROCARBON SOLVENT COMPOSED ESSENTIALLY OF SATURATE HYDROCARBON WITHIN THE C5-C10 RANGE, SETTLING THE MIXTURE AT A TEMPERATURE ABOVE 80* F. TO SEPARATE AN ALCOHOL PHASE FROM AN OIL PHASE, VAPORIZING SOLVENT FROM THE OIL PHASE TO YIELD DE-ASHED OIL, COUNTERCURRENTLY TREATING THE ALCOHOL PHASE WITH HYDROCARBON SOLVENT COMPOSED AS PREVIOUSLY SPECIFIED TO REMOVE RESIDUAL OIL, ACIDIFYING THE COUNTERCURRENTLY TREATED ALCOHOL PHASE, SETTLING THE ACIDIFIED MIXTURE TO SEPARATE A NAPHTHENIC ACID PHASE CONTAINING HYDROCARBON SOLVENT FROM AN AQUEOUS ALCOHOL PHASE CONTAINING SALT, VAPORIZING SOLVENT FROM SAID NAPHTHENIC ACID PHASE TO OBTAIN PURIFIED NAPHTHENIC ACIDS AND DISTILLING ALCOHOL FROM THE LAST-MENTIONED ALCOHOL PHASE TO RECOVER THE SAME AND YIELD SALT WATER AS BOTTOMS.