Solvent dew axing of petroleum oils

Claim 1

IN THE PRODUCTION OF SUBSTANTIALLY OIL-FREE WAX AND DEWAXED OIL FROM WAX-BEARING LUBRICATING OIL STOCK WITH A DEWAXING SOLVENT LIQUID WHICH EXERTS A SUBSTANTIALLY COMPLETE SOLVENT ACTION UPON OIL BUT SUBSTANTIALLY NO SOLVENT ACTION UPON WAX CONSTITUENTS OF THE MIXTURE AT SEPARATION TEMPERATURES OF 10* F. AND BELOW AND IN WHICH WATER IS AT LEAST PARTIALLY MISCIBLE, AND WHEREIN A MIXTURE OF SAID WAX-BEARING LUBRICATING OIL AND SOLVENT ARE CHILLED TO WAX SEPARATION TEMPERATURE AND SUBJECTED TO PRIMARY WAX SEPARATION TO PRODUCE DEWAXED OIL DISSOLVED IN SOLVENT AND ALSO PRIMARY WAX CONTAINING SOME SOLVENT AND A SMALL AMOUNT OF OIL, AND SAID PRIMARY WAX IS DILUTED BY ADMIXTURE WITH A FURTHER QUANTITY OF SOLVENT AND SUBJECTED TO A SECONDARY SEPARATION TO PRODUCE A SECONDARY FILTRACTE COMPRISING SOLVENT CONTAINING ADDITIONAL DEWAXED OIL AND A SECONDARY WAX OF LOW OIL CONTENT, THE IMPROVEMENT WHICH COMPRISES EFFECTING THE DILUTION OF SAID PRIMARY WAX WITH A WET SOLVENT, CARRYING OUT THE SECONDARY SEPARATION AT A TEMPERATURE SUCH THAT WATER CONTAINED IN SAID WET SOLVENT FREEZES TO FORM SOLID ICE CRYSTALS WHICH ARE SEPARATED WITH THE SECONDARY WAX THEREBY YIELDING A SECONDARY FILTRATE COMPRISING DRY SOLVENT, AND INTRODUCING SAID SECONDARY FILTRATE AS DEWAXING SOLVENT LIQUID WITH SAID WAX BEARING LUBRICATING OIL SUCH THAT SAID PRIMARY DEWAXING IS EFFECTED IN THE PRESENCE OF A DRY SOLVENT.