Treatment of middlings stream from hot water process for recovering bitumen from tar sand

Claim 1

IN A CONTINUOUS PROCESS FOR RECOVERING BITUMEN FROM TAR SAND COMPRISING COMBINING THE TAR SAND WITH AIR AND HOT WATER IN A TUMBLER TO DISINTERGRATE THE TAR SAND AND PRODUCE A HOT SLURRY, DILUTING THE SLURRY WITH WATER, INTRODUCING THE DILUTE SLURRY INTO A SEPARATION CELL WHEREIN COARSE SOLIDS SETTLE OUT TO FORM A TAILINGS PRODUCT, AERATED BITUMEN RISES TO THE SURFACE OF THE CELL CONTENTS AND FORMS A FROTH PRODUCT, AND A MIDDLINGS STREAM IS WITHDRAWN FROM THE CELL, SAID STREAM COMPRISING BITUMEN, FINE SOLIDS AND WATER, THE IMPROVEMENT WHICH COMPRISES: DILUTING THE MIDDLINGS STREAM WITH HOT WATER; AND INTRODUCING THE DILUTED MIDDLINGS STREAM INTO A SETTLER VESSEL AND HOLDING IT THEREIN FOR A SUFFICIENT PERIOD OF TIME TO ALLOW THE MAJOR PORTION OF THE BITUMEN IN THE STREAM TO RISE TO THE SURFACE OF THE VESSEL CONTENTS AND FORM A FROTH PRODUCT; WITHDRAWING THE FROTH PRODUCT; AND WITHDRAWING A TAILINGS STREAM FROM THE BASE OF THE VESSEL, SAID TAILINGS STREAM COMPRISING THE MAJOR PORTION OF THE FINE SOLIDS AND WATER INTRODUCED INTO THE VESSEL.