Shale retorting process

Claim 1

IN A PROCESS FOR RETORTING SHALE BY COUNTERCURRENTLY CONTACTING DOWNWARDLY MOVING SHALE PARTICLES WITH HOT GAS IN A RETORTING ZONE TO DECOMPOSE THE ORGANIC CONSTITUENTS OF THE SHALE FORMING SHALE OIL AND SHALE GAS, THE IMPROVED METHOD WHICH COMPRISES WITHDRAWING VAPORS COMPRISING NORMALLY LIQUID AND NORMALLY GASEOUS PRODUCTS FROM THE UPPER PORTION OF THE RETORTING ZONE, COOLING THE VAPORS TO CONDENSE SHALE OIL, WITHDRAWING A MINOR PROPORTION OF THE UNCONDENSED GAS AS A PRODUCT, REHEATING THE MAJOR PROPORTION OF THE UNCONDENSED GAS BY CONTACTING IT WITH HOT SPEND SHALE IN A REHEATING ZONE, WITHDRAWING REHEATED GAS FROM THE REHEATING ZONE AND PASSING IT INTO A COMBUSTION ZONE, INTRODUCING INTO THE COMBUSTION ZONE A QUANTITY OF A FREE OXYGEN-CONTAINING GAS HAVING AN OXYGEN CONTENT STOICHIOMETRICALLY SUFFICIENT TO CAUSE COMBUSTION OF ONLY A MINOR PROPORTION OF THE REHEATED GAS AND BURNING A MINOR PROPORTION OF THE REHEATED GAS SUFFICIENT TO RAISE THE TEMPERATURE OF THE MIXTURE OF COMBUSTION PRODUCTS AND UNBURNED GAS TO RETORTING TEMPERATURE IN THE COMBUSTION ZONE, AND PASSING THE MIXTURE OF COMBUSTION PRODUCTS AND UNBURNED GAS FROM THE COMBUSTION ZONE INTO THE RETORTING ZONE.