Process of calcining alumina trihydrate in fluidized bed

Claim 1

THE CONTINUOUS PROCESS FOR CALCINING FINELY-DIVIDED ALUMINA HYDRATE SOLIDS, COMPRISING THE STEPS OF ESTABLISHING AND MAINTAAINING IN AN ENCLOSED CHAMBER SUPERPOSED BEDS OF FINELY-DIVIDED ALUMINA SOLIDS INCLUDING A PREHEATING BED, A CALCINING BED MAINTAINED AT TEMPERATURES SUFFICIENT TO CONVERT ALUMINA HYDRATE TO SUBSTANTIALLY NONHYGROSCOPIC ANHYDROUS ALUMINA, AND A SOLIDS COOLING BEDS SUBJACENT SAID CALCINING BED AND MAINTAINED A TEMPERATURES LOWER THAN THOSE REQUIRED TO VONVERT ALUMINAHYDRATE TO ITS NON-HYGROSCIPIC FORM IN THE CALCINING BED, PASSING A STREAM OF GAS UPWARDLY THROUGH ALL SAID BEDS SUCCESSIVELY AT VEOLCITIES SUFFICIENT BOTH TO FLUIDIZE THE BED SOLIDS AS TURBULENT SUSPENSION AND TO RETRAIN A PORTION OF SUCH SOLIDS, SUPPLYING FINELY-DIVIDED ALUMINA HYDRATE TO THE PREHEATING BED AND THERETHROUGH TO THE CALCINING BED, CALCINING A PORTION OF SUCH SOLIDS IN THE CALCINING BED TO YIELD SUBSTANTIALLY NON-HYGROSCOPIC ALUMINA WHILE ENTRAINING ANOTHER PORTION OF SUCH SOLIDS IN THE UPRISING GAS STREAM BEFORE THEIR FULL CONVERSINTO THE NON-HYGROSCOPIC FORM ACHIEVED, TRANSFERRING CALCINED SOLIDS FROM THE CALCINING BED TO THE SUBJACENT COOLING BED, DISCHARGING GAS FROM SAID CHAMBER ABOVE THE PREHEATING BED WITH ITS ENTRAINED SOLIDS ACCUMULATED BY ENTRAINMENT FROM THE SUCCESSIVELY LOWER BEDS INCLUDING UNCALCINED HYDROSCOPIC SOLIDS RETRAINED FROM THE PREHEATING BED, INTERCEPTING THE SOLIDS-LADEN GAS AND SEPARATING SOLIDS FROM IT, SUPPLYING SUCH SEPARATED SOLIDS DIRECTLT TO THE SOLID COOLING BED TO COMMINGLE THEREIN WITH THE NON-HYDROSCOPICCALCINED SOLIDS, THEREBY EFFECTING IN SAID COOLINGBED THE CONVERSION OF HYDROSCOPIC SOLIDD SEPRATED FROM THE GAS TO A NON-HYGROSCOPIC FORM, AND DISCHARGING NON-HYGROSCOPIC SOLIDS FROM SUCH COOLING BED.