Calcining method for alumina

Claim 1

IN A PROCESS FOR PRODUCING A LOW-DENSITY, HIGH-POROSITY, HIGH-SURFACE AREA PRODUCT ALUMINA FROM AN AQUEOUS ALUMINA SLURRY CONTAINING UP TO ABOUT 32 WEIGHT PERCENT AL2O3 AND PRODUCED BY: A. HYDROLYZING ALUMINUM ALKOXIDES WITH AN EFFECTIVE AMOUNT OF WATER TO FORM AN ORGANIC REACTION PRODUCT AND AN AQUEOUS ALUMINA SLURRY, AND, B. THEREAFTER SEPARATING THE AQUEOUS ALUMINA SLURRY FROM THE ORGANIC REACTION PRODUCT, WHEREIN SAID AQUEOUS ALUMINA SLURRY IS CONTACTED WITH AN ORGANIC SOLVENT SELECTED FROM THE GROUP CONSISTING OF ETHANOL, PROPANOL, ISOPROPANOL, BUTANOL, ISOBUTANOL AND TERTIARY BUTANOL IN AN AMOUNT SUFFICIENT TO PRODUCE A PRODUCT ALUMINA HAVING A LOOSE BULK DENSITY FROM ABOUT 7.5 TO ABOUT 25 LB/FT3, A SURFACE AREA FROM ABOUT 275 TO ABOUT 400 M2/G AND A PORE VOLUME FROM ABOUT 1 TO ABOUT 2.75 CC/G, TO FORM A SOLVENTAQUEOUS ALUMINA MIXTURE, SAID MIXTURE IS DRIED AND SAID DRIED ALUMINA IS CALCINED AND SAID PRODUCT ALUMINA IS RECOVERED, THE IMPROVEMENT COMPRISING CALCINING SAID DRIED ALUMINA AT A TEMPERATURE IN EXCESS OF 350*F IN AN ATMOSPHERE CONTAINING FROM ABOUT 1.0 TO ABOUT 20.0 VOLUME PERCENT CARBON DIOXIDE IN MIXTURE WITH GASES SELECTED FROM THE GROUP CONSISTING OF AIR, NITROGEN, ARGON, HELIUM, HYDROGEN, CARBON MONOXIDE, SUPERHEATED STEAM, AND MIXTURES OF SUPERHEATED STEAM AND HYDROCARBON COMPOUNDS CONTAINING UP TO ABOUT 30 CARBON ATOMS AND MIXTURES THEREOF AND RECOVERING SAID PRODUCT ALUMINA, SAID PRODUCT ALUMINA BEING SUBSTANTIALLY WHITE AND EXTRUDABLE.